Background
Cannabis (CB) use is increasing nationwide due to legal changes and commercialization. People with HIV (PWH) are more likely to use CB versus people without HIV (PWoH). Data on the effects of CB use on brain structure and cognition in PWH are mixed, with few studies including measures of structural brain integrity.
Methods
In a 2×2 design, participants were classified as CB user (CB+; PWH n=49;PWoH n=37) or non-user (CB-; PWH n=38;PWoH n=49) based on self-report (CB+=average of ≥3 days/week for past ≥12 months; CB-=no use ever, or <10 times total). Participants completed questionnaires assessing lifetime and recent (past 30 days) CB use, cognitive testing, a urine sample to measure metabolites of CB, and a magnetic resonance imaging scan to get regional brain volumes and cortical thickness (CT). Effects of HIV status and CB use, and their interaction, were assessed for cognition, brain volumes, and CT. Regression analyses assessed relationships between lifetime (LT) or recent use, urine metabolites, cognition, and imaging metrics in PWH compared to PWoH. Analyses were adjusted for age, sex, race, education, and other substance use.
Results
PWoH/CB- were younger, more educated, and had less LT use of alcohol and tobacco compared to other groups. CB use amount, duration, and frequency did not differ between PWH/CB+ and PWoH/CB+. Frontal lobe volume was significantly smaller in both CB+ groups compared to CB- (p=.01). HIV and CB significantly interacted in the frontal lobe (Figure 1), temporal lobe, cingulate, and global CT; CB use was associated with cortical thinning in PWH but not PWoH (all p<.01). Regression analyses indicated that greater LT CB use associated with worse delayed recall across all participants (p=.02); smaller frontal, temporal, hippocampal and gray matter volumes in only PWH; and globally reduced CT in only PWH (p<.05). Greater recent use associated with reduced volume and CT in multiple cortical regions, particularly in the frontal lobe, in only PWH (p-values<.05). Higher urine levels of THC-COO-gluc associated with reduced frontal volumes for all participants (p=.03).
Conclusions
LT and recent CB use were detrimental to structural brain integrity, particularly in frontal and temporal regions, with greater changes observed in PWH compared to PWoH. While recent CB use did not impact cognitive performance, greater LT use was associated with worse recall regardless of HIV status. PWH should be cautioned about the potential long-term effects of CB use on brain health.
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