Peanuts improve brain vascular function and memory

  A study from the Institute of Nutrition and Translational Research in Metabolism (NUTRIM) at Maastricht University Medical Center, Maastricht, Netherlands, has found that the consumption of unsalted, skin-roasted peanuts can significantly improve brain vascular function and memory. The findings were published online in the international, peer-reviewed journal Clinical Nutrition.

The NUTRIM study of 31 healthy older adults ranging in age from 60-75 observed that consuming 60 grams (approximately two servings) of peanuts daily for 16 weeks increased global cerebral blood flow (CBF) by 3.6% and verbal memory by 5.8%. In addition to the brain improvements, systolic blood pressure and pulse pressure decreased by 5 mmHg and 4 mmHg, respectively.

“CBF is an important physiological marker of brain vascular function and refers to the amount of blood that flows through the brain, delivering oxygen and nutrients that are essential for maintaining brain health,” says Dr. Peter Joris, the study’s author and an associate professor in the Department of Nutrition and Movement Sciences, NUTRIM, Maastricht University Medical Center. “We found that longer-term consumption of unsalted, skin-roasted peanuts improved global CBF, which suggests an overall enhancement in brain vascular function.”

The peanut intervention also resulted in increased blood flow in the frontal and temporal lobes of the brain, both of which are important for memory and other cognitive functions.

The NUTRIM study is unique because it combined a well-controlled, longer-term dietary intervention with advanced brain imaging techniques, specifically arterial spin labeling magnetic resonance imaging (MRI), to investigate the effects of daily peanut consumption on brain health. Cognitive performance was evaluated using the Cambridge Neuropsychological Test Automated Battery (CANTAB).

“For the first time, we demonstrated that peanut intake improved brain vascular function in healthy older adults. These favorable effects may help explain the observed improvements in memory, providing novel mechanistic insight into how regular peanut consumption can beneficially affect cognitive function,” says Joris.

As people age, vascular brain function can become impaired, contributing to an elevated risk of cognitive decline and dementia. Dementia, unfortunately, is a worldwide health problem that’s increasing in prevalence. Alzheimer’s Disease International predicts that 78 million will be living with dementia by 2030 and by 2050 the number will reach 139 million.

“Peanuts are especially rich in plant-based protein and contain high concentrations of L-arginine, an amino acid important for vascular health. They are also a valuable source of unsaturated fats and polyphenols, both known to support vascular function,” says Joris. “For this study, skin-roasted peanuts were chosen because the peanut skin contains additional dietary fiber and natural plant compounds, specifically antioxidants. Together, these nutrients may help explain the beneficial health effects of skin-roasted peanuts observed in this study.”

NUTRIM Study Details

The study was a randomized, controlled crossover trial - one of the strongest designs in clinical research. Participants in the intervention group were given premeasured packets of skin-roasted peanuts and directed to consume the peanuts in the morning or afternoon. They were allowed to eat the daily amount all at once, spread it out over the day or add the peanuts to their meals. The control group did not consume peanuts. After 16 weeks, the groups switched conditions to further assess the effects of peanut consumption versus no peanuts on brain health.

The principal investigator of the study was Associate Professor Dr. Peter J. Joris. Test days were conducted by Ph.D. candidate Lucia Kerkhof, Department of Nutrition and Movement Sciences, Maastricht University Medical Center.

The NUTRIM study was supported by funding from The Peanut Institute Foundation. The funder did not have a role in the study design, implementation, analysis or interpretation of the data or the writing of the manuscript.

Meditation retreat rapidly reprograms body and mind

A one-week mind-body retreat triggered systematic brain and molecular changes linked to resilience, pain relief and stress recovery

Researchers at the University of California San Diego have found that an intensive retreat combining multiple mind-body techniques, including meditation and healing practices, produced rapid and wide-ranging changes in brain function and blood biology. The researchers found that the retreat engaged natural physiological pathways promoting neuroplasticity, metabolism, immunity and pain relief. The findings, published in Communications Biology, provide insights into how consciousness and psychological practices can enhance physical health.

