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(https://www.psypost.org/hallucinogen-related-er-visits-linked-to-higher-risk-of-schizophrenia-study-finds/) Hallucinogen-related ER visits linked to higher risk of schizophrenia, study finds
Apr 2nd 2025, 10:00

People who visit emergency rooms after using hallucinogenic drugs may face a higher risk of developing schizophrenia spectrum disorders, a new study published in (https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2825649) JAMA Psychiatry suggests.
Hallucinogenic drugs such as LSD and MDMA have gained renewed interest in recent years, with growing attention to their potential therapeutic benefits. Some studies suggest that psychedelics could help treat conditions like alcohol use disorder and PTSD. However, concerns remain about potential mental health risks, particularly when these substances are used outside supervised clinical settings.
While previous studies have hinted at a possible link between hallucinogen use and psychosis, they were often limited by small sample sizes, highlighting the need for larger population-based research. In response, researchers set out to examine whether hallucinogen use might increase the risk of developing psychosis and schizophrenia spectrum disorders—a group of conditions marked by hallucinations, delusions, and disorganized thinking.
To conduct the study, a team led by Daniel T. Myran from the Ottawa Hospital Research Institute in Canada analyzed emergency department data from 9,244,292 individuals aged 14 to 65 years (50% female) in Ontario.
Among them, 5,217 individuals (0.1%) had an emergency visit related to hallucinogen use. These individuals were tracked over time—on average, for about five years—to see whether they later received a diagnosis of a schizophrenia spectrum disorder (SSD).
Statistical analysis revealed that people who had an emergency department visit involving hallucinogen use were 21 times more likely to develop an SSD within three years, compared to the general population.
Even after accounting for factors like age, sex, income, prior mental health conditions, and use of other substances, individuals with a hallucinogen-related ED visit still had a 3.5 times greater risk of developing an SSD.
The researchers also compared outcomes to people who had emergency visits related to other substances. Those who had ED visits involving hallucinogens faced a significantly higher risk of developing schizophrenia or a related disorder within three years compared to those with ED visits involving alcohol (4.7 times higher risk) and cannabis (1.5 times higher risk).
Myran and colleagues acknowledged limitations in their findings. “Our study could not establish a causal link between hallucinogen use requiring care in the emergency department and schizophrenia spectrum disorders, and the associations presented in this study should not be interpreted as causal in nature,” they wrote.
However, they concluded with some suggestions for clinical applications, “Our findings revealed a group that may have high risk of development of schizophrenia spectrum disorders who may benefit from close follow-up and intervention or preventative efforts.”
The study, “(https://jamanetwork.com/journals/jamapsychiatry/fullarticle/2825649) Emergency Department Visits Involving Hallucinogen Use and Risk of Schizophrenia Spectrum Disorder,” was authored by Daniel T. Myran, Michael Pugliese, Jennifer Xiao, Tyler S. Kaster, M. Ishrat Husain, Kelly K. Anderson, Nicholas Fabiano, Stanley Wong, Jess G. Fiedorowicz, Colleen Webber, Peter Tanuseputro, and Marco Solmi.

(https://www.psypost.org/brain-rot-and-the-crisis-of-deep-thought-in-the-age-of-social-media/) Brain rot and the crisis of deep thought in the age of social media
Apr 2nd 2025, 08:00

I teach a course on the relationship between (https://www.pewresearch.org/global/2022/12/06/views-of-social-media-and-its-impacts-on-society-in-advanced-economies-2022/) social media and society at Durham College. As part of their assessments, I ask my students to reflect on their social media use.
A recurring theme is that they cannot be separated from their smartphones. Many admit to spending significant time daily on social media watching short videos without a clear purpose and as a way to procrastinate on more productive activities.
There is a term for this kind of behaviour and its impact on mental health, one that was recently named (https://corp.oup.com/news/brain-rot-named-oxford-word-of-the-year-2024/) Oxford Word of the Year 2024: “(https://www.psypost.org/does-tiktok-really-cause-brain-rot-new-study-links-short-video-addiction-to-brain-abnormalities/) brain rot” — the deterioration of a person’s mental or intellectual state, especially as the result of over-consuming trivial or unchallenging online content.
