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(https://www.psypost.org/depressive-women-are-less-consistent-in-use-of-contraceptives/) Depressive women are less consistent in use of contraceptives
Sep 5th 2024, 10:00

Recent research conducted in Germany explored the links between depression, pregnancy ambivalence, and contraceptive use among individuals who do not wish to become pregnant or conceive a child. Among women, more severe depressive symptoms were associated with less consistent contraceptive behaviors, while among men, higher pregnancy ambivalence was linked to less consistent use of contraceptives. The findings were published in Archives of Sexual Behavior.
Statistics show that one in three pregnancies in Germany is unintended. Overall, 47% of German women who have experienced pregnancy report having at least one unintended pregnancy in their lives. Unintended pregnancies are a significant focus of research because they tend to be associated with various negative outcomes for both the children born from such pregnancies and their parents. For example, studies show that children born from unwanted pregnancies often experience poorer physical and mental health. Women who become pregnant unintentionally are also at an increased risk of developing depression.
Unintended pregnancies primarily result from improper contraception. In the U.S., nonuse or inconsistent use of contraception accounts for around half of unintended pregnancies. Studies demonstrate that people suffering from depression are more likely to be inconsistent in their contraceptive use or to forgo it altogether.
Another factor that may contribute to inconsistent contraceptive use is pregnancy ambivalence. Pregnancy ambivalence refers to mixed or conflicting feelings about becoming or being pregnant, where an individual may simultaneously desire and fear pregnancy. In research studies, pregnancy ambivalence is often observed in individuals who report positive or neutral attitudes toward having a baby but are in situations unfavorable for pregnancy (e.g., being underage).
Study author Sina Kremer and her colleagues aimed to examine the link between inconsistent contraception, depression, and pregnancy ambivalence. They hypothesized that individuals with more severe depressive symptoms would tend to be less consistent in their contraceptive use over time. Their second hypothesis was that individuals with higher ambivalence scores would also be less consistent in their contraceptive use.
The researchers analyzed data from the second and third waves of the German Family Panel pairfam. The German Family Panel pairfam is an interdisciplinary study investigating partnerships and family living arrangements in Germany. It is conducted as a collaboration between the Universities of Bremen, Chemnitz, Mannheim, and the Ludwig Maximilian University of Munich. Launched in 2008-2009, the study adopts a multi-actor design, meaning it includes an anchor person and also interviews that person’s close others (partners, parents, children, etc.). It includes a Germany-wide random selection of over 12,000 anchor participants.
The data used in this study came from three groups of participants: those born between 1991 and 1993, between 1981 and 1983, and between 1971 and 1973. The study authors analyzed data from these individuals collected in 2009/2010 (wave 2) and 2010/2011 (wave 3).
>From these groups, the authors selected participants who did not have children and reported not having tried to conceive or become pregnant in the previous 12 months but had been sexually active within the three months prior to data collection. They selected a group of 95 individuals with depression who met these criteria and matched them on various characteristics with a group of 95 non-depressed individuals. The average age of participants was 24 years, and 92% were unmarried. Of these participants, 117 were women.
The participants completed an assessment of depression in wave 2 (using the State-Trait Depression Scale-Trait) and responded to questions that allowed the researchers to estimate pregnancy ambivalence (e.g., “If you disregard all obstacles for once: Ideally, how many children would you like to have in total?” and “Once you think realistically about children: how many children do you think you will have?”). Participants who expressed a desire to have more or fewer children than they believed they would have were considered ambivalent.
However, the authors included only responses indicating a desire to have more children than the participant realistically expected. Those believing they would have more children than they wanted were excluded. In wave 3, participants reported on their contraceptive behavior (“Have you used contraception in the past 3 months?” and “Please think about the last 3 months: How consistently did you use contraception?”).
Results showed that participants with depression were less consistent in their contraceptive behaviors compared to non-depressed participants. They also believed they would have fewer children. Pregnancy ambivalence did not affect the association between depressive symptoms and contraceptive behavior consistency.
When men and women were analyzed separately, results showed that men with higher levels of pregnancy ambivalence were less consistent in their contraceptive use, while this was not the case for women. On the other hand, depressed women were less consistent in their contraceptive use compared to non-depressed women, a trend not observed in men. Among men, there was no association between depression and contraceptive behavior consistency.
“This study addressed a very important point by examining the relationship between depressive symptoms and consistency of contraceptive behavior. The connection between these two factors has been shown many times and could now be replicated in a German sample; however, the effect is small. The present study thus lays an important foundation for further research in transnational samples,” the study authors concluded.
The study highlights two potentially important factors in unintended pregnancies. However, it should be noted that the study was conducted on a very small and selective group of participants. Additionally, contraceptive consistency was measured using only two self-reported items, which may have left room for reporting and recall bias.
The paper, “(https://doi.org/10.1007/s10508-024-02879-5) Depression, Contraception, and Ambivalence Concerning Fertility,” was authored by Sina Kremer, Alexander L. Gerlach, and Doris Erbe.

(https://www.psypost.org/new-study-shows-gut-microbiome-could-play-role-in-preventing-cognitive-decline/) New study shows gut microbiome could play role in preventing cognitive decline
Sep 5th 2024, 08:00

