Uncovering the role of sociodemographic factors in sex/gender differences in emotional brain activation: an SDM-PSI meta-analysis of fMRI studies

INTRODUCTION: The study of sex/gender (S/G) differences in neuroscience, particularly in emotional processing, has been hindered by methodological inconsistencies, often producing biased conclusions that overgeneralize brain differences between males and females. Moreover, many studies fail to consider how other sociodemographic factors interact with S/G to influence the brain. This study aims to address these gaps by investigating whether potential S/G effects in brain activation during emotion-evoking functional magnetic resonance imaging (fMRI) tasks are influenced by those factors. METHODS: This meta-analysis followed Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and was registered on PROSPERO. We searched for peer-reviewed studies on S/G differences in whole-brain activations during fMRI emotion-evoking tasks. Data analysis was conducted using Seed-based d Mapping with Permutation of Subject Images (SDM-PSI). Subgroup analyses were performed based on the type of tasks and on race, and meta-regressions assessed the impact of age, education, and hormonal contraceptive use on the main effects. RESULTS: 63 studies were included for the meta-analysis, comprising a total of 5,436 individuals from the general population (2,635 females). The main meta-analysis showed no significant S/G activation differences at the whole-brain level. Subgroup analyses, however, revealed significant S/G differences depending on the type of task and the race subgroup, while meta-regression analyses showed significant associations between S/G effects and education and hormonal contraceptive use, with notable shifts in activation patterns across these variables. DISCUSSION: Our findings highlight the need for more complex, intersectional models that consider the dynamic interplay of biological, psychological, and social factors in shaping S/G differences in brain function and mental health.