Cognitive and socio-cognitive functioning of chronic non-medical prescription opioid users.

RATIONALE: Non-medical prescription opioid use (NMPOU) has become a major public health issue in the USA and is also increasing in Europe. However, little is known about neuropsychological associations of NMPOU-specifically regarding social cognition, which is essential for social functioning and treatability of opioid dependence. Previous studies with heroin users and opioid-substituted patients reported deficits in various cognitive functions, but these results are likely confounded by comorbid physical and psychiatric diseases, overdose-associated hypoxia, and adulteration of street heroin. Therefore, the purpose of the present study was to investigate social and non-social cognition in a relatively pure NMPOU sample taking opioid analgesics or antitussives.

METHODS: We assessed 23 individuals with NMPOU objectively confirmed by hair analyses and 29 opioid-naïve, healthy controls, employing a comprehensive neuropsychological test battery.

RESULTS: Significant impairments were found between NMPOU individuals and controls regarding the cognitive domains of attention (p < .01, Hedge's g = .85), declarative memory (p < .05, g = .66), and global cognitive empathy (p < .01, g = 0.99)-the latter included problems with emotion recognition from faces, voices, and complex scenes. Opioid hair concentrations transformed to morphine equivalents were negatively correlated with global cognitive empathy (r = - 0.52, p < .01), suggesting dose-dependent deficits.

CONCLUSION: In contrast to stimulant users primarily displaying deficits in emotional empathy, opioid users showed relatively selective impairments in measures of cognitive empathy, with dose-dependent effects suggesting potential opioid-induced deficits and involvement of the opioid-system in processes of cognitive empathy. These results have important implications for future interventions of opioid dependence targeting social functioning and consequently enhancing therapy outcome and preventing relapse.