Striatal gray matter volumes, externalizing traits, and N-back task performance: An exploratory study of sex differences using the human connectome project data

The striatum is implicated in externalizing traits and cognitive dysfunction. The ventral and dorsal striatal subregions may play differentiable roles in externalizing behaviors and executive functions. We employed voxel-based morphometry to estimate the striatal gray matter volumes (GMVs) of 968 young adults (510 women) of the Human Connectome Project. We examined sex differences in striatal GMVs, tested how striatal GMVs related to an externalizing trait (Extn), and 2-back memory efficiency (Eff2), and examined whether these relationships exhibited sex differences. Men showed significantly higher ventral striatum (VS) and lentiform nucleus (LN) GMVs as well as higher Extn and Eff2 than women. Across all subjects, greater caudate and LN GMVs were correlated significantly with lower Eff2 though with limited effect sizes (r = −0.140, p < .001 and r = −0.093, p = .004, respectively) and the latter correlation was carried primarily by women (z = −3.070, p = .002, slope test). VS GMV showed positive correlation with Extn (r = 0.085, p = .008). Together, striatal GMVs are significantly but only weakly associated with externalizing behaviors and cognitive dysfunction in young adults. As key hubs of the fronto-striatal circuits, the ventral and dorsal striatum may contribute differently to externalizing psychopathology.