Researchers have long known that older females face a higher risk of dementia, cardiovascular disease, and stroke than males. However, the biological reasons behind this increased risk have remained unclear.
Marc Poulin
Research led by Dr. Marc Poulin, PhD, DPhil, a professor in the departments of Physiology & Pharmacology and Clinical Neurosciences at the Cumming School of Medicine, has shed some light on the mechanisms behind the increased risk women face.
The study, recently published in the Journal of Physiology, has important implications for women's health after menopause.
"Our research found that, when compared to men, women experienced greater increases in blood pressure and declines in cerebrovascular function over time," says Poulin. "This could help explain females' higher risk of diseases like dementia."
The study the first of its kind followed 89 men and women with an average age of 66 for six years. Researchers measured brain blood pressure and blood flow at different times to understand how cerebrovascular health changed over time.
According to Connor Snow, a PhD student supervised by Poulin and Dr. Stewart Longman, PhD, females showed better cerebrovascular function, on average, than their male counterparts at the beginning of the study. Over time, however, that advantage diminished as women's brain vascular health declined more rapidly.
"This demonstrates that brain blood vessels may age more quickly in older females, when compared to older males," says Snow, BSc'21.
The research team also examined sex hormones, including estrogen and testosterone, and found clear links between hormone levels and cerebrovascular function. These findings suggest that declining hormone levels, particularly in post-menopausal women, may play an important role in brain vascular health.
"We also found that both males and females with higher sex hormone levels fared better overall," says Snow. "However, hormone level measurements taken at the start of the study weren't a good predictor of brain health over time."
The study also highlighted challenges in tracking hormone changes in aging females. According to Snow, many participants had estrogen levels that were too low to be detected using current technology.
"This was quite surprising to me, given that studies have shown that estrogen is important in predicting the risk of stroke and cardiovascular disease," says Snow.
The findings underscore the need for more sex-specific research to better understand how menopause and hormones influence blood vessel aging and disease risk.
This study was supported by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institutes of Health Research, Diabetes Canada, and the Brenda Strafford Foundation Chair in Alzheimer Research.
The Poulin lab is looking for participants for its Brain in Motion Study II, which is examining the relationship between exercise, cerebral blood flow, and cognition in older adults who are at increased risk of Alzheimer's disease and related dementias and the role that exercise might play in the prevention of cognitive decline. Learn more about the study and find out how you may be able to participate here.
Connor Snow, PhD student. Image supplied
Dr. Marc Poulin, PhD, DPhil, is a professor in the departments of Physiology & Pharmacology and Clinical Neurosciences at the Cumming School of Medicine and the Faculty of Kinesiology. He holds the Brenda Strafford Foundation Chair in Alzheimer Research. Poulin is a member of the Libin Cardiovascular Institute, Hotchkiss Brain Institute, O'Brien Institute for Public Health, and the Calvin, Phoebe and Joan Snyder Institute for Chronic Diseases.
