Tuesday, November 1, 2022

Women and Men are Different, Cardiovascular Edition *

Environmental & Science Education, STEM, Health, Medicine, Nature of Science, History of Science

Ed Hessler

A  cardiovascular study has shown another physiological difference between men and women, one that appears likely to influence health care. STAT's Jane Williamson-Lee reports on the study which had some novel design features because the research team wanted to film hearts in action, during exercise. 

Two research groups were involved from The University of Calgary and the University of Hong Kong The design chosen had  research subjects "lie on their back in a pressure controlled chamber, riding a suspended stationary bike while an ultrasound imager points at their pumping heart." What follows is not a complete report and you need to read the full reporting. 

The results were reported in Science Translational Medicine (19 October 2022) Williamson-Lee summarizes the results in one short sentence. "[W]omen’s lean body mass, composed mostly of skeletal muscle, correlates with a better-functioning heart, while men’s do not.." It is well known that "men had significantly more lean body mass than women." The article is fully available and includes a PDF.  

The study subjects were "70 healthy, white adults. When asked "why other racial or ethnic groups weren't included," co-author David Montero "said that the sophisticated physiological methods used did not allow the researchers to perform a large population study."

Lead author Candela Diaz-Canestro added that "This work is part of a larger body of literature that seeks to overcome previous bias in research favoring male subjects — both in mice and in people.. As a researcher, she has been '“trained to extrapolate these results to women, and as we have seen now in this study, for some details, we can’t do this extrapolation.” 

To which Dr. Emily Lau, Massachusetts General Hospital, added when interviewed by Williamson-Lee, “'For so long in medicine, we’ve really treated men and women as essentially the same thing or if anything, we treat women as little men,' "prioritizing women’s smaller size over other fundamental biological differences. It’s no surprise that there’s a 'myth that heart disease is really a disease of men."”

For information about Candela Diaz-Canestro I direct you to two sources. The research paper linked above and to co-author David Montero under publications.

The decline in knowledge of this health statistic surprised me. Williamson-Lee noted. "When asked, 'What’s the number one cause of death in women?' two-thirds of women in a 2009 American Heart Association survey (linked in the report) were able to answer correctly: heart disease. Ten years later, in 2019, only 44% percent of women were able to say with confidence that heart disease is the leading cause of death in women." 

Limitations of the famous Body Mass Index (BMI) are reported.When a woman's weight exceeds what is expected for her height, one recommendation is to lose weight. However, Williamson-Lee points out that  "The body mass index, commonly used to measure body fat based on height and weight, does not differentiate between a person’s fat mass and their lean body mass."

Montero also told Williamson-Lee that the research “'open(s) the possibility that improving lean body mass, which can be improved with resistance training and other interventions, may be able to improve cardiovascular function and structure, and many strong diagnostic factors [related to] cardiac capacity and aerobic capacity in women.'”

Williamson-Lee also details some of the information about lean body mass, mentions limitations, clinical possibilities, some related observations, made during the study on lean body mass and cardiac effectiveness, textbook re-writing (likely in future and as more data are collected) and notes that the team is in the midst of research on an Asian  population.
*The title is taken from the title of the STAT report cited. I liked it.


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