A comparison of symptoms and family history in schizophrenia with and without prior cannabis use: implications for the concept of cannabis psychosis.
J Boydell, K Dean, R Dutta, E Giouroukou, P Fearon, R Murray
Schizophrenia Research July 2007 DOI: 10.1016/j.schres.2007.03.014 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational case-register study Peer reviewed |
|---|---|
| Sample size | 757 |
| Population | People with first-onset schizophrenia from a case register |
| Measures | OPCRIT checklist |
| Topics | Cannabis |
| Key findings | Cannabis use in the year before first presentation was not significantly associated with any of the hypothesised symptom differences, including negative symptoms or family history of schizophrenia. Only two borderline findings emerged: a non-significant trend toward more insight (OR 0.65, p=0.055) and fewer abusive or accusatory hallucinations (OR 0.65, p=0.049) among cannabis users. The authors argue this argues against a distinct schizophrenia-like psychosis caused by cannabis. |
Abstract
There is considerable interest in cannabis use in psychosis. It has been suggested that the chronic psychosis associated with cannabis use, is symptomatically distinct from idiopathic schizophrenia. Several studies have reported differences in psychopathology and family history in people with schizophrenia according to whether or not they were cannabis users. We set out to test the hypotheses arising from these studies that cannabis use is associated with more bizarre behaviour, more thought disorder, fewer negative symptoms including blunted affect, more delusions of reference, more paranoid delusions and a stronger family history of schizophrenia. We used a case register that contained 757 cases of first onset schizophrenia, 182 (24%) of whom had used cannabis in the year prior to first presentation, 552 (73%) had not and 3% had missing data. We completed the OPCRIT checklist on all patients and investigated differences in the proportion of people with distractibility, bizarre behaviour, positive formal thought disorder, delusions of reference, well organised delusions, any first rank symptom, persecutory delusions, abusive/accusatory hallucinations, blunted affect, negative thought disorder, any negative symptoms (catatonia, blunted affect, negative thought disorder, or deterioration), lack of insight, suicidal ideation and a positive family history of schizophrenia, using chi square tests. Logistic regression modelling was then used to determine whether prior cannabis use affected the presence of the characteristics after controlling for age, sex and ethnicity. There was no statistically significant effect of cannabis use on the presence of any of the above. There remained however a non-significant trend towards more insight (OR 0.65 p=0.055 for "loss of insight") and a finding of fewer abusive or accusatory hallucinations (OR 0.65 p=0.049) of borderline significance amongst the cannabis users. These were in the hypothesised direction. There was no evidence of fewer negative symptoms or greater family history amongst cannabis users. We found few appreciable differences in symptomatology between schizophrenic patients who were or were not cannabis users. There were no differences in the proportion of people with a positive family history of schizophrenia between cannabis users and non-users. This argues against a distinct schizophrenia-like psychosis caused by 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 |
Citations in the library
Cited by 17
- Gone to Pot – A Review of the Association between Cannabis and Psychosis Frontiers in Psychiatry May 22, 2014
- 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
- Cannabis use and cognition in schizophrenia Frontiers in Human Neuroscience 2009
- Familial Predisposition for Psychiatric Disorder Archives of General Psychiatry November 3, 2008
- Psicosis inducida por cannabis: características clínicas y su diferenciación con la esquizofrenia con y sin consumo de cannabis asociado Adicciones July 14, 2020
and 12 more in the library
Cites 6
- Causal association between cannabis and psychosis: examination of the evidence The British Journal of Psychiatry January 30, 2004
- Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: follow-up study of 535 incident cases The British Journal of Psychiatry November 30, 2005
- Is there a specific ‘cannabis psychosis’? Cambridge University Press eBooks May 27, 2004
- Is “cannabis psychosis” a distinct category? European Psychiatry 1992
- Cannabis use and outcome of recent onset psychosis European Psychiatry June 1, 2005
and 1 more in the library