The DOI matches its Crossref record; 15 of the 15 references it cites were found in a registry or an index.
High-potency cannabis and the risk of psychosis
Open accessAbstract
Background: People who use cannabis have an increased risk of psychosis an effect attributed to the active ingredient δ9-tetrahydrocannabinol (Δ9-THC). There has recently been concern over an increase in the concentration of Δ9-THC in the cannabis available in many countries. Aims: To investigate whether people with a first episode of psychosis were particularly likely to use high-potency cannabis. Method: We collected information on cannabis use from 280 cases presenting with a first episode of psychosis to the South London & Maudsley National Health Service (NHS) Foundation Trust, and from 174 healthy controls recruited from the local population. Results: There was no significant difference between cases and controls in whether they had ever taken cannabis, or age at first use. However, those in the cases group were more likely to be current daily users (OR = 6.4) and to have smoked cannabis for more than 5 years (OR = 2.1). Among those who used cannabis, 78% of the cases group used high-potency cannabis (sinsemilla, ‘skunk’) compared with 37% of the control group (OR 6.8). Conclusions: The finding that people with a first episode of psychosis had smoked higher-potency cannabis, for longer and with greater frequency, than a healthy control group is consistent with the hypothesis that Δ9-THC is the active ingredient increasing risk of psychosis. This has important public health implications, given the increased availability and use of high-potency cannabis.
Overview
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
The claims and statistics of this paper haven’t been checked yet.
Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“We provide a weak recommendation against the use of cannabinoids in neuropathic pain, mainly because of negative results, potential misuse, abuse, diversion and long term mental health risks particularly in susceptible individuals.66–71”
From Pharmacotherapy for neuropathic pain in adults: a systematic review and meta-analysis (2015) · cites this paper as [66]
Self-check
Percentages, sums and reported differences re-computed from the paper’s own numbers.
The self-check needs the paper’s full text.
Citations
Cites
Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review.
Moore, T. H., Zammit, S., Lingford-Hughes, A., Barnes, T. R., Jones, P. B., Burke, M., & Lewis, G. (2007) · The Lancet · doi:10.1016/s0140-6736(07)61162-3 · Cited by 2,224
D'Souza, D. C., Perry, E., MacDougall, L., Ammerman, Y., Cooper, T., Wu, Y.-T., Braley, G., Gueorguieva, R., & Krystal, J. H. (2004) · Neuropsychopharmacology · doi:10.1038/sj.npp.1300496 · Cited by 1,024
Psychosis Screening Questionnaire
Bebbington, P., & Nayani, T. (1995) · PsycTESTS Dataset · doi:10.1037/t30040-000 · Cited by 546
From dopamine to salience to psychosis—Linking biology, pharmacology and phenomenology of psychosis
Kapur, S., Mizrahi, R., & Li, M. (2005) · Schizophrenia Research · doi:10.1016/j.schres.2005.01.003 · Cited by 512
The Environment and Schizophrenia: The Role of Cannabis Use
Henquet, C. (2005) · Schizophrenia Bulletin · doi:10.1093/schbul/sbi027 · Cited by 468
Cannabis, the mind and society: the hash realities
Murray, R. M., Morrison, P. D., Henquet, C., & Forti, M. D. (2007) · Nature reviews. Neuroscience · doi:10.1038/nrn2253 · Cited by 329
Self-citationEffects of cannabidiol on schizophrenia-like symptoms in people who use cannabis
Morgan, C. J. A., & Curran, H. V. (2008) · British Journal of Psychiatry · doi:10.1192/bjp.bp.107.046649 · Cited by 300
Self-citationΔ9-Tetrahydrocannabinol Induces Dopamine Release in the Human Striatum
Bossong, M., van Berckel, B. N., Boellaard, R., Zuurman, L., Schuit, R., Windhorst, A., van Gerven, J. V., Ramsey, N., Lammertsma, A., & Kahn, R. (2009) · Neuropsychopharmacology · doi:10.1038/npp.2008.138 · Cited by 262
Potter, D. J., Clark, P., & Brown, M. B. (2008) · Journal of Forensic Sciences · doi:10.1111/j.1556-4029.2007.00603.x · Cited by 230
Cannabis-Induced Psychosis-Like Experiences Are Associated with High Schizotypy
