University of Oulu

Denissoff, A, Mustonen, A, Alakokkare, A-E, Scott, JG, Sami, MB, Miettunen, J, et al. Is early exposure to cannabis associated with bipolar disorder? Results from a Finnish birth cohort study. Addiction. 2022; 117: 2264– 2272.

Is early exposure to cannabis associated with bipolar disorder? : results from a Finnish birth cohort study

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Author: Denissoff, Alexander1,2; Mustonen, Antti3,4; Alakokkare, Anni-Emilia1,5;
Organizations: 1Faculty of Medicine, Department of Psychiatry, University of Turku, Turku, Finland
2Addiction Psychiatry Unit, Department of Psychiatry, Turku University Hospital, Turku, Finland
3Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
4Department of Psychiatry, Seinäjoki Central Hospital, Seinäjoki, Finland
5Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
6QIMR Berghofer Medical Research Institute, Herston, Qld, Australia
7Metro North Mental Health Service, Herston, Qld, Australia
8Institute of Mental Health, University of Nottingham, Nottingham, UK
9Nottinghamshire Healthcare Trust, Nottingham, UK
10Center for Life Course Health Research, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.9 MB)
Persistent link:
Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2022-09-26


Background and aims: There are few longitudinal studies assessing the association of cannabis use and subsequent onset of bipolar disorder. We aimed to measure the association between early cannabis exposure and subsequent bipolar disorder.

Design, Setting and Participants: Observational study linking a sample from the northern Finland birth cohort 1986 (n = 6325) to nation-wide register data to examine the association of life-time cannabis exposure at age 15/16 years and subsequent bipolar disorder until age 33 (until the end of 2018); 6325 individuals (48.8% males) were included in the analysis.

Measurements: Cannabis exposure was measured via self-report. Bipolar disorder was measured via bipolar disorder-related diagnostic codes (ICD-10: F30.xx, F31.xx) collected from the Care Register for Health Care 2001–18, the Register of Primary Health Care Visits 2011–18, the medication reimbursement register of the Social Insurance Institution of Finland 2001–05 and the disability pensions of the Finnish Center for Pensions 2001–16. Potential confounders included demographic characteristics, parental psychiatric disorders, emotional and behavioral problems and other substance use.

Findings: Three hundred and fifty-two adolescents (5.6%) reported any cannabis use until the age of 15–16 years. Of the whole sample, 66 (1.0%) were diagnosed with bipolar disorder. Adolescent cannabis use was associated with bipolar disorder [hazard ratio (HR) = 3.46; 95% confidence interval (CI) = 1.81–6.61]. This association remained statistically significant after adjusting for sex, family structure and parental psychiatric disorders (HR = 3.00; 95% CI = 1.47–6.13) and after further adjusting for adolescent emotional and behavioral problems (HR = 2.34; 95% CI = 1.11–4.94). Further adjustments for frequent alcohol intoxications, daily smoking and lifetime illicit drug use attenuated the associations to statistically non-significant.

Conclusions: In Finland, the positive association between early cannabis exposure and subsequent development of bipolar disorder appears to be confounded by other substance use.

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Series: Addiction
ISSN: 0965-2140
ISSN-E: 1360-0443
ISSN-L: 0965-2140
Volume: 117
Issue: 8
Pages: 2264 - 2272
DOI: 10.1111/add.15881
Type of Publication: A1 Journal article – refereed
Field of Science: 3124 Neurology and psychiatry
Funding: Juho Vainio Foundation; Yrjö Jahnsson Foundation; Finnish Cultural Foundation; Olvi Foundation; Emil Aaltonen Foundation; Päivikki and Sakari Sohlberg Foundation; EU, Grant/Award Number: QLG1-CT-2000-01643
Copyright information: © 2022 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.