Recently, the phrase “Historic document published prior to January 20, 2025” appeared on several U.S. National Institutes of Health (NIH) websites related to its policy on studying sex differences. This change raises concerns among neuroscientists about a potential retreat from research that accounts for sex and gender in health and biology.
Anne Murphy, a neuroscience professor at Georgia State, expressed her disappointment. She helped create the original policy and believes its reversal would hinder scientific progress. “It would set us back in terms of our science,” she said.
The policy, known as “Sex as a Biological Variable (SABV),” was introduced in 2016. It requires NIH-funded studies on vertebrate animals to include both males and females unless researchers provide a valid reason for not doing so.
It’s still unclear how the new labeling affects compliance with the SABV policy. Jill Becker from the University of Michigan mentioned that NIH officials assured her that researchers must include an SABV statement if requested in grant applications.
This label change happens alongside other developments, such as NIH scrutinizing grant proposals for specific terms like “female” and “gender” for compliance with an executive order from former President Trump. This order states there are only two recognized genders and aims to cut activities promoting diversity and inclusion.
“This is concerning, given the broader context,” noted Zoe McElligott, an associate professor at the University of North Carolina.
Before 2016, many researchers, particularly in neuroscience, often excluded female animals from studies. They believed that hormonal changes could skew results. However, without understanding the differences and similarities between sexes, our grasp of biology remains incomplete. Janine Austin Clayton, director of the Office of Research on Women’s Health, emphasized the importance of including both sexes in research findings.
Murphy pointed out that the SABV policy has led to significant discoveries in neuroscience. For instance, McElligott found that the way neurotransmitters affect alcohol consumption varies between male and female mice. Other research has documented distinct sex differences in brain areas and learning strategies. “Considering sex as a biological variable reveals a broader understanding of biology,” McElligott explained.
The policy is enforced during grant review meetings. However, since Trump’s presidency began, many of these meetings have faced delays due to a freeze on NIH communications. This has left scientists, especially those focused on sex differences, uncertain about the future of the policy.
Despite the uncertainty, Murphy remains hopeful. She trusts that the nearly ten years of the SABV policy have sufficiently influenced researchers’ perspectives on the importance of including both sexes in research. “If the policy is reversed, I hope people will still recognize its value,” she said.
