Effects of HIV-1 infection and aging on neurobehavioral functioning: preliminary findings

The effects of aging on the presentation of HIV-associated neurocognitive disorders are largely unknown. In a cross-sectional observational study, we compared the neuropsychological profiles of 67 HIV-positive patients aged at least 50 years with those of 52 participants aged 35 years or less.

Participants received neuropsychological, psychiatric and neuromedical evaluations. Raw neuropsychological test scores were converted to demographically corrected T-scores; all were corrected for the effects of normal aging. Clinical ratings of impairment were assigned to the neuropsychological results.

The two groups did not differ statistically with respect to demographic variables, percentage with AIDS, or CD4 cell counts. The 'younger' group had higher viral burdens in plasma and cerebrospinal fluid (CSF), and fewer were receiving antiretroviral treatment. The proportion of neuropsychologically impaired subjects in the 'older' group was slightly greater than in the younger group, and the older group tended to have higher rates of impairment across most ability domains. When group differences in CSF viral load were modeled statistically, both viral burden and age were significant predictors of neuropsychological impairment, together with a significant interaction between viral burden and age. Older individuals with detectable virus in CSF had twice the prevalence of neuropsychological impairment of those with undetectable levels. Among younger individuals, this proportion was not affected by viral load. Lifetime major depression, substance use disorder, and current depression symptoms were not associated with neuropsychological impairment.

Although further studies with larger and older samples are needed, this investigation suggests that older adults may be at greater risk of HIV-related neurocognitive dysfunction.