Meditation and other mind-body practices have been utilized by cultures worldwide for thousands of years to promote health and wellness; however, the underlying biology of these approaches remains poorly understood. The new study, part of a multi-million-dollar research initiative supported by the InnerScience Research Fund, is the first to comprehensively quantify the biological effects of multiple mind-body techniques administered together over a short period.

"We’ve known for years that practices like meditation can influence health, but what’s striking is that combining multiple mind-body practices into a single retreat produced changes across so many biological systems that we could measure directly in the brain and blood," said senior study author Hemal H. Patel, Ph.D., professor of anesthesiology at UC San Diego School of Medicine and research career scientist at the Veterans Affairs San Diego Healthcare System. “This isn’t about just stress relief or relaxation; this is about fundamentally changing how the brain engages with reality and quantifying these changes biologically.”

As part of the study, 20 healthy adults attended a 7-day residential program led by neuroscience educator and author Joe Dispenza, D.C., featuring daily lecture sessions, approximately 33 hours of guided meditation and group healing practices. These practices used an “open-label placebo” approach, meaning participants knowingly took part in healing activities presented as placebos — procedures or treatments with no active medical ingredient, but which can still produce real benefits through the power of expectation, social connection and shared practices.

Before and after the retreat, participants had their brains scanned using functional magnetic resonance imaging (fMRI), an approach that measures brain activity in real time. The researchers also used blood testing to measure changes in metabolic activity, immune activation and other biological functions.  

The researchers observed several major changes after the retreat:

• Brain network changes: Meditation during the retreat reduced activity in parts of the brain associated with mental chatter, making brain function more efficient overall.
• Enhanced neuroplasticity: When applied to laboratory-grown neurons, blood plasma from post-retreat participants made brain cells grow longer branches and form new connections.
• Metabolic shifts: Cells treated with post-retreat plasma showed an increase in glycolytic (sugar-burning) metabolism, indicating a more flexible and adaptive metabolic state.
• Natural pain relief: Blood levels of endogenous opioids – the body’s natural painkillers – increased after the retreat, indicating that the body’s natural pain-relief systems were activated.
• Immune activation: Meditation increased inflammatory and anti-inflammatory immune signals simultaneously, suggesting a complex, adaptive immune response rather than a simple suppression or activation.
• Gene and molecular signaling changes: Small RNA and gene activity in blood shifted after the retreat, particularly in pathways related to brain function.

Participants also completed the Mystical Experience Questionnaire (MEQ-30) to assess whether they had a “mystical” experience during meditation—characterized by profound feelings of unity, transcendence, and altered states of consciousness. Average MEQ scores increased significantly after the retreat, rising from 2.37 before the retreat to 3.02 afterwards. Higher scores on these surveys were also correlated with greater biological changes after the retreat, including greater integration of brain activity across different regions. In other words, the more connected the brain is, the greater the likelihood of a mystical experience.

The findings suggest that intensive meditation can trigger very similar brain activity to that which has been previously documented with psychedelic substances.

“We're seeing the same mystical experiences and neural connectivity patterns that typically require psilocybin, now achieved through meditation practice alone,” added Patel. “Seeing both central nervous system changes in brain scans and systemic changes in blood chemistry underscores that these mind-body practices are acting on a whole-body scale.”

The study results provide a biological framework for understanding how non-drug mind-body interventions can support health and well-being. By enhancing neuroplasticity and activating the immune system, these practices could help promote mental health, emotional regulation and stress resilience. Additionally, the activation of endogenous opioid pathways suggests that this combination of mind-body practices may also be useful for chronic pain management.

While the retreat’s effects were measured in healthy adults, the researchers emphasize that controlled trials in patient populations are still needed to determine specific clinical benefits and applications. They are particularly interested in whether mind-body retreats can benefit people with chronic pain, mood disorders or immune-related conditions.

Looking ahead, the research team plans to investigate how each individual component of the retreat — meditation, reconceptualization, and open-label placebo healing — works alone and in combination. Additionally, future studies will investigate the duration of these biological changes and whether repeated interventions can enhance or sustain their effects.

