ERP RESPONSES TO TARGET AND NONTARGET VISUAL-STIMULI IN ALCOHOLICS FROM VA AND COMMUNITY TREATMENT PROGRAMS

This study had three aims: 1) to cross-validate previously reported fi ndings that sober alcholics compared to nonalcoholic peers have reduce d ERP P300 amplitudes to visual target stimuli at the Pt electrode; 2) to test the hypothesis that alcoholics from VA Hospital treatment pro grams will manifest more ERP indications of brain dysfunction than pee r alcoholics from community treatment programs (paralleling our neurop sychological findings in these samples); and 3) to explore differences among the groups in ERP responses to the little-studied nontarget sti muli. Nineteen VA alcoholics, 32 community alcoholics, and 24 peer com munity controls were given a visual ''oddball'' stimulus task. The tot al group of alcoholics had significantly lower P300 amplitudes than co ntrols for target stimuli at the Pt electrode but VA and community alc oholic subgroups did not differ. There were no latency differences bet ween or among the groups. On the nontarget stimuli, alcoholics had sig nificantly higher P100 and lower N100 amplitudes than the controls at all three scored electrodes (Fz, Ct, and Pt). We conclude that cross-v alidation of reduced P300 amplitudes at Pt in sober alcoholics was obt ained but that differences in severity of brain dysfunction, at least as measured by neuropsychological test performance, cannot account for alcoholics' ERP changes relative to controls. Finally, our data sugge st that ERP changes to nontarget visual stimuli should be investigated in addition to the more traditional ERP measures to target stimuli.