AUDITORY AND VISUAL EVENT-RELATED POTENTIALS IN A CONTROLLED INVESTIGATION OF HIV-INFECTION

Auditory and visual event-related brain potentials (ERPs) were used to complement neuropsychological and medical assessment in neurologicall y healthy subjects with asymptomatic and symptomatic human immunodefic iency virus type 1 (HIV-1) infection. Auditory and visual ERPs, record ed using standard oddball paradigms, disclosed delays in late waves (N 2 and P3) in symptomatic subjects (CDC stage IV) when compared with ma tched controls. Abnormally delayed P3 waves in at least one modality w ere recorded in 41% of symptomatics and this was associated with defic its in neuropsychological performance, particularly psychomotor slowin g. However, no differences in late wave latencies between asymptomatic and control subjects were found, though asymptomatics showed delays i n auditory N1 and P2 latencies. The number of morphological abnormalit ies, such as indiscernible late waves as well as topographical variabi lity of the P3 wave, was increased in both HIV seropositive groups and possibly indicates a distinct mechanism of impairment, different from latency delay. Whilst P3 delay in symptomatics was not associated wit h changes in immune function (T4 cells) there was, however, a link wit h anaemia and subclinical hepatic dysfunction.