“This study shows that our minds and bodies are deeply interconnected — what we believe, how we focus our attention, and the practices we participate in can leave measurable fingerprints on our biology,” said first author Alex Jinich-Diamant, a doctoral student in the Departments of Cognitive Science and Anesthesiology at UC San Diego. “It’s an exciting step toward understanding how conscious experience and physical health are intertwined, and how we might harness that connection to promote well-being in new ways.”

Link to full paper: https://www.doi.org/10.1038/s42003-025-09088-3  

Additional coauthors of the study include Sierra Simpson, Juan P. Zuniga-Hertz, Ramamurthy Chitteti, Jan M. Schilling, Jacqueline A. Bonds, Laura Case, Andrei V. Chernov, Natalia Esther Amkie Stahl, Michael Licamele, Narin Fazlalipour and, Swetha Devulapalli, at UC San Diego; Joe Dispenza and Michelle A. Poirier at Metamorphosis LLC; Jacqueline Maree and Tobias Moeller-Bertram at VitaMed Research; and Leonardo Christov-Moore and Nicco Reggente at the Institute for Advanced Consciousness Studies.

This work was supported by the InnerScience Research Fund and a Veterans Administration Research Career Scientist Award (BX005229).

Disclosure: One co-author (Joe Dispenza) is employed by Encephalon, Inc., the company offering the retreat; all other authors declare no competing interests.

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Journal

Communications Biology

Researchers reveal rosemary extract in viral skincare trend is worth the hype

 

Penn students and dermatologists were determined to find how rosemary and rosemary extract can repair damaged skin without leaving scars.

Peer-Reviewed Publication

University of Pennsylvania School of Medicine

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Penn undergraduate student Jiayi Pang (left) and Penn PhD candidate Emmanuel Rapp Reyes (right) found that rosemary can help skin wounds heal without causing scars.

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Credit: Courtesy of Penn Medicine

The social media trend touting rosemary and rosemary extract as part of skincare routines is now backed by science. A compound found in rosemary leaves may significantly improve the healing of skin wounds and reduce scarring, according to new research published in JCI Insight from the Perelman School of Medicine at the University of Pennsylvania.

“Many skin injuries end in scars, and in some people, it can lead to long-term cosmetic and even functional issues,” said senior author Thomas Leung, MD, PhD, an associate professor of Dermatology at Penn. “Our findings suggest that rosemary extract, and specifically the antioxidant, carnosic acid, can shift the healing process from scarring to healthy skin regeneration. We don’t have proven ways to consistently do that in humans.”

The hypothesis behind the hype

Penn undergraduate student Jiayi Pang (left) and Penn PhD candidate Emmanuel Rapp Reyes (right) found that rosemary can help skin wounds heal without causing scars.

The inspiration for this study stemmed from an unusual place: TikTok and Instagram. After seeing beauty influencers and other social-media users touting the skin-healing benefits of homemade rosemary extract serums and products with rosemary, Penn undergraduate student Jiayi Pang and Penn PhD candidate Emmanuel Rapp Reyes turned to Leung for expertise. Then, they did what all good scientists do: they went to the lab and ran their own tests.

“We hypothesized there was likely something real behind the hype because rosemary contains  many antioxidants,” said Pang, co-lead author of the study. “But we knew in order to really uncover its potential, we needed to prove its healing properties and uncover how exactly it was facilitating healing.”

Conducting the research in mice, the researchers made cream with carnosic acid, a naturally occurring antioxidant mostly existing in rosemary, to accelerate wound closure and restore hair follicles, oil glands, and cartilage. They also found that a particular nerve sensor in the skin previously identified as essential to scarless healing, TRPA1, was critical for stimulating the healing in this instance, too. When tested in mice without the TRPA1 sensor, which previous research from Leung showed is responsible for scarless healing, carnosic cream lost its impact.

“We also identified other herbs, such as thyme and oregano, that may activate TRPA1. But rosemary stood out for its potency and safety,” said Rapp Reyes, co-lead author of the study. “Other natural ingredients, such as mustard oil, or the topical medication imiquimod are known to also stimulate the TRPA1 receptor, but unlike rosemary, those can cause irritation and inflammation,”

The researchers also found a localized effect from rosemary; scarless healing only occurred when carnosic acid cream was applied to the site of the injury but not when it was applied to skin far from the wound.

