with AIDS,4 though pathological studies show an even higher prevalence of a subacute encephalitis,5 which is believed to be due to HIV itself.6 Five to 10% of subjects also develop signs of damage to the peripheral nervous system,7 and at postmortem as many as 25% show signs of spinal cord disease.8 Controversy exists over the possibility that asymptomatic seropositive individuals might show subclinical evidence of evolving damage to either the central or peripheral nervous system. In particular it has been suggested that such individuals show impaired performance when subjected to a battery of neuropsychological tests.9 At the end of 1987 we therefore embarked upon a longitudinal study ofa cohort of seropositive and seronegative homosexual men, who underwent neurological, neurophysiological, and neuropsychological tests at six to nine month intervals. Annual recording of event related evoked potentials (P300s), central motor conduction times with magnetic stimulation, anid magnetic resonance imaging of the brain (MRI scanning) were added to the assessments at the second visit. This report of the cross sectional comparison of seropositive and seronegative subjects combines the clinical, neuropsychological, and neurophysiological data from the first visit and the MRI, magnetic stimulation, and P300 data collected for the first time at the second visit.

A sample of 26 HIV seronegative, 59 HIV seropositive asymptomatic and 7 HIV seropositive symptomatic homosexual and bisexual men were assessed over two visits, a mean of 11 months apart, using the BDI, STAI, and CIS. Significant differences emerged between the symptomatic group and the other two groups. Past psychiatric history and the somatic items in the assessments accounted for some of these differences. The seropositive asymptomatic and the seronegative groups did not differ on any of the mood or psychiatric assessments, suggesting minimal effect on psychological well-being of seroconversion in the absence of symptoms.

As part of the Medical Research Council prospective study of the neurological and neuropsychological complications of human immunodeficiency virus (HIV) infection, long-latency event-related potentials were recorded in a cohort of homosexual and bisexual men. The latencies and amplitudes of the potentials, recorded from three scalp sites, were compared with the scores from neuropsychological tests of memory, attention, and concentration and with markers of immune function. The findings from 94 men were analyzed in the cross-sectional study of whom 47 were HIV seropositive without symptoms or signs of HIV type 1 (HIV-1) infection, 24 had progressed to the symptomatic stages of the disease, and 23 were persistently HIV seronegative. There were no consistently significant differences between the three subject groups in mean latencies and amplitudes of the P300 and N200 or in the numbers of abnormal P300 latencies. There were no significant correlations between either the neuropsychological tests scores or the immune measures (CD4 lymphocyte count and beta 2 microglobulin level) and the neurophysiological parameters. On repeated testing an average of 2 years later, there was no evidence of a significant trend towards deterioration in 30 HIV-seropositive subjects who remained asymptomatic compared with 22 HIV seronegatives. These findings indicate that there is no neurophysiological evidence of cognitive dysfunction in the asymptomatic stages of HIV-1 infection.