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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/exposure-to-heavy-metals-is-associated-with-higher-likelihood-of-adhd-diagnosis/" 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;">Exposure to heavy metals is associated with higher likelihood of ADHD diagnosis</a>
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<p><p>A study in Spain found that children with higher levels of lead, cadmium, copper, and antimony in their urine had increased odds of being diagnosed with attention-deficit/hyperactivity disorder (ADHD). More specifically, higher levels of copper and cadmium were associated with more severe inattention symptoms, while higher levels of copper and antimony were linked to greater hyperactivity-impulsivity severity. The paper was published in the <a href="https://doi.org/10.1177/10870547251315276"><em>Journal of Attention Disorders</em></a>.</p>
<p>Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition marked by persistent inattention, hyperactivity, and impulsivity that interfere with daily functioning. It typically begins in childhood and can continue into adulthood, adversely affecting academic, occupational, and social life.</p>
<p>Globally, about 8% of children and 2.6% of adults are estimated to have ADHD. Boys are more frequently diagnosed than girls. In the United States, the diagnosis rate among children has risen steadily in recent decades, reaching about 11.4% by 2022. This increase is thought to reflect greater awareness, improved screening, and broader diagnostic criteria rather than a true rise in prevalence. Many adults remain undiagnosed until later in life, especially women and individuals with predominantly inattentive symptoms. ADHD often co-occurs with other conditions such as anxiety, depression, and learning disabilities.</p>
<p>Study author Sharanpreet Kaur and her colleagues note that the causes of ADHD are still not fully understood and that there is a knowledge gap regarding the role heavy metals might play in the development of this disorder. They examined 15 different metals: lead (Pb), arsenic (As), mercury (Hg), cadmium (Cd), chromium (Cr), copper (Cu), cobalt (Co), antimony (Sb), zinc (Zn), selenium (Se), magnesium (Mg), vanadium (V), manganese (Mn), nickel (Ni), and molybdenum (Mo).</p>
<p>Study participants were 190 children between 6 and 15 years of age, residing in the Spanish provinces of Barcelona and Tarragona. Their parents provided early-morning, fasting urine samples for the study. Among the children, 124 were diagnosed with ADHD, while 66 were not. Of the total sample, 131 were boys.</p>
<p>The researchers analyzed the urine samples for concentrations of the 15 listed metals.</p>
<p>Results showed that children with the highest levels of lead, cadmium, copper, and antimony in their urine were more likely to be diagnosed with ADHD. Additionally, higher copper and cadmium levels were associated with more severe inattention symptoms, while higher copper and antimony levels were linked to greater hyperactivity-impulsivity symptoms.</p>
<p>“This exploratory study provides preliminary valuable evidence, suggesting potential associations between environmental factors, such as metal exposure, with ADHD in school-aged children. These findings highlight the importance of further research to support these associations and, if confirmed, explore strategies to mitigate the potential impacts of these toxicants on children’s health,” the study authors concluded.</p>
<p>The study contributes to the scientific understanding of the environmental factors associated with ADHD. However, it should be noted that the design of the study does not allow any definitive causal inferences to be derived from the results.</p>
<p>The paper, “<a href="https://doi.org/10.1177/10870547251315276">Investigating the Association Between Heavy Metals and Attention Deficit Hyperactivity Disorder in Children: An Exploratory Study,</a>” was authored by Sharanpreet Kaur, Josefa Canals-Sans, Paula Morales-Hidalgo, José A. Alda, and Victoria Arija.</p></p>
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<td><a href="https://www.psypost.org/eye-tracking-study-shows-people-fixate-longer-on-female-aggressors-than-male-ones/" 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;">Eye-tracking study shows people fixate longer on female aggressors than male ones</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jun 23rd 2025, 08:00</div>
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<p><p>A new study published in <em><a href="https://www.liebertpub.com/doi/10.1089/vio.2022.0061" target="_blank">Violence and Gender</a></em> has found that when people witness aggressive behavior, they pay more attention to female aggressors than to male ones — both in terms of how quickly they look at them and how long they continue to watch. Yet when it comes to judging the intentions and blameworthiness of those actions, participants tended to view male and female aggressors similarly. </p>
