Background: Drug-related stimuli reliably induce craving in experimental paradigms, yet are rarely cited by drug users as major precipitants of relapse. We examined the motivational significance of drug cues in opiate dependence, by exploring their impact on central attentional processes.
Method: Fourteen methadone-maintained subjects and 14 matched controls were studied. Subjects performed a novel active visual oddball task, consisting of opiate-related and matched neutral pictures, some of which (the oddballs) included a white cup. Subjects were fitted with a 32-channel electrode cap. The P300 for each stimulus category was identified using temporal principal components analysis.
Results: The P300 elicited by opiate stimuli was significantly larger than that elicited by neutral stimuli in the methadone-maintained group but not in the controls. There was also a non-significant trend for the opiate stimuli to elicit larger P300s than the oddball stimuli in the addicted group.
Conclusions: These results suggest that drug cues acquire motivational salience and automatically capture attentional resources in opiate addicts, even when engaged in a non-drug-related task. Enhanced P300s to drug cues may provide an important biological marker of crucial psychological mechanisms relevant to addiction.