Marijuana use in the immediate 5-year premorbid period is associated with increased risk of onset of schizophrenia and related psychotic disorders

• Type of Material: Article
• Authors: Mary Kelley, Emory University; Claire Ramsay Wan, Tufts University; Beth Broussard, Lenox Hill Hospital; Anthony Crisafio, The George Washington University; Sarah Cristofaro, Emory University; Stephanie Johnson, Emory University; Thomas A. Reed, The George Washington University; Patrick Amar, Emory University; Nadine Kaslow, Emory University; Elaine Walker, Emory University; Michael T. Compton, Lenox Hill Hospital
• Language: English
• Date: 2016-03
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016 Elsevier B.V. Published by Elsevier Inc. All rights reserved.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.schres.2016.01.015
• Title of Journal or Parent Work: Schizophrenia Research
• ISSN: 0920-9964
• Volume: 171
• Issue: 1-3
• Start Page: 62
• End Page: 67
• Grant/Funding Information: Research reported in this publication was supported by National Institute of Mental Health grant R01 MH081011 (“First-Episode Psychosis and Pre-Onset Cannabis Use”) to the last author.; This work was supported by grant R01 MH081011 from the National Institute of Mental Health to the last author.
• Keywords: HEALTH; SUBSTANCE USE DISORDERS; MINI-MENTAL-STATE; AGE; 1ST-EPISODE PATIENTS; Psychiatry; Age at onset; First-episode psychosis; 1ST EPISODE SCHIZOPHRENIA; Schizophrenia; Marijuana; CANNABIS USE; SYMPTOMS; Science & Technology; Life Sciences & Biomedicine; DURATION; Cannabis; UNTREATED PSYCHOSIS
• Research Categories: Health Sciences, Public Health; Psychology, Behavioral; Biology, Neuroscience

Abstract

Objectives: Several studies suggest that adolescent marijuana use predicts earlier age at onset of schizophrenia, which is a crucial prognostic indicator. Yet, many investigations have not adequately established a clear temporal relationship between the use and onset. Methods: We enrolled 247 first-episode psychosis patients from six psychiatric units and collected data on lifetime marijuana/alcohol/tobacco use, and ages at onset of prodrome and psychosis in 210 of these patients. Cox regression (survival analysis) was employed to quantify hazard ratios (HRs) for effects of diverse premorbid use variables on psychosis onset. Results: Escalation of premorbid use in the 5 years prior to onset was highly predictive of an increased risk for onset (e.g., increasing from no use to daily use, HR = 3.6, p < 0.0005). Through the analysis of time-specific measures, we determined that daily use approximately doubled the rate of onset (HR = 2.2, p < 0.0005), even after controlling for simultaneous alcohol/tobacco use. Building on previous studies, we were able to determine that cumulative marijuana exposure was associated with an increased rate of onset of psychosis (= 0.007), independent of gender and family history, and this is possibly the reason for age at initiation of marijuana use also being associated with rate of onset in this cohort. Conclusions: These data provide evidence of a clear temporal relationship between escalations in use in the five years pre-onset and an increased rate of onset, demonstrate that the strength of the association is similar pre- and post-onset of prodromal symptoms, and determine that early adult use may be just as important as adolescent use in these associations.