Objective: To evaluate the hypothesis that poor adherence to highly active antiretroviral treatment (HAART) would be more strongly related to cognitive impairment among older than among younger HIV-seropositive adults.
Setting and participants: A volunteer sample of 431 HIV-infected adult patients prescribed self-administered HAART was recruited from community agencies and university-affiliated infectious disease clinics in the Los Angeles area.
Measurements: Neurocognitive measures included tests of attention, information processing speed, learning/memory, verbal fluency, motor functioning, and executive functioning. Medication adherence was measured using microchip-embedded pill bottle caps (Medication Event Monitoring System) and self-report. Latent/structural analysis techniques were used to evaluate factor models of cognition and adherence.
Results: Mean adherence rates were higher among older (>or=50 years) than younger (<50 years) HIV-positive adults. However, latent/structural modeling demonstrated that neurocognitive impairment was associated with poorer medication adherence among older participants only. When cognitive subdomains were examined individually, executive functioning, motor functioning, and processing speed were most strongly related to adherence in this age group. CD4 count and drug problems were also more strongly associated with adherence among older than younger adults.
Conclusions: Older HIV-positive individuals with neurocognitive impairment or drug problems are at increased risk of suboptimal adherence to medication. Likewise, older adults may be especially vulnerable to immunological and neurocognitive dysfunction under conditions of suboptimal HAART adherence. These findings highlight the importance of optimizing medication adherence rates and evaluating neurocognition in the growing population of older HIV-infected patients.