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<td><span style="font-family:Helvetica, sans-serif; font-size:20px;font-weight:bold;">PsyPost – Psychology News</span></td>
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<td><a href="https://www.psypost.org/major-iq-differences-in-identical-twins-linked-to-schooling-challenging-decades-of-research/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Major IQ differences in identical twins linked to schooling, challenging decades of research</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 11th 2025, 10:00</div>
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<p><p>A new analysis of studies spanning the last century finds that differences in schooling appear to explain a large portion of the IQ gap between identical twins who were raised in separate homes. The research suggests that when these twins receive similar educations, their IQ scores are nearly as alike as identical twins raised together, but when their schooling is very different, their IQs can be as dissimilar as those of unrelated strangers. The findings were published in the scientific journal <em><a href="https://doi.org/10.1016/j.actpsy.2025.105072" target="_blank">Acta Psychologica</a></em>.</p>
<p>The study was conducted by researchers Jared C. Horvath of the English Schools Foundation Center for Research and Katie Fabricant of the University of Wisconsin. They undertook this research to re-examine one of the most classic methods used to explore the “nature versus nurture” debate: the study of monozygotic, or identical, twins reared apart. Since these twins share nearly identical genetic material but grow up in different environments, they offer a unique window into the influences of genes and life experiences on human traits like intelligence.</p>
<p>For decades, research on this topic has generally concluded that genetics play a very strong role in determining intelligence as measured by IQ tests. Large studies have typically combined the data from many twin pairs and reported an average IQ difference of about 8 points and a high degree of similarity, measured by a statistic called an intraclass correlation. This high correlation has often been used to argue that intelligence is a largely stable, inborn trait.</p>
<p>The authors of the new paper identified a potential problem with this long-standing conclusion. The historical practice of averaging data from dozens of twin pairs, known as amalgamation, masks the specific life experiences of each individual. One of the most powerful environmental influences known to affect IQ scores is education. Extensive research has shown a causal link between the amount of schooling a person receives and their performance on IQ tests. By lumping all twin pairs together, past studies may have obscured the true impact of educational differences on their cognitive abilities.</p>
<p>To investigate this possibility, the researchers embarked on an exhaustive search of the academic literature published over the last century. They looked for every available study that contained individualized data on monozygotic twins who had been reared apart. To be included in their new analysis, a case had to provide not only the IQ score for each twin but also biographical information about their schooling. </p>
<p>After screening thousands of articles, they compiled a dataset of 87 twin pairs from 19 different studies and two personal communications with other researchers. The authors believe this collection represents the entirety of non-amalgamated data available in the field.</p>
<p>With this unique dataset, Horvath and Fabricant developed a system to quantify the educational differences between each pair of twins. They created an “Ed Diff” score based on three key dimensions of schooling known to impact academic achievement. These were differences in curriculum, such as attending a public versus a Catholic school; differences in pedagogy, such as being educated in different countries or states with distinct teaching frameworks; and differences in duration, meaning the total number of years each twin spent in school.</p>
<p>Based on these scores, the researchers divided the 87 pairs into three categories. The first group had “similar” educational experiences. The second had “somewhat dissimilar” schooling, and the third had “very dissimilar” educational backgrounds. They then analyzed the IQ differences and the intraclass correlation for each group, using the same measures that have been standard in the field for decades. The intraclass correlation is a statistic that measures how strongly individuals within the same group, in this case a twin pair, resemble each other.</p>
<p>First, the researchers analyzed the entire group of 87 pairs together, to see if their dataset was comparable to previous aggregated studies. They found an average absolute IQ difference of 8.6 points and an intraclass correlation of 0.80. These figures aligned closely with the historically reported averages, confirming their sample was representative of the field.</p>
<p>The results changed dramatically when they analyzed the groups based on educational similarity. For the 52 pairs with similar schooling, the average IQ difference was just 5.8 points, and the intraclass correlation was a very high 0.87. This finding makes them almost indistinguishable from monozygotic twins who are raised together in the same home, who typically differ by about 6.0 IQ points.</p>
<p>For the 25 pairs with “somewhat dissimilar” schooling, the average IQ difference grew to 12.1 points, with an intraclass correlation of 0.80. This level of difference is more comparable to that seen between non-twin siblings raised in the same family.</p>
<p>The most striking finding came from the 10 pairs with “very dissimilar” educational experiences. In this group, the average IQ difference was 15.1 points. This gap is approaching the average difference seen between two randomly selected, unrelated individuals, which is about 17 points. The intraclass correlation for this group dropped to 0.56, a value much closer to what is observed between non-twin siblings. The pattern was clear: as the differences in schooling between the identical twins increased, the differences in their IQ scores also increased substantially.</p>
<p>The authors note some limitations to their work. The group with “very dissimilar” education contained only 10 twin pairs. While this represents all such published individual data from the last century, it is a small sample size. It is possible that more twin pairs with significant educational differences exist, but their data has only been included in historical aggregate analyses and has not been made public. The researchers suggest that until this individualized data is shared, it will be impossible to know for certain the full extent of schooling’s impact.</p>
<p>This analysis brings into question the historic use of a single intraclass correlation figure to represent the genetic influence on IQ. The results show that this statistic is not a fixed number but can change significantly depending on environmental factors like education. The study’s authors propose that the field should shift away from large-scale aggregate studies, which are unlikely to yield new information. </p>
<p>Instead, they recommend a focus on in-depth case studies of individual twin pairs to better understand how specific life experiences shape psychological traits. They also issue a call for researchers who conducted past studies to share their de-identified, individualized data. This practice, they argue, is essential for ensuring that socially important theories about genetics and intelligence are as accurate and well-supported as possible.</p>
<p>The study, “<a href="https://doi.org/10.1016/j.actpsy.2025.105072" target="_blank">IQ differences of identical twins reared apart are significantly influenced by educational differences</a>,” was published in July 2025.</p></p>
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<td><a href="https://www.psypost.org/children-exposed-to-antidepressants-before-birth-do-not-face-lasting-mental-health-risks/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Children exposed to antidepressants before birth do not face lasting mental health risks</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 11th 2025, 08:00</div>
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<p><p>Children whose mothers took antidepressants during pregnancy are not more likely to develop long-term anxiety or depression due to the medication itself, suggests a new study published in the <em><a href="https://doi.org/10.1111/jcpp.70056" target="_blank">Journal of Child Psychology and Psychiatry</a></em>. The research examined over 140,000 children in British Columbia and tracked them from birth through adolescence. Although early data appeared to show higher levels of anxiety among children exposed to these medications in the womb, further analysis pointed to family-related factors such as genetics and maternal mental health as the more likely cause.</p>
<p>Depression and anxiety are common during pregnancy. Up to 30 percent of pregnant individuals screen positive for symptoms, and about 10 to 15 percent meet diagnostic criteria for an anxiety disorder. To treat these conditions, doctors often prescribe medications known as serotonin or norepinephrine reuptake inhibitors. These antidepressants cross the placenta and may influence brain development, particularly since serotonin plays an important role in how the fetal brain grows.</p>
<p>Concerns have lingered for years about whether these medications might affect a child’s emotional health later in life. Some earlier studies reported links between prenatal antidepressant exposure and conditions such as attention-deficit disorder or autism. But more recent work has raised the possibility that these associations might not reflect a direct effect of the drugs. Instead, they could be the result of maternal depression itself or other shared factors like genetics or a stressful family environment.</p>
<p>The new study aimed to clarify whether prenatal exposure to these medications was actually driving later anxiety or depression in children, or whether other explanations might better account for the patterns seen in earlier research.</p>