For many adults, a diffuse addiction to the internet, or what clinical psychologists call (https://www.nytimes.com/2025/02/01/magazine/anna-lembke-interview.html?smid=url-share) digital drugs (like online shopping, gaming, gambling, pornography), has become a widespread problem, especially since the lockdowns of the COVID-19 pandemic.
When social media platforms emerged at the beginning of this century, they were welcomed for their potential to (https://doi.org/10.7551/mitpress/6115.001.0001) empower individuals, (https://www.routledge.com/Digital-Storytelling-Capturing-Lives-Creating-Community/Lambert-Hessler/p/book/9781138577664?srsltid=AfmBOoqvVaYy2rJHONwTFG9Ja0Di4vE9-l5IZ6oBXf-KKD5Jmf8H9QsY) facilitate storytelling and (https://doi.org/10.7551/mitpress/7105.001.0001) connect communities.
While they do enable these possibilities, they also pose significant challenges to our relationship with truth and trust — two pillars of a functioning democracy. By spreading misinformation and (https://doi.org/10.1073/pnas.2023301118) creating echo chambers that polarize communities, social media platforms have become a ground for the rise of “(https://doi.org/10.1126/sciadv.adk2031) hate and extremism.”
As a sociologist, I study pop culture. My colleagues and I at Toronto Metropolitan University (TMU) and the University of Ottawa recently published a report on (https://www.torontomu.ca/cerc-migration/research/themes/project-brief/cultural-identity-narratives/) how cultural and identity narratives are evolving amid fast-developing digital technologies.
Shortened attention spans
Among younger generations in the United States, (https://www.commonsensemedia.org/sites/default/files/research/report/2023-cs-smartphone-research-report_final-for-web.pdf#:~:text=On%20a%20typical%20day%2C%20participants%20received%20a%20median%20of%20237%20notifications.&text=About%20a%20quarter%20(23%25)%20of%20notifications%20arrived,are%20more%20dis-%20ruptive%20to%20young%20people.) the average daily consumption is more than five hours on screens and 237 notifications — about one notification every four minutes.
In a culture of constant connectivity, many young people are navigating a digital world of idealized images, from beauty influencers who subject them to unrealistic comparisons that often lead to feelings of (https://www.theatlantic.com/technology/archive/2024/03/teen-childhood-smartphone-use-mental-health-effects/677722/?utm_source=copy-link&utm_medium=social&utm_campaign=share) inadequacy and diminished self-worth to an online bro culture (https://medium.com/@markdery/how-stoicism-became-broicism-123f3aae6aba) that purveys a toxic form of masculinity as a path to success.
For cultural theorist (https://www.newyorker.com/culture/infinite-scroll/the-internets-new-favorite-philosopher) Byung-Chul Han, this is a sign of the decline in storytelling. Modern readers have lost the ability to engage deeply with narratives. The “long, slow, lingering gaze” that allows for daydreaming and true distraction has been replaced by a hyper-focused engagement with constant streams of information. As a result, (https://www.theguardian.com/books/2024/feb/18/the-crisis-of-narration-byung-chul-han-review) narration is in crisis.
Recently, (https://fsc-ccf.ca/wp-content/uploads/2024/08/Work-Quality-Experiences-Among-Young-Workers_TMU-FSC_Report.pdf) a team of researchers at TMU who study workplaces from the perspective of young workers created a (https://www.torontomu.ca/news-events/news/2024/03/tmu-research-investigates-what-better-work-looks-like-young-workers/) two-minute-and-40-second video to engage students on the topic of what young workers want from their work.
Students couldn’t follow the entire video and felt it was too long. As a result, the team had to edit it into a series of much shorter clips — some as brief as 16 seconds — so they could capture the attention of their audience. Should this come as a surprise?
Modern media and technology constantly remind us to preserve our memory and protect our history. However, (https://muse.jhu.edu/pub/4/article/26184) memory is paradoxical in that it involves forgetting and absence with every act of remembrance.
Online platforms, with their ephemeral content, risk contributing to a (https://doi.org/10.33137/ijournal.v8i2.41039) cultural memory loss since so much of what’s shared on these platforms is transitory and geared toward superficial engagement rather than meaningful cultural expression.
When brains rot, truth fades
In his memoir, American writer and naturalist Henry David Thoreau lamented society’s declining capacity for deep thought and intellectual effort, favouring instead simple and superficial thinking.
