Methadone and buprenorphine are among the most widely employed pharmacological treatments currently available for opioid addiction. Cognitive effects of buprenorphine in abstinent heroin abusers are nevertheless far from being understood.

Neuropsychological performance of 18 buprenorphine-maintained patients (BMP) was evaluated relative to that of 32 currently abstinent heroin abusers on naltrexone hydrochloride therapy (FHAN), and 34 non-drug dependent controls. The three groups were demographically balanced. Clinical groups reported histories of similar patterns of drug use and had increased periods of abstinence from any illicit substance use including heroin.

The BMP group performed poorer than controls on the RAVLT (encoding and delayed recall of verbal information), CTT (conceptual flexibility, executive functions) and the RBANS figure copy (visual perception) and delayed recall of visual information. There were no significant differences in any of the cognitive measures between the BMP and FHAN groups or between the FHAN group and controls. Furthermore, there were no differences in the percentage of abnormal cases between the two patient groups.

Overall, results suggest that treatment with naltrexone in abstinent heroin abusers may result in less impairment of cognitive functions compared to treatment with buprenorphine. These findings are relevant for improved prognosis and treatment strategies in opioid dependence.