Abstract
The author evaluated visual steady-state evoked responses (SSER) and auditory amplitude-modulated following responses (AMFR) in 13 cocaine-dependent patients, 5 alcohol-dependent patients, and 12 non-drug-dependent control subjects. The 18 patients were studied after 1, 3, and 12 weeks of verified abstinence; the controls were studied after comparable intervals. Analyses revealed that visual SSER power increased as a function of modulation depth in the cocaine-dependent group, but not in the other groups. The difference among the groups was greatest at the highest modulation depth (80%) and did not diminish over time. Auditory AMFR power was also greater in the cocaine-dependent group relative to the other groups. However, unlike the visual SSER, the auditory AMFR normalized with continued cocaine abstinence. Collectively, the SSER and AMFR findings are interpreted as reflecting a residual cocaine effect which heightens CNS reactivity to sine wave (but not square wave)-modulated visual and auditory input.