Association between formal thought disorder and cannabis use: a systematic review and meta-analysis
Mathilde Argote, Guillaume Sescousse, Jérôme Brunelin, É. Fakra, Mikail Nourredine, Benjamin Rolland
Schizophrenia September 29, 2022 DOI: 10.1038/s41537-022-00286-0 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Meta-analysis Peer reviewed |
|---|---|
| Sample size | 5,191 |
| Population | Individuals along the psychosis continuum (healthy individuals, patients with first-episode psychosis, patients with schizophrenia) |
| Topics | Cannabis CBD |
| Keywords | Psychosis Meta-analysis Psycinfo Schizophrenia object-oriented programming Effects of cannabis Clinical psychology Medline Obsessive-compulsive spectrum disorders |
| Citations | 7 |
| Key findings | Cannabis use is associated with increased formal thought disorder severity across the psychosis continuum. |
Abstract
Formal thought disorder (FTD) is a multidimensional syndrome mainly occurring along the psychosis continuum. Cannabis use is known to increase symptoms of psychosis, particularly positive symptoms. However, the impact of cannabis use on FTD in individuals presenting symptoms along the psychosis continuum remains unclear. To address this knowledge gap, we conducted a meta-analysis examining the association between cannabis use and FTD in those individuals. We hypothesized that cannabis would worsen FTD. We conducted a systematic search of the PubMed, ScienceDirect, PsycINFO, Web of Science, Embase and Google Scholar databases up to July 2022. The results were collated through a random-effects model using the statistical software R. Reference lists of included studies were searched for additional relevant publications. Nineteen studies were included, totalling 1840 cannabis users and 3351 non-cannabis users. The severity of FTD was found to be higher in cannabis users (SMD = 0.21, 95%CI [0.12-0.29], p = 0.00009). Subgroup analyses revealed that FTD severity was increased among cannabis users, regardless of the disorder severity: healthy individuals (SMD = 0.19, 95%CI [0.05-0.33], p = 0.02); patients with first-episode psychosis (SMD = 0.21, 95%CI [0.01-0.41], p = 0.04); patients with schizophrenia (SMD = 0.25, 95%CI [0.11-0.38], p = 0.005). Between-group differences were not significant. In line with its already known effect on positive symptoms in psychosis, cannabis use appears to be associated with increased FTD severity all along the psychosis continuum. Future research should consider potential confounding variables such as other substance use disorders and explore how FTD dimensions are impacted by cannabis use.
Comparable studies
Other systematic reviews and meta-analyses on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Effects of cannabis use on outcomes of psychotic disorders: systematic review People with psychotic disorders, as examined in 13 longitudinal studies | 2008 | Systematic review | |
| 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 Patients with established schizophrenia (meta-analysis: 572) and patients with... | 2010 | Meta-analysis and cross-sectional observational study | n = 700 |
| Medicinal cannabis for psychiatric disorders: a clinically-focused systematic review | 2020 | Systematic review | |
| Neuroimaging in cannabis use: a systematic review of the literature Cannabis users and controls in neuroimaging studies | 2009 | Systematic review | |
| Human Laboratory Studies on Cannabinoids and Psychosis. Healthy human subjects and individuals with schizophrenia | 2016 | Systematic review |
Citations in the library
Cited by 2
- Association between cannabis use and symptom dimensions in schizophrenia spectrum disorders: an individual participant data meta-analysis on 3053 individuals EClinicalMedicine September 8, 2023
- Self-disturbance in first-episode psychosis: Theoretical framework and potential cannabis interactions - a systematic review. Frontiers in Psychiatry 2025
Cites 12
- Are adolescents more vulnerable to the harmful effects of cannabis than adults? A placebo-controlled study in human males Translational Psychiatry November 29, 2016
- Cannabis use and first-episode psychosis: relationship with manic and psychotic symptoms, and with age at presentation Psychological Medicine May 24, 2013
- Psychotic experiences are linked to cannabis use in adolescents in the community because of common underlying environmental risk factors Psychiatry Research April 15, 2015
- Does cannabis use predict psychometric schizotypy via aberrant salience? Schizophrenia Research April 6, 2020
- Symptomatology and neurocognition among first-episode psychosis patients with and without cannabis use in the three months prior to first hospitalization. Schizophrenia Research January 9, 2021
and 7 more in the library