Exploration of possible sex bias in acute social stress research: a semi-systematic review

Stress can have a significant impact on the daily lives of individuals and can increase vulnerability to a number of medical conditions. This study aims to estimate the ratio of male to female participants in acute social stress research in healthy individuals. We examined original research articles published over the last 20 years. Each article was screened to determine the total number of female and male participants. We extracted data from 124 articles involving a total of 9539 participants. A total of 4221 (44.2%) participants were female, 5056 (53.0%) were male and 262 (2.7%) were unreported. Articles incorporating only females were significantly underrepresented compared to articles incorporating only males. Forty articles (63.5%) which presented data from both females and males, failed to analyse and interpret the results by sex, a significant methodological limitation. In conclusion, in the literature published over the last 20 years, female participants are significantly underrepresented. In the studies where females are represented, severe methodological limitations are apparent. Researchers should be conscious of sexual dimorphism, menstrual phase and use of hormonal contraception, which may impact the interpretation of their results.