Effects of methadone on cognition, mood and craving in detoxifying opiate addicts: a dose-response study

Rationale: Methadone is the most widespread pharmacological treatment for o piate dependency but relatively little is known of its effects on cognitive and psychomotor functioning, drug craving and mood. Objective. The present study aimed to assess the acute effects of methadone in patients admitted to an opiate detoxification programme, Methods: Patients were randomly allo cated to one of two groups who received either 50% or 100% of their daily s tabilisation dose, and a placebo, in a double-blind, cross-over design. Twe nty patients completed the study, all were assessed pre- and post-drug on 2 separate testing days. Results: Performance on a task tapping episodic mem ory (delayed recall of a prose passage) was significantly impaired followin g the 100% daily dose of methadone. Methadone treatment had no effect on cr aving or mood. Patients were unable to distinguish between methadone and pl acebo treatments. Conclusions: A single dose of methadone can induce episod ic memory impairment in patients who have a history of heroin use averaging more than 10 years. Such impairment can be avoided by giving methadone in divided doses.