Objective

This study aimed to determine the combined effects of age and HIV infection on the risk of incident neurocognitive disorders.

Method

A total of 146 neurocognitively normal participants were enrolled at baseline into one of four groups based on age (≤ 40 years and ≥ 50 years) and HIV serostatus resulting in 24 younger HIV-, 27 younger HIV+, 39 older HIV-, and 56 older HIV+ individuals. All participants were administered a standardized clinical neuropsychological battery at baseline and 14.3 ± .2 months later.

Results

A logistic regression predicting incident neurocognitive disorders from HIV, age group, and their interaction was significant (χ(2)[4] = 13.56, p = .009), with a significant main effect of HIV serostatus (χ(2)[1] = 5.01, p = .025), but no main effect of age or age by HIV interaction (ps > .10). Specifically, 15.7% of the HIV+ individuals had an incident neurocognitive disorder as compared to 3.2% of the HIV- group (odds ratio = 4.8 [1.2, 32.6]). Among older HIV+ adults, lower baseline cognitive reserve, prospective memory, and verbal fluency each predicted incident neurocognitive disorders at follow-up.

Conclusions

Independent of age, HIV infection confers a nearly fivefold risk for developing a neurocognitive disorder over approximately one year. Individuals with lower cognitive reserve and mild weaknesses in higher-order neurocognitive functions may be targeted for closer clinical monitoring and preventative measures.

With the rising number of individuals in their 50s and 60s who are infected with HIV, concerns have emerged about possible increases in the rates of non-HIV-associated dementias. The current study examined the prevalence of mild cognitive impairment (MCI) in older HIV-infected adults, since MCI is an intermediate state between typical cognitive aging and dementia that emerges in this age range. Participants included 75 adults with HIV disease aged 50 years and older who were on combination antiretroviral therapy (cART) and had undetectable plasma viral loads and 80 demographically similar HIV-seronegative comparison subjects. Participants completed a research neuropsychological evaluation that was used to classify MCI according to the comprehensive diagnostic scheme described by Bondi et al. (J Alzheimers Dis 42:275-289, 2014). HIV-infected persons were over seven times more likely to have an MCI designation (16 %) than their seronegative counterparts (2.5 %). Within the HIV+ cohort, MCI had minimal overlap with diagnoses of asymptomatic neurocognitive impairment and was significantly associated with older age, lower Karnofsky Scale of Performance Scores, and mild difficulties performing instrumental activities of daily living (iADLs). HIV infection in older adults is associated with a notably elevated concurrent risk of MCI, which may increase the likelihood of developing non-HIV-associated dementias as this population ages further.