A new study published in (https://doi.org/10.1038/s41467-024-46116-y) Nature Communications suggests that a daily fiber supplement could improve brain function in older adults. Researchers found that in just 12 weeks, participants who took the supplement showed better performance in memory tests that are often used to detect early signs of Alzheimer’s disease. This placebo-controlled, double-blind trial was conducted on twins over the age of 65, offering insight into how gut microbiome interventions could benefit cognitive health in older adults.
As the global population ages, more people are experiencing cognitive decline, which often progresses into dementia. With rates of Alzheimer’s disease and other forms of dementia expected to rise, there is a growing interest in finding ways to preserve cognitive function in older adults. Currently, exercise and a healthy diet are known to slow some of the effects of aging, but many older adults face challenges in sticking to exercise routines.
In recent years, researchers have also started exploring the link between gut health and brain health, known as the gut-brain axis. The gut microbiome—the community of microbes in the digestive system—plays a critical role in overall health. Some research suggests that changes in the gut microbiome could contribute to conditions like Alzheimer’s disease, though the exact mechanisms are still being studied.
The new study aimed to test whether modulating the gut microbiome through a fiber supplement could improve cognitive function in older adults. The hope was that a simple and affordable intervention could help maintain or even improve brain health in an aging population.
“We know the gut microbiome plays a role in so many processes in the body, but we are still in the early stages of trying to really understand how this works. Ageing brings with it many challenges and we lack treatment options for many age-associated issues, such as the loss of muscle as we age, and changes in our cognition,” said study author Mary Ní Lochlainn, a NIHR clinical lecturer at King’s College London and specialist registrar in geriatric, stroke, and general internal medicine at Guy’s and St Thomas’ NHS Foundation Trust.
“The exciting thing is that the gut microbiome can be influenced from the outside (for example with prebiotics or probiotics), and so could be a target for treatments which aim to improve these age-associated conditions, a potential untapped resource!”
To test their hypothesis, the researchers conducted a randomized, placebo-controlled trial with 72 twins aged 65 or older. Using twins allowed them to control for genetic and environmental factors, making it easier to detect the effects of the fiber supplement. Half of the participants received a fiber supplement that included prebiotics—compounds that promote the growth of beneficial gut bacteria—while the other half received a placebo.
Participants were instructed to take one sachet of their assigned supplement each day for 12 weeks. The fiber supplement contained inulin and fructo-oligosaccharides, both of which are known to nourish beneficial bacteria in the gut. The placebo contained a simple carbohydrate, maltodextrin, which does not have the same prebiotic effects.
All participants were also encouraged to engage in resistance exercises, which have been shown to improve muscle strength and overall health in older adults. The study was conducted remotely, with participants completing cognitive tests and providing stool samples for gut microbiome analysis from their homes. The cognitive tests focused on memory and problem-solving skills, while the stool samples were used to assess changes in the gut microbiome over the course of the study.
After 12 weeks, the participants who took the fiber supplement showed significant improvements in memory tests compared to those who took the placebo. Specifically, they made fewer errors on a test called Paired Associates Learning, which measures visual memory and the ability to learn new information. This particular test is considered an early marker of Alzheimer’s disease, suggesting that the fiber supplement may have protective effects against cognitive decline.
“We knew the potential was there to see an improvement in cognition but the timeframe was surprising,” Lochlainn told PsyPost. “We weren’t sure whether 12 weeks was too short, and so we were pleasantly surprised to see some benefits in this relatively short time frame.”
The researchers also found changes in the gut microbiome of participants who took the fiber supplement. These participants had higher levels of Bifidobacterium, a type of bacteria known for its beneficial effects on gut health. Previous studies have suggested that Bifidobacterium may help reduce inflammation, which is believed to play a role in both cognitive decline and conditions like Alzheimer’s.
The findings indicate “that there is some evidence that a cheap fibrous prebiotic food supplement has the potential to improve cognition, and that it is well tolerated with minimal risk,” Lochlainn said.
However, despite these positive findings for brain health, the study did not find any significant differences in physical strength between the two groups. The researchers had hoped that the fiber supplement might also improve muscle function, but tests like chair-rise time and grip strength showed no notable differences.
While the results of the study are promising, there are several limitations that need to be considered. First, the study was relatively small, with only 72 participants. Although the twin design provided a strong control for genetic and environmental factors, larger studies are needed to confirm the findings. Additionally, the 12-week duration of the study may not have been long enough to fully assess the effects of the supplement on muscle strength, which can take longer to show measurable improvements.
“We really need larger scale studies before we can be sure how much of an effect these prebiotics have on cognition,” Lochlainn said.
Another limitation is the study’s focus on healthy older adults. Future research should explore whether the same intervention could benefit people with more advanced cognitive decline or those at higher risk for Alzheimer’s disease. The researchers also suggested that longer trials could provide more insight into how gut microbiome changes over time and whether sustained improvements in cognitive function can be achieved.
One important area for future research is determining the optimal dosage of fiber supplements for improving both cognitive and physical health. While the 7.5-gram dose used in this study was effective for improving cognition, it may not have been enough to impact muscle strength. Exploring different types of prebiotics and dosages could help identify the most effective interventions for older adults.
“We want to explore these supplements further, staying in the realm of ageing, but considering clinical populations, for example, to help older people build up further resilience for undergoing planned surgery,” Lochlainn explained.
“While we are still learning about the benefits of supplements which aim to target the bacteria in the gut, one thing we are sure of is the benefits of resistance exercise for staying healthy as we age,” she added. “The (https://www.nhs.uk/live-well/exercise/strength-exercises/) NHS website has a good selection of strength exercises, as well as balance exercises, which are a great place to start for anyone thinking about maintaining their independence into old age.”
The study, “(https://www.nature.com/articles/s41467-024-46116-y) Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial,” was authored by Mary Ni Lochlainn, Ruth C. E. Bowyer, Janne Marie Moll, María Paz García, Samuel Wadge, Andrei-Florin Baleanu, Ayrun Nessa, Alyce Sheedy, Gulsah Akdag, Deborah Hart, Giulia Raffaele, Paul T. Seed, Caroline Murphy, Stephen D. R. Harridge, Ailsa A. Welch, Carolyn Greig, Kevin Whelan, and Claire J. Steves.

