University of Oulu

Alexander, D, Niemelä, S, Scott, JG, et al. Does cannabis use in adolescence predict self-harm or suicide? Results from a Finnish Birth Cohort Study. Acta Psychiatr Scand. 2022; 145: 234– 243. doi:10.1111/acps.13384

Does cannabis use in adolescence predict self-harm or suicide? : results from a Finnish Birth Cohort Study

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Author: Denissoff, Alexander1,2; Niemelä, Solja1,2; Scott, James G.3,4;
Organizations: 1Department of Psychiatry, Faculty of Medicine, University of Turku, Turku, Finland
2Addiction Psychiatry Unit, Department of Psychiatry, Turku University Hospital, Turku, Finland
3QIMR Berghofer Medical Research Institute Herston, Herston, Qld, Australia
4Metro North Mental Health Service, Herston, Qld, Australia
5Institute for Social Science Research, The University of Queensland, Brisbane, Australia
6ARC Centre of Excellence for Children & Families over the Life Course, The University of Queensland, Brisbane, Qld, Australia
7School of Public Health, The University of Queensland, Brisbane, Qld, Australia
8Center for Life Course Health Research, University of Oulu, Oulu, Finland
9Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu, Finland
10Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
11Department of Psychiatry, Seinäjoki Central Hospital, Seinäjoki, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 0.3 MB)
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Language: English
Published: John Wiley & Sons, 2022
Publish Date: 2022-03-07


Objective: Longitudinal studies examining the association between adolescent cannabis use and self-harm are rare, heterogeneous and mixed in their conclusions. We study this association utilizing a large general population-based sample with prospective data.

Methods: The Northern Finland Birth Cohort 1986 (n = 6582) with linkage to nationwide register data was used to study the association of self-reported cannabis use at age 15–16 years and self-harm and suicide death until age 33 (until year 2018), based on register information. Cox regression analysis with Hazard Ratios (HR) and 95% confidence intervals (CI) was used. Psychiatric disorders, parental psychiatric disorders and other substance use were considered as confounders.

Results: In all, 6582 (49.2% male) were included in the analysis, and 377 adolescents (5.7%) reported any cannabis use until the age of 15–16 years. Based on register information, 79 (55.7% male) had visited in health care services due to self-harm, and 22 (90.1% male) had died by suicide. In crude analyses, adolescent cannabis use was associated with self-harm (HR = 3.93; 95% CI 2.24–6.90). The association between cannabis use and self-harm remained statistically significant after adjusting for sex, psychiatric disorders at baseline, frequent alcohol intoxications, other illicit drug use, and parental psychiatric disorders (HR 2.06; 95% CI 1.07–3.95). In contrast, the association of cannabis use with suicide did not reach statistical significance even in crude analysis (HR 2.60; 95% CI 0.77–8.78).

Conclusion: Cannabis use in adolescence may increase risk of self-harm independent of adolescent psychopathology and other substance use.

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Series: Acta psychiatrica Scandinavica
ISSN: 0001-690X
ISSN-E: 1600-0447
ISSN-L: 0001-690X
Volume: 145
Issue: 3
Pages: 234 - 243
DOI: 10.1111/acps.13384
Type of Publication: A1 Journal article – refereed
Field of Science: 3124 Neurology and psychiatry
3142 Public health care science, environmental and occupational health
Funding: NFBC1986 received financial support from EU QLG1-CT-2000-01643 (EUROBLCS) Grant no. E51560, NorFA Grant no. 731, 20056, 30167, USA/NIH 2000 G DF682 Grant no. 50945. AD has received funding from Juho Vainio Foundation. SN has received funding from Sohlberg Foundation and Juho Vainio Foundation. JM has received funding from Juho Vainio Foundation and Yrjö Jahnsson Foundation. For this study, AM has received funding from Emil Aaltonen Foundation, The Hospital District of South Ostrobothnia and The Finnish Foundation of Alcohol Studies.
Copyright information: © 2021 The Authors. Acta Psychiatrica Scandinavica published by John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.