<p>These findings, drawn from a series of three experiments, suggest that observers may find female aggression more attention-grabbing because it conflicts with social expectations, not because they see it as more harmful or intentional.</p>
<p>The research was conducted to explore how gender stereotypes shape our attention and judgments in response to aggression. Previous studies have shown that men are more likely than women to use direct physical violence, and that women tend to engage in less visible forms of aggression, such as gossip or social exclusion. As a result, people may have different expectations of aggressive behavior depending on the gender of the person involved. </p>
<p>The researchers wanted to know whether this mismatch between expectation and behavior might cause people to scrutinize female aggressors more closely — and whether that scrutiny would affect how intentional or blameworthy their actions are perceived to be.</p>
<p>To explore these questions, researchers conducted three separate studies. In the first two, participants from the general public were shown images of aggressive interactions between two people, while their eye movements were tracked. Some scenes were ambiguous, meaning it wasn’t entirely clear whether harm was intentional, while others depicted clearly hostile behavior. The third study involved incarcerated violent offenders — individuals who are more familiar with aggressive behavior — to see if they responded differently.</p>
<p>In the first study, 122 adults (mostly in their twenties) viewed ambiguous scenes that could be interpreted in more than one way. These scenes showed two individuals, one potentially causing harm to the other. Each scene had both a male and a female version, so participants would see, for example, a woman shoving another person in one image, and a man doing the same thing in another. While participants looked at the scenes, an eye-tracking device recorded how long they spent looking at each face, and how quickly they first looked at the harm-doer.</p>
<p>After viewing each scene, participants were asked to rate how intentional the harmful behavior seemed and how much blame the aggressor deserved. The researchers found that participants looked faster and longer at the faces of female aggressors compared to male ones. However, they did not see female harm-doers as more intentional than male ones. If anything, women were slightly less likely to be blamed.</p>
<p>In the second study, the researchers replicated this design with another 120 participants, this time including both ambiguous and clearly hostile scenes where the harm-doer’s intentions were unmistakable. Again, the results showed that participants oriented more quickly to female harm-doers and spent more time looking at their faces. But when it came to judgments of intention and blame, there were no clear differences between male and female aggressors. This was true even when the aggression was clearly deliberate.</p>
<p>The third study brought in a very different group: 60 imprisoned individuals who had committed violent offenses, including assault and robbery. This group had more firsthand experience with aggressive behavior and might be expected to have different responses. The researchers again found that participants oriented faster to female aggressors, especially in clearly hostile scenes. In those cases, female faces held their attention longer than male ones. </p>
<p>However, these inmates did not generally judge female aggressors to be more blameworthy than male ones. The only exception came from the female offenders, who were more likely to judge female aggressors as acting intentionally — perhaps reflecting their own lived experiences or expectations.</p>
<p>Taken together, the three studies suggest that people pay more visual attention to female aggressors, even when they don’t judge their actions more harshly. The researchers believe this may be because female aggression stands out as unexpected. Social norms typically associate physical aggression with men, and seeing a woman act violently may prompt people to look longer and more quickly, perhaps to try to make sense of what they’re seeing. This tendency may reflect a kind of cognitive dissonance, where observers try to resolve a mismatch between a stereotype (women are nurturing and nonviolent) and what they are witnessing.</p>
<p>Interestingly, this heightened visual attention did not translate into stronger moral judgment. Across all three studies, female harm-doers were judged as roughly equally intentional as male ones, and sometimes even less blameworthy. This suggests that while female aggression might capture people’s attention, it does not necessarily provoke harsher condemnation — at least in the kinds of situations presented in the study.</p>
<p>There are several possible explanations for this pattern. One is that people may assume that if a woman is being physically aggressive, she must have a good reason for it — possibly because such behavior runs against societal expectations. Another is that people may still hold on to subtle forms of bias that excuse or minimize female aggression more readily than male aggression. This idea, often referred to as “benevolent sexism” or “benevolent genderism,” suggests that women may benefit from assumptions that they are inherently less violent or more morally upright.</p>