<p>“There’s been a long-standing debate about whether taking antidepressants during pregnancy affects children’s long-term emotional or behavioural health. Previous studies often found small associations but couldn’t fully separate the effects of the medication from the effects of maternal depression itself. We wanted to untangle those influences by comparing siblings born to the same mother (one exposed to medication during pregnancy and one not),” said study author Amanda Nitschke, a doctoral student at the University of British Columbia and BC Children’s Hospital Research Institute.</p>
<p>This study used data from British Columbia, where researchers had access to detailed health and educational records. The study followed more than 144,000 children born between 2001 and 2012, tracking their development through the end of 2022. Of these children, nearly 6,000 had been exposed to serotonin or norepinephrine reuptake inhibitors during pregnancy.</p>
<p>At around age five, all children in the study were assessed by their kindergarten teachers using a tool known as the Early Development Instrument. This measure captures a range of emotional, social, and academic skills. Among its components is a scale that reflects anxious and fearful behaviors. Later, the researchers used medical records to identify whether these children went on to receive clinical diagnoses of anxiety or depression during childhood or adolescence.</p>
<p>Initial results suggested that children exposed to antidepressants before birth were more likely to show signs of anxiety in kindergarten and more likely to be diagnosed with anxiety or depression as they grew older. But this association weakened after researchers accounted for factors such as maternal age, income, health history, and use of other medications. Even with these adjustments, a modest association remained: exposed children were still more likely to be diagnosed with anxiety or depression later in life.</p>
<p>However, the picture changed when the researchers looked at siblings. In families where one child had been exposed to antidepressants during pregnancy and another had not, both children had similar rates of anxious behavior and later diagnoses. In these sibling comparisons, there was no longer any significant link between prenatal antidepressant exposure and mental health outcomes.</p>
<p>“We were struck by how much the results changed once we compared siblings within the same family,” Nitschke told PsyPost. “It really highlights how powerful genetics and the family environment are in shaping a child’s emotional development. It also reinforced that population-level associations shouldn’t be interpreted as direct medication effects without considering those shared factors.”</p>
<p>Children who showed anxious behaviors at kindergarten age, regardless of whether they had been exposed to antidepressants, were more likely to receive a diagnosis of anxiety or depression later on. This pattern held true for both boys and girls, although girls were more likely overall to be diagnosed with these conditions.</p>
<p>“Overall, we found no evidence that antidepressant use in pregnancy directly harms children’s later emotional or behavioral development,” Nitschke said. “The differences we saw in the general population disappeared once we accounted for family background and genetics. This means the medication itself likely isn’t the driver, and that it’s more related to the underlying factors, such as genetics or ongoing parental mental health. That’s reassuring news for families making difficult treatment decisions during pregnancy.”</p>
<p>The results from this Canadian study align closely with findings from recent studies in other countries. A <a href="https://www.psypost.org/antidepressant-use-in-pregnancy-not-linked-to-child-mental-health-problems-after-accounting-for-maternal-depression/" target="_blank">large study based in the United States</a>, published in the <em>Journal of the American Academy of Child & Adolescent Psychiatry</em>, also found no long-term risk associated with antidepressant use during pregnancy after accounting for maternal depression. Similar conclusions have emerged <a href="https://capmh.biomedcentral.com/articles/10.1186/s13034-023-00624-9" target="_blank">from research in Denmark</a>, which showed that maternal antidepressant use after pregnancy and paternal use during pregnancy were also linked with child mental health outcomes. These patterns suggest that shared genetics and family dynamics may play a larger role than medication exposure in shaping children’s emotional development.</p>
<p>One particularly telling observation comes from the fact that in both the current study and others, children whose mothers discontinued antidepressant use before pregnancy still showed similar mental health outcomes compared to those whose mothers continued treatment during pregnancy. This again points to maternal mental health and possibly inherited vulnerability as more plausible explanations for any observed differences.</p>
<p>The new study adds to this growing body of evidence by extending the follow-up period into adolescence and using multiple strategies to control for confounding factors. The sibling analysis, in particular, strengthens the argument that observed risks are likely due to shared family influences rather than the medications themselves.</p>
<p>Although the findings provide reassurance for many families, they also raise important questions about how to best support children at risk for anxiety and depression. The study found that children who showed anxious behaviors in kindergarten were more likely to develop anxiety or depression later, whether or not they had been exposed to antidepressants. This suggests that early signs of emotional distress may be useful for identifying children who might benefit from extra support.</p>
<p>The research also points to the complexity of decisions around antidepressant use during pregnancy. Since untreated depression and anxiety in mothers can carry their own risks for both the parent and the child, treatment decisions must consider both the benefits and the potential concerns. The findings suggest that when medication is needed, the long-term risk to the child’s mental health may be lower than previously feared.</p>
<p>At the same time, the study had some limitations. It relied on prescription records to determine medication use, which means there is no certainty that all medications were taken as prescribed. Diagnoses of anxiety or depression were based on health system records, so children who did not receive formal medical evaluations may not have been captured. And while sibling comparisons help address some forms of confounding, they do not control for every possible difference between pregnancies, such as changes in family dynamics or life stress.</p>
<p>Still, the study’s large size, long follow-up period, and detailed methods provide strong evidence that prenatal exposure to serotonin or norepinephrine reuptake inhibitors does not independently raise the risk of long-term anxiety or depression in children. Instead, it supports the view that the underlying mental health conditions in parents, along with family-wide factors, are more likely to shape children’s emotional trajectories.</p>
<p>“Our next step is to look beyond clinical diagnoses and focus on children’s own perspectives,” Nitschke said. “We’re now studying how perinatal depression relates to children’s self-reported well-being, social-emotional health, and sense of connectedness from ages 9 to 13. This will help us understand how early parental mental health shapes children’s experiences as they progress through school.”</p>
<p>“Treating depression during pregnancy is important and deciding whether to take antidepressants is a deeply personal and often difficult choice. Our hope is that studies like this can help reduce stigma and empower people to make informed decisions with their healthcare providers.”</p>
<p>The study, “<a href="https://doi.org/10.1111/jcpp.70056" target="_blank">Association of prenatal antidepressant use with internalizing behaviors from kindergarten to adolescence</a>,” was authored by Amanda S. Nitschke, Paramdeep Kaur, Naomi Phagau, Helena Abreu do Valle, Jeffrey N. Bone, Brenda Poon, Martin Guhn, Simone N. Vigod, Tim F. Oberlander, and Gillian E. Hanley.</p></p>
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<td><a href="https://www.psypost.org/people-on-the-far-right-and-far-left-exhibit-strikingly-similar-brain-responses/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">People on the far-right and far-left exhibit strikingly similar brain responses</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 11th 2025, 06:00</div>
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<p><p>A new study suggests that people with strongly held political beliefs, whether liberal or conservative, tend to process political content in strikingly similar ways at a neurological level. The findings, published in the <em><a href="https://psycnet.apa.org/record/2026-54527-001?doi=1" target="_blank">Journal of Personality and Social Psychology: Attitudes and Social Cognition</a></em>, indicate that emotional reactions may play a central role in driving ideological extremity.</p>
<p>The researchers set out to better understand what might fuel increasingly polarized and extreme political attitudes in the United States. While disagreement and debate are foundational to democratic systems, the political landscape has become more divided in recent years, with a growing number of Americans identifying with viewpoints further from the political center.</p>
<p>Prior research has pointed to several contributors to this trend, including psychological tendencies like intolerance of uncertainty or a preference for black-and-white thinking. But many scholars have also proposed that emotion—especially negative emotion such as fear or anger—plays a powerful role. Emotional reactions can shape how people interpret news, view political opponents, and form alliances. In this study, the researchers asked whether people on the far left and far right not only hold strong beliefs but also experience political information in similarly emotional ways.</p>