(https://www.psypost.org/twitter-polls-exhibit-large-pro-trump-bias-but-these-researchers-have-a-fix/) Twitter polls exhibit large pro-Trump bias — but these researchers have a fix
Sep 5th 2024, 06:00

A recent study published in the (https://doi.org/10.51685/jqd.2024.icwsm.4) Journal of Quantitative Description: Digital Media examined polls conducted on X (more commonly known as Twitter) during the 2016 and 2020 U.S. presidential campaigns. The findings reveal that polls on this platform—particularly those gauging support for candidates—tend to have a significant bias in favor of Donald Trump. This bias appears to stem from the types of users engaging in the polls and the possible influence of inauthentic votes from bot accounts.
The rise of social media has revolutionized political discourse, turning platforms like Twitter into spaces where users can engage in real-time political conversations, share opinions, and even participate in informal polls. These “social polls” have gained popularity during election cycles, often amassing hundreds of thousands of votes. Despite their widespread use, there has been little scholarly attention paid to understanding the accuracy and reliability of these polls as indicators of public opinion.
Given the significant role social media plays in shaping political narratives, the researchers sought to understand the characteristics of Twitter polls, how biases affect their outcomes, and how these polls compare to more traditional polling methods. Their aim was to assess whether social polls can be used to gauge public opinion during elections and to uncover any patterns of bias that might influence the results.
“I’m fascinated by how we can better understand and predict public opinion. My dream is that one day we will be able to forecast and even prevent conflicts like wars,” explained study author Przemyslaw Grabowicz, an assistant professor at the University College Dublin, an adjunct professor at the University of Massachusetts Amherst, and a principal investigator at (https://socialpolls.org/#/home) Social Polls.
“This idea isn’t new. Isaac Asimov, the famous sci-fi writer, conceived the idea of psychohistory during the turmoil of World War II — a conflict that started with Nazi Germany’s attack on Poland, where I grew up. I’ve spent over 15 years studying sociophysics, computational social science, social computing, and algorithmic fairness. Social media polls on politically-relevant issues lie at the intersection of my research interests, which makes them an ideal topic for my studies.”
To carry out their study, the researchers collected Twitter polls during the months leading up to the elections. Using Twitter’s application programming interface (API), they extracted relevant data, including tweets that contained election-related keywords, such as the names of the candidates and the word “vote.”
This approach resulted in a large set of poll data, which was then refined to include only those polls that directly asked users about their voting preferences in either the 2016 or 2020 U.S. presidential elections. A total of 1,753 Twitter polls were deemed relevant for analysis, providing a snapshot of public opinion as expressed through this social media platform during both election cycles.
In addition to the polls themselves, the researchers also collected data about the users who participated in or engaged with the polls. This included information about the poll authors, retweeters, and users who favorited the polls, as well as the number of followers of these users. By doing this, the researchers were able to analyze the characteristics of the people who were likely interacting with the polls. Using advanced machine learning tools, the researchers inferred the demographic attributes of users, such as age, gender, and political orientation.
One of the main findings was that Twitter polls exhibited a strong bias towards Donald Trump, particularly in comparison to traditional election polls and the actual election outcomes. On average, Trump received significantly more support in Twitter polls than he did in traditional polls, with a 17% gap in 2020. This discrepancy was even more pronounced in the most popular polls, where Trump’s support sometimes reached up to 86%. The researchers attributed this bias to several factors, including the demographic skew of Twitter users and the presence of bots.
Twitter users who participated in these polls were not representative of the broader U.S. voting population. Twitter poll authors were more likely to be young, male, and conservative compared to the general population, which likely contributed to the overrepresentation of Trump supporters.
The researchers also found that poll participants—those who retweeted or favorited the polls—were even more likely to be conservative than the authors themselves. This skew toward right-leaning users helped explain the consistently higher support for Trump in the polls.
“Political polls on platforms like X (formerly Twitter) are increasingly used in political campaigning,” Grabowicz told PsyPost. “For example, on August 20, Elon Musk (https://x.com/elonmusk/status/1826015426658415033) created and Donald Trump (https://x.com/Jules31415/status/1826392365327941831) shared a poll showing Trump winning over Harris by a landslide, 73% to 27%, based on 5 million votes. However, such social polls often have a strong bias towards Trump, more so in 2024 than in 2020 or 2016, due to fake votes and respondents who aren’t representative of the US voting population. To be fair, traditional polls in the past decade also showed a bias, albeit slight–typically a few percentage points–towards Democratic candidates.”
Another important source of bias identified by the study was the presence of bot accounts. The researchers found that bot activity was particularly high among retweeters of political polls, with these automated accounts being four times more likely to retweet polls than human users. This suggested that some degree of astroturfing—artificial manipulation of political opinion—was occurring within the Twitter poll environment, further contributing to the skew in favor of Trump.
“In another (https://arxiv.org/abs/2405.11146) peer-reviewed study (accepted for publication at ICWSM’25), we found that X (formerly Twitter) correctly identifies fake votes purchased from external vendors but does not remove them from public vote counts,” Grabowicz explained. “We know this because X/Twitter did remove these fake votes from the private vote counts visible only to poll authors.”
“Additionally, we discovered that the fraction of fake votes was significantly larger before the election than after. While prior studies have shown that social media platforms can significantly impact democratic processes, the question remains: can these platforms have a positive impact if they are not impartial and free from manipulation?”
Interestingly, the researchers were (https://arxiv.org/html/2406.03340v1) able to correct the bias in social media poll by using a statistical techniques called regression with poststratification. This approach involves first using a regression model to account for biases in the data based on demographic and political characteristics of Twitter users, such as age, gender, and political ideology.
Poststratification was applied to adjust the poll outcomes by reweighting the data to match the broader U.S. population’s demographics and political makeup, similar to methods used in traditional polling. This approach reduced the error margin of Twitter poll predictions to as low as 1-2%, showing that, with proper corrections, social media polls can become a more reliable source of public opinion.
“It is remarkable how accurate bias-corrected social polls can be,” Grabowicz said. “Our live website, (https://socialpolls.org/#/home) socialpolls.org, tracks thousands of both social and traditional polls and demonstrates that these biases can be corrected to provide more accurate estimates of public support for presidential candidates.”
Future research could expand on this study in several ways. One potential avenue is to investigate the motivations behind social polling—why do people create and participate in these polls, and how do their perceptions of public opinion influence their voting behavior? Another interesting area for exploration is the impact of social polls on offline political mobilization—can participating in a Twitter poll encourage people to vote in real-world elections? Lastly, researchers could explore how social polling varies across different platforms, such as Facebook or Instagram, and across different political systems, including non-U.S. elections.
“We’re excited to discover the uncharted world of social media polls, but our studies are just the tip of the iceberg,” Grabowicz told PsyPost. “There is still much to learn, particularly about how exposures to biased polls affect perceptions of public opinion and how accurately bias-corrected polls reflect true public support. More research is needed to understand these complexities and to improve the reliability of social media polling as a tool for measuring public support.”
“Our long-term goal is to develop accurate forecasting models for major elections and to better understand the dynamics of public opinion. By improving how we measure and interpret social media polls, we aim to provide more reliable insights into electoral trends and voter behavior, ultimately contributing to more informed democratic processes.”
The study, “(https://journalqd.org/article/view/5897) Analyzing Support for U.S. Presidential Candidates in Twitter Polls,” was authored by Stephen Scarano, Vijayalakshmi Vasudevan, Mattia Samory, Junghwan Yang, and Przemyslaw A. Grabowicz.

