Cannabis Use and the Course of Schizophrenia: 10-Year Follow-Up After First Hospitalization

Abstract

Objective The authors examined the relationship between cannabis use and the course of illness in schizophrenia over 10 years following first psychiatric hospitalization. Method We assessed 229 patients with a schizophrenia-spectrum disorder five times: during the first admission, and 6 months, 2 years, 4 years, and 10 years later. Ratings of cannabis use and psychiatric symptoms (psychotic, negative, disorganized, and depressive) were made at each assessment. Results The lifetime rate of cannabis use was 66.2%, and survival analysis revealed that this usage was associated with an earlier onset of psychosis. The rates of current use ranged from 10% to 18% across assessments. Cannabis status was moderately stable, with concordance between waves ranging rtet = 0.48 – 0.78. Mixed-effects logistic regression revealed that changes in cannabis use were associated with changes in psychotic symptoms over time even after gender, age, socio-economic status, other drug use, antipsychotic medication use, and other symptoms were controlled. Structural equation modeling indicated that the association with psychotic symptoms was bi-directional. Conclusions Cannabis use is associated with an adverse course of psychotic symptoms in schizophrenia, and vice versa, even after taking into account other clinical, substance, and demographic variables. The specificity of this relationship suggests that clinical interventions to reduce cannabis use may be best targeted at individuals with prominent psychotic symptoms.

Association of abnormal semantic processing with delusion-like ideation in frequent cannabis users: an electrophysiological study

“…Cannabis use in healthy individuals also predicts subsequent higher levels of psychosis-like experiences that do not meet the threshold for diagnosis of schizophrenia, including unusual ideation or perceptual experiences that are less fixed than delusions or hallucinations, respectively (Rossler et al 2007;van Os et al 2002). Moreover, in persons who have developed schizophrenia, ongoing cannabis use increases psychotic symptoms (Foti et al 2010) and relapse risk (Zammit et al 2008). However, the specific neurocognitive mechanisms whereby cannabis exerts its effect on the development of psychotic symptoms remain unclear.…”

Potential Psychological Factors Associated with High Risk for Cannabis Abuse: Evidence from Multiple Logistic Regression

“…The involvement of cannabis use in various psychiatric disorders has been established in many studies, including in schizophrenia [14,15], mood disorders [16][17][18][19], depression [20][21][22], anxiety [6] and behavioral disorders among young people. Brook [23,24] examined the association between psychosocial risk and protective factors and cannabis use disorders.…”

“…Each item is scored on a fourpoint scale from 0 (not present) to 3 (considerable). Subscale scores are divided into 4 ranges: normal (0-7), mild (8-10), moderate (11)(12)(13)(14)(15) and severe (16)(17)(18)(19)(20)(21). The French version of the HADS was validated by [55].…”

Impulsivity, Sensation Seeking and Anhedonia as Possible Explanations for Cannabis Abuse Comorbidity among First Psychotic Episode Inpatients

“…The comorbidity of schizophrenia (psychosis) and the abuse of cannabis (marijuana) is a well-known clinical finding [1]. However, despite the significant prevalence of substance use disorders in schizophrenia and its clinical implications, little is known about why these two disorders are so predominantly comorbid.…”