Semantic priming and verbal learning in current opiate users, ex-users and non-user controls.

OBJECTIVE: Despite a growing interest in memory functions of chronic drug users, investigation of semantic and episodic memory in opiate users is limited, and findings of studies have been inconsistent. The present study aimed to assess semantic memory and episodic memory for both drug-related and neutral stimuli in current and ex-users of opiates. METHODS: Using an independent group design, we assessed semantic priming and verbal learning in 16 current opiate users on a methadone maintenance programme, 16 ex-opiate users in rehabilitation programmes and 16 healthy controls. The groups were matched on verbal IQ, age and employment status. RESULTS: We found that current and ex-users showed intact automatic and controlled semantic priming. Ex-users who had been abstinent for an average of 19 months showed a verbal learning impairment compared with controls. Both current and ex-users were impaired in recalling semantically unrelated words but unimpaired in recalling semantically related words. CONCLUSION: The findings suggest a relative lack of spontaneous use of mnemonic strategies and imply that highly structured information would help opiate-using clients in treatment.

Attentional bias, inhibitory control and acute stress in current and former opiate addicts.

BACKGROUND: Drug dependence is associated with both attentional biases to drug-related cues and inhibitory control deficits. Although acute stress is known to increase craving, it is not known whether this effect is mediated via changes in attentional bias and inhibitory control. OBJECTIVES: To examine the effect of a mild stressor on inhibitory control, attentional bias and craving in current opiate users (methadone maintained), ex-users (currently abstinent) and non-users (healthy controls). METHOD: Forty-eight participants (16 in each group) were exposed to both stress and non-stress conditions, after which inhibitory control and attentional bias was assessed using a Go-No-go and dot probe task respectively. Subjective ratings of stress levels and drug craving were repeatedly monitored. RESULTS: Current opiate users had significantly higher cravings ratings than both other groups at all times, and their craving tended to increase following the stress task. Current users had a greater attentional bias towards drug-related stimuli than the ex-users. Interestingly, ex-users showed a bias away from drug-related stimuli in the stress condition and this correlated positively with their length of abstinence. On the Go/No-go task, all groups had fewer false alarms in the stress condition. CONCLUSIONS: These results indicate that successful treatment is associated with a bias away from drugs, and that this bias may be protective against the effects of stress.