Controversy Over the Diagnosis of ‘Cannabis-Induced Psychosis’
M. Arendt
European Psychiatry 2009 DOI: 10.1016/s0924-9338(09)70266-4 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cohort Peer reviewed |
|---|---|
| Sample size | 535 |
| Population | Patients who had received psychiatric treatment for cannabis-induced psychosis in Denmark |
| Duration | At least 3 years |
| Topics | Cannabis |
| Key findings | Cannabis-induced psychosis could be an early sign of schizophrenia rather than a distinct clinical entity. |
Abstract
Background:Both the ICD-10 and the DSM-IV operate with a diagnosis of cannabis-induced psychotic disorder. Despite this, the diagnosis is controversial.A number of studies have shown that cannabis can induce short-lived psychotic symptoms, and that this could depend on factors such as genetic predisposition. To qualify for a diagnosis of ‘cannabis-induced psychosis’, however, the symptoms must last for at least 48 hours according to the ICD-10. This diagnosis has traditionally been regarded as benign, but this is based on a very limited number of studies.Methods:We have conducted two studies based on Danish treatment registers. Firstly, all patients who had received psychiatric treatment for cannabis-induced psychosis were followed for at least 3 years to determine the rate of subsequent treatment for schizophrenia-spectrum disorders. Secondly, familial predisposition for psychiatric disorders among subjects treated for cannabis-induced psychosis and schizophrenia was compared using competing risk analyses.Results:Schizophrenia spectrum disorders were diagnosed in 44.5% of the 535 subjects included in the first study. New psychotic episodes of any type were diagnosed in 77.2% and 47.1% received a diagnosis of schizophrenia spectrum disorders more than a year after the cannabis-induced psychosis.Those who develop cannabis-induced psychosis and schizophrenia spectrum disorders both show elevated levels of predisposition for schizophrenia, other psychotic conditions, and other psychiatric disorders in first-degree relatives. In general, the level of predisposition is of similar magnitude in individuals treated for cannabis-induced psychosis and schizophrenia.Conclusion:Cannabis-induced psychosis could be an early sign of schizophrenia rather than a distinct clinical entity.
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 |