Up to now, clinical trials and research studies have—to a great extent—relied on male participants. However, a first-of-its-kind study led by VCH Research Institute researchers Dr. Teresa Liu-Ambrose and Cindy Barha shows how important insights into treatments are lost when female subjects are bypassed.
Their study compares how aerobic exercise affects the cognitive function, memory and physical fitness of men and women with vascular cognitive impairment. Published in the Journal of Alzheimer’s Disease in November 2017, their findings reveal that women’s brains benefited more from six months of aerobic training than men’s.
“This may be related to a protein made in the brain called brain-derived neurotrophic factor. BDNF is involved in keeping old neurons healthy, making new neurons and helping increase existing connections between neurons,” says Barha.
Women involved in the study experienced an increase in certain types of cognitive functioning. They also saw increased levels of BDNF—while men saw a decrease. Similar results were also found in a review of randomized controlled trials of older adults co-authored by Barha and Liu-Ambrose, and published in July 2017.
Physicians and other health care providers may recommend different exercise routines for men and women based on the knowledge that aerobic activity benefits women cognitively and physically, while men only get a cardiovascular boost, says Liu-Ambrose.
“Results from clinical trials that include both men and women may well impact what treatments clinicians recommend for their patients.”
Why female participants in clinical trials matter
Personalized medicine—a form of care that tailors treatments to individual patients based on certain characteristics—is increasingly seen as the future of health care. Medical advances have made this more possible than ever before, and research that examines the differences between how treatments affect men and women is a critical next step. So why is an overhaul not already underway? A sticking point has been added costs and time associated with controlling for female patients.
“There is still a stigma about examining sex differences in science, and a belief that men and women should be prescribed the same treatments.”
Many medications are only tested on males before they become publically available, Barha adds, but this approach overlooks a lot of individual variation between men and women.
“Women have menstrual cycles that impact hormone levels,” Barha says. Because hormones are potent regulators of brain and behaviour, looking at both men and women in a clinical trial means researchers must account for changing hormone levels.
While this might mean researchers would likely need to raise more money to test additional research subjects, Barha believes it is worth the added cost.
“Instead of being afraid of hormones, embrace them and look at how they might be driving test results.”
The benefit to medicine could be more treatments designed specifically for men and women, and greater access to personalized care for both sexes.