MRI scans of 120 adults in the United States found that people with higher psychopathic traits had a striatum—an area involved in reward and motivation—that was about 10% larger on average than those with few or no such traits, according to a study in the Journal of Psychiatric Research.
Neuroscientists have reported a measurable brain difference associated with psychopathic traits, based on structural MRI scans and clinical-style assessments.
Researchers from Nanyang Technological University in Singapore, the University of Pennsylvania and California State University, Long Beach published their findings in the Journal of Psychiatric Research in a paper titled “Larger striatal volume is associated with increased adult psychopathy.”
In the study, the team assessed psychopathic traits using the Psychopathy Checklist–Revised (PCL-R) and compared those scores with participants’ brain scans. They found that the striatum—a deep forebrain region involved in reward-related processing and motivation—was larger in people with higher psychopathy scores.
The authors reported that, in a matched comparison of 18 individuals classified as psychopathic and 18 controls, striatal volume was 9.4% higher in the psychopathic group. The study also reported that stimulation-seeking and impulsivity partly mediated the relationship between striatal volume and psychopathy, accounting for 49.4% of that association.
The paper analyzed MRI data from 108 community-dwelling adult men and included an exploratory analysis of a smaller sample of women, which the authors described as preliminary because of its limited size.
