Medical research into sex differences falls 'woefully short,' expert says

Scientists said Wednesday they had taken a key step towards stem cell therapy for rare mitochondrial disorders, passed on from mother to child. (©angellodeco/shutterstock.com)

Research into both diseases and treatments still too often overlooks the differences between the sexes, according to a new study out of the University of British Columbia.

Dr. Liisa Galea, professor in the department of psychology and lead of the Women’s Health Research Cluster, says it has been nearly three decades since it became mandatory to include females in research.

That change was ushered in because too often studies of symptoms, diseases, and treatments excluded female subjects.

"Our medical research has been focused largely on male physiology," she explains.

"The basic structure is all based on the 'norm' of males. It's kind of important to look at the role that our biology plays in diseases, but it's very rarely looked at.

While having single-sex studies makes sense in some cases, in others it can be dangerous not to include research subjects from both sexes.

"People probably do understand that there are differences in diseases, obviously, between males and females, females have uterine cancer, males have prostate cancer because of the different kinds of organs that we have. But even in diseases that we share, there are differences," she explains.

"It's not just about how many people are getting these different diseases, but do they manifest differently."

The "classic" example, according to Galea, is heart disease. While males typically experience chest pain when having a heart attack, women are more likely to feel a sore jaw or flu-like symptoms. Not knowing how a different disease manifests can mean not diagnosing or treating it, sometimes with fatal consequences.

Galea also says new research out of Denmark also found disease diagnosis among females is generally delayed.

"Females were diagnosed on average two years later than males with the same disease. There's a lot of reasons for that, but probably one of them is that the manifestations of disease can be different," she explains.

Galea and her team's most-recent research tried to measure not only how often both sexes were included, but whether the inclusion translated to a meaningful study of sex differences.

What she found, she describes as falling "woefully short."

In reviewing 3,193 neuroscience and psychiatry studies from 2009 and 2019, they found that only 53 per cent of the studies included both males and females. Just 17 per cent included an equal number of males and females, and only four per cent used "best practices for discovering possible differences between the sexes."

So, even if the percentage of studies that include both sexes has improved, Galea says it appears to be being done in a way that "ticks a box" and not in a way that treats sex differences as a significant variable.

"It's kind of important to look at the role that our biology plays in diseases, but it's very rarely looked at," she says.