<p>They also aimed to test a concept sometimes referred to as the “horseshoe theory,” which suggests that political extremes may resemble each other more than they do moderates. If true, then individuals on opposite ideological ends could be more psychologically alike than different, at least in how they respond to political content.</p>
<p>“This research was inspired by the growing political polarization and ideological extremism observed around us. Recent political crises such as the COVID-19 pandemic and the war between Israel and Gaza have intensified extreme views across both ends of the political spectrum, which motivated us to look beyond left-right differences,” said study author Daantje de Bruin, a PhD student at Brown University and member of <a href="https://www.feldmanhalllab.com/" target="_blank">the FeldmanHall lab</a>.</p>
<p>“Instead, we asked whether there might be common neurophysiological mechanisms underlying political extremism, regardless of ideological content. This idea aligns with the ‘horseshoe theory’ of politics, which suggests that the far left and far right, despite opposing beliefs, often resemble each other in psychological and behavioral ways.”</p>
<p>To explore these questions, the team recruited 44 participants from across the political spectrum, with a particular focus on those at the ideological extremes. Participants were identified based on how far they leaned from the political center on a 100-point scale, ranging from extremely liberal to extremely conservative.</p>
<p>The participants watched a politically charged segment of the 2016 vice-presidential debate between Tim Kaine and Mike Pence while undergoing brain scans in a magnetic resonance imaging (MRI) machine. At the same time, the researchers recorded physiological responses—specifically, galvanic skin conductance, which measures emotional arousal through changes in sweat gland activity. Eye-tracking was also used to assess where participants focused their attention.</p>
<p>Analysis of the brain imaging data revealed a consistent pattern: participants with stronger political beliefs, regardless of whether they were liberal or conservative, showed increased activity in brain areas associated with emotion and threat detection. These included the amygdala, known for processing fear; the periaqueductal gray, which is involved in defensive behaviors; and the posterior superior temporal sulcus, a region linked to interpreting social cues and understanding others’ intentions.</p>
<p>“Our findings were in line with our hypothesis that holding extreme views (regardless of the content of those views) means that individuals share, at least on some dimensions, similar processing of the world around them,” de Bruin told PsyPost. “This helps explain how the language or actions of die-hard liberals or conservatives can appear eerily similar to the language and actions of those on the other side.”</p>
<p>This finding suggests that extreme political views may be tied to stronger emotional reactions to political material. In other words, the more ideologically extreme a person was, the more emotionally charged their brain response appeared to be when watching political content.</p>
<p>The researchers also analyzed how similarly participants’ brains responded to the debate. By comparing moment-to-moment brain activity across pairs of participants, they found that those who both held extreme views—even if one was very liberal and the other very conservative—showed more synchronized brain responses than moderates did. This synchronization was especially pronounced in areas of the brain involved in understanding others’ perspectives and emotions, such as the temporoparietal junction and adjacent regions.</p>
<p>Importantly, this effect was not merely the result of shared ideology. Participants with very different political beliefs still showed similar patterns of brain activity if both were high in extremity. This provides evidence that the way people process political content may be shaped more by the intensity of their beliefs than by the direction of those beliefs.</p>
<p>Another layer of the study looked at the role of language. The researchers used a machine learning tool to evaluate the level of extreme language in the debate video. They found that parts of the video containing more extreme or provocative language tended to strengthen the brain synchrony effect among extreme individuals. In other words, the most emotionally intense parts of the political content seemed to draw extreme viewers into an even more aligned neurological state.</p>
<p>Finally, the researchers examined physiological arousal. While they did not find that more extreme individuals had higher average arousal levels overall, they did find that shared physiological responses between pairs—specifically synchronized spikes in skin conductance—correlated with greater neural synchrony. This relationship held especially true for participants with the most extreme beliefs. In other words, when extreme individuals not only shared strong views but also experienced similar emotional reactions in their bodies, their brains tended to process political content in more closely aligned ways.</p>
<p>“We find that people with more extreme political views, on either end of the political spectrum, show stronger brain responses to the political content in areas involved in emotions, such as fear, threat detection, and understanding the perspective of others,” de Bruin explained. “We also find that more extreme individuals, regardless of their political ideology, show more similar neural responses to political content.” </p>
<p>“Despite stark differences in political beliefs, extreme individuals on opposite sides of the political spectrum thus process political content in similar ways, providing neurophysiological support for the horseshoe theory of politics. This suggests that ideological opposites may be more alike in how they process politics than they realize. Recognizing this shared experience could foster greater empathy and reduce dehumanization across the political divide.”</p>
<p>The study provides evidence that emotion plays a central role in shaping how people with extreme beliefs experience political content, but it also comes with some limitations. First, the political material used covered only a narrow set of topics, specifically immigration and policing. It is not clear whether similar results would emerge with different political subjects or more recent content.</p>
<p>Second, the research was conducted entirely within the United States and may not generalize to other countries or political systems. Cultures with different norms, levels of polarization, or media environments might show different patterns of emotional and neurological responses.</p>
<p>Despite these limitations, the study provides new insight into how emotion and social perception influence political extremity. The fact that people with opposing ideologies can show similar patterns of brain activity suggests that emotional experience may be a shared thread connecting those on both sides of the political divide. Recognizing this shared experience might help reduce hostility and open the door to more understanding, even in a time of rising polarization.</p>
<p>“Our findings support the theorized link between extremism and affective processing, highlighting the importance of understanding polarization and radicalization as not just a cognitive or ideological process, but also one that considers emotion,” de Bruin said. “In future work, we aim to further investigate how affective processing might be altered in more extreme individuals, and why their responses may differ from moderates. Ultimately, we aim to use these insights to inform approaches that reduce polarization and help people engage with political information more thoughtfully.”</p>
<p>The study, “<a href="https://psycnet.apa.org/record/2026-54527-001?doi=1" target="_blank">Politically Extreme Individuals Exhibit Similar Neural Processing Despite Ideological Differences</a>,” was authored by Daantje de Bruin and Oriel FeldmanHall.</p></p>
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<td><a href="https://www.psypost.org/injection-of-reelin-protein-may-reverse-leaky-gut-caused-by-chronic-stress/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Injection of Reelin protein may reverse “leaky gut” caused by chronic stress</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 10th 2025, 16:00</div>
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<p><p>New research suggests that chronic stress disrupts the body’s natural mechanisms for repairing the intestinal lining by reducing levels of a specific regenerative protein. Scientists found that administering a single dose of this protein, called Reelin, reversed these damaging effects in rats, restoring protective cell populations and signs of normal cell turnover within the small intestine. The study was published in the journal <em><a href="https://doi.org/10.1177/24705470251381456" target="_blank">Chronic Stress</a></em>.</p>
<p>The lining of the gut serves as a critical biological barrier, selectively allowing nutrients into the bloodstream while preventing the entry of harmful bacteria, toxins, and large molecules. When this barrier is damaged, it can become overly permeable, a condition often referred to as “leaky gut,” which is frequently observed following exposure to prolonged psychological stress. When the intestinal barrier fails, inflammatory substances originating from the gut contents can enter circulation, potentially contributing to systemic inflammation and worsening symptoms of stress-related mental health conditions, such as major depressive disorder.</p>
<p>The gut barrier maintains its integrity through continuous and rapid regeneration. The entire lining of the intestine must be replaced every three to five days, ensuring that older, potentially damaged cells are promptly shed and replaced by healthy, functional cells. The large extracellular matrix protein, Reelin, is present in the gut lining and is thought to play a key role in promoting the migration of new intestinal epithelial cells up the villi to replace old ones, thereby regulating this turnover.</p>
