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. 2014 Jan;152(1):283-8.
doi: 10.1016/j.schres.2013.11.014. Epub 2013 Dec 2.

A controlled family study of cannabis users with and without psychosis

Ashley C Proal  1 , Jerry Fleming  2 , Juan A Galvez-Buccollini  2 , Lynn E Delisi  3
Affiliations

A controlled family study of cannabis users with and without psychosis

Ashley C Proal et al. Schizophr Res. 2014 Jan.

Abstract

Background: Cannabis is one of the most highly abused illicit drugs in the world. Several studies suggest a link between adolescent cannabis use and schizophrenia. An understanding of this link would have significant implications for legalization of cannabis and its medicinal value. The present study aims to determine whether familial morbid risk for schizophrenia is the crucial factor that underlies the association of adolescent cannabis use with the development of schizophrenia.

Methods: Consecutively obtained probands were recruited into four samples: sample 1: 87 non-psychotic controls with no drug use; sample 2: 84 non-psychotic controls with cannabis use; sample 3: 32 patients with a schizophrenia spectrum psychosis with no drug use; sample 4: 76 patients with schizophrenia spectrum psychosis with cannabis use. All cannabis using subjects used this drug during adolescence, and no other substance, with the exception of alcohol. Structured interviews of probands and family informants were used to obtain diagnostic information about probands and all their known relatives.

Results: There was an increased morbid risk for schizophrenia in relatives of the cannabis using and non-using patient samples compared with their respective non-psychotic control samples (p=.002, p<.001 respectively). There was no significant difference in morbid risk for schizophrenia between relatives of the patients who use or do not use cannabis (p=.43).

Conclusions: The results of the current study suggest that having an increased familial morbid risk for schizophrenia may be the underlying basis for schizophrenia in cannabis users and not cannabis use by itself.

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Conflict of interest statement

AUTHOR DISCLOSURES:

All co-authors submit that they have no conflicts of interest to report.

Comment in

References

    1. Andréasson S, Allebeck P, Rydberg U. Schizophrenia in users and nonusers of cannabis. A longitudinal study in Stockholm County. Acta Psychiatr Scand. 1989;79(5):505–510. - PubMed
    1. Boydell J, Dean K, Dutta R, Giouroukou E, Fearon P, Murray R. A comparison of symptoms and family history in schizophrenia with and without prior cannabis use: implications for the concept of cannabis psychosis. Schizophr Res. 2007;93(1–3):203–210. - PubMed
    1. Caspi A, Moffitt TE, Cannon M, McClay J, Murray R, Harrington H, Taylor A, Arseneault L, Williams B, Braithwaite A, Poulton R, Craig IW. Moderation of the effect of adolescent-onset cannabis use on adult psychosis by a functional polymorphism in the catechol-O-methyltransferase gene: longitudinal evidence of a gene X environment interaction. Biol Psychiatry. 2005;57(10):1117–1127. - PubMed
    1. Compton MT, Kelley ME, Ramsay CE, Pringle M, Goulding SM, Esterberg ML, Stewart T, Walker EF. 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. Am J Psychiatry. 2009;166(11):1251–1257. - PMC - PubMed
    1. Deiana S. Medical use of cannabis. Cannabidiol: A new light for schizophrenia? Drug Test Anal. 2013;5(1):46–51. - PubMed

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