<p>The study also highlights the difference between automatic attention and conscious judgment. People’s eyes were drawn more quickly and for longer to female aggressors — an automatic, bottom-up process that likely reflects a need to process surprising or novel stimuli. But when asked to reflect on what they saw and assign blame or intent, participants relied on more deliberate, top-down reasoning, which appeared to be less influenced by the aggressor’s gender.</p>
<p>Future research could explore whether similar patterns hold in real-life scenarios or dynamic video footage, rather than still images. It could also examine whether these visual and cognitive responses are affected by the race, age, or other characteristics of the aggressors. Understanding how these social cues influence perception and judgment has important implications — especially in fields like criminal justice, where assumptions about intent and blame can have serious consequences.</p>
<p>The study, “<a href="https://doi.org/10.1089/vio.2022.0061" target="_blank">Judgment and Attention Toward Male and Female Harm-Doers: An Eye-Tracking Investigation in Community Adults and Inmates</a>,” was authored by Anna Zajenkowska, Marta Bodecka, Ewa Duda, Izabela Kazmierczak, Adrianna Jakubowska, Anna Zarazinska-Chrominska, Claire Lawrence, and Łukasz Okruszek.</p></p>
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<td><a href="https://www.psypost.org/romantic-breakups-follow-a-two-stage-decline-that-begins-years-before-the-split-study-finds/" 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;">Romantic breakups follow a two-stage decline that begins years before the split, study finds</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jun 23rd 2025, 06:00</div>
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<p><p>The end of a romantic relationship is often not a sudden or unexpected event. A new study published in the <em><a href="https://psycnet.apa.org/record/2025-94309-001?doi=1" target="_blank">Journal of Personality and Social Psychology</a></em> has found that relationship satisfaction tends to decline gradually at first, followed by a much steeper drop around one to two years before a breakup. This “terminal decline” pattern was consistent across large samples in four national studies, highlighting how the unraveling of a relationship often begins long before the final decision to separate.</p>
<p>The researchers were interested in better understanding how romantic relationships change over time—specifically, what happens in the lead-up to a breakup. Although previous studies have looked at how relationship satisfaction tends to drop in the early years of a partnership, the focus has generally been on time since the relationship began. </p>
<p>But in this study, the researchers asked a different question: What happens when we look at satisfaction based on how close a couple is to ending things? Their idea was inspired by research on aging, which has shown that well-being often drops sharply in the years just before death—a pattern referred to as “terminal decline.” The team applied this concept to romantic relationships, wondering if something similar might happen in the years leading up to a separation.</p>
<p>To explore this idea, researchers Janina Larissa Bühler and Ulrich Orth analyzed data from four large-scale, nationally representative longitudinal studies conducted in Germany, Australia, the United Kingdom, and the Netherlands. These studies followed thousands of individuals over many years, collecting annual information about their romantic lives, including their satisfaction with their relationships and whether they had separated from a partner. In total, the study analyzed data from over 15,000 individuals who experienced a breakup and compared them to a matched group of individuals who stayed in their relationships.</p>
<p>To make sure their comparisons were fair, the researchers used a statistical technique called propensity score matching. This method helped them account for pre-existing differences between people who eventually broke up and those who didn’t, such as age, personality traits, income, education level, and initial relationship satisfaction. This allowed them to more confidently attribute any observed changes in satisfaction to the process of separating, rather than other factors.</p>
<p>The main focus of the analysis was to examine how satisfaction changed in relation to the timing of a breakup. Instead of looking at how satisfaction changed over the total length of a relationship, they focused on the number of years leading up to the separation—a measure they called “time-to-separation.” When they plotted this data, they found a clear and consistent pattern: satisfaction declined in two distinct phases. First came a slow, gradual drop, lasting for several years. Then came a steeper decline that began roughly one to two years before the relationship ended. This second phase, which the researchers labeled the “terminal phase,” marked a period of rapid deterioration.</p>
