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.

Seventy-six homosexual or bisexual men underwent two cranial MRI studies at a mean interval of 13 months; 23 were HIV seronegative, 41 seropositive but asymptomatic (Center for Disease Control (CDC) groups II1III), and 12 had AIDS related complex (ARC)IAIDS (CDC group IV). Agreement between two neuroradiologists was rated as very good for assessment of enlargement of ventricles and good for widening of cerebral sulci and the presence of focal lesions. For assessment of serial studies, the agreement was moderate. The prevalence of cerebral atrophy and focal white matter lesions was no higher in the asymptomatic patients (CDC group II/III) than in appropriate seronegative controls. Some patients with ARC/AIDS showed evidence of developing cerebral atrophy during the study period when serial scans were compared. The imaging evidence supports the other data obtained from this cohort, which suggest that no significant CNS involvement occurs in HIV infection before the development of ARC/AIDS.

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