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Study Shows Cannabis Could Prevent Cognitive Decline in People with HIV

Approximately half of all people living with HIV experience cognitive decline due to neurological damage triggered by the virus. Chemicals found in cannabis, particularly THC, could slow down the rate of cognitive decline in people living with HIV by suppressing chronic inflammation in the brain, according to a recent study.

The paper, published in November in the journal AIDS, compared blood samples from HIV-positive donors who use cannabis to blood samples from those who do not use cannabis. Compared to non-users, cannabis users showed significantly lower levels of activated monocytes circulating in their blood. Monocytes are a type of white blood cell that, when activated, triggers inflammation and neurotoxic damage. By lowering the level of activated monocytes in the blood, the compounds found in cannabis may decelerate the rate of cognitive decline in people living with HIV.

In addition to comparing the levels of activated monocytes in patients’ blood, researchers also found that exposing human monocytes to THC in a petri dish prevented them from becoming activated. This finding highlights that THC is most likely the chemical responsible for the anti-inflammatory effects of cannabis.

“This research is still in its early stages, but it suggests that marijuana use may be beneficial due to THC, and potentially other constituents of marijuana, by suppressing monocyte processes that contribute to HIV-associated chronic inflammation,” said Michael Rizzo, the lead author of the study and doctoral student at Michigan State University.

He emphasized that the study did not examine the direct effects of marijuana use on cognitive function. Instead, the aim of the study was to determine how chemicals found in cannabis may signal the immune system to suppress the damaging effects of inflammation on the brain. Through suppressing inflammation in the brain, cannabis could indirectly improve cognitive function.

“By understanding the cellular mechanism by which THC acts,” added Rizzo, “this research can ultimately lead to the development of therapeutic drugs to target cellular pathways of disease.”

Activated monocytes are also implicated in other disease states, such as cardiovascular disease, systemic lupus, multiple sclerosis, and Parkinson’s disease. The findings of this study suggest that cannabis use also may help suppress the inflammation found in individuals with these diseases, too.

As the current study only used blood samples from 40 individuals living in Michigan, future studies are needed to confirm whether similar effects of cannabis are seen long-term in broader populations living with HIV. Authors pointed out the difficulty in assessing the amount of cannabis use by each participant in the study. Without such information, it would be impossible to conclude whether more frequent usage of cannabis would result in even lower levels of inflammation and cognitive decline.

Since HIV infection causes individuals to be in a state of chronic inflammation – meaning too much immune system activation – cannabis use to reduce inflammation could be especially beneficial among this population.