Cannabis use predicts future psychotic symptoms, and vice versa

  1. Robert F. Ferdinand1,
  2. Frouke Sondeijker1,
  3. Jan Van Der Ende1,
  4. Jean-Paul Selten2,
  5. Anja Huizink1,
  6. Frank C. Verhulst1

Article first published online: 22 APR 2005

DOI: 10.1111/j.1360-0443.2005.01070.x

Issue

Addiction

Addiction

Volume 100, Issue 5, pages 612–618, May 2005

Additional Information

How to Cite

Ferdinand, R. F., Sondeijker, F., Van Der Ende, J., Selten, J.-P., Huizink, A. and Verhulst, F. C. (2005), Cannabis use predicts future psychotic symptoms, and vice versa. Addiction, 100: 612–618. doi: 10.1111/j.1360-0443.2005.01070.x

Author Information

  1. 1

    Department of Child and Adolescent Psychiatry, Erasmus Medical Center Rotterdam/Sophia Children's Hospital, the Netherlandsand

  2. 2

    Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Center Utrecht, the Netherlands

*Robert F. Ferdinand Erasmus Medical Center Rotterdam/Sophia Children's Hospital Department of Child and Adolescent Psychiatry Dr Molewaterplein 60 3015 GJ Rotterdam the Netherlands Tel: + 31 10 4636671 Fax: + 31 10 4636803 E-mail: r.f.ferdinand@erasmusmc.nl

Publication History

  1. Issue published online: 22 APR 2005
  2. Article first published online: 22 APR 2005
  3. Submitted 3 September 2004; initial review completed 22 September 2004; final version accepted 11 January 2005

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Keywords:

  • Adolescents;
  • cannabis;
  • CIDI;
  • psychosis

ABSTRACT

Aims  To assess if cannabis use is a risk factor for future psychotic symptoms, and vice versa, in adolescents and young adults from the general population.

Design  Cohort study.

Setting/participants  ‘Zuid Holland’ study, a 14-year follow-up study of 1580 initially 4–16-year-olds who were drawn randomly from the Dutch general population. Because cannabis use is generally condoned in the Netherlands, false-negative reports of cannabis use may occur less frequently than in countries with stricter drug policies, which supports the value of the present study.

Measurements  Life-time cannabis use and psychotic symptoms, assessed with the Composite International Diagnostic Interview (CIDI).

Findings  Cannabis use, in individuals who did not have psychotic symptoms before they began using cannabis, predicted future psychotic symptoms (hazard ratio = 2.81; 95% confidence interval = 1.79–4.43). However, psychotic symptoms in those who had never used cannabis before the onset of psychotic symptoms also predicted future cannabis use (hazard ratio = 1.70; 95% confidence interval = 1.13–2.57).

Conclusions  The results imply either a common vulnerability with varying order of onset or a bi-directional causal relationship between cannabis use and psychosis. More research on patterns and timings of these relationships is needed to narrow down the possibilities.

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