Cannabis use and cognition in schizophrenia
Frontiers in Human Neuroscience 2009 DOI: 10.3389/neuro.09.053.2009 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Review Peer reviewed |
|---|---|
| Population | People with schizophrenia and related psychosis, including cannabis users and non-users |
| Topics | Cannabis |
| Citations | 83 |
| Key findings | Across 23 studies, 14 reported better cognitive performance in cannabis-using schizophrenia patients than non-users, eight found no or minimal differences, and one found better performance in non-users; the authors' own data confirmed better performance in cannabis users. The authors propose that cannabis causes a transient cognitive breakdown that enables psychosis to develop, imitating schizophrenia's typical cognitive vulnerability, supported by earlier age of onset and fewer neurological soft signs in cannabis-related schizophrenia. |
Abstract
People with schizophrenia frequently report cannabis use, and cannabis may be a risk factor for schizophrenia, mediated through effects on brain function and biochemistry. Thus, it is conceivable that cannabis may also influence cognitive functioning in this patient group. We report data from our own laboratory on the use of cannabis by schizophrenia patients, and review the existing literature on the effects of cannabis on cognition in schizophrenia and related psychosis. Of the 23 studies that were found, 14 reported that the cannabis users had better cognitive performance than the schizophrenia non-users. Eight studies reported no or minimal differences in cognitive performance in the two groups, but only one study reported better cognitive performance in the schizophrenia non-user group. Our own results confirm the overall impression from the literature review of better cognitive performance in the cannabis user group. These paradoxical findings may have several explanations, which are discussed. We suggest that cannabis causes a transient cognitive breakdown enabling the development of psychosis, imitating the typical cognitive vulnerability seen in schizophrenia. This is further supported by an earlier age of onset and fewer neurological soft signs in the cannabis-related schizophrenia group, suggesting an alternative pathway to psychosis.
Comparable studies
Other narrative reviews on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Causal association between cannabis and psychosis: examination of the evidence | 2004 | Review | |
| Cannabis sativa: A comprehensive ethnopharmacological review of a medicinal plant with a long history. General (historical and pharmacological review) | 2018 | Review | |
| Psychiatric effects of cannabis | 2001 | Review | |
| Beyond THC: The New Generation of Cannabinoid Designer Drugs | 2011 | Review | |
| Cannabidiol, a Cannabis sativa constituent, as an antipsychotic drug | 2006 | Review |
Citations in the library
Cited by 16
- The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample Schizophrenia Bulletin July 25, 2010
- The Effect of Cannabis Use and Cognitive Reserve on Age at Onset and Psychosis Outcomes in First-Episode Schizophrenia Schizophrenia Bulletin March 9, 2011
- Cannabis use and cognitive dysfunction Indian Journal of Psychiatry 2011
- Pathways from Cannabis to Psychosis: A Review of the Evidence Frontiers in Psychiatry 2013
- Premorbid Adjustment and IQ in Patients With First-Episode Psychosis: A Multisite Case-Control Study of Their Relationship With Cannabis Use Schizophrenia Bulletin July 2, 2019
and 11 more in the library
Cites 14
- Causal association between cannabis and psychosis: examination of the evidence The British Journal of Psychiatry January 30, 2004
- Distinct Effects of Δ9-Tetrahydrocannabinol and Cannabidiol on Neural Activation During Emotional Processing Archives of General Psychiatry 2009
- COMT Val158Met moderation of cannabis‐induced psychosis: a momentary assessment study of ‘switching on’ hallucinations in the flow of daily life Acta Psychiatrica Scandinavica September 19, 2008
- Cannabinoid ‘model’ psychosis, dopamine–cannabinoid interactions and implications for schizophrenia Cambridge University Press eBooks May 27, 2004
- The acute effects of synthetic intravenous Delta9-tetrahydrocannabinol on psychosis, mood and cognitive functioning. Psychological Medicine October 2009
and 9 more in the library