Increased volume of the striatum in psychopathic individuals.

Background: The corpus striatum, comprised of the caudate, putamen, and globus pallidus, plays an important role in reward processing and may be involved in the pathophysiology of antisocial behavior. Few studies have explored whether differences are present in the striatum of antisocial individuals. Here, we examine the structure of the striatum in relation to psychopathy.

Methods: Using a case-control design, we examined the volume of the striatum in psychopathic individuals compared with control subjects matched for age, sex, ethnicity, and substance dependence. Twenty-two psychopathic individuals assessed using the Psychopathy Checklist-Revised and 22 comparison subjects underwent structural magnetic resonance imaging. Volumes of the left and right lenticular nucleus (putamen and globus pallidus), caudate head, and caudate body were assessed and the psychopathic and control groups were compared.

Results: Psychopathic individuals showed a 9.6% increase in striatum volumes. Analyses of subfactors of psychopathy revealed that caudate body volumes were primarily associated with the interpersonal and affective features of psychopathy, while caudate head volumes were primarily associated with the impulsive, stimulation-seeking features.

Conclusions: These findings provide new evidence for differences in the striatum of psychopathic individuals. This structural difference may partially underlie the reward-seeking and decision-making deficits associated with psychopathy.