<p>Prior research has established a link between chronic stress and reduced Reelin levels in the brain and blood plasma, often mirroring findings in individuals diagnosed with major depressive disorder. The researchers aimed to understand if this relationship extended to the gut, specifically investigating how chronic stress alters Reelin expression in the small intestine and whether a single dose of recombinant Reelin could restore intestinal health markers.</p>
<p>“This study aimed to understand the role of Reelin in the gut, especially under conditions of chronic stress,” said Hector Caruncho, professor of medical sciences at the University of Victoria and corresponding author on the study. He explained that “The gut-brain axis is becoming essential to understanding many psychiatric disorders, including depression.”</p>
<p>Ciara S. Halvorson, a neuroscience doctoral student at the University of Victoria and first author on the paper, emphasized the importance of the regenerative process being studied. “Under healthy conditions, the gut lining is renewed every four to five days,” Halvorson noted. “This is important as the cells in the gut lining are constantly exposed to damaging factors in the gut.”</p>
<p>To evaluate these questions, the researchers utilized male Long Evans rats, a common model for stress studies. The animals were divided into four experimental groups to test the effects of chronic stress and Reelin treatment. For three weeks (21 days), rats received daily subcutaneous injections of either a vehicle solution (the control) or a high dose of corticosterone, a glucocorticoid hormone used to simulate the powerful physical effects of chronic stress.</p>
<p>On the final day of the daily injections, the rats received a single intravenous injection administered via the lateral tail vein. Half of the corticosterone-treated rats received recombinant Reelin (three micrograms), and the other half received the vehicle solution. The control rats (which had received vehicle injections for 21 days) also received either Reelin or vehicle on the final day.</p>
<p>Four days following the single Reelin injection, the scientists harvested the small intestines from the animals. They then processed the tissue to analyze two primary markers associated with gut health: the density of cells producing Reelin, and the number of cells undergoing programmed cell death, known as apoptosis.</p>
<p>Reelin is primarily released from cells located in the lamina propria, the connective tissue layer situated directly beneath the epithelial cells that form the gut lining. By analyzing the density of Reelin-immunoreactive cells, the scientists could assess the local population of Reelin-producing cells in the intestine.</p>
<p>The findings showed that rats exposed to 21 days of corticosterone (the chronic stress group) experienced a significant decrease in the density of Reelin-immunoreactive cells in the lamina propria, showing a reduction of approximately 50 percent compared to the control animals. This indicated that chronic stress directly diminished the population of Reelin-producing cells in the gut environment.</p>
<p>When the corticosterone-treated rats received a single intravenous injection of Reelin, this reduction was completely reversed. The density of Reelin-immunoreactive cells returned to levels statistically indistinguishable from the healthy control rats that had never received corticosterone.</p>
<p>The researchers also evaluated apoptosis using cleaved caspase-3, a protein fragment recognized as a key signal for cells entering their terminal phase of life. In a healthy gut, apoptosis is concentrated at the very tips of the villi (the finger-like projections lining the intestine). This controlled death and subsequent shedding ensures that damaged or old cells are cleared out as new ones migrate up from the base of the villi.</p>
<p>The results showed that chronic corticosterone administration caused a marked decrease (about 55 percent) in the number of cleaved caspase-3 immunoreactive cells at the villi tips compared to control animals. This reduction suggests that chronic stress significantly slowed the necessary shedding and replacement of cells in the gut lining.</p>
<p>The introduction of recombinant Reelin partially restored this cellular process. The single injection increased the cleaved caspase-3 cell counts in the corticosterone-treated rats by roughly 55 percent compared to the stressed animals that did not receive Reelin treatment. This suggests that the Reelin injection helped reactivate the normal cycle of epithelial cell turnover.</p>
<p>The scientists also compared the gut markers with neurobiological markers measured in the hippocampus of the same rats, which were reported in a previous related study. Specifically, they looked for relationships between intestinal Reelin cell density or apoptosis counts and hippocampal Reelin cell counts or the counts of the GluA1 receptor subunit, an important marker for brain signaling.</p>
<p>The analysis revealed no significant correlations between any of the measured intestinal markers and the measured neurobiological markers, regardless of whether the animals were stressed or treated with Reelin. The researchers suggest this lack of correlation might indicate that, although the gut and brain communicate, reduced Reelin production in the gut does not necessarily reflect reduced Reelin levels in other, distant regions of the body for any individual animal.</p>
<p>The research proposes that by supporting the integrity of the gut lining, Reelin may act as a protective factor against stress-induced damage. If chronic stress causes the loss of Reelin-producing cells and slows epithelial renewal, the gut barrier becomes weaker. Reelin administration appears to correct this issue, potentially supporting a healthier gut barrier composition.</p>
<p>The rats used in this study had previously exhibited depressive-like behaviors following the chronic corticosterone exposure, including increased immobility in the forced swim test, which were also reversed by the single injection of Reelin. This suggests that Reelin’s benefits extend beyond the gut, offering therapeutic potential across multiple physiological systems affected by chronic stress.</p>
<p>While the findings are promising, the study was conducted in an animal model using a pharmacological agent (corticosterone) to simulate chronic stress. Future research will need to explore the exact molecular pathways by which Reelin influences cell migration and turnover in the gut. Scientists also need to confirm these effects in human clinical settings.</p>
<p>The results of this study support the idea that treatments aimed at restoring gut barrier function could offer a prophylactic approach, potentially increasing resistance to stress-induced inflammation.</p>
<p>“Reelin-based therapeutics could potentially offer such treatment,” according to Caruncho.</p>
<p>Halvorson concluded by reflecting on the broader implications of the findings for patient populations. “Taken together, these results may have important implications for the management of major depressive disorder,” she said. “This is especially true for people who live with both depression and gastrointestinal conditions.”</p>
<p>“If Reelin protects against leaky gut by supporting the renewal of the gut lining, Reelin may thereby protect against the worsening of depression symptoms triggered by inflammatory immune responses to leaked gut material,” Halvorson summarized.</p>
<p>The study, “<a href="https://doi.org/10.1177/24705470251381456" target="_blank">An Intravenous Injection of Reelin Rescues Endogenous Reelin Expression and Epithelial Cell Apoptosis in the Small Intestine Following Chronic Stress</a>,” was authored by Ciara S. Halvorson, Carla Liria Sánchez-Lafuente, Brady S. Reive, Lara S. Solomons, Josh Allen, Lisa E. Kalynchuk, and Hector J. Caruncho.</p></p>
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<td><a href="https://www.psypost.org/do-breast-implants-alter-neuromuscular-control/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Do breast implants alter neuromuscular control?</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 10th 2025, 14:00</div>
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<p><p>A new study investigating the immediate effects of breast implants on the body has found that they can produce subtle changes in muscle activity around the shoulder blades and slightly reduce a person’s reaching ability. These short-term changes, however, did not appear to cause significant negative shifts in overall posture or balance in healthy young women. The research was published in the journal <em><a href="https://doi.org/10.3390/app15020579" target="_blank">Applied Sciences</a></em>.</p>
<p>The decision to conduct this research was prompted by trends in cosmetic surgery. Breast augmentation is one of the most common surgical procedures performed worldwide. At the same time, the number of women choosing to have their implants removed has also grown. While complications like infection are known reasons for removal, researchers have become interested in less-discussed issues, such as the development of musculoskeletal and postural problems. An added weight on the front of the body could disrupt posture and lead to dysfunction over time.</p>
<p>Diana C. Guedes and a team of researchers from the Polytechnic of Porto in Portugal noted that much of the existing research focused on women with naturally large breasts or on patients who received implants for reconstruction after a mastectomy. A gap existed in understanding the immediate biomechanical effects of cosmetic implants on healthy women. The team aimed to explore how adding weight to the chest area, simulating common implant sizes, would instantly affect postural control during both static and dynamic tasks.</p>
