Quantitative frontal and temporal structural MRI studies in personality-disordered offenders and control subjects.

High rates of temporal and frontal lobe dysfunction have been reported in neuropsychological and EEG studies of incarcerated personality-disordered (PD) offenders, but there have been few quantitative structural magnetic resonance imaging (MRI) studies. We investigated whether impulsive-aggressive male PD patients showed evidence of reduced brain volumes in frontal and temporal brain regions on MRI compared with healthy control subjects. All subjects were screened for axis I pathology and brain abnormalities. Quantitative measures of frontal and temporal lobe volume were computed on MR images of the brain in 19 control subjects and 18 patients who did not show any evidence of brain pathology on diagnostic MRI scans. Temporal lobe volumes were 20% smaller in PD patients than control subjects, but the predicted reductions in frontal lobe volume did not occur, despite evidence of impairments in executive function. There was no evidence of differences in asymmetry of brain structures. The study further implicates temporal lobes in the pathogenesis of severe personality disorder, but does not support the notion that PDs characterised by impulsive-aggressive traits have abnormalities in brain symmetry similar to those reported in mentally ill populations. Higher-resolution MRI studies are needed to localise the abnormalities and to determine their nature.