August 5, 2022

“Sex Differences in the Brain” Commentary Argues for Ongoing Sex Differences Research  

By Monica Lefton, Communications Manager.  

“The presence, magnitude, and significance of sex differences in the human brain are hotly debated topics in the scientific community and popular media… largely fueled by studies containing strong, opposing conclusions: either little to no evidence exists for sex differences in human neuroanatomy, or there are small-to-moderate differences in the size of certain brain regions that are highly reproducible,” authors of a new commentary paper in the Biology of Sex Differences journal write.  

Using two recent papers —  “Dump the ‘dimorphism’: Comprehensive synthesis of human brain studies reveals few male–female differences beyond size” and “Sex differences in the brain are not reduced to differences in body size” — that adopt opposing views, authors Alex R. DeCasien, Elisa Guma, Siyuan Liu, and Armin Raznahan explore how these conflicting beliefs could have emerged and then discuss how “to promote more effective progress in both scientific and lay discourses on sex differences in human brain anatomy.”  

Highlights from this Biology of Sex Differences commentary, “Sex differences in the human brain: a roadmap for more careful analysis and interpretation of a biological reality,” include:  

Read the Biology of Sex Differences commentary piece here

The Society of Women’s Health Research (SWHR) was founded to promote research on biological sex differences in disease, advance women’s health research, and ultimately, improve women’s health.  

SWHR believes studying sex differences is beneficial for everyone’s health. Because females and males can present with different disease symptoms and respond to treatments differently, studying sex differences and applying what is learned to clinical practice can better inform care options and improve health outcomes. Studying sex differences is especially beneficial to females, who have historically been left out of research. The subsequent lag in women’s health research has created notable health disparities in women facing conditions that exclusively affect women (menopause, fertility, endometriosis, and uterine fibroids, to name a few) or that differently or disproportionally affect women compared to men (for example, Alzheimer’s disease, cardiovascular disease, and autoimmune diseases).  

Beyond its women’s health programming, SWHR remains a leader in the sex differences space and dedicated significant effort to support the 1993 NIH Revitalization Act (mandating that women and minorities be included in all NIH-funded clinical research and that Phase III clinical trials be analyzed for sex differences) and the NIH 2015 Policy on Sex as a Biological Variable (SABV) (requiring grant applicants to account for SABV in their research design, analyses, and reporting in vertebrate animal and human studies). SWHR helped found the Organization for the Study of Sex Differences (OSSD) in 2006. OSSD and SWHR founded the Biology of Sex Differences journal in 2010.  

In response to the commentary’s publication, Biology of Sex Differences Editor-in-Chief Dr. Jill Becker released a statement remarking on the importance for sex differences research:  

Defining biological sex by gonadal and chromosomal characteristics at birth, multiple large datasets reflecting current best-practice show convergent evidence for small to moderate sex differences in human brain volume above and beyond sex-differences in brain size… There also diverse biological, psychological and social factors that could contribute to regional sex-differences in human brain anatomy. Untangling these causes is hard in humans, but may be helped by research in animal models… We offer this Commentary from DeCasien et al regarding sex-based differences in the human brain and argue that it is not sexist to discuss sex differences in the human brain. In fact, it is pro-human to understand where there are and where there are not differences in the human brain based on the sex of the individual. 

Read Dr. Becker’s full statement about the commentary on the journal’s homepage here and learn more about her research program and goals for the journal here 

Follow Biology of Sex Differences on Twitter at @BiologySexDiff for the latest on sex differences research.