NewsMakers
Stress does turn hair gray (and it’s reversible)
And while it may seem intuitive that stress can accelerate graying, the researchers were surprised to discover that hair color can be restored when stress is eliminated, a finding that contrasts with a recent study in mice that suggested that stressed-induced gray hairs are permanent.
Legend has it that Marie Antoinette’s hair turned gray overnight just before her beheading in 1791. Though the legend is inaccurate–hair that has already grown out of the follicle does not change color–a new study from researchers at Columbia University Vagelos College of Physicians and Surgeons is the first to offer quantitative evidence linking psychological stress to graying hair in people.
And while it may seem intuitive that stress can accelerate graying, the researchers were surprised to discover that hair color can be restored when stress is eliminated, a finding that contrasts with a recent study in mice that suggested that stressed-induced gray hairs are permanent.
The study, published June 22 in eLife, has broader significance than confirming age-old speculation about the effects of stress on hair color, says the study’s senior author Martin Picard, PhD(link is external and opens in a new window), associate professor of behavioral medicine (in psychiatry and neurology) at Columbia University Vagelos College of Physicians and Surgeons.
“Understanding the mechanisms that allow ‘old’ gray hairs to return to their ‘young’ pigmented states could yield new clues about the malleability of human aging in general and how it is influenced by stress,” Picard says.
“Our data add to a growing body of evidence demonstrating that human aging is not a linear, fixed biological process but may, at least in part, be halted or even temporarily reversed.”
Studying hair as an avenue to investigate aging
“Just as the rings in a tree trunk hold information about past decades in the life of a tree, our hair contains information about our biological history,” Picard says. “When hairs are still under the skin as follicles, they are subject to the influence of stress hormones and other things happening in our mind and body. Once hairs grow out of the scalp, they harden and permanently crystallize these exposures into a stable form.”
Though people have long believed that psychological stress can accelerate gray hair, scientists have debated the connection due to the lack of sensitive methods that can precisely correlate times of stress with hair pigmentation at a single-follicle level.
Splitting hairs to document hair pigmentation Ayelet Rosenberg, first author on the study and a student in Picard’s laboratory, developed a new method for capturing highly detailed images of tiny slices of human hairs to quantify the extent of pigment loss (graying) in each of those slices. Each slice, about 1/20th of a millimeter wide, represents about an hour of hair growth.
“If you use your eyes to look at a hair, it will seem like it’s the same color throughout unless there is a major transition,” Picard says. “Under a high-resolution scanner, you see small, subtle variations in color, and that’s what we’re measuring.”
The researchers analyzed individual hairs from 14 volunteers. The results were compared with each volunteer’s stress diary, in which individuals were asked to review their calendars and rate each week’s level of stress.
The investigators immediately noticed that some gray hairs naturally regain their original color, which had never been quantitatively documented, Picard says.
When hairs were aligned with stress diaries by Shannon Rausser, second author on the paper and a student in Picard’s laboratory, striking associations between stress and hair graying were revealed and, in some cases, a reversal of graying with the lifting of stress.
“There was one individual who went on vacation, and five hairs on that person’s head reverted back to dark during the vacation, synchronized in time,” Picard says.
Blame the mind-mitochondria connection
To better understand how stress causes gray hair, the researchers also measured levels of thousands of proteins in the hairs and how protein levels changed over the length of each hair.
Changes in 300 proteins occurred when hair color changed, and the researchers developed a mathematical model that suggests stress-induced changes in mitochondria may explain how stress turns hair gray.
“We often hear that the mitochondria are the powerhouses of the cell, but that’s not the only role they play,” Picard says. “Mitochondria are actually like little antennas inside the cell that respond to a number of different signals, including psychological stress.”
The mitochondria connection between stress and hair color differs from that discovered in a recent study of mice, which found that stress-induced graying was caused by an irreversible loss of stem cells in the hair follicle.
“Our data show that graying is reversible in people, which implicates a different mechanism,” says co-author Ralf Paus, PhD, professor of dermatology at the University of Miami Miller School of Medicine. “Mice have very different hair follicle biology, and this may be an instance where findings in mice don’t translate well to people.”
Hair re-pigmentation only possible for some
Reducing stress in your life is a good goal, but it won’t necessarily turn your hair to a normal color.
“Based on our mathematical modeling, we think hair needs to reach a threshold before it turns gray,” Picard says. “In middle age, when the hair is near that threshold because of biological age and other factors, stress will push it over the threshold and it transitions to gray.
“But we don’t think that reducing stress in a 70-year-old who’s been gray for years will darken their hair or increasing stress in a 10-year-old will be enough to tip their hair over the gray threshold.”
NewsMakers
Study links coffee consumption to metabolic health and sex hormones
Despite having a similar body mass index (BMI), individuals with higher coffee consumption had lower total and visceral fat and greater skeletal muscle mass than those who consumed less coffee.