The team at Penn, however, notes that individuals should speak with their doctors before incorporating  rosemary skincare products in their daily regimens or mixing up their own rosemary-based concoctions. Nevertheless, given rosemary’s accessibility and low cost, the researchers hope their findings will inspire further investigation into its use in human wound care, especially for patients at risk of excessive scarring.

“If rosemary is part of your skincare regimen and you think it’s working, it likely is,” said Leung. “I’m proud that the young scientists that led this research sought answers to questions in their everyday lives.”

Low-dose aspirin linked to lower cardiovascular event risk for adults with Type 2 diabetes

 

Research Highlights:

• Adults with Type 2 diabetes (T2D) and at moderate or high risk of cardiovascular disease who took low-dose aspirin were less likely to experience a serious cardiovascular event, including a heart attack, stroke or death, than peers who did not take aspirin.
• Any low-dose aspirin use was associated with significantly lower risk of having a heart attack or stroke compared to no low-dose aspirin use, with greater benefit observed among those individuals who took it the most often.
• Low-dose aspirin use was associated with similarly lower risks of a cardiovascular event for people with T2D no matter their blood sugar levels, though this reduction was more substantial in individuals who had lower HBA1c levels, indicating their T2D was better controlled. 
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as full manuscripts in a peer-reviewed scientific journal.

Embargoed until 4 a.m. CT/5 a.m. ET, Monday, Nov. 3, 2025

DALLAS, Nov. 3, 2025 — People with Type 2 diabetes (T2D) and an elevated risk for cardiovascular disease (CVD) who took low-dose aspirin were less likely to experience a major cardiovascular event, including heart attack, stroke or death, than people with T2D at similar CVD risk who did not take low-dose aspirin, according to a preliminary study to be presented at the American Heart Association’s Scientific Sessions 2025. The meeting, Nov. 7-10, in New Orleans, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

“We know that in recent studies aspirin hasn’t proven beneficial for primary prevention in people who don’t have established cardiovascular disease. However, Type 2 diabetes is a known risk factor for cardiovascular disease,” said corresponding study author Aleesha Kainat, M.D., a clinical assistant professor of medicine at the University of Pittsburgh Medical Center. “In our study, we wanted to better understand low-dose aspirin use in this very niche group of adults with Type 2 diabetes and with a moderate-to-high risk of cardiovascular disease – so, a population group who may or may not have been included in previous trials.”

For this study, researchers analyzed 10 years of electronic health record data on more than 11,500 adults. The individuals were previously diagnosed with Type 2 diabetes and had a moderate or high risk for a cardiovascular event. Additionally, the researchers reviewed the potential effects of whether individuals had their blood glucose levels under control, along with whether they took medications as prescribed more frequently. 

“We were somewhat surprised by the magnitude of the findings,” Kainat said. “People with Type 2 diabetes and a higher risk of CVD who reported taking low-dose aspirin were much less likely to have had a heart attack, stroke or death over 10 years when compared to similar individuals who did not report taking low-dose aspirin. That benefit was greatest for those who took aspirin consistently, throughout most of the follow-up time.”

The analysis found:

• Adults with Type 2 diabetes who took low-dose aspirin were less likely to have a heart attack (42.4%) than the participants who did not take low-dose aspirin (61.2%).
• For those on a low-dose aspirin regimen, the risk of stroke was also lower (14.5% aspirin group vs. 24.8% no aspirin group), as was the risk of death from any cause within 10 years (33% aspirin group compared to 50.7% no aspirin group).
• Any low-dose aspirin use among the participants was linked to reduced risk of heart attack and stroke, with the greatest benefit seen among those who took low-dose aspirin most frequently. 
• In subgroup analyses, low-dose aspirin use was associated with similarly lower risk of a cardiovascular event no matter the participant’s HBA1c, or blood glucose, levels, though this reduction was more substantial in individuals who had lower HBA1c levels, indicating their T2D was better controlled

“It’s worth noting that our analysis excluded the records of people who had a high risk of bleeding, and we did not track bleeding events or other side effects in our study,” said Kainat. “That’s an important limitation because aspirin’s bleeding risk is crucial in real-life decision making and a person's independent bleeding risk has to be accounted for whenever we are prescribing a medication.”

