Neuropsychological Changes in a Prospectively Followed Cohort of Intravenous Drug Users with and without HIV

We followed a cohort of 223 intravenous drug users (99 HIV and 124 HIV+) for up to 3.5 years, examining change in performance over time as a function of HIV status, disease severity, and neurological signs and symptoms. Analyses were performed by applying generalized estimating equations (GEE) to regression analyses with repeated measures, and controlled for age, education, and length of substance use. None of the subjects had AIDS at baseline. There were 147 men (85 HIV+ and 62 HIV) and 76 women (39 HIV+ and 37 HIV). Memory performance was worse in the HIV+ than HIV− women. In the men, performance on the memory, executive, language, and attention factors improved significantly overtime, but this improvement was attenuated in the HIV men for the attention and orientation factors. In the HIV+ women. AIDS was associated with worsening performance on attention tests. The presence or onset of clinically significant neurological findings was associated with poorer language and motor speed performance. In the HIV+ men, memory performance was worse when the CD4 count fell below 200: it declined over time in men with AIDS but not in those without. A learning effect for language was attenuated in men who developed AIDS. The presence or development of a clinically significant neurological sign was associated with poorer memory, executive, language, attention, and motor speed performance. Our findings parallel those that we previously reported in a prospectively followed cohort of gay men. In combination, our studies of gay men and IDU cohorts suggest that (a) HIV can affect cognition early, even when the patient is medically asymptomatic; (b) cognitive difficulties worsen as the severity of HIV infection increases; and (c) the advent of clinically significant neurologic signs is associated with progression to more severe cognitive deficits. Our data suggest that the neurological and neuropsychological changes are both manifestations of the central effect of HIV on the CNS.