In 1854, he wrote in his book (https://www.gutenberg.org/files/205/205-h/205-h.htm) Walden:
“While England endeavors to cure the potato-rot, will not any endeavor to cure the brain-rot, which prevails so much more widely and fatally?”
Thoreau may have seen a future where the U.S. would be led by a president who not only lacks the capacity for deep thought and self-reflection but also disregards historical facts and moral values.
Despite his reputation as a (https://democracy21.org/news/freds-weekly-note/donald-trump-and-his-cult-of-liars) pathological liar, Donald Trump exemplifies what philosopher Harry Frankfurt (https://press.princeton.edu/books/hardcover/9780691122946/on-bullshit?srsltid=AfmBOoopbB1H9pNGEo6KcQQOs8tQj6Dv7HehPYQs0CIRSrtpS7ItEXv3) defined as a bullshitter — a person who does not mislead in the way a liar does, by deliberately making false claims about reality, but rather by speaking without any regard for truth at all.
Bullshitters shift the rules of conversation by making questions of truth and falsehood irrelevant. Lies and the truth simply become tools that can be used to tell their story — regardless of the facts.
The bigger picture
(https://www.blackwellpublishing.com/content/bpl_images/content_store/sample_chapter/0631225137/bridge.pdf) Georg Simmel was one of the first social scientists who expressed concern about the impact of modern life on mental health. In 1903, writing about Berlin, he described (https://roam.macewan.ca:8443/server/api/core/bitstreams/19031f82-a816-490b-83a1-408041120d96/content) blasé attitude as a psychological condition that arises when the brain is subjected to an overwhelming number of stimuli. To cope, it develops a defense mechanism: becoming indifferent to its surroundings.
One century later, when our online feeds are flooded with endless digital content, it is uncanny to revisit Simmel’s observation. We must move beyond traditional diagnostic (https://unevoc.unesco.org/home/Digital+Competence+Frameworks) digital literacy and competency frameworks. The problem lies not only in the technology itself, but in the broader socio-economic system in which it operates — (https://www.theoryculturesociety.org/blog/review-jonathan-crary-scorched-earth) a consumer-capitalist-digital complex that is eroding our brains and cultures.
Humans have always been fascinated by stories. We need them to (https://thecreativemind.substack.com/p/salman-rushdie-on-why-we-need-stories) understand ourselves. However, social media’s profit-driven algorithms homogenize experiences and ultimately undermine cultural diversity. We have become storysellers instead of storytellers.
 
This article is republished from (https://theconversation.com) The Conversation under a Creative Commons license. Read the (https://theconversation.com/online-brain-rot-is-undermining-our-ability-to-tell-meaningful-stories-248984) original article.

(https://www.psypost.org/collective-narcissism-paranoia-and-distrust-in-science-predict-climate-change-conspiracy-beliefs/) Collective narcissism, paranoia, and distrust in science predict climate change conspiracy beliefs
Apr 2nd 2025, 06:00

A new study published in(https://link.springer.com/article/10.1007/s12144-024-06975-6)  Current Psychology has found that Turkish teachers who scored higher in collective narcissism, paranoid thinking, and distrust in science were more likely to believe in conspiracy theories about climate change. Surprisingly, other commonly discussed factors such as gender, ideological identity, and social media usage did not significantly predict climate change conspiracy beliefs in this sample. These findings add new cultural context to a growing body of research examining why some people reject scientific consensus on global warming.
Conspiracy beliefs about climate change, such as claims that it is a hoax or part of a global political agenda, are widespread across the world. These beliefs can reduce public support for environmental policies and undermine collective action. Most research on this topic has focused on Western societies, particularly the United States, where political ideology and media consumption have been shown to influence conspiracy thinking.
The new study, conducted by Menşure Alkış Küçükaydın, sought to investigate how these and other factors relate to belief in climate change conspiracy theories in Turkey, a country with different political and cultural dynamics.
Climate change is one of the most pressing global issues, but efforts to address it are often hampered by public skepticism and misinformation. Some individuals deny that climate change is caused by human activity, while others believe it is part of a coordinated effort to control the population or advance hidden agendas. These ideas are not only scientifically inaccurate but also socially damaging. Researchers are increasingly interested in identifying the psychological and social factors that make people more likely to endorse such beliefs.
The current study focused on Turkey because, despite experiencing the effects of climate change, the country has not been the subject of much research in this area. Turkish society does not have the same political culture around climate science debates as countries like the United States. Instead, beliefs in Turkey may be shaped more by social identity and personal experience than by political ideology. Understanding these cultural differences is important for developing effective public education strategies and climate policy.