“This study offers some interesting insights into helping reduce the incidence of major cardiovascular events among people with Type 2 diabetes. This is very important because cardiovascular disease continues to be the leading cause of death among people with Type 2 diabetes, and furthermore, Type 2 diabetes is a leading risk factor contributing to a recent rise in heart disease and stroke,” said Amit Khera, M.D., M.Sc., FAHA, the volunteer chair of the American Heart Association’s Advocacy Coordinating Committee and recipient of the Association’s 2025 Chairman’s Award. “While the American Heart Association does not currently recommend low-dose aspirin for primary prevention of cardiovascular disease for adults with Type 2 diabetes who have no history of cardiovascular disease, this study raises some good questions for further research and validation. The clear message is to always work directly with your health care team to identify your specific risk factors and conditions and together decide whether the benefits of any treatment outweigh the potential risks.” Khera, who was not involved in this study, is a professor of medicine, clinical chief of cardiology and director of preventive cardiology at UT Southwestern Medical Center in Dallas

The study had additional limitations. The analysis was observational, meaning the researchers examined past, real-world data from patient records rather than enrolling participants in a clinical trial. The findings cannot prove low-dose aspirin prevented or reduced major cardiovascular event. Also, the researchers measured low-dose aspirin use based on reports within individuals’ health records, which may not accurately reflect how often people actually took low-dose aspirin or if they took other unreported over-the-counter medications. Additionally, there may have been other unidentified differences across the groups of individuals who took low-dose aspirin versus those who did not, which could influence the findings.

“We’ll need to look at how we balance the cardiovascular benefits of low-dose aspirin with its known bleeding risks for individual high-risk individuals, such as those who have high inflammatory burden or subclinical coronary calcifications,” Kainat said. “It is also an open area of inquiry to see how low-dose aspirin’s benefit might interact with the myriad of emerging therapies for Type 2 diabetes and heart disease, such as GLP-1 medications and other lipid lowering agents besides statins, so we look forward to conducting more research on this important topic.”

Study details, background and design:

• Low-dose aspirin use among the participants was based on how frequently it was noted on the medication list of their medical records over the follow-up period of about eight years. It was classified as: no use, seldom use (<30% of the time), sometimes used (between 30-70% of the time) and frequently used (>70% of the time).
• The study included health records for 11,681 adults with Type 2 diabetes who had a moderate or high risk score as determined by the 10-year Atherosclerotic Cardiovascular Disease (ASCVD) risk score, a standardized cardiovascular disease calculator outlined in a 2018 special report from the American Heart Association and the American College of Cardiology. All records were from a primary prevention registry within the University of Pittsburgh Medical Center multihospital system, which includes over 35 hospitals and 400 outpatient clinics in Pennsylvania, Maryland and West Virginia.
• Participants had an average age of 61.6 years, 46.24% were female and 53.76% were male. People who were at a higher risk for bleeding were excluded.
• Participants were divided into four groups, depending on how often their medical records noted they took low-dose aspirin over the course of about eight years of follow-up: no low-dose aspirin, low-dose aspirin taken less than 30% of the time, low-dose aspirin taken 30-69% of the time and low-dose aspirin taken more than 70% of the time. 
• The analyses compared the incidence of stroke, heart attack and death from any cause within 10 years across all four participant groups.
• Across the study’s 10-year follow-up, 88.6% of all participants reported taking low-dose aspirin and 53.15% reported taking statins, or cholesterol-lowering medications.
• An additional analysis investigated potential links between low-dose aspirin use and heart attack, stroke and death based on participants’ levels of blood sugar, or HbA1C results.

Heart attack and stroke are leading causes of death in the U.S., and people with Type 2 diabetes are at increased risk for these events. According to the American Heart Association’s 2025 Heart Disease and Stroke Statistics, more than half (57%) of all adults in the U.S. have Type 2 diabetes or pre-diabetes.

