Marijuana effects on changes in brain structure and cognitive function among HIV+ and HIV− adults

Background The current study examined the independent and interactive effects of HIV and marijuana (MJ) use on brain structure and cognitive function among a sample of HIV-positive (HIV + ) and HIV-negative (HIV-) individuals. Methods Participants (HIV+, n = 48; HIV-, n = 29) individuals underwent cognitive testing, questionnaires about substance use, and brain MRI. The HIV+ group was clinically stable based upon current plasma CD4 count, 50% had undetectable viral load (i.e., < 20 copies/mL), and all were on a stable regimen of cART. Results For HIV+ and HIV- participants, higher levels of MJ use were associated with smaller volumes in the entorhinal cortex and fusiform gyrus. HIV status (but not MJ use) was associated with cingulate thickness, such that HIV+ participants evidenced smaller thickness of the cingulate, as compared to HIV- controls. Regarding neurocognitive functioning, there was a HIV*MJ interactive effect on global cognition, such that when the amount of MJ use was less than 1.43 g per week, the HIV- group displayed significantly better neurocognitive performance than the HIV+ group (t = 3.14, p = 0.002). However, when MJ use reached 1.43 g per week, there were no significant HIV group differences in global cognitive performance (t = 1.39, p = 0.168). Conclusions Our results show independent and interactive effects of HIV and MJ on brain structure and cognition. However, our results do not support that HIV+ MJ users are at greater risk for adverse brain or cognitive outcomes compared to HIV- MJ users.