<p>Across the different datasets, the timing of this terminal phase varied slightly, with the sharp decline typically beginning between seven months and a little over two years before the breakup. These findings suggest that many relationships begin to unravel long before a couple officially ends things. The researchers also compared this pattern to changes in life satisfaction. While people’s overall life satisfaction did tend to decrease before a breakup, the change was much smaller and less consistent than what they saw in relationship satisfaction. This supports the idea that terminal decline is more specific to the relationship itself rather than a general drop in well-being.</p>
<p>Interestingly, when the researchers compared this approach to the more traditional method of looking at time since the relationship began, they found that time-to-separation was a much better predictor of changes in satisfaction. In other words, knowing how close a couple is to breaking up offers more insight into their declining relationship satisfaction than knowing how long they’ve been together.</p>
<p>The study also explored some key differences between people who initiated the breakup and those who were on the receiving end. In one of the datasets, individuals who initiated the separation showed signs of dissatisfaction earlier, beginning their terminal decline more than a year before the breakup. Those who were left by their partner, on the other hand, often didn’t show a sharp decline in satisfaction until much closer to the end—sometimes just a few months beforehand. But once their satisfaction began to drop, it did so more quickly than for the initiators.</p>
<p>The researchers also looked at whether other factors—like age, gender, marital status, and previous relationship experience—played a role in how satisfaction changed. They found that age at separation and marital status sometimes influenced the patterns of decline, although the results were mixed across different studies. For example, in some cases, being married appeared to buffer against a steep terminal decline, while in others, it seemed to make the decline steeper. Gender and prior relationship experience didn’t consistently affect the results.</p>
<p>These findings suggest that while many couples do experience slow erosion in satisfaction over time, the shift toward an inevitable breakup often accelerates significantly in the final one to two years. This period of rapid decline may reflect growing conflict, emotional disengagement, or the realization that efforts to fix the relationship are no longer working.</p>
<p>Although the study was comprehensive, it had some limitations. All four datasets came from Western countries, so the findings may not apply in the same way to other cultural contexts where norms around marriage, divorce, and long-term relationships differ. Additionally, while the data covered long timespans and included many participants, it was still based on self-reported measures, which can be affected by memory biases or changes in how people interpret their experiences.</p>
<p>The researchers also noted that more frequent data collection—such as monthly instead of yearly assessments—might give a clearer picture of how the final stages of a relationship unfold. And while this study focused on average trends, future work could explore how these patterns differ between individuals, including those who experience personal growth, increased life satisfaction, or new romantic relationships after a breakup.</p>
<p>The study, “<a href="https://dx.doi.org/10.1037/pspp0000551" target="_blank">Terminal Decline of Satisfaction in Romantic Relationships: Evidence From Four Longitudinal Studies</a>,” was authored by Janina Larissa Bühler and Ulrich Orth.</p></p>
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<td><a href="https://www.psypost.org/believing-news-will-find-me-is-linked-to-sharing-fake-news-study-finds/" 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;">Believing “news will find me” is linked to sharing fake news, study finds</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jun 22nd 2025, 14:00</div>
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<p><p>A new study sheds light on how people come to share false or exaggerated news stories on social media. The research, published in <em>Computers in Human Behavior</em>, suggests that the belief that “news will find me” can increase the likelihood of sharing fake news. </p>
<p>While much attention has focused on malicious actors or bots, recent evidence suggests that much of the spread of fake news comes from ordinary users who may not realize they’re sharing false information. The researchers behind the new study focused on the role of passive news exposure, especially among people who rely on social media and mobile phones to encounter news without actively seeking it out.</p>