Aspirin is a blood-thinning medication and is often used in low doses to reduce CVD risk. Low-dose aspirin is recommended for secondary prevention in the American Heart Association’s 2025 Guideline for the Management of Patients With Acute Coronary Syndrome for adults who have already had a cardiac event and in the Association’s 2021 Guideline for the Prevention of Stroke in Patients with Stroke and Transient Ischemic Attack for adults who have already had a stroke. However, the Association’s 2019 Guideline on the Primary Prevention of Cardiovascular Disease states that daily low-dose aspirin might be considered in select adults 40-70 years of age who are at higher risk for heart disease but not at increased bleeding risk. The Association’s 2024 Guideline for the Primary Prevention of Stroke states that in people with diabetes or other common vascular risk factors and no prior stroke, the use of aspirin to prevent a first stroke is not well established.

Long-term use of melatonin supplements to support sleep may have negative health effects

 

Research Highlights:

• A review of 5 years of health records for more than 130,000 adults with insomnia who had used melatonin for at least a year found they were more likely to be diagnosed with heart failure, require hospitalization for the condition or die from any cause.
• The association between melatonin and increased risk of heart failure or death found in this study, which cannot prove a cause-and-effect relationship, raises safety concerns about the use of melatonin, which is widely available, and may warrant more research on melatonin to assess its cardiovascular safety, researchers said.
• Note: The study featured in this news release is a research abstract. Abstracts presented at American Heart Association’s scientific meetings are not peer-reviewed, and the findings are considered preliminary until published as full manuscripts in a peer-reviewed scientific journal.

Long-term use of melatonin supplements, often used to promote sleep and address insomnia, was associated with a higher risk of heart failure diagnosis, heart failure hospitalization and death from any cause in chronic insomnia, according to a preliminary study to be presented at the American Heart Association’s Scientific Sessions 2025. The meeting, Nov. 7-10, in New Orleans, is a premier global exchange of the latest scientific advancements, research and evidence-based clinical practice updates in cardiovascular science.

Melatonin is a hormone naturally produced in the body by the pineal gland, and it helps regulate the body’s sleep-wake cycle. Melatonin levels increase during darkness and decrease during daylight. Chemically identical synthetic versions of the hormone are often used to treat insomnia (difficulty falling and/or staying asleep) and jet lag. The supplements are widely available over the counter in many countries, including the U.S. In the U.S., over-the-counter supplements are not regulated, so each brand of supplement can vary in strength, purity, etc.

In this study, researchers classified people who had used melatonin long-term (with long-term use defined as a year or more documented in their electronic health records) as part of the “melatonin group.” In contrast, those who never had melatonin recorded anywhere in their medical records were classified as the “non-melatonin group.”

“Melatonin supplements may not be as harmless as commonly assumed. If our study is confirmed, this could affect how doctors counsel patients about sleep aids,” said Ekenedilichukwu Nnadi, M.D., lead author of the study and chief resident in internal medicine at SUNY Downstate/Kings County Primary Care in Brooklyn, New York.

Melatonin supplements are promoted and marketed as a safe sleep aid; however, data demonstrating their long-term cardiovascular safety are lacking, which prompted the researchers to examine whether melatonin use alters the risk of heart failure, specifically in chronic insomnia patients. According to the American Heart Association’s 2025 Heart Disease and Stroke Statistics, heart failure occurs when the heart can’t pump enough oxygen-rich blood to the body’s organs for them to function properly and is a common condition that affects 6.7 million adults in the U.S.

Using a large international database (the TriNetX Global Research Network), the researchers reviewed 5 years of electronic health records for adults with chronic insomnia who had melatonin recorded in their health records and used it for more than a year. They were matched with peers in the database who also had insomnia but never had melatonin recorded in their health records. People were excluded from the analysis if they had previously been diagnosed with heart failure or had been prescribed other sleep medications.

The main analysis found:

• Among adults with insomnia, those whose electronic health records indicated long-term melatonin use (12 months or more) had about a 90% higher chance of incident heart failure over 5 years compared with matched non-users (4.6% vs. 2.7%, respectively).
• There was a similar result (82% higher) when researchers analyzed people who had at least 2 melatonin prescriptions filled at least 90 days apart. (Melatonin is only available by prescription in the United Kingdom.)

