| Psychopathy is a personality disorder that is exemplified by affective and interpersonal characteristics such as grandiosity, pathological lying, manipulative use of others, and a profound lack of empathy, guilt, and remorse. Psychopaths also typically demonstrate a constellation of problematic and dangerous behavioral characteristics including sensation seeking, impulsivity, and both instrumental and reactive aggression. Psychopathy and substance use disorders (i.e., abuse and dependence) are significant sources of financial and emotional burden in the United States, as both are strongly linked to severe and repetitive criminal activity. They are also highly comorbid, with psychopaths being about two to three times more likely to have a drug use disorder than nonpsychopaths. Using structural and functional neuroimaging and cluster analysis, this comorbidity was investigated in a series of studies involving incarcerated adult males and females, incarcerated adolescent males and females, and nonincarcerated adult males and females. Across samples, structural differences related to psychopathic traits were largely consistent, lending support to the idea that a network of regions across the paralimbic system is abnormal, at least structurally. Several of the regions identified in the structural studies were also hypoactive during the viewing of drug cues in a functional magnetic resonance imaging study of craving, suggesting a close link between structural and functional abnormalities. Finally, cluster analysis was used to identify typologies of substance users, and differential correlations with personality and individual differences variables were found. These results suggest that substance users are actually a heterogeneous group in terms of severity, drugs of choice, and personality correlates. This heterogeneity also suggests that individual differences should be taken into account when designing substance use treatment strategies. Analogous to the notion of personalized medicine, this philosophy could be at once both more effective and more efficient when applied to substance use treatment. In turn, the extreme financial and emotional burden that psychopathy and substance use disorders cause could be reduced. |