<p>To investigate this, the scientists designed a cross-sectional study involving 35 healthy female volunteers with an average age of 24. Participants were excluded if they had a history of breast surgery, were pregnant, or had any existing conditions that could interfere with their posture or movement. </p>
<p>The study was designed to simulate breast augmentation, isolating the effect of weight from the complexities of actual surgery. Participants were fitted with demonstration implants in three common volumes: 220, 315, and 365 milliliters. These sizes equate to a range of enhancements, from adding about one pound to the chest for a single-cup-size increase, to adding nearly two pounds for a larger, two-cup-size augmentation. The implants were held in place by a supportive sports bra, allowing the researchers to directly assess how the added frontal load immediately affected each participant’s posture and muscle activity.</p>
<p>Each participant was evaluated in a laboratory setting under four conditions in a randomized order: a control condition with no implants, and one condition for each of the three implant sizes. The researchers used a suite of advanced equipment to capture detailed information. A motion capture system with reflective markers placed on the spine tracked the angles of the head, neck, and back. </p>
<p>A force plate embedded in the floor measured the participant’s center of pressure, which indicates small shifts in balance and stability. To measure muscle function, the team placed eight surface electromyography sensors on the dominant side of each participant’s body. These sensors recorded the electrical activity of key muscles in the neck, upper back, chest, and abdomen.</p>
<p>The participants performed two main tasks. The first was a static test where they were asked to stand still on the force plate for one minute. The second was a dynamic assessment called the Functional Reach Test. For this test, participants stood and reached forward with their dominant arm as far as they could without losing their balance or moving their feet. This test measures stability during movement. Alongside these physical measurements, participants also filled out questionnaires to describe their subjective feelings of comfort, effort, and the perceived weight of the implants for each condition.</p>
<p>When analyzing the data from the one-minute standing test, the researchers found that the added weight of the implants did not cause any significant changes to the participants’ spinal alignment. Their head, neck, and back posture remained consistent across all four conditions. Similarly, the force plate measurements showed no meaningful differences in their balance. The participants were able to stand just as steadily with the implants as they could without them.</p>
<p>The muscle activity data from the standing test revealed a more complex picture. For most of the muscles monitored, there were no significant changes in activity. One muscle, the levator scapulae, which helps lift the shoulder blade, showed an unexpected pattern. Its activity was significantly lower when participants wore the smallest 220 milliliter implant compared to the control condition with no implant. This suggests that the body’s response to a new frontal load is not a simple case of muscles working harder, but may involve more intricate adjustments in neuromuscular control.</p>
<p>During the Functional Reach Test, the research team observed a clear difference in performance. When wearing any of the three implant sizes, participants were not able to reach as far forward as they could in the control condition. Although the reduction in reach distance was small, it was statistically significant, indicating that the added weight had a subtle but immediate impact on their functional stability and mobility.</p>
<p>The muscle activity during the reaching test also showed notable adjustments, particularly in the large trapezius muscles of the upper back. When reaching forward with the 315 milliliter and 365 milliliter implants, participants showed increased activity in the lower part of the trapezius muscle compared to the control condition. </p>
<p>At the same time, activity in the upper part of the trapezius muscle decreased with some implant sizes. This suggests a shift in muscle strategy, where the body recruits the lower trapezius more heavily to help stabilize the shoulder blades against the forward pull of the added weight.</p>
<p>The participants’ subjective reports aligned with the physical changes. As the implant volume increased, their perception of comfort decreased. They also reported that the tasks required more effort and that the implants felt progressively heavier. Even with the largest size, however, participants generally described the experience as comfortable and requiring only light effort, showing good short-term tolerance for the added weight. </p>
<p>The findings suggest that in this group of young, healthy, and physically active women, the body is capable of making immediate, subtle adjustments to manage the added load of common implant sizes without a major disruption to overall posture.</p>
<p>The authors pointed out some limitations to their study. The research captured only the immediate, short-term effects of the simulated implants, and the long-term consequences of carrying such weight could be different. The study’s sample consisted of a homogenous group of young, active women with a normal body mass index, which may not be representative of all individuals who seek breast augmentation. Using a sports bra to hold the implants is also not identical to having them surgically placed within the body, which involves tissue healing and other physiological changes.</p>
<p>Future research could build on these findings by conducting long-term studies that follow women after they have had augmentation surgery. Including a more diverse sample with different ages, body types, and physical activity levels would also provide a more complete understanding of how implants affect the body. </p>
<p>The results of this study offer a baseline understanding, suggesting that while common implant sizes may not cause immediate biomechanical harm in healthy individuals, they do prompt the neuromuscular system to adapt. This information could be useful for surgeons and physical therapists in advising patients on implant size and postoperative care.</p>
<p>The study, “<a href="https://doi.org/10.3390/app15020579" target="_blank">The Influence of Artificial Breast Volume Induction on Postural Stability, Postural Orientation, and Neuromuscular Control in Healthy Women: A Cross-Sectional Study</a>,” was authored by Diana C. Guedes, Daniela F. Carneiro, Leonel A. T. Alves, Ana S. C. Melo, Juliana Moreira, Bruno Cunha, Rubim Santos, Andreia Noites, and Andreia S. P. Sousa.</p></p>
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<td><a href="https://www.psypost.org/rfk-jr-just-linked-circumcision-to-autism-what-is-he-talking-about-heres-the-research/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">RFK Jr. just linked circumcision to autism. What is he talking about? Here’s the research</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 10th 2025, 13:00</div>
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<p><p>In a recent cabinet meeting, U.S. Health Secretary Robert F. Kennedy Jr. suggested a potential connection between male circumcision and autism, a claim that echoes a debate within certain corners of scientific and public discourse. While the assertion may seem surprising, a handful of scientific papers have explored this very question, examining statistical correlations and potential biological pathways. These studies, however, are not without significant limitations and have faced substantial criticism from other researchers in the field.</p>
<p>During the meeting, Kennedy addressed President Donald Trump with his concerns, linking the procedure to autism through the use of a common pain reliever. “There are two studies which show children who are circumcised early have double the rate of autism, it’s highly likely, because they were given Tylenol,” Kennedy told President Donald Trump in Thursday’s meeting. An examination of the scientific literature reveals the studies to which he was likely referring.</p>
<p>The first of these papers was an exploratory analysis published in the journal <em><a href="https://doi.org/10.1186/1476-069X-12-41" target="_blank">Environmental Health</a></em> in 2013 by researchers Ann Z. Bauer and David Kriebel. The authors sought to investigate a hypothesis that the use of paracetamol, also known as acetaminophen and sold under brand names like Tylenol, during pregnancy or in early infancy might be a risk factor for autism spectrum disorder. </p>
<p>Their rationale was based on several observations. The prevalence of autism and the consumption of paracetamol both increased dramatically after 1980. Some studies also suggest children with autism may have a decreased capacity to metabolize the drug, potentially leading to oxidative stress and immune system effects.</p>
<p>Bauer and Kriebel noted that in the mid-1990s, medical guidelines began recommending the use of analgesics like paracetamol to manage pain for infant circumcisions, a procedure previously performed often without pain relief. This change in practice a provided unique opportunity. The researchers hypothesized that if paracetamol exposure increases autism risk, then populations with higher circumcision rates after 1995 might also show higher rates of autism in males. They proposed using circumcision rates as a proxy, or stand-in measure, for early life paracetamol exposure in boys.</p>
<p>To test their ideas, the researchers conducted two separate ecological analyses, which look for correlations in population-level data rather than in individuals. The first analysis compared prenatal paracetamol usage rates with autism prevalence rates in eight countries where data was available. </p>
<p>The second, more central analysis compared male circumcision rates against male autism prevalence rates. They divided their data into two time periods: one for boys born before 1995, when it was assumed paracetamol was rarely used for the procedure, and one for boys born after 1994, when pain management with paracetamol became more common.</p>
