Impact of cannabis use on white matter hyperintensities in adults with and without chronic HIV disease

White matter hyperintensities (WMH) are prevalent among people living with HIV (PLWH), even with sustained viral suppression on antiretroviral therapy. This study investigated whether cannabis use contributes to additional WMH load among PLWH and its association to neurocognitive function. A total of 296 adult participants, stratified by HIV and cannabis status (74 control, 73 cannabis-only, 76 HIV-only and 73 HIV+cannabis) were enrolled. High resolution anatomical MRI and fluid-attenuated inversion recovery (FLAIR) images were collected, along with a battery of neuropsychological tests. Periventricular (pvWMH) and deep (dWMH) WMH loads were quantified using an automated pipeline. Statistical tests were employed to examine the main and interaction effects of HIV and cannabis use on WMH, and to explore the association of WMH loads with neuropsychological performance. The cohort had a mean age of 39.84 years, and all PLWH had sustained viral suppression. pvWMH loads were higher in the cannabis-only and HIV-only groups compared to controls. A significant interaction effect of HIV by cannabis was found for pvWMH load, such that participants with co-occurring HIV and cannabis use had similar pvWMH load compared to controls. In addition, increased pvWMH load significantly correlated with lower cognitive performance. Our findings suggest that cannabis use does not contribute additively to WMH burden in PLWH and may potentially be associated with a reduced WMH burden. However, future work is warranted to substantiate this finding, particularly with respect to type and levels of circulating cannabinoid metabolites.