Differential effect of HIV infection and alcoholism on conflict processing, attentional allocation, and perceptual load: Evidence from a Stroop Match-to-Sample task

Background: Alcoholism and human immunodeficiency virus (HIV) injection each can impair components of selective attention, probably through disruption of the integrity of the frontoparietal neural systems that underlie conflict processing, attentional allocation, and perceptual load. Methods: We studied 18 patients with alcoholism (ALC) alone, 19 with HIV infection alone (HIV), 20 with both disorders (H+ A), and 19 healthy control subjects (CTL). We used a novel paradigm (Stroop Match-to-Sample tasks), in which subjects saw either a valid or invalid color cue before a target word, printed in a color that was either congruent or incongruent with the word's meaning. Results: All groups showed a significant Stroop effect, cue-target color Match effect, and interaction between Match and Stroop, with an exaggerated Stroop effect for the Match condition. The HIV patients were comparable to CTL, whereas ALC showed mild delays, with further delays associated with comorbidity with HIV. Although H+ A profited from a valid match to Stroop stimuli, they were compromised in disengaging attention from the invalidly cued color. Conclusions: Impairment in conflict processing and attentional allocation in alcoholism suggests disruption of frontal-parietal attentional systems. Although HIV alone did not demonstrate detectable impairment in performance, HIV conferred liability on attentional processes when combined with alcohol abuse.