<p>The results showed positive correlations. In the first analysis, the researchers found a strong correlation (r=0.80) between a country’s average prenatal paracetamol use and its autism prevalence. In the second analysis of boys born after 1995, they found a very strong correlation (r = 0.98) between male circumcision rates and autism prevalence across nine countries. This trend suggested that a 10% increase in a country’s circumcision rate was associated with an increase in male autism prevalence of 2.01 per 1,000 boys. </p>
<p>A similar strong correlation (r=0.95) was found among 14 U.S. states. For boys born before 1995, the correlation was still present but weaker (r = 0.89), with a 10% change in circumcision rate associated with a much smaller increase in autism prevalence of 0.35 per 1,000 boys.</p>
<p>Prompted in part by Bauer and Kriebel’s findings, a different team of researchers conducted a follow-up study. Published in the <em><a href="https://doi.org/10.1177/0141076814565942" target="_blank">Journal of the Royal Society of Medicine</a></em> in 2015, the study by Morten Frisch and Jacob Simonsen aimed to test the hypothesis directly in a large national cohort. They noted that painful or stressful events in early life have been linked to long-term psychological consequences and that even with modern pain relief, circumcision involves procedural and postoperative pain. Their investigation sought to determine if this early life stressor could be an adverse outcome for some boys, specifically by increasing their risk of developing autism spectrum disorder.</p>
<p>Frisch and Simonsen conducted a national register-based cohort study in Denmark. They identified a group of 342,877 boys born between 1994 and 2003 and followed them for up to ten years. Using Denmark’s comprehensive national health registries, they identified which boys underwent ritual circumcision, which were diagnosed with autism spectrum disorder or other conditions like hyperkinetic disorder and asthma, and a host of other potential influencing factors such as birth weight, gestational age, and parents’ country of origin. </p>
<p>The analysis used statistical models to compare the risk of developing autism in circumcised boys versus intact boys, while attempting to control for cultural background and other perinatal risk factors.</p>
<p>The study found that, overall, ritually circumcised boys were 46% more likely to be diagnosed with autism spectrum disorder before age 10 compared to uncircumcised boys. The risk appeared highest for infantile autism diagnosed before age five, where circumcised boys had twice the risk of their intact peers. </p>
<p>The researchers also found an unexpected increased risk of hyperkinetic disorder among circumcised boys from non-Muslim families. By contrast, they found no association between circumcision and asthma, an outcome they checked for comparison. </p>
<p>The Danish study soon drew criticism. In <a href="https://doi.org/10.1177/0141076815590404" target="_blank">a letter</a> to the <em>Journal of the Royal Society of Medicine</em> published later in 2015, Brian J. Morris and Thomas E. Wiswell argued the claims were flawed. They pointed out that the statistical significance was marginal and the absolute number of affected boys was small. </p>
<p>They also highlighted a key issue with the data: the study recorded only 10.9% of boys from Muslim backgrounds as being circumcised, a figure they described as “improbable” and one that undermines the findings. Ritual circumcision is a near-universal religious and cultural practice for Muslim families. The actual circumcision rate in this demographic group should be close to 100%, not the 10.9% captured by the study’s methods. </p>
<p>The critics also questioned the study’s focus. “Since the Danish study was about pain why didn’t Frisch and Simonsen examine other painful conditions? Urinary tract infections are associated with excruciating pain, are common and very much higher in uncircumcised male infants and boys,” they wrote. They suggested that if the pain hypothesis were correct, autism should be associated with being uncircumcised, due to higher rates of these infections. They also proposed alternative explanations, such as the effects of anesthesia or the possibility that both early circumcision and autism diagnosis reflect higher levels of parental conscientiousness.</p>
<p>Seeking to bring clarity to a range of similar claims, a team of researchers led by Morris published a systematic review in the <em><a href="https://doi.org/10.1111/jebm.12482" target="_blank">Journal of Evidence-Based Medicine</a></em> in 2022. The aim of the review was to identify all the various psychological, psychophysiological, and psychosocial consequences attributed to circumcision in early childhood and to critically examine the quality of the evidence for and against these purported harms. The review was the first of its kind to systematically evaluate the breadth of these claims.</p>
<p>In their review, Morris and his colleagues strongly criticized the supposed link between circumcision and autism. They reiterated that the statistical association in the Danish study was weak and that the very low reported circumcision rate among Muslim boys cast doubt on the data’s validity. </p>
<p>The reviewers emphasized the point made by the original study’s author, Ann Bauer, that her 2013 paper was about paracetamol, not circumcision itself. The association with autism was much stronger in the time period after paracetamol use became common for the procedure, which they argue supports the paracetamol hypothesis over a pain-trauma hypothesis. </p>
<p>Other potential explanations for the findings in the Danish study include confounding factors, such as cultural differences and the fact that more attentive parents might be more likely to both have their sons circumcised and seek an early autism diagnosis.</p>
<p>Overall, Morris and his colleagues concluded in their review that “the highest quality evidence suggest that neonatal and later circumcision has limited or no short-term or long-term adverse psychological effects.”</p>
<p>All the studies involved acknowledge significant limitations, a point that is central to understanding the current state of the science on this topic. A major issue is the lack of research that can establish a direct causal link. Bauer and Kriebel were clear that their work was a “hypothesis generating exploratory analysis.” As an ecological study, it looked for patterns in large population groups, not in individuals. This type of analysis can never prove that one thing causes another. It can only show that two trends appear to move in tandem within a population.</p>
<p>The core weakness of an ecological study is what is known as the “ecological fallacy.” This is the error of assuming that relationships observed for groups necessarily hold true for individuals. For example, a city with a high number of libraries might also have a high rate of college graduates, but this does not mean that every person who uses a library is a college graduate. </p>
<p>In the context of the 2013 study, a high rate of circumcision in a country and a high rate of autism do not prove that circumcision causes autism in any given child. There could be countless other hidden factors, or confounders—such as differences in healthcare systems, access to diagnostic services, parental reporting habits, or genetic predispositions in certain populations—that could be the real reason for the statistical correlation. The use of circumcision as a proxy for paracetamol use adds another layer of indirectness, further weakening any causal interpretation.</p>
<p>The second major limitation across this body of research is the scarcity of high-quality longitudinal evidence. A longitudinal study is considered a much more powerful tool for investigating potential causes because it follows the same group of individuals forward in time. An ideal study on this topic would enroll a large cohort of newborn boys, carefully document which ones are circumcised (including details on pain management used), and then follow all of them for many years to see who develops Autism Spectrum Disorder. This design allows researchers to establish a clear timeline—that the proposed cause happened before the effect—and to systematically collect data on many other potential contributing factors over the course of a child’s development.</p>
<p>The research that exists is largely not of this type. The Danish study by Frisch and Simonsen was a step closer, as it was a cohort study that looked back at registry data. However, as the authors and critics noted, it had its own problems with incomplete data, potentially misclassifying boys who were circumcised outside the public health system. </p>
<p>The 2022 systematic review by Morris and colleagues underscored this problem, concluding that the field is hampered by studies that are mostly cross-sectional. A cross-sectional study is a snapshot of data — it captures data from a group of people at a single point in time. It can show an association but it cannot untangle the sequence of events or rule out the possibility that other life experiences are the true cause. Without robust longitudinal studies, it is difficult to separate a potential effect of a single procedure in infancy from the complex interplay of genetics and a lifetime of other environmental influences.</p>
<p>In a statement posted to the social media platform X (formerly Twitter) on Friday, Kennedy said that one of the studies he was referencing was <a href="https://www.preprints.org/manuscript/202508.0006/v1" target="_blank">a 2025 preprint research article</a>. A preprint is a version of a scientific manuscript that has not yet been subjected to peer review, the formal evaluation process where independent experts in the same field scrutinize a study’s methods, data, and conclusions before it is published in a scientific journal. This particular preprint was authored by a team of researchers including M. Vishnu Patel and William Parker.</p>
