Welcome to the Nexus of Ethics, Psychology, Morality, Philosophy and Health Care

Welcome to the nexus of ethics, psychology, morality, technology, health care, and philosophy

Tuesday, September 5, 2023

How does marijuana affect the brain?

Heather Stringer
Monitor on Psychology
Vol. 54, No. 5, p. 20

Here is an excerpt:

Mixing marijuana with mental health issues

Psychologists also share a sense of urgency to clarify how cannabis affects people who suffer from preexisting mental health conditions. Many veterans who suffer from PTSD view cannabis as a safe alternative to other drugs to alleviate their symptoms (Wilkinson, S. T., et al., Psychiatric Quarterly, Vol. 87. No. 1, 2016). To investigate whether marijuana does in fact provide relief for PTSD symptoms, Jane Metrik, PhD, a professor of behavioral and social sciences at the Brown University School of Public Health and a core faculty member at the university’s Center for Alcohol and Addiction Studies, and colleagues followed more than 350 veterans for a year. They found that more frequent cannabis use worsened trauma-related intrusion symptoms—such as upsetting memories and nightmares—over time (Psychological Medicine, Vol. 52, No. 3, 2022). A PTSD diagnosis was also strongly linked with cannabis use disorder a year later. “Cannabis may give temporary relief from PTSD because there is a numbing feeling, but this fades and then people want to use again,” Metrik said. “Cannabis seems to worsen PTSD and lead to greater dependence on the drug.”

Metrik, who also works as a psychologist at the Providence VA Medical Center, has also been studying the effects of using cannabis and alcohol at the same time. “We need to understand whether cannabis can act as a substitute for alcohol or if it leads to heavier drinking,” she said. “What should we tell patients who are in treatment for problem drinking but are unwilling to stop using cannabis? Is some mild cannabis use OK? What types of cannabis formulations are helpful or harmful for people who have alcohol use disorder?”

Though there are still many unanswered questions, Metrik has seen cases that suggest adding cannabis to heavy drinking behavior is risky. Sometimes people can successfully quit drinking but are unable to stop using cannabis, which can also intensify depression and lead to cannabis hyperemesis syndrome—repeated and severe bouts of vomiting that can occur in heavy cannabis users, she said. Cannabis withdrawal symptoms such as irritability, anxiety, increased cravings, aggression, and restlessness usually subside after 1 to 2 weeks of abstinence, but insomnia tends to persist longer than the other symptoms, she said.

Cannabis may also interfere with pharmaceutical medications patients are taking to treat mental health issues. Cannabidiol (CBD) can inhibit the liver enzymes that metabolize medications such as antidepressants and antipsychotics, said Ryan Vandrey, PhD, a professor of psychiatry and behavioral sciences at Johns Hopkins University and president of APA’s Division 28 (Psychopharmacology and Substance Abuse). “This could lead to side effects because the medication is in the body longer and at higher concentrations,” he said. In a recent study, he found that a high dose of oral CBD also inhibited the metabolism of THC, so the impairment and the subjective “high” was significantly stronger and lasted for a longer time (JAMA Network Open, Vol. 6, No. 2, 2023). This contradicts the common conception that high levels of CBD reduce the effects of THC, he said. “This interaction could lead to more adverse events, such as people feeling sedated, dizzy, [or] nervous, or experiencing low blood pressure for longer periods of time,” Vandrey said.

The interactions between CBD, THC, and pharmaceutical medications also depend on the dosing and the route of administration (oral, topical, or inhalation). Vandrey is advocating for more accurate labeling to inform the public about the health risks and benefits of different products. “Cannabis is the only drug approved for therapeutic use through legislative measures rather than clinical trials,” he said. “It’s really challenging for patients and medical providers to know what dose and frequency will be effective for a specific condition.”