Sex differences in the relationship between orbitofrontal cortex gray matter volume and risk-taking

Objective Risk-taking and impulsivity are related constructs that are often studied independently of each other, and sex differences in their neurobiological mechanisms are not well understood. Methods This study included 164 (69M/95F) individuals from the Nathan Kline Institute Rockland Sample between the ages of 18 and 40 who completed self-report measures of risk-taking and impulsivity (urgency being one of them). Gray matter volume in the lateral and medial orbitofrontal cortex was derived from T1-weighted images using FreeSurfer to examine the relationship to risk-taking and impulsivity. Results Males demonstrated greater risk-taking overall compared with females without sex differences on any specific subscale. In contrast, there were sex differences on specific subscales of impulsivity with females having greater (lack of) premeditation compared with males, but males having greater positive urgency and sensation-seeking compared with females. There was a significant positive correlation between total risk-taking and impulsivity in males and females, but this relationship was significantly stronger in females. Greater risk-taking was significantly and positively correlated with lateral orbitofrontal gray matter volume in males, but not females. Mediation analysis indicated that sensation-seeking partially mediated the relationship between lateral orbitofrontal gray matter volume and risk-taking in males. None of the correlations between medial orbitofrontal cortex volume and either risk-taking or impulsivity were significant in males or females. Conclusion Our findings provide evidence for sex differences in the relationship between lateral orbitofrontal cortex volume and risk-taking. Furthermore, among males, this relationship was partially mediated by sensation-seeking, providing novel information regarding sex differences in healthy brain–behavior relations.