(https://www.psypost.org/scientists-uncover-brain-circuit-that-balances-eating-for-necessity-and-eating-for-pleasure/) Scientists uncover brain circuit that balances eating for necessity and eating for pleasure
Sep 4th 2024, 20:00

Researchers have uncovered new insights into how the brain controls eating behavior, which could have significant implications for tackling obesity. Their study, published in (https://www.nature.com/articles/s42255-024-01099-4) Nature Metabolism, shows that certain neurons in the brains of mice can either promote eating due to hunger or suppress eating for pleasure, depending on the circumstances. These findings offer a deeper understanding of how different types of eating are regulated in the brain and could lead to new treatments for obesity.
The motivation behind this study stems from the need to understand the dual nature of eating: eating out of necessity (because of hunger) and eating for pleasure (often linked to the consumption of calorie-dense, sugary, or fatty foods). While hunger-driven eating is essential for survival, pleasure-driven eating is often associated with overeating and the development of obesity, along with related metabolic disorders.
Despite the significant public health implications of obesity, the neural mechanisms that control these different types of eating behaviors have remained largely unclear. This study aimed to shed light on these mechanisms, specifically focusing on a group of neurons identified by the proenkephalin marker in the diagonal band of Broca, a region of the mouse brain.
The research team focused on neurons in the diagonal band of Broca (DBB) of male mice. These neurons are marked by a protein called proenkephalin, which is involved in the body’s opioid system and has been linked to feeding behavior in previous studies. The researchers wanted to determine whether these neurons play a role in regulating hunger-driven and pleasure-driven eating differently.
To do this, they used a variety of techniques, including optogenetics, a method that allows scientists to control neurons with light. By activating or deactivating specific groups of neurons, they could observe how these changes affected the eating behavior of the mice. The researchers also used advanced imaging techniques to track the activity of these neurons in real-time as the mice were exposed to different types of food under different conditions, such as during hunger or when presented with high-fat, high-sugar (HFHS) foods.
In their experiments, they found that DBB proenkephalin neurons could be divided into two subgroups based on where their projections led within the brain. One group of neurons projected to the paraventricular nucleus of the hypothalamus (PVH), a brain region involved in hunger regulation. The other group projected to the lateral hypothalamus (LH), which is known to be involved in pleasure-driven eating.
When the neurons projecting to the PVH were activated, the mice were more likely to eat regular chow, especially when they were hungry. This suggests that these neurons help promote hunger-driven feeding, making sure that the body gets the energy it needs when it is running low on fuel.
On the other hand, the neurons projecting to the LH had the opposite effect when it came to pleasure-driven eating. Activation of these neurons decreased the consumption of high-fat, high-sugar foods, even when these foods were freely available and typically very appealing to the mice. This indicates that these neurons can suppress pleasure-driven eating, potentially acting as a brake to prevent overeating.
“Ideal feeding habits would balance eating for necessity and for pleasure, minimizing the latter,” said co-corresponding author Yong Xu, a professor of pediatrics and associate director for basic sciences at the USDA/ARS Children’s Nutrition Research Center at Baylor College of Medicine. “In this study we identified a group of neurons that regulates balanced feeding in the brain.”
Further investigation showed that these effects were linked to how the neurons were wired into different brain circuits. The PVH-projecting neurons were specifically active when food was presented during periods of fasting, which aligns with the idea that they promote hunger-driven eating. Conversely, the LH-projecting neurons became active when the mice were presented with high-calorie foods, but instead of encouraging eating, they inhibited it. This was a surprising discovery because it was previously thought that neurons in this area of the brain would promote pleasure-driven feeding rather than suppress it.
“A subset of DBB-Penk neurons that projects to the paraventricular nucleus of the hypothalamus is preferentially activated upon food presentation during fasting periods, facilitating hunger-driven feeding,” Xu said. “On the other hand, a separate subset of DBB-Penk neurons that projects to a different brain region, the lateral hypothalamus, is preferentially activated when detecting high-fat, high-sugar (HFHS) foods and inhibits their consumption. This is the first study to show a neural circuit that is activated by a reward, HFHS, but leads to terminating instead of continuing the pleasurable activity.”
When the researchers disabled the entire population of DBB proenkephalin neurons in some mice, the results were dramatic. These mice, when given the choice between regular chow and high-fat, high-sugar foods, ate less chow and more of the HFHS diet, leading to rapid weight gain and the onset of obesity-related metabolic issues. This finding underscores the importance of these neurons in maintaining a balance between hunger-driven and pleasure-driven eating.
The study concludes that these DBB proenkephalin neurons play a critical role in controlling eating behavior by either promoting hunger-driven eating or suppressing pleasure-driven eating. The balance between these two types of eating is crucial for maintaining a healthy body weight and metabolism. The researchers suggest that disruptions in this balance could contribute to obesity and other metabolic disorders.
“Our findings indicate that the development of obesity is associated with impaired function of some of these brain circuits in mice,” Xu said. “We are interested in further investigating molecular markers within the circuits that could be suitable targets for treatment of human diseases such as obesity.”
The study, “(https://www.nature.com/articles/s42255-024-01099-4) Distinct basal forebrain-originated neural circuits promote homoeostatic feeding and suppress hedonic feeding in male mice,” was authored by Hailan Liu, Jonathan C. Bean, Yongxiang Li, Meng Yu, Olivia Z. Ginnard, Kristine M. Conde, Mengjie Wang, Xing Fang, Hesong Liu, Longlong Tu, Na Yin, Junying Han, Yongjie Yang, Qingchun Tong, Benjamin R. Arenkiel, Chunmei Wang, Yang He, and Yong Xu.