To explore these questions, the researcher surveyed 556 preservice teachers from two universities in Turkey. Participants ranged in age from 19 to 30, with most identifying as female (75 percent). The study used a prediction model to determine whether various psychological and social variables could explain belief in climate change conspiracy theories. These variables included gender, ideological identity, social media use and frequency, collective narcissism, paranoid thoughts, and trust in science.
Participants completed a series of standardized questionnaires. One scale measured climate change conspiracy beliefs, such as the idea that scientists exaggerate climate data or that governments use climate change to push political reforms. Another assessed collective narcissism, or the belief that one’s national group is exceptional and underappreciated. Paranoid thinking was measured using a scale that included statements like “People are talking about me behind my back.” Trust in science was evaluated using a ten-item questionnaire about confidence in scientists and scientific research. Participants were also asked about their ideological leanings and social media habits.
The researcher conducted a detailed statistical analysis to determine which factors predicted belief in climate change conspiracy theories. The results showed that three variables stood out: collective narcissism, paranoid thoughts, and distrust in science. Participants who scored higher on these measures were more likely to believe that climate change is part of a hidden agenda or deception. In contrast, gender, ideological identity, and social media use did not significantly predict conspiracy beliefs in this sample.
Collective narcissism emerged as a strong predictor. This type of belief emphasizes the superiority of one’s national group and perceives criticism from outsiders as an attack. In this context, some participants may have viewed climate change messaging as a threat to national pride or autonomy, leading them to reject scientific explanations. The researcher noted that this defensive attitude could make people more susceptible to conspiracy theories that blame foreign powers or elites for environmental problems.
Paranoid thinking was also significantly associated with conspiracy beliefs. This supports previous research showing that people who feel personally targeted or suspicious of others are more likely to believe in hidden plots and coordinated deception. Climate change conspiracy theories often involve claims of secret manipulation by scientists, governments, or global organizations—ideas that align with a paranoid mindset.
Distrust in science was the third significant predictor. Participants who were skeptical of scientific authority were more likely to believe that climate change is fabricated or exaggerated. This finding aligns with other studies suggesting that trust in scientific institutions is essential for public acceptance of evidence-based policies. In situations where trust is low, people may turn to alternative explanations, including conspiracy theories.
Interestingly, the study found no significant link between ideological identity and conspiracy beliefs. This contrasts with findings from the United States, where conservative political identity is often associated with climate change denial. The researcher suggested that in Turkey, climate issues are not deeply embedded in political discourse, which may explain why ideological leanings did not play a strong role. Similarly, social media use and frequency were not significant predictors, even though social media is a well-known channel for spreading misinformation. This suggests that the content and context of social media use may be more important than simply how often people use it.
The study also found that overall levels of belief in climate change conspiracy theories were relatively low among the participants, as were levels of paranoia. However, collective narcissism was higher on average. Trust in science was moderate. These patterns suggest that while conspiracy thinking is not widespread in this group, certain psychological traits may still play a role in shaping climate attitudes.
As with all research, the study has some limitations. The sample consisted entirely of university students training to become teachers, who may not represent the broader Turkish population. Most participants were women and identified as ideologically moderate, which may have reduced the variability needed to detect certain effects. The cross-sectional design also limits the ability to draw conclusions about cause and effect. Longitudinal studies that follow participants over time would be useful to explore how beliefs evolve.
Despite these limitations, the study makes an important contribution by examining climate change conspiracy beliefs in a non-Western cultural context. It highlights the role of psychological factors like collective identity and paranoia, which may be more influential in certain societies than political ideology. The findings suggest that addressing these beliefs may require different strategies depending on the cultural setting.
The study, “(https://doi.org/10.1007/s12144-024-06975-6) Predictors of climate change conspiracy beliefs: collective narcissism, paranoid thoughts, and distrust in science,” was authored by Menşure Alkış Küçükaydın.

(https://www.psypost.org/people-with-strong-political-beliefs-can-still-be-intellectually-humble-study-finds/) People with strong political beliefs can still be intellectually humble, study finds
Apr 1st 2025, 14:00

A new study published in (https://doi.org/10.1080/17439760.2024.2352739) The Journal of Positive Psychology suggests that people do not have to weaken their political beliefs in order to be open-minded. Researchers found that intellectual humility—the ability to recognize the limits of one’s own knowledge—was not meaningfully related to how strongly someone held their political beliefs. At the same time, the study revealed a small association between intellectual humility and a more liberal political orientation.
