Top neuroscience research papers are eight times more likely to only study male participants or samples compared with female-only studies, a review has found. In addition, only 4 per cent of papers look for sex differences in their data, suggesting that neurological disorders in women may be being overlooked.
at the University of British Columbia, Canada, and her colleagues analysed the sex of samples used in every new research paper published by three of the world’s most respected neuroscience journals between 2009 and 2019.
“Many neurological and psychiatric disorders have sex differences in the prevalence of the disease,” says Galea, noting that depression is more in women than men, for example.
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“On average, women are diagnosed two years later than men for the same disease,” she says. While there are a variety of reasons for this, Galea says .
The researchers looked at more than 2000 papers published in Nature Neuroscience, Neuron and Journal of Neuroscience. Their analysis included looking at the sex of rodents used, the sex of human participants and the type of fetal or cell lines studied. Around 21 per cent of the papers involved human subjects. It wasn’t known whether the studies in the review included transgender or intersex people.
Studies looking at male and female sexes rose from 20 per cent in 2009 to 70 per cent in 2019, but only 4 per cent of the studies actually looked for sex differences in the data, because the female samples were too small to be effectively analysed.
Galea and her team also found that just 3 per cent of the papers they looked at were female-only studies, compared with 25 per cent involving just male subjects.
“Single-sex studies are important because women’s health is not just how they differ from men,” says Galea. “It’s about how the female’s unique physiology and gendered effects may be driving some of the differences in outcomes, disease rates and treatment needs.”
“We’ve known for a very long time that sex affects a wide array of disease traits,” says Judith Mank at the University of British Columbia, who wasn’t involved in the study. “This analysis makes it evident that scientific journals also need to make their expectations clear about data analysis methodology, and educate their peer reviewers about those expectations.”
“[We] are very much aware of this issue and we are working with the scientific community to improve practices to ensure that impacts of sex differences are assessed and integrated into experimental designs for both human and animal studies,” says a Nature Neuroscience spokesperson.
Nature journals have required researchers to declare the sex of subjects used since 2013, and have since 2020 recommended authors follow more stringent guidelines so that they can better consider sex differences in their findings, says the Nature Neuroscience spokesperson. “We appreciate that there is still more to do and we will continue to engage with researchers, institutions, funders and others to improve standards.”
Journal of Neuroscience editor-in-chief Marina Picciotto says: “At JN we believe reporting sex in the studies we publish is very important, but due to the international nature of the Journal and the varying policies of governments worldwide, we do not have an official stand on inclusion of males and females in our published research.”
Neuron anddidn’t respond to requests for comment.
bioRxiv
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