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COMT Val158Met Polymorphism, Cardiometabolic Risk, and Nadir CD4 Synergistically Increase Risk for Neurocognitive Impairment in Men Living with HIV.

OBJECTIVE
The Val allele of the Val158Met single-nucleotide polymorphism of the catechol-o-methyltransferase gene (COMT) results in faster metabolism and reduced bioavailability of dopamine (DA). Among persons living with HIV (PLWH), Val carriers display neurocognitive deficits relative to Met carriers, presumably due to exacerbation of HIV-related depletion of DA. COMT may also impact neurocognition by modulating cardiometabolic function, which is often dysregulated among PLWH. We examined the interaction of COMT, cardiometabolic risk, and nadir CD4 on neurocognitive impairment (NCI) among HIV+ men.


METHODS
329 HIV+ men underwent COMT genotyping and neurocognitive and neuromedical assessments. Cohort-standardized z-scores for body mass index, systolic blood pressure, glucose, triglycerides, and high-density lipoprotein cholesterol were averaged to derive a cardiometabolic risk score (CMRS). NCI was defined as demographically-adjusted global deficit score≥0.5. Logistic regression modelled NCI as a function of COMT, CMRS, and their interaction, covarying for estimated premorbid function, race/ethnicity, and HIV-specific characteristics. Follow-up analysis included the 3-way interaction of COMT, CMRS, and nadir CD4.


RESULTS
Genotypes were 81 (24.6%) Met/Met, 147 (44.7%) Val/Met, and 101 (30.7%) Val/Val. COMT interacted with CMRS (p=0.02) such that higher CMRS increased risk of NCI among Val/Val (OR=2.13, p<.01), but not Val/Met (OR=0.93, p>.05) or Met/Met (OR=0.92, p>.05) carriers. Among Val/Val, nadir CD4 moderated the effect of CMRS (p<.01) such that higher CMRS increased likelihood of NCI only when nadir CD4<180.


DISCUSSION
Results suggest a tripartite model by which genetically-driven low DA reserve, cardiometabolic dysfunction, and historical immunosuppression synergistically enhance risk of NCI among HIV+ men, possibly due to neuroinflammation and oxidative stress.