The longitudinal and interactive effects of HIV status, stimulant use, and host genotype upon neurocognitive functioning

BACKGROUND: Both HIV-1 infection and illicit stimulant use can adversely impact neurocognitive functioning, and these effects can be additive. However, significant variability exists such that as-of-yet unidentified exogenous and endogenous factors affect ones risk for neurocognitive impairment. Both HIV and stimulant literature indicates that host genetic variants in immunologic and dopamine-related genes are one such factor. In this study the individual and interactive effects of HIV status, stimulant use, and genotype upon neurocognitive functioning was examined longitudinally over a 10 year period. METHODS: 952 Caucasian HIV+ and HIV− cases from the Multicenter AIDS Cohort Study were included. All cases had at least two comprehensive neurocognitive evaluations between 1985 and 1995. Pre-HAART data was examined in order to avoid the confounding effect of variable drug regimens. Linear mixed models were used, with neurocognitive domain scores as the outcome variables. RESULTS: No 4-way interactions were found, indicating that HIV and stimulant use do not interact over time to affect neurocognitive functioning as a function of genotype. Multiple 3-way interactions were found that involved genotype and HIV status. All immunologic-related genes found to interact with HIV status affected neurocognitive functioning in the expected direction; however, only CCL2 and CCL3 affected HIV+ individuals specifically. Dopamine-related genetic variants generally affected HIV-negative individuals only. Neurocognitive functioning among HIV+ individuals who also used stimulants was not significantly different from those who did not use stimulants. CONCLUSION: The findings support the role of immunologic-related genetic differences in CCL2 and CCL3 in neurocognitive functioning among HIV+ individuals; however their impact is minor. Consistent with findings from another cohort, DA-related genetic differences do not appear to impact the longitudinal neurocognitive functioning of HIV+ individuals