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Especially important for older men need to stay hydrated
Not only does dehydration make our mouths dry and make us want to drink water, it also impacts the regulation of body temperature. When we become dehydrated, we sweat less and, as a result, lose less heat and become less able to cool the body.
Our ability to regulate body temperature and keep our bodies from becoming dehydrated declines as we get older. New research published today in The Journal of Physiology improves our understanding of the relation between temperature regulation and dehydration.
This research can help us to better tailor strategies for managing both body temperature regulation and hydration during heat exposure in older adults. For example, because of reductions in thirst and our ability to preserve body fluid, as we age, we may require more frequent reminders to drink water during work in the heat or during heatwaves.
Exercise, especially when performed in a hot environment, exposes the body to heat stress, which causes body temperature to increase.
In these situations, we rely on sweating to help remove heat from the body and prevent continued rises in body temperature, which may increase the risk of heat-related illness or injury (such as heat stroke).
However, prolonged sweating can cause too much fluid to be lost from the body. Unless the person drinks water or a sports drink, this can lead to dehydration. Dehydration also reduces the volume of circulating blood and increases the blood’s salt content.
Not only does dehydration make our mouths dry and make us want to drink water, it also impacts the regulation of body temperature. When we become dehydrated, we sweat less and, as a result, lose less heat and become less able to cool the body.
While this can be disadvantageous to regulating body temperature, these adjustments limit further fluid losses and slow the rate of dehydration. Thus, our body’s response to dehydration acts to balance the body’s fluid and temperature regulatory needs.
Until recently, however, our understanding of the effects of dehydration on body temperature regulation came primarily from studies conducted in young adults.
Dehydration did not reduce heat loss or increase body temperature in the older adults during exercise. At first glance this seems like a beneficial response. However, this meant that the older adults did not attempt to adjust the rate of sweat loss to prevent further dehydration. As a result, they experienced greater strain on the heart as evidenced by a more pronounced increase in heart rate compared to younger men.
Previous literature indicates that as we age, our body responds less efficiently to dehydration, and some have suggested that this is due to an impaired ability of the body to ‘sense’ increases in salt levels in the blood (i.e. lack of water) that would normally trigger thirst and drinking.
Since the reduction in sweat rate during dehydration is beneficial for reducing fluid loss, researchers at the Human and Environmental Physiology Research Unit at the University of Ottawa reasoned that a reduced sensitivity to elevated blood osmolality (which is a measure of the bloods saltiness) may also explain the blunted effect of dehydration on heat loss and body temperature regulation in older adults during exercise in the heat.
To evaluate this hypothesis, the research group had young and older men perform exercise in the heat. Before exercise, blood salt content was increased artificially by giving them infusions of saline (salt water).
The participants performed the exercise in a device called a whole-body direct calorimeter, which precisely tracks the amount of heat lost from the entire body, which is caused by increases in sweating and blood flow to the skin.
The primary finding of the study was that, in contrast to young adults, the regulation of body temperature in the older adults was not influenced by increases in the saltiness of the blood.
Less efficient regulation of body temperature and hydration status are thought to contribute to the increased risk of mild (e.g. heat exhaustion) and severe (e.g., heat stroke) heat-related injuries as well as adverse heart problems experienced by older adults during heat stress, such as during occupational work in the heat (e.g., electrical utilities, construction) or in their homes/communities during heatwaves.
Since the young and older adults were physically active without any overt chronic health conditions it is difficult to know whether our findings translate to more sedentary individuals or those with common age-related chronic diseases such as Type 2 diabetes.
Commenting on the study, first author Robert Meade said: “Given that common age-related chronic health conditions such as type-2 diabetes are associated with less efficient regulation of body temperature and hydration status, future research should be conducted to see whether our findings translate to or are exaggerated in those populations. While our research design allowed us to test the independent effect of osmolality on heat loss, the effect of reduced blood volume (termed hypovolemia) on sweating in older adults is currently unknown.”
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Stress, BMI, and hormones linked to earlier puberty in girls
Higher levels of key steroid hormones—combined with elevated stress and body mass index (BMI)—are associated with earlier onset of puberty in girls.
Higher levels of key steroid hormones—combined with elevated stress and body mass index (BMI)—are associated with earlier onset of puberty in girls, according to a new study at Columbia University Mailman School of Public Health.
The findings are published in The Journal of Clinical Endocrinology & Metabolism.
Elevated prepuberty urinary levels of glucocorticoids, androgens, and progesterone were strongly linked to accelerated breast development (thelarche). Girls with high glucocorticoid levels alongside high BMI and stress entered puberty an average of seven months earlier than peers with lower levels.
“While stress and BMI have long been recognized as independent predictors of puberty, few studies have examined how they interact with a girl’s hormones,” said Lauren Houghton, PhD, assistant professor of Epidemiology at Columbia Mailman School, and first author. “Our findings challenge conventional research that has largely focused on estrogen and body size, highlighting instead the role of stress and androgens – typically thought of as male hormones– in shaping pubescent development.”