(https://www.psypost.org/microplastics-discovered-in-human-brains-for-the-first-time-what-it-means-for-our-health/) Microplastics discovered in human brains for the first time: What it means for our health
Sep 4th 2024, 18:00

Plastic is in our clothes, cars, mobile phones, water bottles and food containers. But recent research adds to growing concerns about the impact of tiny plastic fragments on our health.
A (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11100893/) study from the United States has, for the first time, found microplastics in human brains. The study, which has yet to be independently verified by other scientists, has been described in the media as (https://people.com/study-microplastics-found-in-brain-tissue-liver-kidneys-and-lungs-8700882) scary, (https://futurism.com/neoscope/percentage-brains-microplastics) shocking and (https://www.ecowatch.com/microplastics-contamination-human-brain-health.html) alarming.
But what exactly are microplastics? What do they mean for our health? Should we be concerned?
What are microplastics? Can you see them?
We often consider plastic items to be indestructible. But plastic breaks down into (https://www.epa.gov/water-research/microplastics-research) smaller particles. Definitions vary but generally microplastics are smaller than five millimetres.
This makes some too small to be seen with the naked eye. So, many of the images the media uses to illustrate articles about microplastics are misleading, as some show much larger, clearly visible pieces.
Microplastics have been reported in many sources of (https://www.sciencedirect.com/science/article/pii/S0043135419301794) drinking water and (https://www.sciencedirect.com/science/article/pii/S0048969722069340?casa_token=VSEsoEXWnjQAAAAA:M1PYZLjEQtqb1bojduo6awulmd6rOwvva6pAhq0aJK_Zv7DZmTGRUAf18BHqM67lgLC7tRNOkw) everyday food items. This means we are constantly exposed to them in our diet.
Such widespread, chronic (long-term) exposure makes this a serious concern for human health. While research investigating the potential risk microplastics pose to our health is limited, (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10038118/) it is growing.
How about this latest study?
The (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11100893/) study looked at concentrations of microplastics in 51 samples from men and women set aside from routine autopsies in Albuquerque, New Mexico. Samples were from the liver, kidney and brain.
These tiny particles are difficult to study due to their size, even with a high-powered microscope. So rather than trying to see them, researchers are beginning to use complex instruments that identify the chemical composition of microplastics in a sample. This is the technique used in this study.
The researchers were surprised to find up to 30 times more microplastics in brain samples than in the liver and kidney.
They hypothesised this could be due to high blood flow to the brain (carrying plastic particles with it). Alternatively, the liver and kidneys might be better suited to dealing with external toxins and particles. We also know the brain does not undergo the same amount of cellular renewal as other organs in the body, which could make the plastics linger here.
The researchers also found the amount of plastics in brain samples increased by about 50% between 2016 and 2024. This may reflect the rise in environmental plastic pollution and increased (https://www.unep.org/interactives/beat-plastic-pollution/) human exposure.
The microplastics found in this study were mostly composed of polyethylene. This is the most (https://doi.org/10.1016/B978-0-323-37100-1.00002-8) commonly produced plastic in the world and is used for many everyday products, such as bottle caps and plastic bags.
This is the first time microplastics have been found in human brains, which is important. However, this study is a “pre-print”, so other independent microplastics researchers haven’t yet reviewed or validated the study.
How do microplastics end up in the brain?
Microplastics typically enter the body through contaminated food and water. This can disrupt the (https://www.sciencedirect.com/science/article/pii/S0304389423020848?via%3Dihub) gut microbiome (the community of microbes in your gut) and cause inflammation. This leads to effects in the whole body via the immune system and the complex, two-way communication system between the gut and the brain. This so-called (https://www.mdpi.com/1467-3045/46/5/256) gut-brain axis is implicated in many aspects of health and disease.
We can also (https://www.sciencedirect.com/science/article/pii/S0304389421010888) breathe in airborne microplastics. Once these particles are in the gut or lungs, they can move into the bloodstream and then travel around the body into (https://www.sciencedirect.com/science/article/pii/S030438942201932X?via%3Dihub) various organs.
Studies have found microplastics in human (https://doi.org/10.1021/acs.est.1c03924) faeces, (https://doi.org/10.1016/j.jhazmat.2023.132640) joints, (https://doi.org/10.1016/j.ebiom.2022.104147) livers, (https://doi.org/10.1016/j.scitotenv.2023.167760) reproductive organs, (https://doi.org/10.1016/j.envint.2022.107199) blood, (https://doi.org/10.1371/journal.pone.0280594) vessels and (https://doi.org/10.1021/acs.est.2c07179) hearts.
Microplastics also migrate to the brains of (https://pubmed.ncbi.nlm.nih.gov/36711285/) wild fish. In (https://doi.org/10.1016/j.jhazmat.2022.128431) mouse studies, ingested microplastics are absorbed from the gut into the blood and can enter the brain, becoming lodged in other (https://www.nature.com/articles/srep46687) organs along the way.
To get into brain tissue, microplastics must cross the (https://theconversation.com/our-blood-brain-barrier-stops-bugs-and-toxins-getting-to-our-brain-heres-how-it-works-230965) blood-brain-barrier, an intricate layer of cells that is supposed to keep things in the blood from entering the brain.
Although concerning, this is not surprising, as microplastics must cross similar cell barriers to enter the (https://www.mdpi.com/2305-6304/11/1/40) urine, (https://doi.org/10.1016/j.scitotenv.2023.165922) testes and (https://doi.org/10.1016/j.chemosphere.2023.140301) placenta, where they have already been found in humans.
Is this a health concern?
We don’t yet know the effects of microplastics in the human brain. Some laboratory experiments suggest microplastics increase (https://www.sciencedirect.com/science/article/pii/S0045653522007548) brain inflammation and (https://www.sciencedirect.com/science/article/pii/S001393512301215X?via%3Dihub) cell damage, alter (https://particleandfibretoxicology.biomedcentral.com/articles/10.1186/s12989-020-00358-y) gene expression and change (https://www.sciencedirect.com/science/article/pii/S0304389421027849) brain structure.
Aside from the effects of the microplastic particles themselves, microplastics might also pose risks if they carry (https://www.sciencedirect.com/science/article/pii/S0269749123021929) environmental toxins or (https://doi.org/10.1007/s10661-023-11890-7) bacteria  into and around the body.
(https://annalsofglobalhealth.org/articles/10.5334/aogh.4459?_rsc=13r6v) Various plastic chemicals could also leach out of the microplastics into the body. These include the famous (https://theconversation.com/science-shows-that-bpa-and-other-endocrine-disruptors-are-harmful-to-human-health-which-should-incite-tighter-regulations-178872) hormone-disrupting chemicals known as BPAs.
But microplastics and their effects are difficult to study. In addition to their small size, there are so many different types of plastics in the environment. More than (https://www.unep.org/resources/report/chemicals-plastics-technical-report) 13,000 different chemicals have been identified in plastic products, with more being developed every year.
Microplastics are also weathered by the environment and digestive processes, and this is hard to reproduce in the lab.
A goal of our research is to understand how these factors change the way microplastics behave in the body. We plan to investigate if improving the integrity of the gut barrier through diet or probiotics can prevent the uptake of microplastics from the gut into the bloodstream. This may effectively stop the particles from circulating around the body and lodging into organs.
How do I minimise my exposure?
Microplastics are widespread in the environment, and it’s difficult to avoid exposure. We are just (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10038118/) beginning to understand how microplastics can affect our health.
Until we have more scientific evidence, the best thing we can do is reduce our (https://www.cspinet.org/cspi-news/reduce-plastic-use-home-planets-health-and-ours) exposure to plastics where we can and (https://www.aph.gov.au/Parliamentary_Business/Committees/House/Climate_Change_Energy_Environment_and_Water/Plasticpollution/Report/Chapter_3_-_A_national_approach_to_reducing_plastic_pollution) produce less plastic waste, so less ends up in the environment.
An easy place to start is to avoid foods and drinks packaged in single-use plastic or reheated in plastic containers. We can also minimise exposure to synthetic fibres in our home and clothing.
 
