We assessed the coherence of evidence from epidemiological, genetic, experimental, and preclinical studies to assess relationships between daily cannabis use and the increased incidence, prevalence, and persistence of psychosis, bipolar disorder, anxiety, depression, and suicidal behaviours.
There are several ways frequent cannabis use could influence the risk of developing anxiety, depression, and psychotic disorders. First, it could bring forward the onset of disorders in people who were at high risk of developing them. Second, it could increase the incidence of mental disorders, ie, produce disorders that would not have developed in the absence of cannabis use. Third, frequent cannabis use could increase the chronicity of these mental disorders and thereby their prevalence in the population. Studies that follow representative samples of adolescents into adulthood are best designed to assess these possibilities, because they often measure exposure to cannabis use before symptoms of mental disorders develop and provide evidence on the course of these disorders.
(Source: https://www.sciencedirect.com/science/article/pii/S2215036626000866)