The strongest associations were observed for progesterone, androgens, and glucocorticoids, indicating that multiple hormonal pathways—not just estrogen—play a critical role in the timing of puberty.
For example:
- Higher glucocorticoid, androgen, and progesterone metabolites were associated with earlier onset of puberty
- Elevated androgens and progesterone were also linked to a longer duration of puberty
- Estrogen metabolites were associated with delayed onset, not acceleration
- The effects of hormones on puberty timing were significantly modified by BMI and stress levels.
Notably, the associations were consistent regardless of family history of breast cancer.
“Our objective was to identify the full set of hormonal patterns linked to accelerated puberty and test whether BMI and stress modify this relationship,” said Houghton, who is also assistant professor at the Herbert Irving Comprehensive Cancer Center at Columbia. “We predicted that girls with elevated BMI and stress would experience the earliest onset—and that the stress response shifts during this key time for girls.”
The researchers drew on data from the LEGACY Girls Study, a cohort of 1,040 girls ages 6 to 13 recruited across the U.S. States and Canada. Participants were followed every six months with clinical assessments, questionnaires, and biospecimen collection.
The analysis included 327 girls who were at the pre-puberty stage at baseline and provided urine samples at least one year before the onset of puberty. Houghton and colleagues measured a comprehensive panel of steroid metabolites using first-morning urine samples and tracked puberty development using validated clinical scales.
Mothers of the girls completed an Internalizing Composite Scale, which includes subscales for anxiety, depression, and other at-risk status. They also provided information on girls’ family history of all cancers as well as on pregnancy and infancy, including birth weight and their child’s race and ethnicity. Trained research staff measured height and weight twice every 6 months.
“Unlike prior research, this study simultaneously examined hormonal patterns, BMI, and psychosocial stress—captured through standardized behavioral assessments—within the same cohort,” said senior author Mary Beth Terry, PhD, professor of Epidemiology at Columbia Mailman School, and the Herbert Irving Cancer Center, and Silent Spring Institute. “Interestingly, we also learned that the associations were consistent regardless of family history of breast cancer.”
The findings may help explain the ongoing trend toward earlier puberty and point to actionable prevention strategies, observed the authors.
“Stress-reducing interventions and healthy lifestyle changes may help delay early puberty and improve long-term health outcomes,” said Houghton. ‘Because early puberty is linked to increased breast cancer risk later in life, the results have important implications for both pediatric care and public health.”
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Cancer risk is significantly higher for adults who never married, large study finds
Adults who were never married had substantially higher rates of developing cancer compared with those who were or had been married. For some cancers, the association was even stronger: adult men who were never married had approximately five times the rate of anal cancer compared with married men.
Adults who have never been married face a significantly higher risk of developing cancer than those who have been married, according to a study of more than 4 million cases.
The increased risk spans nearly every major cancer type and is especially pronounced for preventable cancers—those linked to infections, smoking and reproductive factors. Led by researchers at Sylvester Comprehensive Cancer Center, part of the University of Miami Miller School of Medicine, the study appears in the April 8 issue of Cancer Research Communications.
A link to the article is here.
“These findings suggest that social factors such as marital status may serve as important markers of cancer risk at the population level,” said Paulo Pinheiro, Ph.D., study co-author and a Sylvester physician-scientist whose lab conducts population-based cancer epidemiology.
The novel observation does not mean that getting married prevents cancer or that people need to get married.
“It means that if you’re not married, you should be paying extra attention to cancer risk factors, getting any screenings you may need, and staying up to date on health care,” said Frank Penedo, Ph.D., associate director for population sciences and director of the Sylvester Survivorship and Supportive Care Institute (SSCI).
“For prevention efforts, our findings point to the importance of targeting cancer risk awareness and prevention strategies with attention to marital status,” he added.
Marriage is already associated with earlier cancer diagnosis and better survival. Married individuals often, but not always, have stronger support systems, greater economic stability and are more likely to adhere to cancer treatment regimens.
But previous work on the links between marriage and cancer focused almost entirely on what happens at and after diagnosis. Only a few small, older studies explored whether marriage affects the odds of getting cancer in the first place.
“We wanted to know who is more likely to get cancer: married people or unmarried people?” Pinheiro said.
To find out, the researchers analyzed a large dataset covering 12 states that included demographic and cancer data from more than 4 million cancer cases in a population of more than 100 million people, collected between 2015 and 2022. They examined cases of malignant cancers diagnosed at age 30 or older and compared rates of various cancers by marital status, further broken down by sex and race and adjusted for age.
The researchers categorized marital status into two groups: those who were or had been married, including married, divorced and widowed individuals, and those who had never been married. The study began in 2015 because that year, the U.S. Supreme Court legalized gay marriage, allowing same-sex couples to be included in the married category. One in five adults in the study had never married.
Pinheiro expected to see some associations, given established relationships between marriage and lifestyle factors such as smoking, routine medical care and having children. But the strength of some findings surprised him.
