Reduced frontal grey matter, life history of aggression, and underlying genetic influence

Physically healthy, adult, same-sexed twins (n = 287) from a population-based twin cohort underwent high-resolution magnetic resonance imaging (MRI) to identify fronto-limbic brain regions significantly associated with lifetime history of aggression. MRI scans used a 3D magnetization-prepared rapid acquisition gradient-echo (MP-RAGE) sequence, for voxel-based morphometry (VBM) and history of aggressive behavior was assessed using the Life History of Aggression measure. Aggression had modest, inverse associations with grey matter volume (GMV) in medial prefrontal cortex (mPFC, b = -0.20, se = 0.05, p < 0.001) and lateral prefrontal cortex (lPFC, b = -0.23, se = 0.06, p < 0.001). These associations were not confounded by other demographic, psychiatric, or personality factors. Biometrical twin analyses revealed significant heritabilities of 0.57 for GMV in the mPFC cluster and 0.36 for GMV in the lPFC cluster. Genetic factors accounted for the majority of the phenotypic correlations between aggression and mPFC GMV (85.3%) and between aggression and lPFC GMV (63.7%). Reduced GMV of prefrontal brain regions may be a neuronal characteristic of individuals with substantial histories of aggressive behavior regardless of psychiatric diagnosis. As such, these data suggest an anatomical correlate, with a possible genetic etiology, associated with functional deficits in social-emotional information processing.