<p>“As usual, the mainstream media attacks me for something I didn’t say in order to distract from the truth of what I did say,” Kennedy wrote. “An August 2025 http://Preprints.org review by Patel et al. directly validates my point that the observed autism correlation in circumcised boys is best explained by acetaminophen exposure, not circumcision itself.”</p>
<p>“So once again, MSM chooses to character assassinate me instead of educating Americans by digging into the science. The paper I was referring to identifies the 2015 Danish circumcision study as ‘the most compelling ‘standalone’ evidence that acetaminophen triggers autism in susceptible babies and children.'”</p>
<p>The preprint does not present a new experiment but is instead a systematic analysis of previously published scientific literature. The central argument of the paper is that “overwhelming evidence shows that exposure of susceptible babies and children to acetaminophen (paracetamol) triggers many if not most cases of autism spectrum disorder.” The authors state that their goal was to understand why this conclusion has not been widely accepted by the medical and regulatory communities. They assert that the failure to accept this link is due to mishandling of evidence within the scientific literature itself.</p>
<p>The preprint authors identify three primary ways they believe the evidence has been mishandled by other researchers. The first error, they state, is a fundamental statistical mistake. They argue that many studies incorrectly treat factors like infection, maternal stress, or genetics as separate “confounding” factors. The preprint’s authors contend these are actually “interacting” variables that create a state of oxidative stress, making a child susceptible to acetaminophen. By statistically “adjusting” for these factors, they claim, researchers have inadvertently erased the very signal they should be looking for—the combined effect of acetaminophen and susceptibility.</p>
<p>A second problem identified is that researchers often look at too narrow a slice of the evidence. For example, a study might only examine acetaminophen use during pregnancy while ignoring the post-birth period, which the preprint authors argue is a time of high sensitivity. They also note that many papers discussing the topic fail to cite what they consider to be seminal earlier studies, including the papers by Frisch and Simonsen and by Bauer and Kriebel. Finally, the paper claims that key earlier studies suggesting a link were subjected to “irrational criticisms” that used invalid reasoning to unfairly dismiss important findings, preventing the scientific community from taking the hypothesis seriously.</p></p>
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<td><a href="https://www.psypost.org/startling-study-finds-people-overtrust-ai-generated-medical-advice/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Startling study finds people overtrust AI-generated medical advice</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 10th 2025, 12:00</div>
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<p><p>A new study involved participants evaluating medical responses that were either written by a medical doctor or generated by a large language model. Results showed participants could not distinguish between doctors’ responses and AI-generated responses, but preferred AI-generated ones. They found high-accuracy AI responses to be the best, but rated low-accuracy AI responses and those given by a medical doctor similarly. The paper was published in <a href="https://doi.org/10.1056/AIoa2300015"><em>NEJM AI</em></a>.</p>
<p>The use of artificial intelligence (AI) systems in the field of medicine and health care has increased dramatically in recent years. This increase has occurred across various domains, from radiology imaging and mental health chatbots to drug discovery.</p>
<p>One particular application of AI, especially large language models (LLMs), in the medical field is answering patients’ questions. One study showed that ChatGPT was able to generate higher quality and more empathetic responses to patient questions compared to those from medical doctors. AI also seems to excel in diagnostics. One study found that AI alone outperformed physicians in making diagnoses, while a follow-up showed that physicians augmented with AI performed comparably to AI alone, and both groups outperformed physicians working without AI.</p>
<p>Study author Shruthi Shekar and her colleagues wanted to investigate how well people distinguish between responses to patients’ questions given by medical doctors and those generated by AI. Participants were also asked to rate the validity, trustworthiness, completeness, and other aspects of the answers.</p>
<p>The researchers retrieved 150 anonymous medical questions and doctors’ responses from the forum <a href="https://www.healthtap.com/">HealthTap</a>. These questions covered six domains of medicine: preventative and risk factors; conditions and symptoms; diagnostics and tests; procedures and surgeries; medication and treatments; and recovery and wellness, with equal distribution.</p>
<p>The researchers then used GPT-3 to create AI responses for each of those questions. These AI-generated responses were then evaluated by four physicians to establish their accuracy. This process was used to classify AI responses into high- and low-accuracy ones.</p>
<p>Next, in the first experiment, a group of 100 online study participants were presented with 10 medical question-response pairs randomly selected from a collection of 30 high-accuracy AI responses, 30 low-accuracy AI responses and 30 doctors’ responses.</p>
<p>In the second experiment, 100 online participants rated their understanding of the question and the response and its perceived validity. They also rated the trustworthiness of the response, its completeness and their satisfaction with it, whether they would search for additional information based on the response, whether they would follow the given advice, and whether they would seek subsequent medical attention based on the response.</p>
<p>In the third experiment, 100 online participants provided the same ratings for the responses, but participants were randomly informed that the responses were from either a doctor, an AI, or a doctor assisted by an AI.</p>
<p>Results showed that participants were unable to effectively distinguish between AI-generated responses and doctors’ responses. However, they showed a preference for AI-generated responses, rating high-accuracy AI-generated responses as significantly more valid, trustworthy, and complete than the other two types of responses. Low-accuracy AI responses tended to receive ratings similar to those given to doctors’ responses.</p>
<p>Interestingly, participants not only found the low-accuracy AI responses to be as trustworthy as those given by doctors, they also reported a high tendency to follow the potentially harmful medical advice contained in those responses and to incorrectly seek unnecessary medical attention as a result of the response. These problematic reactions were comparable with the reactions they displayed toward doctors’ responses, and sometimes even stronger. The study authors note that both experts (raters) and nonexperts (participants) tended to find AI-generated responses to be more thorough and accurate than doctors’ responses, but they still valued the involvement of a doctor in the delivery of their medical advice.</p>
<p>“The increased trust placed in inaccurate or inappropriate AI-generated medical advice can lead to misdiagnosis and harmful consequences for individuals seeking help. Further, participants were more trusting of high-accuracy AI-generated responses when told they were given by a doctor, and experts rated AI-generated responses significantly higher when the source of the response was unknown,” the study authors concluded.</p>
<p>The study sheds light on how humans perceive medical advice generated by AI systems. However, it should be noted that the questions and responses used in the study were taken from an online forum, where medical doctors tend to contribute their content voluntarily. It is likely that the answers were given with the aim of being useful and not with the aim of being the best or the most thorough answers the medical doctors providing them could give. The results of studies comparing answers of doctors clearly aiming to provide their best answers with AI-generated content might not be identical.</p>
<p>The paper, “<a href="https://doi.org/10.1056/AIoa2300015">People Overtrust AI-Generated Medical Advice despite Low Accuracy,</a>” was authored by Shruthi Shekar, Pat Pataranutaporn, Chethan Sarabu, Guillermo A. Cecchi, and Pattie Maes.</p></p>
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<td><a href="https://www.psypost.org/scientists-use-ai-to-detect-adhd-through-unique-visual-rhythms-in-groundbreaking-study/" style="font-family:Helvetica, sans-serif; letter-spacing:-1px;margin:0;padding:0 0 2px;font-weight: bold;font-size: 19px;line-height: 20px;color:#222;">Scientists use AI to detect ADHD through unique visual rhythms in groundbreaking study</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Oct 10th 2025, 11:00</div>
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<p><p>A recent study published in <em><a href="https://doi.org/10.1371/journal.pone.0310605" target="_blank">PLOS One</a></em> suggests that adults with attention-deficit/hyperactivity disorder (ADHD) exhibit a distinct pattern in how they visually process information over time. This pattern differs enough from that of neurotypical adults that a machine learning algorithm was able to accurately classify individuals with ADHD based on these visual traits with over 90 percent accuracy. The same approach was also able to distinguish whether a person with ADHD regularly takes stimulant medication. These findings indicate that ADHD may involve a consistent, underlying difference in how the brain handles brief moments of perception.</p>
<p>ADHD is a neurodevelopmental condition characterized by symptoms such as inattention, impulsivity, and hyperactivity. It affects around 3 to 4 percent of Canadian adults and about 2.6 percent of adults worldwide. While researchers have known for some time that ADHD influences attention, memory, and executive functioning, less is known about how it affects the brain’s handling of incoming sensory information—especially how that processing changes from one moment to the next.</p>
