Psychopathic heroin addicts are not uniformly impaired across neurocognitive domains of impulsivity.

BACKGROUND: Impulsivity is a hallmark characteristic of drug addiction and a prominent feature of externalizing disorders such as psychopathy that are commonly comorbid with drug addiction. In a previous study (Vassileva et al., 2007) we have shown that psychopathic heroin addicts evidence more impulsive decision-making on the Iowa Gambling Task relative to non-psychopathic heroin addicts. The goal of the current study was to investigate whether the observed impulse-control deficits in psychopathic heroin addicts would generalize to other neurocognitive domains of impulsivity, such as delay discounting and behavioral inhibition among a group of relatively "pure" heroin addicts in Bulgaria who participated in our previous study.

METHODS: We tested 92 currently abstinent male heroin addicts, classified as psychopathic or non-psychopathic based on the Hare Psychopathy Checklist - Revised (PCL-R). We administered two neurocognitive tasks of impulsivity: (1) Delayed Rewards Discounting Task, a measure of temporal discounting of rewards; and (2) Passive Avoidance Learning Task, a measure of behavioral inhibition.

RESULTS: Psychopathic heroin addicts were not impaired relative to non-psychopathic heroin addicts on the Delayed Rewards Discounting Task and the Passive Avoidance Learning Task, on the latter of which they showed better attentional capacity.

CONCLUSIONS: These results indicate that psychopathic heroin users are not uniformly impaired across neurocognitive domains of impulsivity. Combined with our previous findings, results suggest that the presence of psychopathy may exacerbate decision-making deficits in psychopathic heroin addicts, but it may not have significant effect on other neurocognitive domains of impulsivity in this population.