Development Over Time of the Population-Attributable Risk Fraction for Cannabis Use Disorder in Schizophrenia in Denmark

Abstract

everal studies and meta-analyses 1,2 have indicated that the risk of schizophrenia and related psychoses is increased for people who use cannabis. The association appears to be particularly driven by heavy and frequent cannabis use. 2,3 This has led to a persisting hypothesis that cannabis may be a component cause of schizophrenia, at least in some people. This hypothesis is strengthened by several factors, such as strong attempts to control for reverse causation (eg, people self-medicating prodromal symptoms of schizophrenia). Similarly, cannabis-induced psychosis has been found to be associated with later onset of schizophrenia. [4][5][6] Furthermore, experimental evidence strongly suggests that cannabis, even in relatively low doses, causes psychoticlike symptoms in healthy individuals. [7][8][9]

Presentation and Short-term Course of New Onset Cannabis Induced Psychotic Disorder in Males

“…With the liberalization of cannabis laws, commercialization of cannabis, increased access to cannabis, and greater potency of herbal cannabis and edibles, the negative consequences of cannabis exposure are expected to increase. The rates of psychoses attributable to cannabis have reportedly increased 13,21 , and there is a linear dose-response relationship 22 .As the rates of CIPD are expected to increase 21 . Thus, characterizing the shortand long-term course, expression, and biology is critical to develop tailored treatments for it and to limit iatrogenic problems.…”

“…With commercialization, increased access to cheaper and more potent cannabis will increase use among current users 12 . Hjorthøj et al, reported a doubling in the incidence of CIPD between 2006 and 2016 in Denmark coincident with an increase in the potency of cannabis 13 . Hjorthøj et al, noted that rates of CIPD increased independent of the increase in dually diagnosed patients i.e., comorbid cannabis use by patients with established schizophrenia.…”

The Epigenetics of Psychosis: A Structured Review with Representative Loci

“…Administration of moderate doses of the psychoactive ingredient of cannabis (THC) in the clinic elicits psychotic symptoms in individuals without a family history of psychosis [86][87][88]. In Denmark, a country with rigorous tracking of health metrics in its population, the increase in cannabis use and cannabis use disorder has been mirrored by an overall increase in schizophrenia cases [89].…”

A perspective review of cannabis use and sexual offenses

“…It is estimated that cannabis users increase their risk of schizophrenia roughly twofold, accounting for 8%–14% of cases, with frequent use or use of cannabis with high THC potency increasing the risk of schizophrenia sixfold (Volkow et al., 2016). Moreover, a recent notable population‐based longitudinal analysis showed the proportion of cases of schizophrenia associated with cannabis use disorder increased as the potency of cannabis also increased, suggesting a positive relationship between cannabis and increased population burden of psychiatric illness (Hjorthøj et al., 2021). Cannabis use also appears to adversely affect the course of psychotic illness as its use following first‐episode psychosis is associated with a poorer prognosis even after controlling for other forms of substance use (Alvarez‐Jimenez et al., 2012; Foti et al., 2010).…”