<p>“People increasingly rely on serendipitous encounters with news, as opposed to actively seeking it out, to be informed. This study extends <a href="https://www.psypost.org/news-finds-me-study-identifies-a-widespread-phenomenon-linked-to-fake-news-susceptibility/" target="_blank">previous research</a> on this ‘news-finds-me’ perception by showing it can lead to sharing news that is inaccurate or exaggerated, i.e., fake,” said study author Scott W. Campbell, a professor and Rinehart Chair in Mediated Communication at The Ohio State University.</p>
<p>The researchers conducted a longitudinal survey of 337 U.S. adults who self-identified as having strong “Alt-Right” beliefs. All participants identified as white, used social media regularly, and leaned politically Republican. Most were women (55%), and the average age was 43.5 years. </p>
<p>Participants were surveyed at three time points between August 2022 and March 2023. They were asked about their social media habits, mobile phone use, news-sharing behaviors, and how much they agreed with statements indicating a belief that important news would naturally reach them through their peers and platforms.</p>
<p>The researchers measured fake news-sharing with items that asked whether participants had shared news stories that were later found to be false or exaggerated—either knowingly or unknowingly. The news-finds-me perception was assessed with questions like “I can be well informed even when I don’t actively follow the news” and “I rely on my friends to tell me what’s important when news happens.”</p>
<p>The study found that people who scored higher on the news-finds-me perception at the second time point were more likely to report sharing fake news at the third time point, even after accounting for earlier behaviors. This supports the idea that passively encountering news through social media and friends can make people more susceptible to spreading misinformation.</p>
<p>“This study shows that when people rely on serendipitous encounters with news, they are more likely to pass along news that is inaccurate or exaggerated,” Campbell told PsyPost. “In other words, fake news can ‘slip through the cracks’ when their guard is down.”</p>
<p>In addition to this direct effect, the researchers examined how specific uses of social media and mobile phones were related to the news-finds-me perception—and, in turn, fake news-sharing. Some social media platforms were more likely to foster this perception than others. </p>
<p>Using Facebook and Instagram, which are built around social interaction, was linked to stronger beliefs that news would reach the user without effort. This belief, in turn, predicted greater sharing of fake news. On the other hand, using Reddit—a platform more oriented toward information-gathering—was associated with a reduced belief in the news-finds-me idea and less fake news-sharing.</p>
<p>The researchers also looked at alternative social media platforms, such as Parler, Gab, Truth Social, Rumble, and Telegram. Of these, only Telegram showed a significant link to the news-finds-me perception and subsequent fake news-sharing. The researchers suggest that Telegram’s private messaging and group chat features may reinforce the sense that news can be trusted when it comes from peers, which is central to the news-finds-me mindset.</p>
<p>Mobile phone use showed similar patterns. People who frequently used their phones to stay socially connected were more likely to develop the news-finds-me perception and later share fake news. </p>
<p>Interestingly, people who used their phones specifically to get political information were less likely to rely on the news-finds-me belief and shared less fake news overall. This suggests that purposeful political engagement may counteract the tendency to passively accept information as accurate.</p>
<p>The researchers note that their findings help expand understanding of both the psychological and technological conditions that foster fake news-sharing. Rather than blaming individuals for intentionally spreading misinformation, the study emphasizes how certain digital environments and habits make passive engagement with news more likely. </p>
<p>“Much of our mobile and social media use today is done without a lot of thinking or agency, and we increasingly rely on algorithms and online contacts to keep us informed,” Campbell said. “Under these conditions, people should heighten their awareness of media, to be more mindful and agentic, rather than passive, in constructing their information and communication environments.”</p>
<p>But as with all research, there are limitations to consider. The study relied on self-reported behaviors, which can be influenced by memory biases or social desirability. In addition, the participants were all drawn from a specific ideological group, which may limit how well the findings apply to the broader public. “Future research should use a more generalizable sample,” Campbell said.</p>
<p>“We have a follow-up study in press that shows how important it is to have an agentic mindset while using social media,” he added. “Having an agentic mindset helps makes users be more aware and active in their social media usen(i.e., less habitual), which hinders the ‘news-finds-me’ perception.”</p>