The study was motivated by growing interest in how intellectual humility can help people engage more constructively with those who hold opposing political views. Political hostility, especially in the United States, has reached alarming levels in recent years. People often express more hatred for members of the opposing political party than they feel love for members of their own. This deep emotional divide—known as affective polarization—has been linked to political violence, misinformation, and a breakdown in democratic dialogue. Researchers are increasingly looking for ways to reduce these tensions, and intellectual humility has emerged as a promising candidate.
Prior research shows that intellectually humble individuals are more likely to seek accurate political information, are less prone to dismiss others’ opinions, and tend to engage in more respectful political discussions. But there has been lingering uncertainty in the field: are people who show more intellectual humility simply less polarized to begin with? Are they just people with weaker political convictions or less ideological commitment?
“Much of our research focuses on how intellectual humility predicts resistance to political hostility, conflict, and bias,” explained study author Jonah Koetke, a graduate student at the University of Pittsburgh. “However, we must also consider whether intellectual humility itself is more common among those who are already less ideologically polarized. If so, this would be a concerning confound. The goal of this work was to examine whether (1) intellectual humility is associated with strength of political belief, and (2) intellectual humility is associated with certain political views.”
To explore this issue, the researchers conducted a large-scale analysis using data from nine different surveys, involving a total of 3,248 participants. These surveys had been collected over the course of two years and included people with diverse political beliefs, many of whom were recruited to ensure a balance of liberals and conservatives. The researchers used two well-established measures of intellectual humility. The first, used in eight of the samples (Sample A), measured general intellectual humility through self-report items like “I accept that my beliefs and attitudes may be wrong.” The ninth sample (Sample B) used a more detailed, multidimensional scale that included items about openness to revising one’s views, respect for others’ viewpoints, and avoidance of overconfidence.
Participants also answered questions about their political beliefs. In Sample A, this included how strongly they identified with their political ideology. In Sample B, participants rated how certain they were that their political views were correct, and how much those views reflected their core moral values. Political orientation was measured in both samples by asking participants to rate themselves on economic and social issues, from very liberal to very conservative.
The main question was whether intellectual humility was linked to the strength of political belief. Across the data, the researchers found that the association was either very small or nonexistent. In the larger sample, intellectual humility had a very weak negative relationship with political belief strength, but the effect size was so small that it was likely only statistically significant because of the large number of participants. In the smaller sample that used more detailed measures, there was no significant relationship between intellectual humility and how strongly people held or moralized their political beliefs.
This finding suggests that intellectual humility is not the same as political detachment. People can feel strongly about their political positions while still being open to the possibility that they might be wrong. In other words, conviction and humility are not mutually exclusive. This supports the idea that intellectual humility is less about doubt or indecisiveness, and more about how people relate to their own beliefs—recognizing the possibility of error without automatically discarding their views.
“Across a fairly large sample, we found that intellectual humility was not reliably associated with strength of one’s political beliefs,” Koetke told PsyPost. “This is encouraging because it implies that even people who strongly identify with their political ideology can be intellectually humble. This has promising implications for reducing polarization, as it suggests that the benefits of intellectual humility for reducing political hostility might extend even to those who have more entrenched political views.”
The second key question was whether intellectual humility is connected to political orientation—that is, whether people who are more intellectually humble tend to be more liberal or more conservative. Here, the researchers found a small but consistent association: people with higher intellectual humility tended to report a more liberal political orientation. This was true in seven of the eight samples in Sample A, and while the association was smaller and not statistically significant in Sample B, it pointed in the same direction.
“We found that intellectual humility was associated with holding a more liberal political orientation,” Koetke said. “This indicates that we need to more carefully consider the moderating role of political orientation in our research.”
One possibility is that liberal ideology, which tends to emphasize openness to new experiences and tolerance for ambiguity, may attract or encourage traits like intellectual humility. Another possibility is that recent political leaders and cultural norms have shaped different expectations around intellectual openness within liberal and conservative circles. For example, political figures who model humility or self-reflection may reinforce those traits among their followers, while those who reject error or claim infallibility may discourage them.