Coffee is one of the world’s most widely consumed beverages, and previous research has linked its consumption to a lower risk of conditions such as type 2 diabetes and cardiovascular disease. However, the biological mechanisms behind these benefits remain unclear. A new Finnish study links habitual coffee consumption to healthier body composition and metabolic markers, while revealing distinct associations with sex hormones in men and women.
The study, conducted at the University of Oulu, analysed data from 2,264 participants aged 46 in the Northern Finland Birth Cohort 1966. Researchers examined how habitual coffee consumption was associated with circulating metabolites, cardiometabolic risk markers and sex hormones.
Despite having a similar body mass index (BMI), individuals with higher coffee consumption had lower total and visceral fat and greater skeletal muscle mass than those who consumed less coffee.
In both men and women, higher coffee consumption was correlated with lower circulating levels of branched-chain amino acids, biomarkers that have previously been linked to insulin resistance and an increased risk of type 2 diabetes when chronically elevated.
The strongest sex-specific associations were observed in men. Higher coffee consumption was linked to a more favourable glucose–insulin profile, higher concentrations of total and bioavailable testosterone, and increased levels of sex hormone-binding globulin (SHBG). At the same time, free testosterone and the free androgen index were modestly lower. In women, hormonal associations were more limited and were primarily characterised by higher SHBG and lower measures of free androgens.
“Coffee is consumed by millions of people every day, yet we still know surprisingly little about how it relates to our metabolism and hormones. What stood out in our findings was a distinct hormonal signature that didn’t disappear even after we took into account BMI and lifestyle factors, with several of these associations differing between men and women,” says Luca Verroest, lead author of the study and Doctoral Researcher at the University of Oulu.
The results suggest that hormonal pathways may partly explain the relationship between coffee consumption and metabolic health. However, as this was an observational study, the findings demonstrate associations rather than cause-and-effect relationships.
The study is particularly relevant in Finland, one of the world’s highest coffee-consuming countries, where annual consumption averages around 11.8 kilograms per person.
The researchers say the findings provide a foundation for future studies aimed at determining whether coffee itself drives these biological changes and identifying the compounds responsible. These questions are currently being investigated in animal models, with the long-term goal of progressing to human intervention studies. Further research will be needed before the findings could inform dietary recommendations.
The study, Associations of habitual coffee intake with testosterone and cardiometabolic markers: the Northern Finland Birth Cohort 1966 study, has been published in the European Journal of Nutrition.
NewsMakers
Scheduling dental care during prenatal visits boosts oral health care during pregnancy
Scheduling a dental appointment during prenatal clinic visits—a simple, no-cost task that doesn’t require extra staff—increases the likelihood that patients later see a dentist during pregnancy.
Prenatal visits might include bloodwork, discussions of due dates and vitamins, and ultrasounds. What if these visits could also improve oral health care among pregnant patients?
New research shows that scheduling a dental appointment during prenatal clinic visits—a simple, no-cost task that doesn’t require extra staff—increases the likelihood that patients later see a dentist during pregnancy.
The study, published in the American Journal of Public Health, demonstrates the benefit of coordination among health providers and integrating oral health into prenatal care, especially for vulnerable patient populations.
Historically, dentists avoided treating women during pregnancy unless it was an emergency, or only provided care during the second trimester. This guidance changed once studies showed that routine and emergency dental care is safe during pregnancy—and current obstetric and dental guidelines stress that dental care can and should be provided during this critical period.
Moreover, pregnancy increases the risk of some oral health conditions, including gum inflammation and sometimes tooth decay, making routine dental care even more important during pregnancy. Some oral health issues may affect the fetus or even be transmissible to the child after birth.
Marginalized groups, including low-income individuals and those insured by Medicaid, are known to have higher rates of dental disease. Yet women enrolled in Medicaid are far less likely to see a dentist for a cleaning during pregnancy compared to women with private insurance.
“Many of those vulnerable to oral disease enter pregnancy with dental disease, and this may worsen during pregnancy,” said study author Stefanie Russell, associate professor at Rutgers School of Dental Medicine and an adjunct associate professor at NYU College of Dentistry, who led this research while at NYU.
One way to try and increase dental care among pregnant women is to reach them where they already are: their prenatal appointments. To bridge this gap, researchers and clinicians at NYU College of Dentistry teamed up with neighboring NYC Health + Hospitals/Bellevue, the oldest public hospital in the US, to create the New York University/Bellevue Prenatal Oral Health Program.
During weekly sessions at Bellevue’s prenatal clinic, pregnant patients receive a standardized screening to assess their oral health. Those with dental needs are referred to NYU College of Dentistry for follow-up care, educated about the importance and safety of dental care during pregnancy, and informed that Medicaid covers dental care in New York.
From 2018 to 2020, 420 prenatal patients with Medicaid coverage were referred to NYU Dentistry for follow-up dental care; the majority were Hispanic, and roughly half spoke Spanish as their first language. Referrals for dental care took two forms: immediately scheduled dental appointments made before the patient left the prenatal clinic or through a patient navigator. The patient navigator—a bilingual professional—educated patients regarding oral health, reminded patients of their upcoming dental appointments, and followed up after to identify any issues.
