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 opiate 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 allocated to one of two groups who received either 50% or 100% of their daily stabilisation dose, and a placebo, in a double-blind, cross-over design. Twenty patients completed the study, all were assessed pre- and post-drug on 2 separate testing days. Results: Performance on a task tapping episodic memory (delayed recall of a prose passage) was significantly impaired following the 100% daily dose of methadone. Methadone treatment had no effect on craving or mood. Patients were unable to distinguish between methadone and placebo treatments. Conclusions: A single dose of methadone can induce episodic 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.