Enhanced recognition of facial expressions of disgust in opiate users receiving maintenance treatment.

AIMS Accurate recognition of facial expressions of emotion is critical in interpersonal interaction but is impaired in alcoholics, even after a period of abstinence. Little is known of whether other drug-dependent populations also show these impairments. This study aimed to investigate facial expression recognition by chronic opiate users. DESIGN An independent group design was used to compare 20 participants receiving opiate substitution treatment, 20 ex-opiate users in rehabilitation (average abstinence of 6 months) and 21 unemployed healthy controls. MEASUREMENTS The accuracy and speed of recognizing morphed emotional facial expressions were assessed using an emotional hexagon task. FINDINGS Current opiate users were significantly more accurate than ex-users at recognizing expressions of disgust. They were also generally slower than controls in recognizing all expressions, and slower than ex-opiate users in recognizing surprise, happy and fearful expressions. CONCLUSIONS Opiate users in maintenance treatment show a heightened ability to recognize facial expressions of disgust. We suggest that this may reflect increased exposure to other people's expressions of disgust and/or priming by the physical and social environments encountered by opiate-dependent individuals. Further, opiate maintained individuals' global slowness in processing emotional expressions may reflect the sedative effects of methadone.