Vigilance in recovering cocaine-dependent and alcohol-dependent patients: a prospective study

Electroencephalographic activity and psychomotor performance were evaluated in 11 cocaine-dependent and 4 alcohol-dependent patients, after 1, 3, and 12 weeks of verified abstinence, and 15 non-drug-dependent age-matched controls, while they performed a 30-min signal-detection task. The task consisted of lower and higher pitched tones, 100 msec in duration, occurring in randomized order at a rate of 1 every 2 seconds. Subjects were asked to press a response key whenever they detected the less frequent (p = 0.3), higher pitched tone. Over the course of the 30 min task, subjects responded less frequently and more slowly to the higher pitched tone. Also, the amount of slow wave (i.e., alpha) activity in their EEGs increased. There were no differences among the groups with respect to the rate or magnitude of these time-related decrements in performance and electroencephalographic arousal. The only dependent variable which differentiated groups was reaction time, averaged across the duration of the task. Overall, the cocaine dependent group responded 80-100 msec slower than the other groups. In the context of other findings, this finding of increased reaction time among recovering cocaine dependent patients is interpreted as reflecting an effect of previous cocaine use on neural processes involved in the programming and/or execution of motor responses.