But the researchers caution against drawing strong conclusions about ideological differences between groups. While the association between intellectual humility and liberalism was consistent, it was relatively small.
“We were surprised that intellectual humility was associated with more liberal political orientation, as this had not been found reliably in prior work,” Koetke explained. “However, it is important to remember that this association was relatively small in magnitude.
As with all research, there are also some limitations. “There are two caveats to this work that are important to consider,” Koetke said. “First, we do not yet understand the underlying reasons for the association between liberal political orientation and intellectual humility. Is it that people who are more liberal develop more intellectual humility over time, or that people who are more intellectually humble become more liberal over time? Alternatively, there could be a third variable causing the association between intellectual humility and liberal views. Second, because our samples for this study were all collected online, the generalizability of these findings may be limited.”
The study, “(https://doi.org/10.1080/17439760.2024.2352739) Is intellectual humility polarized too? A systematic examination of intellectual humility, political orientation, and strength of political belief,” was authored by Jonah Koetke and Karina Schumann.

(https://www.psypost.org/largest-single-cell-map-of-the-aging-brain-reveals-vulnerable-cell-types-and-regions/) Largest single-cell map of the aging brain reveals vulnerable cell types and regions
Apr 1st 2025, 12:00

A new study published in (https://www.nature.com/articles/s41586-024-08350-8) Nature offers the most detailed map to date of how individual cell types in the brain change with age. Scientists analyzed over 1.2 million brain cells from young and aged mice and found that many specific cells undergo significant gene expression changes as animals grow older. These changes were not spread evenly throughout the brain. Instead, they clustered in a particular region: the hypothalamus, a part of the brain that helps regulate hunger, hormones, and energy balance.
While past research has identified general signs of aging—such as increased inflammation or reduced capacity for repair—it has been difficult to pinpoint which specific cell types are most affected and where in the brain these changes take place. The brain is an incredibly diverse and structured organ, with thousands of cell types performing different functions across various regions. Understanding how these cells change over time could offer clues into not only normal aging but also conditions like Alzheimer’s and Parkinson’s disease.
“Our brain consists of thousands of types of cells which carry out different functions. We study the molecular basis of the diversity of brain cell types and how the different cell types change with time (in development and aging),” said study author (https://alleninstitute.org/person/hongkui-zeng/) Hongkui Zeng, the executive vice president and director of the Allen Institute for Brain Science.
To investigate aging in the brain, the research team used an advanced technique called single-cell transcriptomics to profile the gene activity of individual cells. They examined brains from young adult mice (around two months old) and older mice (18 months old), which is roughly equivalent to middle age in humans. In total, they profiled 16 major regions across the brain, covering about 35% of its total volume. This produced a dataset of over a million high-quality brain cell transcriptomes—the most extensive single-cell brain aging dataset ever produced in mice.
By comparing gene activity in young and aged brains, the researchers identified 2,449 genes that changed with age. Many of these changes were specific to individual cell types. For example, the gene Ccnd2, which is involved in cell cycle regulation, was found to decrease in several types of neurons and glial cells. Other genes, like Oasl2 and Ifit1, which are linked to immune responses, increased in activity, especially in cells like microglia, the brain’s resident immune cells.
“Changes in these genes point to deteriorated neuronal structure and function in many neuronal and glial cell types, as well as increased immune response and inflammation in the brain’s immune and vascular (blood vessel) cell types,” Zeng told PsyPost.
One of the key takeaways was that aging does not affect all brain cells equally. Certain types of glial cells—support cells that are not neurons—were especially sensitive. These included microglia, border-associated macrophages, oligodendrocytes (which help insulate nerve fibers), ependymal cells (which help circulate cerebrospinal fluid), and tanycytes (which line the walls of the brain’s third ventricle and interact with circulating hormones and nutrients). Many of these cells showed signs of increased inflammation, altered nutrient processing, and changes in their ability to support neurons.
But perhaps the most striking finding was the discovery of a specific “hotspot” for aging-related changes in the hypothalamus. This region sits near the base of the brain and plays a central role in energy homeostasis, hormone regulation, and feeding behavior.
“A major new finding is that cell types concentrated around the third ventricle in the hypothalamus, a major interface between brain and blood for hormone and chemical exchange, exhibit especially pronounced changes in both decreased neuronal function and increased immune response,” Zeng said. “These cell types are well-known regulators of food intake and energy homeostasis. Thus, our finding suggests that the brain’s controlling center for metabolism and energy homeostasis is a hotspot for aging.”
