Substance use in individuals at clinical high risk of psychosis.
BACKGROUND
A series of research reports has indicated that the use of substances such as cannabis, alcohol and tobacco are higher in youth at clinical high risk (CHR) of developing psychosis than in controls. Little is known about the longitudinal trajectory of substance use, and findings on the relationship between substance use and later transition to psychosis in CHR individuals are mixed.


METHODS
At baseline and 6- and 12-month follow-ups, 735 CHR and 278 control participants completed the Alcohol and Drug Use Scale and a cannabis use questionnaire. The longitudinal trajectory of substance use was evaluated with linear mixed models.


RESULTS
CHR participants endorsed significantly higher cannabis and tobacco use severity, and lower alcohol use severity, at baseline and over a 1-year period compared with controls. CHR youth had higher lifetime prevalence and frequency of cannabis, and were significantly younger upon first use, and were more likely to use alone and during the day. Baseline substance use did not differentiate participants who later transitioned to psychosis (n = 90) from those who did not transition (n = 272). Controls had lower tobacco use than CHR participants with a prodromal progression clinical outcome and lower cannabis use than those with a psychotic clinical outcome at the 2-year assessment.


CONCLUSIONS
In CHR individuals cannabis and tobacco use is higher than in controls and this pattern persists across 1 year. Evaluation of clinical outcome may provide additional information on the longitudinal impact of substance use that cannot be detected through evaluation of transition/non-transition to psychosis alone.
Department of Psychiatry,University of Calgary,Calgary,Alberta,Canada.
L
L
Buchy
Department of Psychiatry,UCSD,San Diego,CA,USA.
K S
KS
Cadenhead
Department of Psychology,Yale University,New Haven,CT,USA.
T D
TD
Cannon
Department of Psychiatry,Zucker Hillside Hospital,Long Island,NY,USA.
B A
BA
Cornblatt
Department of Psychiatry,Yale University,New Haven,CT,USA.
T H
TH
McGlashan
Department of Psychiatry,University of North Carolina,Chapel Hill,NC,USA.
D O
DO
Perkins
Department of Psychiatry,Harvard Medical School at Beth Israel Deaconess Medical Center and Massachusetts General Hospital,Boston,MA,USA.
L J
LJ
Seidman
Department of Psychology,Yale University,New Haven,CT,USA.
M T
MT
Tsuang
Departments of Psychology and Psychiatry,Emory University,Atlanta,GA,USA.
E F
EF
Walker
Department of Psychiatry,Yale University,New Haven,CT,USA.
S W
SW
Woods
Schizophrenia Spectrum Research Program, Division of Adult Translational Research,National Institute of Mental Health,Bethesda,MD,USA.
R
R
Heinssen
Departments of Psychiatry and Biobehavioral Sciences and Psychology,UCLA,Los Angeles,CA,USA.
C E
CE
Bearden
Departments of Psychiatry,University of California,San Francisco,San Francisco,CA,USA.
D
D
Mathalon
Department of Psychiatry,University of Calgary,Calgary,Alberta,Canada.
J
J
Addington
D000293:Adolescent; D000328:Adult; D002188:Cannabis; D016022:Case-Control Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D062706:Prodromal Symptoms; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000175:diagnosis*; D012307:Risk Factors; D012720:Severity of Illness Index; D019966:Substance-Related Disorders / Q000145:classification* / Q000453:epidemiology*; D055815:Young Adult; D062789:Tobacco Products
Alcohol; cannabis; prodrome; substance use; tobacco