Adolescent cannabis use and later development of schizophrenia: An updated systematic review of longitudinal studies

Abstract

Background The study aimed to review recent literature not included in previous reviews and ascertain the correlation between early marijuana use among adolescents, between 12 and 18 years of age, and the development of schizophrenia in early adulthood. A further aim was to determine if the frequency of use of marijuana demonstrated any significant effect on the risk of developing schizophrenia in early adulthood. Methods Five hundred and ninety‐one studies were examined; six longitudinal cohort studies were analyzed using a series of nonparametric tests and meta‐analysis. Results Nonparametric tests, Friedman tests, and Wilcoxon signed tests showed a highly statistically significant difference in odds ratios for schizophrenia between both high‐ and low‐cannabis users and no‐cannabis users. Conclusion Both high‐ and low‐frequency marijuana usage were associated with a significantly increased risk of schizophrenia. The frequency of use among high‐ and low‐frequency users is similar in both, demonstrating statistically significant increased risk in developing schizophrenia.

The Relationship Between Cannabinoids and Neural Oscillations: How Cannabis Disrupts Sensation, Perception, and Cognition

“…This may be particularly relevant to the disorder of schizophrenia, as cannabis use has been consistently shown to be a risk factor in the development of psychosis. 112 For instance, thought disorder in schizophrenia may reflect an underlying disintegration of the brain's ability to generate and maintain neural oscillations in functionally relevant frequencies (ie, theta and gamma). 48,62,[113][114][115] Several decades of research examining transient and steady-state evoked, perceptually/ cognitive-induced, and resting-state neural oscillations have provided strong evidence that disruptions in both theta-and gamma-range neural synchrony is a core feature of psychosis (for review see Pittman-Polletta et al, 2015).…”

Associations of cannabis use, tobacco use and incident anxiety, mood, and psychotic disorders: a systematic review and meta-analysis

“…1 Existing observational evidence demonstrates prospective associations between cannabis use, tobacco use and mental ill-health; including depression, [2][3][4][5][6][7][8][9][10][11][12] anxiety, [7][8][9][10][12][13][14][15][16] and psychosis. 10,[17][18][19][20][21][22][23][24][25][26] However, it remains unclear if the associations in question are causal or if they result from observational data biases (e.g., confounding, reverse causality). 27 Numerous reviews of these substances and mental ill-health highlight confounding as a key limitation when interpreting results.…”

Cannabis use among youth in Canada: a scoping review protocol

“…3 In Canada, recreational cannabis use was legalised in 2018 across the 10 provinces and 3 territories, and one of the key objectives of the Cannabis Act is to protect the health and safety of youth. 5 Despite this objective, cannabis use among youth continues to be a public health concern linked with physical and mental health concerns including anxiety, 6 depression, 7 8 psychosis, [9][10][11] attention deficit hyperactivity disorder, respiratory problems and use of other illicit substances. 12 Youth with mental health concerns have higher rates of cannabis use, 13 and early initiation of cannabis use is linked with increased mental health concerns.…”