Kelly Hughes

Tags: HIV/AIDS, cannabis, neurocognitive impairment, cognition, neuroAIDS

 

The problem: Current drug treatments for HIV mean that people who have HIV can now live almost as long as those who don’t have HIV. However, aging and HIV infection both have negative effects on the central nervous system (CNS), like cellular damage and inflammation. Individually, these effects can increase the risk of neurocognitive impairment (NCI), and together, aging with HIV can have further detrimental effects on the CNS and a much higher risk of NCI.

 

Why do this study? People living with HIV report using cannabis to alleviate symptoms of HIV/AIDS like neuropathic pain, nausea, mood problems, and appetite and weight loss. People living with HIV/AIDS report using it at a rate almost three times higher than the general population. In general, most research suggests that cannabis has either a minimal, or an adverse effect on cognition. However, the anti-inflammatory properties of cannabis may mean that, in the context of aging and HIV, cannabis could have beneficial effects. This study looked at the effects of HIV and cannabis on NCI, and how these effects might be modulated by age.

 

The study: This study looked at the combined effects of cannabis, HIV, and aging on cognition, using data previously collected for a number of other studies. The analysis included data from 952 participants, of whom 679 were adults living with HIV and 273 were HIV-negative adults. These two groups were divided into those who did or did not use cannabis and analyzed for any association between cannabis use, NCI, and age. Approximately half of the HIV-positive cohort had detectable virus circulating at the time of participation. Participants ranged from 18-79 years of age, identified as white (49.8%), Black or African American (26.7%), Hispanic or Latino (17.3%), or other (6.2%) and were predominately male (76.4%). Neurocognitive performance was evaluated across 7 domains: verbal fluency, executive function, processing speed, learning, delayed recall, working memory/attention, and motor skills. The study found that cannabis use was associated with a lower rate of NCI among people living with HIV, regardless of whether or not they had detectable viral loads. Cannabis exposure had no relation to NCI among HIV-negative individuals. When cognative performance was broken down by domain, cannabis exposure was associated with higher verbal fluency and learning performance among people living with HIV (but not among HIV-negative participants). These effects did not vary by age.

 

Conclusions: These results suggest that, in the context of HIV, cannabis use is related to a lower chance of neurocognitive impairment.

 

What does this study add? This study is the first to show that cannabis exposure is linked to a reduced chance of NCI, including better verbal and learning performance, in the context of HIV. These results suggest that the anti-inflammatory effects of cannabis may be particularly important for people living with HIV. However, more studies are needed to determine the extent of these benefits and the best treatment to maximize them.  

 

Funder: No funding indicated for this study. Participant data was used from various NIH- and NIMH (National Institute of Mental Health)-funded research protocols at the University of California San Diego's HIV Neurobehavioral Research Program (HNRP)

 

Author conflicts: None

 

Commentary: (Kelly Hughes).

This study analyzed data collected from various studies, thus the study was not specifically designed to address the relationship that cannabis use, HIV and aging may have on neurocognitive impairment. In particular, different studies may have different definitions of “cannabis exposure” which means that participants in the “cannabis use” groups were probably not using the same doses of cannabis. However, this analysis includes data from a large, and ethnically diverse cohort, suggesting that the results are likely valid for most people livng with HIV.  It is interesting to note that there was no difference in the beneficial effect of cannabis use between those who were or were not virally suppressed, in the cohort of people living with HIV. This suggests that any anti-inflammatory benefits cannabis may have for people living with HIV may still be relevant, even in the absence of viral replication. However, we need to do more studies to refine the details of dosing, timing, and cannabis composition to determine what might be the best treatment regimen to minimize neurocognitive decline in vulnerable populations.