Users of high-potency cannabis are four times more likely to report associated problems and twice as likely to report anxiety disorder than users of lower-potency strains, according to new research from the University of Bristol.
Published in JAMA Psychiatry, the study uses data from the children of the 1990s long-term health study of more than 14,000 pregnant women and their babies born in and around Bristol in the early 1990s.
This is the first research of its kind to look at data from a general population sample. Previous research into the links between cannabis potency and mental health has only looked at clinical and self-selecting samples of people who use drugs.
Past-year cannabis use was reported by 1087 participants (mean age at onset of cannabis use, 16.7 years). Of these, 141 participants (13.0%) reported the use of high-potency cannabis.
Use of high-potency cannabis was associated with increased frequency of cannabis use (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).
Adjustment for frequency of cannabis use attenuated the association with psychotic experiences (aOR, 1.29; 95% CI, 0.67-2.50), 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). There was no evidence of association between the use of high-potency cannabis and alcohol use disorder or depression.
The authors say that the study, to the best of their knowledge, is the first general population evidence suggesting that the use of high-potency cannabis is associated with mental health and addiction.
Limiting the availability of high-potency cannabis may be associated with a reduction in the number of individuals who develop cannabis use disorders, the prevention of cannabis use from escalating to a regular behaviour and a reduction in the risk of mental health disorders, they say.