Cannabis and Cognition and HIV

Frequent current marijuana use may lead to more cognitive dysfunction among people living with HIV infections, according to a new study.
Surprisingly, there was no consistent pattern of association with lifetime marijuana use or alcohol use and measures of cognitive dysfunction.

“People with HIV infection have many reasons to have cognitive dysfunction, from the virus itself to medications for HIV infection and related conditions, particularly as they age," said senior author Richard Saitz, MD, MPH, Professor and Chair of Community Health Sciences at Boston University School of Public Health. “They also have symptoms like chronic pain and mental health symptoms, and use of marijuana, medically or recreationally, may seem like an option to consider. But at least among people with substance use disorders, it appears to have detrimental effects on cognitive function.”

The researchers published their results online October 23, 2017 in Substance Abuse.

Saitz and colleagues conducted cross-sectional regression analyses of 215 HIV-infected adults with diagnosed substance dependence or who had injected illicit drugs. Participants were part of the Boston Alcohol Research Collaboration on HIV/AIDS cohort, 18 years or older, and had current alcohol or other drug dependence.

The researchers tested the associations between current marijuana or heavy alcohol use, lifetime marijuana or alcohol use, duration of heavy alcohol use, and 3 measures of cognitive dysfunction-including memory, attention, and cognitive function. They adjusted their analyses for demographics, primary language, depressive symptoms, anxiety, comorbidities, antiretroviral therapy, hepatitis C virus, duration of HIV infection, HIV-viral load, CD4 cell count, lifetime and recent cocaine use, and recent illicit and prescribed opioid use.

Current marijuana use was significantly and negatively associated with cognitive function one one score. Lifetime marijuana use and current heavy and lifetime alcohol use and duration of heavy alcohol use were not associated with any measure of cognitive dysfunction, and no evidence appeared of synergistic effects on cognition.

In addition, neither alcohol nor marijuana use appeared to affect simple tests of memory or attention. The authors postulated that such effects were not detected, even though they are expected at the least with heavy alcohol use, because of multiple other exposures and comorbid health conditions that participants had.

Few, if any, studies have examined the combined effects that alcohol and marijuana use may have on cognition in people living with HIV, the authors wrote. “Such an understanding could contribute to efforts to reduce harmful substance use and prevent clinical consequences, particularly in an era in which 'moderate' drinking is at times discussed in terms of possible beneficial effects, and in which marijuana is discussed as a relatively safe and even therapeutic substance,” they stated.

Understanding the mechanism by which marijuana and alcohol may worsen cognition warrants larger, longer studies with more precise and diverse measurements of cognitive function, they concluded.