Association between age at onset of psychosis and age at onset of cannabis use in non-affective psychosis

Abstract

Introduction Several studies have associated cannabis use with the development of schizophrenia. However, it has been difficult to disentangle the effects of cannabis from that of other illicit drugs, as previous studies have not evaluated pure cannabis users. To test whether the onset of cannabis use had an effect on the initiation of psychosis, we examined the time relationship between onset of use and onset of psychosis, restricting our analysis to a cohort of individuals who only used cannabis and no other street drugs. Methods Fifty seven subjects with non-affective psychoses who used cannabis prior to developing a psychosis were interviewed using the Diagnostic Interview for Genetic Studies (DIGS). The Family Interview for Genetic Studies (FIGS) was also used to interview a family informant about psychiatric illness in the patient and the entire family. Multiple linear regression techniques were used to estimate the association between variables. Results After adjusting for potential confounding factors such as sex, age, lifetime diagnosis of alcohol abuse or dependence, and family history of schizophrenia, the age at onset of cannabis was significantly associated with age at onset of psychosis (β=0.4, 95% CI=0.1–0.7, p=0.004) and age at first hospitalization (β=0.4, 95% CI=0.1–0.8, p=0.008). The mean time between beginning to use cannabis and onset of psychosis was 7.0±4.3. Age at onset of alcohol use was not associated with age at onset of psychosis or age at first hospitalization. Conclusion Age at onset of cannabis is directly associated with age at onset of psychosis and age at first hospitalization. These associations remain significant after adjusting for potential confounding factors and are consistent with the hypothesis that cannabis could cause or precipitate the onset of psychosis after a prolonged period of time.

Daily Use, Especially of High-Potency Cannabis, Drives the Earlier Onset of Psychosis in Cannabis Users

“…This cutoff also reflected the existing literature that indicates an age at first use of cannabis younger than 15 years as a critical window of exposure associated with a greater risk of developing psychosis. 8,[22][23][24][25][26] KM graphs of survival functions and Nelson-Aalen (NA) plots as well a formal numerical test were used to assess the assumption of proportionality required for a Cox regression. Associations between potential confounders with both AOP and cannabis use were assessed using chi-squared tests.…”

Recovery from cannabis use disorders: Abstinence versus moderation and treatment-assisted recovery versus natural recovery.

“…In a systematic review, it has been reported that cannabis users who also smoke tobacco are more dependent on cannabis, have more psychosocial problems, and have poorer cessation outcomes than those who use cannabis but not tobacco (Peters, Budney, & Carroll, 2012); and a separate review concluded that some mechanisms linking cannabis and tobacco are distinct from those contributing to co-occurring drug use in general (Agrawal, Budney, & Lynskey, 2012). Finally, there has been a surge of research in recent years that has demonstrated not only robust links between cannabis use and risk of subsequent psychosis, but also a possible causal role of cannabis use in the development of psychosis among a subset of vulnerable individuals (Barkus & Murray, 2010;Dekker et al, 2012;Di Forti et al, 2012;Galvez-Buccollini et al, 2012;Griffith-Lendering, Wigman, van Leeuwen, Huijbregts, & Huizink, 2013;Large, Sharma, Compton, Slade, & Nielsson, 2011;Manrique-Garcia et al, 2012;Moore et al, 2007;Tosato et al, 2013).…”

Reciprocal alterations in cortical cannabinoid receptor 1 binding relative to protein immunoreactivity and transcript levels in schizophrenia

“…Cannabis use during early adolescence has been linked to a higher risk of developing schizophrenia, an earlier age of onset, and greater illness severity (D'Souza et al 2005; Compton et al 2009; Foti et al 2010; Casadio et al 2011; Galvez-Buccollini et al 2012). These associations may indicate that the disease process of schizophrenia involves disturbances in endogenous cannabinoid signaling which may in turn predispose at-risk adolescents to greater debilitating effects of cannabis use.…”