<p>Previous studies using brainwave recordings have shown that people with ADHD often display different patterns of electrical activity, particularly in the alpha and theta frequency bands. However, these findings have not always been consistent. To better understand the functional impacts of such oscillations, the researchers behind this new study used a method called random temporal sampling, which allows them to track how efficiently someone processes visual information across tiny slices of time.</p>
<p>Their goal was to explore whether ADHD is associated with a distinct rhythm or timing in visual perception, which could reflect underlying neural oscillations. If such a rhythm exists and is consistent across individuals with ADHD, it could provide a new behavioral marker for identifying the condition.</p>
<p>“In light of the relatively high incidence of ADHD, there is surprisingly little that we know about it for sure,” said study author Martin Arguin, a professor of psychology at the University of Montreal and director of <a href="https://www.neurocognitionvisionlab.org/en" target="_blank">the Neurocognitive Vision Lab</a>.</p>
<p>“This is especially true of the neural bases of the disorder. My lab had recently brought to maturity the technique of random temporal sampling, which serves to capture temporal variations in perceptual efficiency. Given that these temporal variations can be assumed originate from oscillatory neural activity, we thought that examining ADHD from this perspective might bring a positive contribution to our knowledge of the disorder.”</p>
<p>The researchers recruited young adult participants from two colleges in Quebec. A total of 49 people were included in the final analysis: 26 were neurotypical controls and 23 had received a formal ADHD diagnosis. Among those with ADHD, 17 regularly used stimulant medication while six did not. All participants had normal or corrected vision and completed a battery of visual tasks under controlled conditions.</p>
<p>The central experiment involved briefly showing participants a series of five-letter French words overlaid with visual noise. The visibility of each word varied rapidly during the 200 milliseconds it appeared on the screen. Participants were asked to read the word aloud, and researchers recorded whether they were correct. The contrast of the noise was continuously adjusted so that each participant would average about 50 percent correct responses, ensuring a balanced challenge across individuals.</p>
<p>What set this experiment apart was how the noise varied. It wasn’t static; instead, the signal-to-noise ratio changed throughout the 200-millisecond window in a pattern composed of multiple sine waves at different frequencies. This random fluctuation allowed researchers to analyze how well participants could extract the word at each moment in time, depending on the frequency of the noise changes. The technique generated what are called classification images—maps showing how efficiently each person processed the visual input at different times and frequencies.</p>
<p>By comparing the classification images of those with and without ADHD, the researchers could examine whether there were consistent group differences in the rhythm of visual processing. They then used a machine learning model trained on features extracted from these classification images to see if it could distinguish between the two groups.</p>
<p>The classification images revealed consistent differences in visual processing patterns between participants with ADHD and those without. Although the general structure of visual processing looked similar across both groups, certain frequencies showed marked differences. These included processing oscillations at 5, 10, and 15 cycles per second (Hz), particularly when the noise in the stimulus oscillated at 30 to 40 Hz.</p>
<p>“The immediate implication of our results is that, in ADHD, there seems to be a systematic divergence in visual function from that of individuals with typical development,” Arguin told PsyPost. “This divergence points to a difference in brain function that has yet to be clearly determined.”</p>
<p>When these patterns were fed into a machine learning algorithm, it was able to classify individuals as either ADHD or neurotypical with 91.8 percent accuracy, using only about 3 percent of the total features. The sensitivity (the algorithm’s ability to correctly identify ADHD participants) was over 96 percent, while its specificity (the ability to correctly identify neurotypical individuals) was 87 percent.</p>
<p>“The literature largely emphasizes the individual differences among persons with ADHD as a potential indicator of varied causes for the disorder,” Arguin said. “Our findings rather indicate that we can actually classify 100% of our participants into their respective group (i.e. ADHD vs typical development) from their individual data patterns pertaining to perceptual oscillations; thereby pointing to a possibly unique cause.”</p>
<p>“This high classification rate in itself was also rather unexpected. However, at the time we carried out the data analyses, we had already completed a similarly designed project comparing perceptual oscillations across young vs elderly participants with normal cognitive functioning (<a href="https://doi.org/10.3389/fpsyg.2024.1323493" target="_blank">Lévesque & Arguin, 2024</a>). In that study too, we found an accuracy of 100% in the classification of individual participants into their respective group based on their patterns of perceptual oscillations. This somewhat contributed to raise our expectations for the outcomes of the ADHD study.”</p>
<p>The researchers also examined whether the algorithm could tell apart individuals with ADHD who were on stimulant medication from those who were not. Despite the small sample size, the model performed well, achieving 91.3 percent accuracy. It was particularly sensitive to identifying those taking medication, with 100 percent accuracy in that subgroup. Only a few features were needed to make this distinction, suggesting that regular medication use has a measurable effect on the timing of visual processing.</p>
<p>Interestingly, when the researchers directly compared the classification images of medicated and unmedicated participants with ADHD, they did not find statistically significant differences using traditional statistical methods. However, the machine learning approach was able to detect consistent patterns, indicating that the medication status leaves subtle but consistent traces in the visual processing rhythms.</p>
<p>In summary, the findings indicate “that there is a particular pattern to perceptual oscillations that seems to uniquely characterize most, if not all, persons with ADHD,” Arguin explained. “This fact suggests that there may be a single atypical brain mechanism underlying ADHD. This is at variance from a large portion of the relevant literature, which seems to assume a variety of potential causes in attempting to account for sometimes significant individual differences among ADHD sufferers.”</p>
<p>Although the findings are promising, the study has some limitations. The sample size was modest, especially for the comparison between medicated and non-medicated ADHD participants. Larger and more diverse samples are needed to confirm the generalizability of the results. The participants were mostly young adults, so it is not yet clear whether similar patterns would be found in older adults or children.</p>
<p>Another issue is that while the classification method was very effective, the specific link between the observed visual processing patterns and underlying neural mechanisms remains unclear. The classification images are thought to reflect brain oscillations, but this assumption has not yet been directly tested using brain imaging techniques. Future studies could combine this behavioral method with electroencephalography or functional MRI to identify the brain regions and networks involved.</p>
<p>The researchers also point out that the task they used—a repetitive word recognition task with limited cognitive flexibility—may have made it especially sensitive to the effects of ADHD and medication. It remains to be seen whether similar processing differences would appear in more complex or varied tasks.</p>
<p>Despite these caveats, the findings suggest that random temporal sampling may offer a powerful and objective tool for identifying ADHD. The ability to classify individuals with such high accuracy, based on a brief visual task, suggests that there may be a single core difference in perceptual timing that characterizes the condition. This idea stands in contrast to much of the current literature, which tends to emphasize individual differences and multiple potential causes for ADHD.</p>
<p>If the technique proves reliable in broader populations and under different testing conditions, it could eventually be adapted into a clinical tool.</p>
<p>“Based on our investigation in adults with ADHD, we are now pursuing a related study to examine whether we can replicate its findings in children in the age range where an assessment for possible ADHD is most often sought (10-14 year olds),” Arguin explained. “If so, it would indicate that random temporal sampling could constitute an excellent test for the assessment of ADHD. Such a test could eventually prove very useful in the current context where: 1. access to the relevant specialists is often very difficult; 2. assessment for possible ADHD may be very costly; 3. the diagnosis of ADHD is based on symptomatology.”</p>
<p>The study, “<a href="https://doi.org/10.1371/journal.pone.0310605" target="_blank">Visual processing oscillates differently through time for adults with ADHD</a>,” was authored by Pénélope Pelland-Goulet, Martin Arguin, Hélène Brisebois, and Nathalie Gosselin.</p></p>
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<p><strong>Forwarded by:<br />
Michael Reeder LCPC<br />
Baltimore, MD</strong></p>
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