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Is “cannabis psychosis” a distinct category?

Graham Thornicroft, Graham Meadows, Pierluigi Politi

European Psychiatry 1992 DOI: 10.1017/s0924933800002157 (opens in new tab)

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Study at a glance

AI-extracted from the abstract
Characteristics Case-control study Peer reviewed
Sample size 45
Population Psychotic patients admitted to hospital, comprising 45 cases with cannabis-positive admission urinalysis and matched psychotic controls without evidence of cannabis use
Topics Cannabis
Citations 24
Key findings Cases with cannabis-positive urinalysis differed from controls only in being more likely to be Afro-Caribbean (P = 0.01), to show incoherent speech (P = 0.02), and to be agitated (P = 0.01); otherwise the groups were indistinguishable. The authors state these findings do not support the view that 'cannabis psychosis' has a distinct psycho-phenomenological pattern.

Abstract

Summary Forty-five cases of psychotic patients with admission urinalysis positive for cannabis were compared with psychotic controls without evidence of cannabis use. Cases and controls were matched for age, sex and year of admission, and were compared for socio-demographic data, circumstances of admission, diagnosis, and symptoms at admission. Three differences were found: cases were more likely to be Afro-Caribbean than white (P = 0.01), to manifest incoherence of speech (P= 0.02) and agitation (P= 0.01). In other respects the case and control groups were indistinguishable, and no pattern of symptoms characterised the “cannabis psychosis“group. These findings do not support the view that “cannabis psychosis” has a distinct psycho-phenomenological pattern Epidemiological studies are required to further clarify the association for psychotic patients between Afro-Caribbean ethnic groups and the likelihood of having a positive urine test for cannabis.

Comparable studies

Other observational and cohort studies on cannabis, most cited first.

Study Year Design Participants
High-potency cannabis and the risk of psychosis People with first episode of psychosis and healthy controls from the local population 2009 Case-control study n = 454
Ayahuasca-Assisted Therapy for Addiction: Results from a Preliminary Observational Study in Canada Rural aboriginal population 2013 Observational study
Impaired cognitive performance in drug free users of recreational ecstasy (MDMA) Otherwise healthy young people 2000 Observational
Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study Individuals from the general population in Germany aged 14-24 at baseline 2011 Observational cohort n = 1,923
Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases Patients treated for cannabis-induced psychotic symptoms in Denmark between 1994 and... 2005 Observational cohort n = 535

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