A secondary analysis found:

• Participants taking melatonin were nearly 3.5 times as likely to be hospitalized for heart failure when compared to those not taking melatonin (19.0% vs. 6.6%, respectively).
• Participants in the melatonin group were nearly twice as likely to die from any cause than those in the non-melatonin group (7.8% vs. 4.3%, respectively) over the 5-year period.

“Melatonin supplements are widely thought of as a safe and ‘natural’ option to support better sleep, so it was striking to see such consistent and significant increases in serious health outcomes, even after balancing for many other risk factors,” Nnadi said.

”I’m surprised that physicians would prescribe melatonin for insomnia and have patients use it for more than 365 days, since melatonin, at least in the U.S., is not indicated for the treatment of insomnia. In the U.S., melatonin can be taken as an over-the-counter supplement and people should be aware that it should not be taken chronically without a proper indication,” said Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, chair of the writing group for the American Heart Association’s 2025 scientific statement, Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health. St-Onge, who was not involved in this study, is a professor of nutritional medicine in the division of general medicine and director of the Center of Excellence for Sleep & Circadian Research in the department of medicine at Columbia University Irving Medical Center in New York City.

The study has several limitations. First, the database includes countries that require a prescription for melatonin (such as the United Kingdom) and countries that don’t (such as the United States), and patient locations were not part of the de-identified data available to the researchers. Since melatonin use in the study was based only on those identified from medication entries in the electronic health record, everyone taking it as an over-the-counter supplement in the U.S. or other countries that don’t require a prescription would have been in the non-melatonin group; therefore, the analyses may not accurately reflect this. Hospitalization figures were also higher than those for initial diagnosis of heart failure because a range of related diagnostic codes may be entered for the hospitalization, and they may not always include the code for a new diagnosis of heart failure. The researchers also lacked information on the severity of insomnia and the presence of other psychiatric disorders.

“Worse insomnia, depression/anxiety or the use of other sleep-enhancing medicines might be linked to both melatonin use and heart risk,” Nnadi said. “Also, while the association we found raises safety concerns about the widely used supplement, our study cannot prove a direct cause-and-effect relationship. This means more research is needed to test melatonin’s safety for the heart.”

Study details, background and design:

• The study included 130,828 adults (average age of 55.7 years; 61.4% women) diagnosed with insomnia.
• The study data was from TriNetX, established in 2013, a growing global network of real-world, de-identified patient data available for research.
• 65,414 participants had been prescribed melatonin at least once and reported taking it for at least a year.
• A second group of people were examined for comparison (control group) — those who had never been prescribed melatonin and were matched to the group taking melatonin on 40 factors including demographic information, health conditions and medications. 
• Participants were excluded if they had already been diagnosed with heart failure or had been prescribed other types of sleeping pills such as benzodiazepines.
• The melatonin and control groups were matched for age, sex, race/ethnicity, heart and nervous system diseases, medications for heart and nervous system diseases, blood pressure and body mass index. Researchers looked at electronic medical records from the five years after the matching date.
• For the main findings, records were searched for codes related to an initial diagnosis of heart failure. Secondary findings included codes for hospitalization related to heart failure or death.
• Following the initial analyses, researchers validated the credibility of their findings by conducting a sensitivity analysis. This involved slightly changing the criteria: they required participants in the melatonin group to have filled at least two melatonin prescriptions that were at least 90 days apart. This adjustment aimed to determine whether the extended duration of confirmed melatonin prescriptions influenced the outcomes.
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Does intermittent fasting affect mental performance?

 

The health benefits of intermittent fasting are proven – but are you a little less sharp mentally when you’re deprived of food?

A review of 71 studies from around the world offers reassurance for adults, finding no meaningful difference in mental performance when going without food for between about eight and 24 hours.

“People often worry that if they fast they won’t be able to concentrate at work or study effectively,” says Dr David Moreau, a neuroscientist at the University of Auckland who was the senior author of the paper in Psychological Bulletin.

“Our results show that, for most adults, short-term fasting is unlikely to have a major impact on mental sharpness.”

However, children and adolescents tended to perform more poorly, reinforcing the importance of a proper breakfast before school.

There were also some nuances.