The researchers were particularly intrigued by the role of tanycytes. These cells not only help regulate the blood-brain barrier in key regions but may also retain some ability to generate new neurons. With age, tanycytes showed reduced expression of genes involved in neurogenesis and increased expression of immune-related genes, hinting at a possible decline in the brain’s ability to regenerate itself over time.
“The most surprising finding to us is the hypothalamic cell types showing pronounced changes in genes related to both neuronal function and immune response,” Zeng explained. “These cell types are tiny populations located at the bottom of the brain and sitting at the juncture between brain and blood. These are tantalizing cell types with unique structure and function. They include the special glia cell types called tanycytes and ependymal cells lining the wall of the brain’s third ventricle and mediating the hormone and nutrient exchange with the blood.”
“They also include the adjacent special neuron types that express well-known ‘feeding neuropeptides’ AGRP and NPY, or express leptin and GLP-1 receptors that are known to be important regulators of food intake and energy homeostasis. Thus, our finding suggests a hotspot of neuroinflammation in the aging brain at the interface of brain and blood, and reveals a connection between diet, metabolism, immunity, and aging.”
In addition to these broad trends, the scientists also identified specific clusters of cells that were either more common or less common in older brains. For example, they found certain clusters of microglia that were enriched in older brains and displayed a pro-inflammatory gene activity profile, further supporting the idea of increased inflammation in the aging brain.
“Aging is the most important risk factor for many brain diseases,” Zeng told PsyPost. “Our study provides a highly detailed genetic map for which brain cell types may be most affected by aging and suggests new gene and cell targets for developing new treatments for aging-related brain diseases.”
But while the dataset provides an unprecedented view into the aging brain, the authors acknowledge some limitations. Most importantly, the study is correlational. It shows which genes change in which cell types, but it does not prove that these changes are the cause of aging or cognitive decline. Future research will be needed to test whether reversing some of these gene changes can actually alter the course of brain aging or protect against neurodegenerative diseases.
“Our study lays the groundwork by providing a detailed genetic map and potential new gene and cell targets for future studies that investigate their roles in aging and test if the reversal of the changes could delay the aging process,” Zeng explained.
The researchers also plan to extend this work to human brains. While mice share many brain features with humans, they do not develop age-related brain diseases in the same way. Nonetheless, the mouse data provides a valuable reference point for identifying vulnerable cell types and potential therapeutic targets.
“We want to understand how different types of cells in the brain change in their molecular, structural and functional properties in healthy aging and diseased conditions, in both mouse and human,” Zeng said.
“For years scientists studied the effects of aging on the brain mostly one cell at a time. Now, with innovative brain mapping tools – made possible by (https://braininitiative.nih.gov/) the NIH’s BRAIN Initiative – researchers can study how aging affects much of the whole brain,” added John Ngai, the director of The BRAIN Initiative. “This study shows that examining the brain more globally can provide scientists with fresh insights on how the brain ages and how neurodegenerative diseases may disrupt normal aging activity.”
The study, “(https://doi.org/10.1038/s41586-024-08350-8) Brain-wide cell-type-specific transcriptomic signatures of healthy ageing in mice,” was authored by Kelly Jin, Zizhen Yao, Cindy T. J. van Velthoven, Eitan S. Kaplan, Katie Glattfelder, Samuel T. Barlow, Gabriella Boyer, Daniel Carey, Tamara Casper, Anish Bhaswanth Chakka, Rushil Chakrabarty, Michael Clark, Max Departee, Marie Desierto, Amanda Gary, Jessica Gloe, Jeff Goldy, Nathan Guilford, Junitta Guzman, Daniel Hirschstein, Changkyu Lee, Elizabeth Liang, Trangthanh Pham, Melissa Reding, Kara Ronellenfitch, Augustin Ruiz, Josh Sevigny, Nadiya Shapovalova, Lyudmila Shulga, Josef Sulc, Amy Torkelson, Herman Tung, Boaz Levi, Susan M. Sunkin, Nick Dee, Luke Esposito, Kimberly A. Smith, Bosiljka Tasic, and Hongkui Zeng.

Forwarded by:
Michael Reeder LCPC
Baltimore, MD

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