Cannabis use, microbial diversity and Dialister abundance in older adults with HIV: A cross-sectional study

People with HIV frequently experience gastrointestinal symptoms linked to dysbiosis, impaired mucosal barrier integrity and persistent immune activation. Cannabis is widely used for symptom management by people with HIV, but its effects on the gut microbiome are unclear.

We conducted a cross-sectional analysis of 63 people with HIV (mean age 59.4 years; 71.4% Black or Hispanic) enrolled in the Marijuana Associated Planning and Long-term Effects study and its microbiome and Alzheimer's substudies, which included participants with and without mild cognitive impairment (MCI). Participants provided faecal samples for 16S rRNA sequencing. Cannabis use was quantified using a validated Timeline Followback. Alpha diversity was estimated using the Shannon index, beta diversity with Bray-Curtis dissimilarity and permutational multivariate analysis of variance (PERMANOVA), and genus-level abundance using the IFAA method. All models were adjusted for age, sex and education.

Higher cannabis consumption showed a statistically significant association with reduced alpha diversity (β = -0.062 per 50-mg Tetrahydrocannabinol (THC) per use-day; 95% confidence interval [CI]: -0.12 to -0.004; p = 0.038). No statistically significant differences in beta diversity were observed between high and low-to-no groups (p = 0.35). At the genus level, Dialister abundance showed a statistically significant dose-dependent association with cannabis use, with a 14.4% reduction in abundance per 50-mg increase in THC per use-day (q = 0.034).

Cannabis consumption in older people with HIV, including those with and without MCI, was associated with lower microbial diversity and reduced Dialister abundance, a taxon with dual roles in mucosal integrity and gastrointestinal symptom modulation. Reduced alpha diversity and Dialister depletion are notable given links to impaired mucosal barrier integrity, microbial translocation and systemic immune activation in HIV. These findings suggest cannabis may modify HIV-associated dysbiosis, warranting further longitudinal studies to disentangle symptomatic benefits from long-term impacts on mucosal health and systemic inflammation.