This article is republished from (https://theconversation.com) The Conversation under a Creative Commons license. Read the (https://theconversation.com/microplastics-are-in-our-brains-how-worried-should-i-be-237401) original article.

(https://www.psypost.org/humans-are-the-exception-new-research-reveals-surprising-brain-size-trends-across-mammals/) Humans are the exception: New research reveals surprising brain size trends across mammals
Sep 4th 2024, 16:00

A recent study has upended a long-held assumption in biology: the idea that brain size increases proportionally with body size across all animals. While this relationship has been widely accepted for over a century, new research published in (https://doi.org/10.1038/s41559-024-02451-3) Nature Ecology and Evolution reveals that it is not as straightforward as once believed. The study shows that larger animals do not necessarily have proportionally larger brains, with humans being a significant exception to this rule.
For decades, scientists have worked under the assumption that there was a linear relationship between an animal’s brain size and its body size. This assumption has been foundational to many theories about animal intelligence, social behavior, and evolution. The basic idea was that as animals grew larger, their brains would increase in size at a consistent rate relative to their body.
However, there has been considerable debate about this assumption, particularly when it comes to large animals like elephants and whales, which have brains that seem disproportionately small compared to their massive bodies. The researchers aimed to resolve this controversy by conducting a comprehensive analysis across a wide range of mammalian species. They hoped to determine whether the relationship between brain and body size was indeed linear or if it followed a more complex pattern.
To explore this question, the researchers gathered a vast amount of data on brain and body sizes from over 1,500 species of mammals. This dataset included measurements of both brain mass and body mass, collected from a variety of sources. The researchers were meticulous in their efforts to ensure that the data were accurate and comparable across species. For instance, they prioritized brain mass measurements over brain volume, as mass is a more direct indicator of the amount of neural tissue. Additionally, they aimed to use data where both brain and body sizes were measured from the same individuals to ensure consistency.
With this data in hand, the researchers used advanced statistical models to analyze the relationship between brain and body size. These models allowed them to test whether the relationship was indeed linear or if it followed a different pattern. They also looked for variation in the rate of brain size evolution across different groups of mammals, such as primates, rodents, and carnivores. By doing so, they could identify which species followed the expected trend and which deviated from it.
Rather than finding a simple linear relationship between brain and body size, the researchers discovered that the relationship is actually a curve. This means that as animals become larger, their brains do not increase in size as quickly as their bodies do. In other words, very large animals have smaller brains than would be expected if the relationship were truly linear.
This finding was consistent across all the mammals studied, with some notable exceptions. For example, humans, primates, rodents, and carnivores all showed unique patterns of brain evolution. Humans, in particular, were found to be outliers, with brain sizes that have evolved much faster than those of other mammals. This rapid evolution has resulted in the large brains that characterize our species today.
“For more than a century, scientists have assumed that this relationship was linear – meaning that brain size gets proportionally bigger, the larger an animal is,” explained Chris Venditti, lead author of the study from the University of Reading. “We now know this is not true. The relationship between brain and body size is a curve, essentially meaning very large animals have smaller brains than expected.”
“Our results help resolve the puzzling complexity in the brain-body mass relationship,” added Rob Barton, co-author of the study from Durham University. “Our model has a simplicity that means previously elaborate explanations are no longer necessary – relative brain size can be studied using a single underlying model.”
The researchers also identified that bats, which are among the smaller mammals, have undergone rapid changes in brain size early in their evolution, but their brain sizes have remained relatively stable since then. This suggests that there may be evolutionary constraints related to the demands of flight that limit brain size in bats.
In contrast, the study found that three groups of mammals—primates, rodents, and carnivores—have consistently shown increases in brain size relative to their body size over time. This phenomenon is known as the Marsh-Lartet rule, which posits a trend toward increasing relative brain mass through time. However, this trend was not observed across all mammals, indicating that it is not a universal pattern as previously believed.
One of the most intriguing findings from the study is the identification of what the researchers called a “curious ceiling” in brain size. In the largest animals, there seems to be a limit preventing brains from getting too large. This ceiling might be due to the high energy costs associated with maintaining a large brain, though the exact cause remains unclear. Interestingly, similar patterns were observed in birds, suggesting that this phenomenon may be widespread among animals with very different biological makeups.
“Our results reveal a mystery,” said Joanna Baker, co-author of the study from the University of Reading. “In the largest animals, there is something preventing brains from getting too big. Whether this is because big brains beyond a certain size are simply too costly to maintain remains to be seen. But as we also observe similar curvature in birds, the pattern seems to be a general phenomenon – what causes this ‘curious ceiling’ applies to animals with very different biology.”
The study, “(https://www.nature.com/articles/s41559-024-02451-3) Co-evolutionary dynamics of mammalian brain and body size,” was authored by Chris Venditti, Joanna Baker, and Robert A. Barton.

