Daily Cannabis Use Linked to Reduced Neuroinflammation in People With HIV
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Frequent cannabis use may reduce neuroinflammation in people with HIV, resulting in possible benefits to cognition, new research published in the Journal of the International Neuropsychological Society suggests.
While the study was retrospective and therefore cannot prove any cause-effect relationships, the researchers say that their findings demonstrate a need for more targeted mechanistic studies exploring frequent cannabis use and its effect on cognition in people with HIV.
Frequent cannabis use may reduce levels of key pro-inflammatory compounds
The study, carried out by researchers at the University of California, San Diego, looked at a total of more than 260 individuals who fell into one of four groups: HIV+ non-cannabis users, HIV+ moderate cannabis users (defined as any use ranging between three times in the past six months, to three times or less per week), HIV+ daily or near-daily cannabis users, and a control group consisting of HIV- non-cannabis users.
All of the participants were found through enrollment in NIH-funded studies at the UC San Diego’s HIV Neurobehavioral Research Program and consented to provide urine, blood plasma, and cerebrospinal fluid samples for analysis. Participants were questioned on their history of drug use and asked to complete a standardized battery of cognitive performance tests to measure their global cognitive performance and specific performance in domains such as learning, executive function, and motor skills.
The study found that HIV+ people who used cannabis daily had lower levels of two pro-inflammatory biomarkers in their cerebrospinal fluid compared to HIV+ non-cannabis users. Both of these biomarkers – the cytokines MCP-1 and IP-10 – are known to play important roles in immune cell migration, HIV pathogenesis, and HIV-related neuroinflammation. No differences in significant blood plasma biomarkers were seen across the three cannabis using groups relative to each other, though IP-10 levels were higher overall in the cannabis users compared to the HIV- non-cannabis group.
In the cognition testing, the researchers discovered a statistically significant association between the lower levels of both these two cytokines in the cerebrospinal fluid and improved learning performance in the tests. This perceived improvement in at least one cognitive domain is significant as neurocognitive disorders are known to affect a large proportion of people living with HIV.
The researchers also noted that the HIV+ daily cannabis users were observed to perform slightly better than HIV+ moderate and non-cannabis users in the domains of verbal fluency, attention/working memory, processing speed, learning, and motor skills. However, this finding did not meet the tests for statistical significance here. Still, the researchers note that this does echo a similar pattern observed in another recent study and so suggests a neuroprotective effect that does warrant further investigation.
HIV, cognition, and cannabis research
The HIV virus impacts the body’s immune cells and weakens its ability to fight off other infections or diseases. To combat this, patients are normally given some form of combination antiretroviral therapy (cART) that prevents the virus from making copies of itself within the body. This treatment can lessen the damage to the immune system and allow people with HIV to live near-normal lives. For many people with HIV, using cART can bring their viral load down to undetectable levels, meaning the virus is also not transmittable to others.
Unfortunately, HIV can affect more than just the immune system. Many people with HIV, including those who are taking cART treatments, also experience mild cognitive impairment as a result of the virus. These HIV-associated neurocognitive disorders (HAND) can affect a person’s memory, concentration, and may be associated with higher mortality rates.
Cannabis is currently being studied as a potential adjunct therapy for treating HAND. Last June, researchers at George Mason University were granted $450,000 in funding from the National Institutes of Health (NIH) to support additional research into the use of THC and CBD for this purpose.
The funding, awarded to GMU’s Dr Fatah Kashanchi, professor and virology director of the Laboratory of Molecular Virology, and Dr Lance Liotta, co-director and co-founder of the Center for Applied Proteomics and Molecular Medicine, will allow the two laboratories to advance their current study of HIV pathogenesis in the central nervous system.
“The new NIH funding for the Kashanchi lab is based on the proposal that up to 50 percent of people with HIV/AIDS suffer from HAND, despite effective cART. HAND therefore represents a significant cause of morbidity in these patients,” Professor Kashanchi told Analytical Cannabis.
“The inability of cART to prevent viral transcription and neurocognitive dysfunction confirms the need for adjunct therapies that target underlying mechanisms that contribute to HAND.”
One of these mechanisms is thought to be the delivery of “selective cargo” in extracellular vesicles (EVs) that are released from HIV-infected macrophages or microglia. This EV cargo then goes on to damage other cells and neurons, leading to the development of HAND.
Kashanchi and colleagues believe that using cannabinoids on HIV-infected cells may positively alter this harmful cargo, neutralizing its negative effects and making cannabinoids a potentially useful adjunct therapy for HAND. The NIH funding for this research began in May 2020 and is due to conclude in late April 2022.