Barkus, E., Stirling, J., Hopkins, R., & Lewis, S. W. (2006) · Psychopathology · doi:10.1159/000092678 · Cited by 170
Different Effects of Nabilone and Cannabidiol on Binocular Depth Inversion in Man
Leweke, F. M., Schneider, U., Radwan, M., Schmidt, E., & Emrich, H. M. (2000) · Pharmacology Biochemistry and Behavior · doi:10.1016/s0091-3057(00)00201-x · Cited by 150
Association of cannabis use with prodromal symptoms of psychosis in adolescence
Miettunen, J., Törmänen, S., Murray, G. K., Jones, P. B., Mäki, P., Ebeling, H., Moilanen, I., Taanila, A., Heinimaa, M., Joukamaa, M., et al. (2008) · British Journal of Psychiatry · doi:10.1192/bjp.bp.107.045740 · Cited by 85
HIGH POTENCY CANNABIS: THE FORGOTTEN VARIABLE
Smith, N. (2005) · Addiction · doi:10.1111/j.1360-0443.2005.01295.x · Cited by 35
(1995) · The Lancet · doi:10.1016/s0140-6736(95)91853-1 · Cited by 16
ALCOHOL INDUSTRY AND PUBLIC HEALTH RESEARCH ARE A POOR MIX
Holder, H. D. (2005) · Addiction · doi:10.1111/j.1360-0443.2005.01283.x · Cited by 4
Flagged first, then by citations
Research works printed but not linked: 5
- 2005, The Classification of Cannabis under the Misuse of Drugs Act 1971
- 1992, Schedules for Clinical Assessment in Neuropsychiatry (SCAN)
- 1992, The ICD–10 Classification of Mental and Behavioural Disorders. Clinical Description and Diagnostic Guidelines
- British Crime Survey, 2006–2007
- Hardwick, 2008, Home Office Cannabis Potency Study
Cited by
Sorted by citations
Pharmacotherapy for neuropathic pain in adults: a systematic review and meta-analysis
Finnerup, N. B., Attal, N., Haroutounian, S., McNicol, E., Baron, R., Dworkin, R. H., Gilron, I., Haanpää, M., Hansson, P., Jensen, T. S., et al. (2015) · The Lancet Neurology · doi:10.1016/s1474-4422(14)70251-0 · Cited by 3,980
The environment and schizophrenia
van Os, J., Kenis, G., & Rutten, B. P. F. (2010) · Nature · doi:10.1038/nature09563 · Cited by 1,572
An Introduction to the Endogenous Cannabinoid System
Lu, H.-C., & Mackie, K. (2016) · Biological Psychiatry · doi:10.1016/j.biopsych.2015.07.028 · Cited by 1,234
Kahn, R. S., Sommer, I. E., Murray, R. M., Meyer‐Lindenberg, A., Weinberger, D. R., Cannon, T. D., O’Donovan, M. C., Correll, C. U., Kane, J. M., van Os, J., et al. (2015) · Nature Reviews Disease Primers · doi:10.1038/nrdp.2015.67 · Cited by 1,163
Self-citationMeta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis
Marconi, A., Di Forti, M., Lewis, C. M., Murray, R. M., & Vassos, E. (2016) · Schizophrenia Bulletin · doi:10.1093/schbul/sbw003 · Cited by 899
Self-citation
Metadata
- Authors
- Di Forti, M., Morgan, C., Dazzan, P., Pariante, C., Mondelli, V., Marques, T. R., Handley, R., Luzi, S., Russo, M., Paparelli, A., Butt, A., Stilo, S. A., Wiffen, B., Powell, J., & Murray, R. M.
- Affiliations
- Springfield University Hospital (GB)
- ORCID
- Venue
- British Journal of Psychiatry
- Publisher
- Royal College of Psychiatrists
- Published
- 2009-12
- Volume
- 195
- Issue
- 6
- Pages
- 488-491
- ISSN
- 0007-1250 (ISSN-L)
- 1472-1465
- PMC
- PMC2801827
- OpenAlex
- W2104532446
- Cited by
- 567
- References
- 15
- Citations by year
- 2026: 10 · 2025: 11 · 2024: 25 · 2023: 30 · 2022: 38 · 2021: 41 · 2020: 54 · 2019: 31 · 2018: 35 · 2017: 38 · 2016: 46 · 2015: 36 · 2014: 28 · 2013: 36 · 2012: 29
- FWCI
- 25.87
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- The British Journal of Psychiatry (publishedVersion)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Research Portal (King's College London) (submittedVersion)
- Funders
- King's College London
- Topics
- Health Sciences › Medicine › Pharmacology (medical) › Cannabis and Cannabinoid Research
- Health Sciences › Medicine › Psychiatry and Mental health › Schizophrenia research and treatment
- Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Toxicology › Forensic Toxicology and Drug Analysis
- Keywords
- high-potency cannabis, psychosis, first-episode psychosis, delta-9-tetrahydrocannabinol, cannabis use, daily cannabis use, public health implications
- MeSH terms
- Adolescent, Adult, Age Factors, Aged, Cannabis, Female, Humans, London, Male, Marijuana Smoking, Middle Aged, Psychoses, Substance-Induced, Risk Factors, Dronabinol, Case-Control Studies, Young Adult
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review