(https://www.psypost.org/parents-concerns-about-future-reproduction-shape-their-reactions-to-a-childs-sexual-orientation-disclosure/) Parents’ concerns about future reproduction shape their reactions to a child’s sexual orientation disclosure
Sep 4th 2024, 14:00

New research published in (https://doi.org/10.1007/s10508-024-02945-y) Archives of Sexual Behavior found that parental negativity toward their child disclosing a minoritized sexual orientation may be influenced by reproductive concerns.
Previous research has shown that many parents respond negatively when their child comes out as lesbian, gay, or bisexual (LGB), with reactions ranging from disappointment to outright rejection. This negativity has been linked to various risk factors, including parental religiosity, family stress, and traditional views on gender and reproduction. However, most of this research has relied on correlational methodologies, limiting the ability to determine causal relationships.
Danielle J. DelPriore and colleagues sought to explore a potentially modifiable psychological factor that could be influencing these negative reactions: parental concerns about their children’s reproductive outcomes.
Building on evolutionary theory, which suggests that parents are invested in their children’s reproductive success as a way to pass on their genes, the researchers hypothesized that parents might respond negatively to their child’s disclosure of a minoritized sexual orientation because they perceive it as a threat to their child’s reproductive potential.
Previous studies have indicated that same-gender attraction is associated with lower reproductive intentions, which might heighten parental concerns about their own genetic legacy.
In Study 1, the researchers recruited 386 parents (192 mothers and 194 fathers) with children under age 6 through Prolific Academic. Participants were all cisgender and heterosexual, with the majority identifying as non-Hispanic White. To measure reproductive concerns, participants completed a survey that included five items adapted from the Life Role Salience Scales, such as “I would feel disappointed if my child[ren] chose to not have children of their own.”
Attitudes toward having an LGB child were assessed using four items that reflected negative attitudes, such as “I would prefer that my child not be gay/lesbian/bisexual because she/he could not get married.” Expected initial reactions to a hypothetical LGB disclosure by their child were measured using nine questions adapted from the Perceived Parental Reactions Scale, asking participants to rate how they would respond to their child disclosing an LGB orientation.
Additionally, parents’ beliefs about the possibility of LGB reproduction were assessed with three items developed for this study, measuring how likely parents believed it was for someone who is gay, lesbian, or bisexual to have a biological child.
In Study 2, the researchers tested whether providing information about reproductive assistance available to same-gender couples would influence mothers’ attitudes toward their child’s potential LGB orientation. They recruited 327 cisgender heterosexual mothers with young children (under age six) from Prolific Academic.
Participants were randomly assigned to one of two conditions: the experimental group read an article about reproductive assistance (e.g., in vitro fertilization, artificial insemination) emphasizing the ease and accessibility of these procedures, while the control group read an article about genetically modified tomatoes, which was unrelated to reproductive issues. After reading the assigned article, participants completed the same set of measures used in Study 1.
Study 3 replicated the experimental design of Study 2 but focused on fathers rather than mothers. A total of 279 cisgender heterosexual fathers were recruited, and the procedures were similar to those used in Study 2. The participants were again randomly assigned to read either the reproductive assistance article or the control article about genetically modified tomatoes. After reading their assigned article, fathers completed the same measures as in the previous studies.
In Study 1, the researchers found that parental reproductive concerns were significantly associated with more negative attitudes and expected reactions toward their child’s hypothetical LGB disclosure. Parents who had higher concerns about their children’s reproductive outcomes—such as the possibility that their child might not have children of their own—were more likely to report negative views toward their child potentially identifying as LGB.
Parents who believed that LGB individuals would face significant reproductive challenges or were less likely to have biological children expressed more negative attitudes. This suggests that parents’ pessimistic beliefs about the reproductive possibilities for LGB individuals exacerbate the negative impact of their reproductive concerns on their attitudes toward their child’s sexual orientation.
In Study 2, the experimental manipulation showed that mothers who read the article about reproductive assistance available to same-gender couples reported significantly more positive attitudes toward having an LGB child compared to those who read the control article. Exposure to information about the availability of reproductive options for LGB individuals led to a reduction in the negativity of mothers’ attitudes toward the possibility of their child being LGB.
Mothers who were informed about reproductive assistance were more optimistic about the reproductive potential of LGB individuals, which in turn led to more positive attitudes toward their child’s potential LGB orientation and a greater acceptance of the LGB community as a whole.
Study 3 extended these findings to fathers, showing that fathers who received information about reproductive assistance also reported more positive attitudes toward having an LGB child and less negative expected initial reactions compared to those who read the control article. Similar to the findings in Study 2, fathers who were informed about reproductive assistance held more optimistic beliefs about the reproductive possibilities for LGB individuals, which led to more favorable attitudes and a reduction in anticipated negative reactions.
Overall, the findings suggest that reproductive concerns play a significant role in shaping parental negativity toward their child’s disclosure of a minoritized sexual orientation. Alleviating these concerns through information about reproductive assistance could be a potential strategy for improving parental attitudes and fostering more supportive family environments.
Notably, the studies focused on parents’ expected reactions to hypothetical disclosures rather than actual reactions, which may limit the generalizability of the findings to real-world situations.
The research “(https://doi.org/10.1007/s10508-024-02945-y) Parents’ Reproductive Concerns and Negativity Toward Their Child Disclosing a Minoritized Sexual Orientation”, was authored by Danielle J. DelPriore, Olivia Ronan, and Pamela Lantz.

