High-potency cannabis use may impact mental health, addiction risk
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High-potency cannabis use appeared associated with mental health and addiction, according to results of a cohort study published in JAMA Psychiatry.
“A large body of research suggests that people who use cannabis have a higher likelihood of experiencing mental health issues than those who don’t use the drug, but it’s difficult to understand whether cannabis causes these issues, as we often don’t know if cannabis use preceded, or followed, the start of symptoms of mental health problems,” Lindsey A. Hines, PhD, senior research associate at Bristol Medical School, told Healio Psychiatry. “Studies have suggested that high potency cannabis is linked to higher likelihood of psychosis, depression, anxiety and cannabis dependence, but these studies hadn’t been able to account for people’s early mental health symptoms, and hadn’t always taken into account whether the risks of high potency use were over and above the risks from using cannabis every day.”
No studies have described the link between cannabis potency and concurrent mental health among a general population sample or used longitudinal data to address confounding. Hines and colleagues sought to account for preceding mental health and frequency of cannabis use while evaluating the association between cannabis potency and substance use and mental health outcomes. They used data from the Avon Longitudinal Study of Parents and Children — a birth cohort of individuals born in the U.K. between April 1991 and December 1992. Data analyzed in the current study included outcomes and exposures between June 2015 and October 2017 of participants aged 24 years who reported recent cannabis use. Self-reported cannabis type most frequently used in the past year, coded to a binary exposure of use of lower-potency cannabis or high-potency cannabis, served as the exposure. Main outcomes and measures included frequency of cannabis use, recent use of other illicit drugs, reported cannabis use problems, alcohol use disorder, tobacco dependence, generalized anxiety disorder, depression and psychotic-like experiences.
Of 1,087 participants who reported past-year cannabis use, 141 (13%) reported high-potency cannabis use, which was associated with increased frequency of cannabis use (adjusted OR [aOR] = 4.38; 95% CI, 2.89-6.63), cannabis problems (aOR = 4.08; 95% CI, 1.41-11.81) and increased likelihood of anxiety disorder (aOR = 1.92; 95% CI, 1.11-3.32). The researchers adjusted for frequency of cannabis use and reported an attenuated association with psychotic experiences (aOR = 1.29; 95% CI, 0.67-2.5), tobacco dependence (aOR = 1.42; 95% CI, 0.89-2.27) and other illicit drug use (aOR = 1.29; 95% CI, 0.77-2.17). They observed no evidence of associations between high-potency cannabis use and depression or alcohol use disorder.
“Our data aren’t longitudinal, and we’re relying on people to accurately know whether the cannabis they’re using is low or high potency, so we still can’t say whether the problems started after the use of high potency cannabis, or whether people who began developing problems also sought out stronger forms of the drug,” Hines told Healio Psychiatry. “I would love to be able to do more research to understand the order of events, but that’s very difficult without randomized trials. In countries where high-potency cannabis is widely available, we need to make sure there are clear treatment pathways for people with cannabis use problems, and that mental health support is readily available.”