<p>The study, “<a href="https://doi.org/10.1016/j.chb.2025.108658" target="_blank">(Fake) news-finds-me: Interactive social and mobile media uses and incidental news reliance as antecedents of fake news-sharing</a>,” was authored by Ian Hawkins and Scott W. Campbell.</p></p>
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<td><a href="https://www.psypost.org/a-common-parasite-not-only-invades-the-brain-it-can-also-decapitate-human-sperm/" 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;">A common parasite not only invades the brain — it can also decapitate human sperm</a>
<div style="font-family:Helvetica, sans-serif; text-align:left;color:#999;font-size:11px;font-weight:bold;line-height:15px;">Jun 22nd 2025, 12:00</div>
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<p><p>Male fertility rates have been plummeting <a href="https://doi.org/10.1093/humupd/dmac035">over the past half-century</a>. An analysis from 1992 noted a steady decrease in sperm counts and quality <a href="https://doi.org/10.1136/bmj.305.6854.609">since the 1940s</a>. A more recent study found that male infertility rates <a href="https://doi.org/10.1186/s12889-023-16793-3">increased nearly 80% from 1990 to 2019</a>. The reasons driving this trend remain a mystery, but frequently cited culprits include <a href="https://doi.org/10.1097/mou.0000000000000745">obesity, poor diet and environmental toxins</a>.</p>
<p><a href="https://www.fertility-academy.co.uk/blog/7-stis-that-affect-male-fertility/">Infectious diseases</a> such as gonorrhea or chlamydia are often overlooked factors that affect fertility in men. Accumulating evidence suggests that a common single-celled parasite called <a href="https://www.cdc.gov/toxoplasmosis/about/index.html"><em>Toxoplasma gondii</em></a> may also be a contributor: An April 2025 study showed for the first time that “human sperm <a href="https://doi.org/10.1111/febs.70097">lose their heads</a> upon direct contact” with the parasite.</p>
<p>I am a microbiologist, and <a href="https://medicine.iu.edu/faculty/13502/sullivan-william">my lab studies <em>Toxoplasma</em></a>. This new study bolsters emerging findings that underscore the importance of preventing this parasitic infection.</p>
<h2>The many ways you can get toxoplasmosis</h2>
<p>Infected cats defecate <em>Toxoplasma</em> eggs into the litter box, garden or other places in the environment where they can be <a href="https://doi.org/10.1079/ahr2005100">picked up by humans or other animals</a>. <a href="https://doi.org/10.3390/foods11162542">Water, shellfish and unwashed fruits and vegetables</a> can also harbor infectious parasite eggs.</p>
<p>In addition to eggs, tissue cysts present in the meat of warm-blooded animals can spread toxoplasmosis as well if they are not destroyed by <a href="https://www.fda.gov/food/people-risk-foodborne-illness/toxoplasma-food-safety-moms-be">cooking to proper temperature</a>.</p>
<p>While most hosts of the parasite can control the initial infection with few if any symptoms, <em>Toxoplasma</em> remains in the body for life as <a href="https://doi.org/10.1111/j.1574-6976.2011.00305.x">dormant cysts in brain, heart and muscle tissue</a>. These cysts can reactivate and cause additional episodes of severe illness that damage critical organ systems.</p>
<p>Between <a href="https://doi.org/10.1371/journal.pone.0090203">30% and 50% of the world’s population</a> is permanently infected with <em>Toxoplasma</em> due to the many ways the parasite can spread.</p>
<h2><em>Toxoplasma</em> can target male reproductive organs</h2>
<p>Upon infection, <em>Toxoplasma</em> spreads to <a href="https://doi.org/10.1111/pim.12163">virtually every organ and skeletal muscle</a>. Evidence that <em>Toxoplasma</em> can also target human male reproductive organs first surfaced <a href="https://pubmed.ncbi.nlm.nih.gov/3755328">during the height of the AIDS pandemic</a> in the 1980s, when some patients presented with the <a href="https://doi.org/10.5812/jjm.7184">parasitic infection in their testes</a>.</p>
<p>While immunocompromised patients are most at risk for testicular toxoplasmosis, it can also occur in <a href="https://doi.org/10.1136/bcr-2018-224962">otherwise healthy individuals</a>. Imaging studies of infected mice confirm that <em>Toxoplasma</em> parasites <a href="https://doi.org/10.1111/j.1462-5822.2005.00517.x">quickly travel to the testes</a> in addition to the brain and eyes within days of infection.</p>
<p>In 2017, my colleagues and I found that <em>Toxoplasma</em> can also <a href="https://doi.org/10.1002/pros.23362">form cysts in mouse prostates</a>. Researchers have also observed these parasites in the <a href="https://doi.org/10.5812/jjm.7184">ejaculate of many animals</a>, including <a href="https://doi.org/10.1016/j.jinf.2022.10.034">human semen</a>, raising the possibility of <a href="https://doi.org/10.1016/j.mehy.2020.109725">sexual transmission</a>.</p>
<p>Knowing that <em>Toxoplasma</em> can reside in male reproductive organs has prompted analyses of fertility in infected men. A small 2021 study in Prague of 163 men infected with <em>Toxoplasma</em> found that <a href="https://doi.org/10.1111/andr.12969">over 86% had semen anomalies</a>.</p>