(https://www.psypost.org/family-based-foster-care-reduces-irritability-in-teens-exposed-to-early-psychosocial-deprivation-study-finds/) Family-based foster care reduces irritability in teens exposed to early psychosocial deprivation, study finds
Sep 4th 2024, 12:00

A recent study published in the journal (https://link.springer.com/article/10.1007/s10802-024-01193-x) Research on Child and Adolescent Psychopathology has found that adolescents with a history of early psychosocial deprivation exhibit lower levels of irritability when placed in high-quality, family-based foster care. The study also found that adolescents who spent more time in institutional care or were not placed with a family by the age of 16 showed higher levels of irritability. These findings underline the importance of stable, family-based placements in mitigating the effects of early adverse experiences on irritability, a condition that can lead to various negative outcomes during adolescence.
Irritability is a common issue among adolescents and is characterized by frequent and intense anger and frustration. It is associated with a range of negative outcomes, including difficulties in relationships, academic challenges, and an increased risk of mental health problems. Understanding the factors that influence irritability is crucial, particularly because it is linked to both external behaviors, like aggression, and internal struggles, such as anxiety and depression.
Researchers have long known that early adverse experiences, such as neglect or lack of stable caregiving, can increase the risk of developing irritability. However, there has been less clarity on whether positive caregiving experiences, such as those provided in high-quality foster care, can reduce irritability, particularly following severe early deprivation. This study aimed to address this gap by examining the long-term effects of foster care on irritability in adolescents who had been exposed to early psychosocial deprivation.
“Irritability is linked to a wide range of adverse outcomes in children and adolescents, including relationship difficulties and suicidal risk. Given the significant public health implications of irritability, it is important to investigate potential risk factors that may contribute to its development,” explained study author (http://www.vusealab.com/) Kathryn L. Humphreys, an associate professor of psychology and human development at Vanderbilt University.
The study was part of (https://www.bucharestearlyinterventionproject.org/) the Bucharest Early Intervention Project, a landmark randomized controlled trial that began in the early 2000s. The trial was designed to evaluate the impact of foster care as an alternative to institutional care for young children living in orphanages in Bucharest, Romania.
Participants included 136 children who were initially living in institutions. These children, all under the age of 31 months at the start of the study, were randomly assigned to one of two groups: a high-quality foster care group or a care-as-usual group, where they continued to live in institutional settings. An additional group of 72 children who had never experienced institutional care was recruited from the community to serve as a comparison.
At the age of 16, the adolescents were assessed for irritability using the Affective Reactivity Index, a widely used measure that captures the frequency and intensity of irritability over the past six months. Both the adolescents and their caregivers completed this measure. The researchers also gathered information about the participants’ caregiving histories, including how long they had spent in institutional care, their age at placement into foster care, and whether they were currently living with a family.
The study found that adolescents who had been in institutional care exhibited significantly higher levels of irritability compared to those who had never been institutionalized. However, among those with a history of institutionalization, those who were placed in high-quality foster care had lower levels of irritability than those who remained in institutional care.
Specifically, the study found that the duration of time spent in institutional care was directly related to higher levels of irritability. Adolescents who had spent more time in institutional care were more irritable, but this relationship was not linear. The researchers observed that after a certain point, additional time spent in institutional care did not further increase irritability, suggesting a saturation effect.
The researchers also discovered that adolescents who were still living in a family setting at age 16, whether with their biological family, an adoptive family, or a foster family, showed lower irritability compared to those who were not in a family setting. Additionally, while the age at which children were placed into foster care did not significantly impact irritability, those who experienced more stable foster care placements tended to be less irritable.
“Our findings suggest that irritability can be shaped by one’s family environment,” Humphreys told PsyPost. “Using a randomized controlled trial design, we were able to determine that children who experienced high-quality family-based care had lower levels of irritability compared to those who spent a greater amount of time living in orphanages/institutional care.”
“This highlights that enhancing the caregiving environment, rather than just alleviating symptoms, may be particularly impactful in reducing irritability and its associated negative outcomes. Further, at a societal level it supports policies that promote stable family placements for children without regular caregivers.”
While the findings are compelling, the study has a few limitations that should be considered. First, the sample size, though substantial for a study of this nature, was still relatively small, limiting the ability to explore more detailed questions, such as whether the effects of foster care differ between boys and girls.
“One additional point worth noting is that, while the randomized controlled trial design of the Bucharest Early Intervention Project allows us to make causal inferences about the impact of the foster care intervention, the observational analyses exploring factors such as stability of placements and time spent in institutional care are correlational in nature,” Humphreys explained. “As such, we cannot rule out the possibility of reverse causality, where individual predispositions in child irritability may shape the caregiving environment over time. Disentangling these complex, transactional processes will be an important focus of future research.”
In terms of future research, the authors suggest that it would be valuable to investigate the underlying mechanisms by which early caregiving environments influence irritability.
“Our long-term goals are to further elucidate the mechanisms by which early caregiving environments shape the development of irritability and related psychopathology,” Humphreys explained. “This may involve examining the neurobiological underpinnings of irritability, as well as investigating how specific aspects of the caregiving environment (e.g., responsiveness, emotion socialization) contribute to its trajectories. Ultimately, we hope that this line of research will inform the development of family-based interventions to prevent and treat irritability and its associated negative outcomes.”
The study, “(https://doi.org/10.1007/s10802-024-01193-x) Foster Care Leads to Lower Irritability Among Adolescents with a History of Early Psychosocial Deprivation,” was authored by Yanbin Niu, George A. Buzzell, Ana Cosmoiu, Nathan A. Fox, Charles A. Nelson, Charles H. Zeanah, and Kathryn L. Humphreys.

Forwarded by:
Michael Reeder LCPC
Baltimore, MD

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