Association of pre-onset cannabis, alcohol, and tobacco use with age at onset of prodrome and age at onset of psychosis in first-episode patients.
OBJECTIVE
Several reports suggest that cannabis use is associated with an earlier age at onset of psychosis, although not all studies have operationalized cannabis use as occurring prior to onset of symptoms. This study addressed whether pre-onset cannabis use, alcohol use, and tobacco use are associated with an earlier age at onset of prodromal and psychotic symptoms. Effects of the progression of frequency of use were examined through time-dependent covariates in survival analyses.


METHODS
First-episode patients (N=109) hospitalized in three public-sector inpatient psychiatric units underwent in-depth cross-sectional retrospective assessments. Prior substance use and ages at onset of prodromal and psychotic symptoms were determined by standardized methods, and analyses were conducted using Cox regression modeling.


RESULTS
Whereas classifying participants according to maximum frequency of use prior to onset (none, ever, weekly, or daily) revealed no significant effects of cannabis or tobacco use on risk of onset, analysis of change in frequency of use prior to onset indicated that progression to daily cannabis and tobacco use was associated with an increased risk of onset of psychotic symptoms. Similar or even stronger effects were observed when onset of illness or prodromal symptoms was the outcome. A gender-by-daily-cannabis-use interaction was observed; progression to daily use resulted in a much larger increased relative risk of onset of psychosis in females than in males.


CONCLUSIONS
Pre-onset cannabis use may hasten the onset of psychotic as well as prodromal symptoms. Age at onset is a key prognostic factor in schizophrenia, and discovering modifiable predictors of age at onset is crucial.
Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA 30303, USA. mcompto@emory.edu
Michael T
MT
Compton
Mary E
ME
Kelley
Claire E
CE
Ramsay
Makenya
M
Pringle
Sandra M
SM
Goulding
Michelle L
ML
Esterberg
Tarianna
T
Stewart
Elaine F
EF
Walker
D000328:Adult; D017668:Age of Onset; D000437:Alcoholism / Q000175:diagnosis / Q000453:epidemiology*; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000175:diagnosis / Q000453:epidemiology*; D011379:Prognosis; D016016:Proportional Hazards Models; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis / Q000453:epidemiology*; D012307:Risk Factors; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology; D016019:Survival Analysis