Fasting people tended to perform worse in tests later in the day, suggesting the lack of food may amplify natural dips in circadian rhythm.  

Tasks involving food-related cues, such as judging portion sizes or responding to food images, seemed to impede performance, perhaps because hungry individuals get distracted.   

“It seems the brain is quite resilient in the face of temporary food shortages,” says Moreau, who works in the University’s School of Psychology, leading the Brain Dynamics Lab.

“Humans evolved with periods of food scarcity, so it makes sense our cognitive systems can function well without constant refuelling,” he says. “That said, children and teenagers appear more vulnerable, which fits with what we know about their high energy demands.”

In the studies, the median fasting duration was 12 hours and only a few extended beyond 24 hours.

Lead author Dr Christoph Bamberg was a PhD student at the University of Auckland and is now at Lodron University Salzburg.

“These results don’t mean fasting is risk-free for everyone,” says Moreau. “People with health conditions, children, and those fasting for extended periods may still experience negative effects. Our review highlights the need for careful consideration in these groups.”

Even modest amounts of physical activity may slow Alzheimer’s disease among at-risk older adults

 

Increasing your steps by even a little bit may help slow down the progression of Alzheimer’s disease among people at heightened risk, according to a new study. In a paper published in Nature Medicine, Mass General Brigham researchers found that physical activity was associated with slower rates of cognitive decline in older adults with elevated levels of amyloid-beta, a protein associated with Alzheimer’s.

Cognitive decline was delayed by three years on average for people who walked just 3,000-5,000 steps per day, and by seven years in people who walked 5,000-7,500 steps per day. Sedentary individuals had a significantly faster buildup of tau proteins in the brain and more rapid declines in cognition and daily functioning.

“This sheds light on why some people who appear to be on an Alzheimer’s disease trajectory don't decline as quickly as others,” said senior author Jasmeer Chhatwal, MD, PhD, of the Mass General Brigham Department of Neurology. “Lifestyle factors appear to impact the earliest stages of Alzheimer's disease, suggesting that lifestyle changes may slow the emergence of cognitive symptoms if we act early.”

The researchers analyzed data from 296 participants aged 50-90 years old in the Harvard Aging Brain Study who were all cognitively unimpaired at the beginning of the study. They used PET brain scans to measure baseline levels of amyloid-beta in plaques and tau in tangles and assessed the participants’ physical activity using waistband pedometers. The participants received annual follow-up cognitive assessments for between two and 14 years (average = 9.3 years), and a subset received repeated PET scans to track changes in tau.

Higher step counts were linked to slower rates of cognitive decline and a slower buildup of tau proteins in participants with elevated baseline levels of amyloid-beta. The researchers’ statistical modeling suggested that most of the physical activity benefits associated with slowing cognitive decline were driven by slower tau buildup. By contrast, in people with low baseline levels of amyloid-beta, there was very little cognitive decline or accumulation of tau proteins over time and no significant associations with physical activity.

 “We are thrilled that data from the Harvard Aging Brain Study has helped the field better understand the importance of physical activity for maintaining brain health,” said co-author Reisa Sperling, MD, a neurologist in the Mass General Brigham Department of Neurology and co-principal investigator of the Harvard Aging Brain Study. “These findings show us that it’s possible to build cognitive resilience and resistance to tau pathology in the setting of preclinical Alzheimer’s disease. This is particularly encouraging for our quest to ultimately prevent Alzheimer’s disease dementia, as well as to decrease dementia due to multiple contributing factors.”

Looking ahead, the researchers plan to dive deeper into which aspects of physical activity may be most important, for example exercise intensity and longitudinal activity patterns. They also plan to investigate the biological mechanisms linking physical activity, tau buildup, and cognitive health. Critically, the authors believe that this work may help design future clinical trials that test exercise interventions to slow late-life cognitive decline, especially in individuals who are at heightened risk due to preclinical Alzheimer’s disease.

“We want to empower people to protect their brain and cognitive health by keeping physically active,” said first-author Wai-Ying Wendy Yau, MD, a cognitive neurologist in the Mass General Brigham Department of Neurology. "Every step counts — and even small increases in daily activities can build over time to create sustained changes in habit and health.”