Punishment and psychopathy: a case-control functional MRI investigation of reinforcement learning in violent antisocial personality disordered men.

BACKGROUND

Men with antisocial personality disorder show lifelong abnormalities in adaptive decision making guided by the weighing up of reward and punishment information. Among men with antisocial personality disorder, modification of the behaviour of those with additional diagnoses of psychopathy seems particularly resistant to punishment.

METHODS

We did a case-control functional MRI (fMRI) study in 50 men, of whom 12 were violent offenders with antisocial personality disorder and psychopathy, 20 were violent offenders with antisocial personality disorder but not psychopathy, and 18 were healthy non-offenders. We used fMRI to measure brain activation associated with the representation of punishment or reward information during an event-related probabilistic response-reversal task, assessed with standard general linear-model-based analysis.

FINDINGS

Offenders with antisocial personality disorder and psychopathy displayed discrete regions of increased activation in the posterior cingulate cortex and anterior insula in response to punished errors during the task reversal phase, and decreased activation to all correct rewarded responses in the superior temporal cortex. This finding was in contrast to results for offenders without psychopathy and healthy non-offenders.

INTERPRETATION

Punishment prediction error signalling in offenders with antisocial personality disorder and psychopathy was highly atypical. This finding challenges the widely held view that such men are simply characterised by diminished neural sensitivity to punishment. Instead, this finding indicates altered organisation of the information-processing system responsible for reinforcement learning and appropriate decision making. This difference between violent offenders with antisocial personality disorder with and without psychopathy has implications for the causes of these disorders and for treatment approaches.

FUNDING

National Forensic Mental Health Research and Development Programme, UK Ministry of Justice, Psychiatry Research Trust, NIHR Biomedical Research Centre.