Association of cannabis potency with mental ill health and addiction: a systematic review.
Kat Petrilli, Shelan Ofori, Lindsey A. Hines, Gemma Taylor, Sally Adams, Tom P. Freeman
The Lancet Psychiatry September 2022 DOI: 10.1016/s2215-0366(22)00161-4 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Systematic review Longitudinal Peer reviewed |
|---|---|
| Population | Human participants in observational studies comparing high-potency and low-potency cannabis use |
| Topics | Addiction Cannabis |
| Key findings | Higher-potency cannabis use, compared with lower-potency cannabis, was associated with increased risk of psychosis and cannabis use disorder, while evidence for depression and anxiety was mixed. The authors contend that potency is relevant for health-care settings and public health guidelines and policies on cannabis sales, and they call for standardized exposure measures and longitudinal designs. |
Abstract
Cannabis potency, defined as the concentration of Δ9-tetrahydrocannabinol (THC), has increased internationally, which could increase the risk of adverse health outcomes for cannabis users. We present, to our knowledge, the first systematic review of the association of cannabis potency with mental health and addiction (PROSPERO, CRD42021226447). We searched Embase, PsycINFO, and MEDLINE (from database inception to Jan 14, 2021). Included studies were observational studies of human participants comparing the association of high-potency cannabis (products with a higher concentration of THC) and low-potency cannabis (products with a lower concentration of THC), as defined by the studies included, with depression, anxiety, psychosis, or cannabis use disorder (CUD). Of 4171 articles screened, 20 met the eligibility criteria: eight studies focused on psychosis, eight on anxiety, seven on depression, and six on CUD. Overall, use of higher potency cannabis, relative to lower potency cannabis, was associated with an increased risk of psychosis and CUD. Evidence varied for depression and anxiety. The association of cannabis potency with CUD and psychosis highlights its relevance in health-care settings, and for public health guidelines and policies on cannabis sales. Standardisation of exposure measures and longitudinal designs are needed to strengthen the evidence of this association.
Comparable studies
Other systematic reviews and meta-analyses on cannabis for addiction, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Effects of Ayahuasca and its Alkaloids on Drug Dependence: A Systematic Literature Review of Quantitative Studies in Animals and Humans | 2016 | Systematic review | |
| Cannabis and cannabinoids for the treatment of mental and substance use disorders and symptoms: A systematic review and meta-analysis of experimental and observational studies. Adults (≥18 years) with ADHD, anxiety, depression, PTSD, psychosis or Tourette... | 2026 | Systematic review and meta-analysis | |
| Highway to hell or magic smoke? The dose-dependence of Δ9-THC in place conditioning paradigms. Rodents (rats and/or mice) in place-conditioning studies | 2018 | Meta-analysis |
Citations in the library
Cited by 18
- High-Concentration Delta-9-Tetrahydrocannabinol Cannabis Products and Mental Health Outcomes : A Systematic Review. Annals of Internal Medicine October 1, 2025
- The acute effects of cannabis, with and without cannabidiol, on attentional bias to cannabis related cues: a randomised, double-blind, placebo-controlled, cross-over study Psychopharmacology February 28, 2024
- Cannabis use and glutamate across the psychosis spectrum: in vivo evidence from 7T proton magnetic resonance spectroscopy Molecular Psychiatry June 27, 2026
- Mental health consequences of contemporary cannabis use in Europe: potency, patterns of use, and health system context Frontiers in Psychiatry June 10, 2026
- Emergency department use by individuals with and without psychosis after state-level cannabis legalization and commercialization Nature Mental Health June 19, 2026
and 13 more in the library
Cites 11
- High-potency cannabis and the risk of psychosis The British Journal of Psychiatry November 30, 2009
- Daily use of high-potency cannabis is associated with more positive symptoms in first-episode psychosis patients: the EU-GEI case–control study Psychological Medicine March 18, 2020
- Risk factors for the onset of dependence and chronic psychosis due to cannabis use: Survey of patients with cannabis‐related psychiatric disorders Neuropsychopharmacology Reports September 7, 2020
- A within-person comparison of the subjective effects of higher vs. lower-potency cannabis. Drug and Alcohol Dependence November 1, 2020
- How does cannabidiol (CBD) influence the acute effects of delta-9-tetrahydrocannabinol (THC) in humans? A systematic review. Neuroscience & Biobehavioral Reviews September 30, 2019
and 6 more in the library