<p>A 2002 study in China found that <a href="https://pubmed.ncbi.nlm.nih.gov/12479125/">infertile couples are more likely</a> to have a <em>Toxoplasma</em> infection than fertile couples, 34.83% versus 12.11%. A 2005 study in China also found that <a href="https://pubmed.ncbi.nlm.nih.gov/16078665">sterile men are more likely to test positive</a> for <em>Toxoplasma</em> than fertile men.</p>
<p><a href="https://pubmed.ncbi.nlm.nih.gov/26622295/">Not all studies</a>, however, produce a link between toxoplasmosis and sperm quality.</p>
<h2><em>Toxoplasma</em> can directly damage human sperm</h2>
<p>Toxoplasmosis in animals mirrors infection in humans, which allows researchers to address questions that are not easy to examine in people.</p>
<p>Testicular function and sperm production are sharply diminished in <em>Toxoplasma</em>-infected <a href="https://doi.org/10.1371/journal.pone.0096770">mice</a>, <a href="https://doi.org/10.1016/j.exppara.2023.108571">rats</a> and <a href="https://doi.org/10.3390/pathogens9121004">rams</a>. Infected mice have significantly lower sperm counts and a higher proportion of <a href="https://doi.org/10.1016/j.celrep.2020.107573">abnormally shaped sperm</a>.</p>
<p>In that April 2025 study, researchers from Germany, Uruguay and Chile observed that <em>Toxoplasma</em> can reach the testes <a href="https://www.cancer.gov/publications/dictionaries/cancer-terms/def/epididymis">and epididymis</a>, the tube where sperm mature and are stored, <a href="https://doi.org/10.1111/febs.70097">two days after infection</a> in mice. This finding prompted the team to test what happens when the parasite comes into direct contact with human sperm in a test tube.</p>
<p>After only five minutes of exposure to the parasite, <a href="https://doi.org/10.1111/febs.70097">22.4% of sperm cells were beheaded</a>. The number of decapitated sperm increased the longer they interacted with the parasites. Sperm cells that maintained their head were often <a href="https://doi.org/10.1111/febs.70097">twisted and misshapen</a>. Some sperm cells had holes in their head, suggesting the parasites were trying to invade them as it would any other type of cell in the organs it infiltrates.</p>
<p>In addition to direct contact, <em>Toxoplasma</em> may also damage sperm because the infection promotes <a href="https://doi.org/10.1002/pros.23362">chronic inflammation</a>. Inflammatory conditions in the male reproductive tract are <a href="https://pubmed.ncbi.nlm.nih.gov/26913230/">harmful to sperm production and function</a>.</p>
<p>The researchers speculate that the harmful effects <em>Toxoplasma</em> may have on sperm could be contributing to large global declines in male fertility over the past decades.</p>
<h2>Preventing toxoplasmosis</h2>
<p>The evidence that <em>Toxoplasma</em> can infiltrate male reproductive organs in animals is compelling, but whether this produces health issues in people remains unclear. Testicular toxoplasmosis shows that parasites can invade human testes, but <a href="https://doi.org/10.1016/j.diagmicrobio.2025.116709">symptomatic disease is very rare</a>. Studies to date that show defects in the sperm of infected men are too small to draw firm conclusions at this time.</p>
<p>Additionally, some reports suggest that rates of toxoplasmosis in high-income countries <a href="https://doi.org/10.1016/j.pt.2022.10.003">have not been increasing</a> over the past few decades while male infertility was rising, so it’s likely to only be one part of the puzzle.</p>
<p>Regardless of this parasite’s potential effect on fertility, it is wise to avoid <em>Toxoplasma</em>. An infection can cause miscarriage or birth defects if someone acquires it for the first time during pregnancy, and it can be life-threatening for immunocompromised people.</p>
<p>Taking <a href="https://stacks.cdc.gov/view/cdc/23408">proper care of your cat</a>, promptly cleaning the litter box and thoroughly washing your hands after can help reduce your exposure to <em>Toxoplasma</em>. You can also protect yourself from this parasite by washing fruits and vegetables, <a href="https://www.foodsafety.gov/food-safety-charts/safe-minimum-internal-temperatures">cooking meat to proper temperatures</a> before consuming and avoiding <a href="https://doi.org/10.1086/605433">raw shellfish</a>, <a href="https://theconversation.com/how-does-raw-water-compare-to-tap-water-a-microbiologist-explains-why-the-risks-outweigh-the-benefits-246866">raw water</a> and <a href="https://doi.org/10.1001/jama.1982.03330140038029">raw milk</a>.</p>
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<p><em>This article is republished from <a href="https://theconversation.com">The Conversation</a> under a Creative Commons license. Read the <a href="https://theconversation.com/a-common-parasite-can-decapitate-human-sperm-with-implications-for-male-fertility-256892">original article</a>.</em></p></p>
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<p><strong>Forwarded by:<br />
Michael Reeder LCPC<br />
Baltimore, MD</strong></p>
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