Adults who were never married had substantially higher rates of developing cancer compared with those who were or had been married. For some cancers, the association was even stronger: adult men who were never married had approximately five times the rate of anal cancer compared with married men. Adult women who were never married had nearly three times the rate of cervical cancer compared with women who were or had been married.
Both anal and cervical cancers are strongly related to HPV infection, so these differences likely reflect variation in exposure, and for cervical cancer, also differences in screening and prevention. In contrast, for cancers such as endometrial and ovarian, differences by marital status may partly reflect the protective effect of parity, which is more common among married individuals.
“It’s a clear and powerful signal that some individuals are at a greater risk,” Penedo said.
Men and women showed slightly different patterns. Men who were never married were about 70% more likely to develop cancer than married men, while women who never married were about 85% more likely to develop cancer than women who were or had been married.
This represents a small but noteworthy reversal of a broader trend: Men often benefit more from marriage than women in terms of health and social factors. In this case, women appeared to benefit slightly more from marriage than men.
The strongest associations between marriage and cancer were seen for cancers related to infection, smoking or alcohol use, and, for women, cancers related to reproduction, such as ovarian and endometrial cancer.
The researchers found weaker associations for cancers with robust screening programs, including breast, thyroid and prostate cancers.
They also observed patterns across race and marital status. Black men who were never married had the highest overall cancer rates. However, married Black men had lower cancer rates than married White men, indicating a strong protective association with marriage in that group.
The study has limitations. People who smoke less, drink less, take better care of themselves and are more socially integrated may also be more likely to get married.
Still, the researchers found that associations between marriage and cancer were stronger in adults older than 50, suggesting that as people age and accumulate cancer risk exposures, the benefits associated with marriage may become more pronounced.
The study also excluded individuals who are unmarried but in committed partnerships. That group is likely small relative to the size of the dataset, Pinheiro said, but worth exploring in future research.
Future studies could further subdivide the married category into married, divorced and widowed individuals and follow people over decades to better understand how marital transitions affect cancer risk.
Overall, getting married does not magically prevent cancer, both authors stressed.
“But the association between marriage status and cancer risk is an interesting, new observation that deserves more research,” Pinheiro said.
NewsMakers
Social support, sleep, pain management linked to mental health in later life
Older people who are socially connected, physically healthy, and spiritually engaged are significantly more likely to experience complete mental health.
Older people who are socially connected, physically healthy, and spiritually engaged are significantly more likely to experience complete mental health.
This is according to a new study, “Flourishing older Canadians: What characteristics are associated with complete mental health?”, that was published in PLOS One.
Using data from 2,024 respondents in Statistics Canada’s 2022 Mental Health and Access to Care Survey (MHACS), researchers examined factors associated with both the absence of psychiatric disorder (APD) and complete mental health (CMH), a broader measure that combines freedom from mental illness with high emotional, psychological, and social well-being.
“Our findings shift the conversation away from mental illness alone and toward understanding what helps older adults truly flourish,” said first author Daniyal Rahim, PhD Candidate, Ontario Institute for Studies in Education, University of Toronto. “Complete mental health reflects not just the absence of disorders, but the presence of meaning, satisfaction, and strong social connections.”
The study found that older adults were more likely to experience APD and CMH if they were married or in a common-law relationship, had strong social support, rated their physical health as fair or better, and reported no chronic pain, sleep problems, or limitations in daily activities. Social support emerged as one of the strongest predictors, more than doubling the odds of achieving complete mental health.
“Social relationships appear to be a cornerstone of mental well-being in later life,” said coauthor Shannon Halls, Research Coordinator, Institute for Life Course & Aging, University of Toronto. “Having people to rely on during stressful times may buffer against psychological distress and promote resilience, happiness, and a sense of purpose.”
Spirituality was also strongly associated with mental well-being. Older adults who reported that religion or spirituality was important in their daily lives had significantly higher odds of both APD and CMH.
“Spiritual beliefs may help older adults cope with adversity by providing meaning, hope, and a sense of community,” said co-author Ying Jiang, a senior epidemiologist in the Applied Research Division, Centre for Surveillance and Applied Research, Public Health Agency of Canada. “These factors can be particularly relevant during periods of declining health or life transitions.”
Physical health factors played a critical role. Freedom from chronic pain, sleep problems, and limitations in instrumental activities of daily living was consistently associated with better mental health outcomes. Conversely, living in a large urban center was linked to lower odds of complete mental health compared to rural living.
“These findings underscore that mental health in aging is shaped by a complex interplay of social, physical, and environmental factors,” said senior author Esme Fuller-Thomson, Director, Institute for Life Course & Aging, University of Toronto, Factor-Inwentash Faculty of Social Work, University of Toronto. “Public health strategies that strengthen social support, address pain and sleep problems, and promote meaningful engagement could substantially improve well-being among older adults.”
The authors emphasize that many of the identified factors are modifiable, suggesting opportunities for targeted interventions, including social programming, pain management, sleep treatment, and community-based supports to help more older Canadians achieve complete mental health.
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