Nearly 44 percent of patients referred to NYU College of Dentistry followed through with a dental appointment. Both immediate appointment scheduling and the patient navigator increased the chances of a patient receiving dental care, but those who had appointments scheduled at their prenatal visit were 2.6 times more likely to see a dentist than those without appointments scheduled—even more likely than those who worked with the patient navigator.
“This suggests that immediately scheduled dental appointments can be an effective way to increase dental care utilization during pregnancy, without needing to hire extra staff,” said study author Shulamite Huang, assistant professor of epidemiology and health promotion at NYU College of Dentistry.
The authors conclude that integrating oral health screening in a prenatal clinic is feasible and increases engagement with dental care during pregnancy. They are continuing their research to measure whether this care improves oral health outcomes and to better understand how dental screening can be successfully integrated with prenatal care in other settings.
“A warm hand-off is key for addressing part of the barriers to dental care during pregnancy. Our team plans to further investigate and optimize interventions addressing both patient-, provider-, and healthcare system-level barriers to dental care during pregnancy,” said Huang.
Additional study authors include Richard Heyman and Mary Kang of NYU Dentistry; Belkys Saba, formerly of NYU Dentistry; Chloe Bird of the Tufts University School of Medicine; and Chengwu Yang of the Florida Atlantic University Schmidt College of Medicine.
NewsMakers
Why a UTI hurts — and why that might be a good thing
Australian researchers have discovered a previously overlooked group of bladder nerves that help detect urinary tract infections (UTIs) and trigger the body’s response to clear them, providing a potential new target for future bladder pain therapies.
Australian researchers have discovered a previously overlooked group of bladder nerves that help detect urinary tract infections (UTIs) and trigger the body’s response to clear them, providing a potential new target for future bladder pain therapies.
The study shows that bladder nerves located close to the lining of the bladder act as a frontline infection sensor, helping the body recognise UTIs and trigger responses that reduce the severity and spread of infection.
UTIs are among the most common bacterial infections worldwide, with more than 400 million cases reported every year. Nearly one in three women will experience UTIs before the age of 24, and many elderly people and those with bladder issues from spinal cord injuries can experience multiple UTIs in a single year.
Symptoms often include frequent urination, a sudden urge to urinate, pain during urination, and pelvic discomfort can be debilitating for some patients.
Flinders University’s Dr Luke Grundy says that while scientists have long understood how the bladder senses as it fills and triggers urination, the role of a specialised group of bladder nerves near the bladder lining has remained unclear.
“Most bladder nerves act like a fuel gauge, telling the brain when the bladder is filling up and needs emptying,” says Dr Grundy, Head of the NeuroUrology Research Group at Flinders University.
“The nerves we studied in this research are different. They sit close to the bladder lining and appear to act more like an early warning system, detecting infection and inflammation.
“They don’t just sense infection. They help coordinate the body’s response to it by triggering pain and urinary frequency, behaviours that appear to help clear bacteria from the bladder as part of the body’s defence system.”
Lead author and recently graduated PhD student Dr Cindy Tay says the discovery changes how these nerves are understood.
“These mucosal nerves have puzzled scientists for almost two decades because they stay quiet while the bladder fills and empties, which is the main job of the bladder,” says Dr Tay.
“What we’ve found is that they have a hidden job — acting as an early warning system that springs into action the moment infection takes hold.”
The research team developed a novel method to selectively study a specialised group of sensory nerves in the bladder lining of mice, revealing that while these nerves play little role in normal bladder function, they become highly responsive during a UTI and help detect and respond to infection.
“When the bladder is healthy, these nerves are relatively quiet, but during a urinary tract infection they become highly sensitive and respond to the presence of bacteria and inflammation,” says Dr Grundy.
“It may feel unpleasant, but urinating more frequently actually helps clear the infection by flushing out the harmful bacteria.”
The study also helps explain why people with conditions affecting nerve function may be more prone to recurrent or severe UTIs.
“If the nerves that detect infection aren’t working properly, the body may not respond as effectively,” says Dr Grundy.
Building on previous research, the new study reveals a deeper understanding of how UTIs affect bladder function and the nervous system, and could help develop new treatments that target these nerves to relieve UTI-related symptoms.
“Our findings provide new insight into how the bladder detects and responds to infection, helping explain the biological processes that drive the pain, urgency and discomfort commonly experienced during UTIs,” says Dr Grundy
Researchers say the next challenge is to develop therapies that ease the pain and urgency associated with UTIs while preserving the protective role these nerves play in fighting infection.
The paper, ‘Bladder mucosal afferents detect UTI and aid pathogen clearance,’ by Cindy Tay, Harman Sharma, Stewart Ramsay (University of Adelaide), Georgia Bourlotos, Sarah K Manning, Natalie E Stevens, Sophie J Miller, Geraint B Rogers, David J Lynn, Feargal J Ryan, Andrea M Harrington (University of Adelaide), Vladimir Zagorodnyuk, Steven L Taylor and Luke Grundy was published in Proceedings of the National Academy of Sciences (PNAS).
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