The association between cannabis use and anxiety disorders is best explained by the self-medication hypothesis, in which anxiety predisposes individuals toward cannabis use, rather than cannabis use causing anxiety disorders. A systematic review of the literature found that while some studies report no correlation, a meta-analysis of 15 studies showed a modest correlation between anxiety and cannabis use (odds ratio 1.24), and a meta-analysis of 13 studies showed a stronger correlation between anxiety and cannabis use disorder (odds ratio 1.68). Causal interpretations and the common factor theory lack substantial support.
Semi-legal cannabinoids synthesized from cannabidiol (CBD) and sold after the 2018 US Farm Bill may pose a growing health risk. Research has focused mainly on Δ8-THC and O-acetyl-THC, the latter raising concerns about pulmonary toxicity. Newer cannabinoids with sidechain variants of CBD show stronger activity at cannabinoid receptor 1 than Δ9-THC, and acetate esters are being added to other THC analogues. Products lack regulatory oversight and often contain unlabeled side products. The authors urge monitoring this market and investigating the pharmacology of these cannabinoids to prevent a potential vaping-related health crisis.