Our knowledge about the neurobiology of suicide is limited. It has been proposed that suicidal behavior generally requires biological abnormalities concomitant with the personality trait of impulsivity/aggression, besides an acute psychiatric illness or psychosocial stressor. We investigated fronto-limbic anatomical brain abnormalities in suicidal and non-suicidal adult female patients with unipolar depression. Our sample consisted of seven suicidal unipolar patients, 10 non-suicidal unipolar patients and 17 healthy female comparison subjects. The criterion for suicidality was one or more documented lifetime suicide attempts. A 1.5T GE Signa Imaging System running version Signa 5.4.3 software was used to acquire the magnetic resonance imaging images. All anatomical structures were measured blindly, with the subjects' identities and group assignments masked. We used analysis of covariance with age and intracranial volume as covariates and the Tukey-Kramer procedure to compare suicidal patients, non-suicidal patients and healthy comparison subjects. Suicidal patients had smaller right and left orbitofrontal cortex gray matter volumes compared with healthy comparison subjects. Suicidal patients had larger right amygdala volumes than non-suicidal patients. Abnormalities in the orbitofrontal cortex and amygdala in suicidal patients may impair decision-making and predispose these patients to act more impulsively and to attempt suicide.
