title: Cannabis use, depression and anxiety: A 3-year prospective population-based study.
abstract: BACKGROUND
  Whether or not cannabis use may increase the risk for depression and/or anxiety is not clear. For one thing, it has not been possible to draw a definitive conclusion regarding the direction of causality, i.e. whether cannabis use increases the risk for depression/anxiety or vice versa. This study aimed at examining possible associations between cannabis use, depression and anxiety, using all three measures as both exposure and outcome.
  
  
  METHODS
  Data were obtained from a longitudinal cohort study comprising 8598 Swedish men and women, aged 20-64, with a three-year-follow-up.
  
  
  RESULTS
  Adjusted for sex and age, cannabis use at baseline was associated with an increased relative risk (RR) for depression and anxiety at follow-up, with RR=1.22 [1.06-1.42 Cl 95%] for depression and RR=1.38 [1.26-1.50 Cl 95%] for anxiety. Adjusted for all confounders (alcohol and illicit drug use, education, family tension, place of upbringing), the associations were no longer statistically significant; RR=0.99 [0.82-1.17 Cl 95%] for depression and RR=1.09 [0.98-1.20 Cl 95%] for anxiety. Age-adjusted, reporting depression or anxiety at baseline increased the risk of cannabis onset at follow-up three years later; RR=1.62 [1.28-2.03 CI 95%] and RR=1.63 [1.28-2.08 CI 95%] respectively. However, adjusted for other illicit drug use the associations were no longer statistically significant.
  
  
  CONCLUSIONS
  Lack of information on frequency of cannabis use and of age of initiation of use.
  
  
  CONCLUSIONS
  We found no longitudinal associations between cannabis use and incidence of depression/anxiety, or between depression/anxiety and later cannabis use onset.
authors.affiliation: Karolinska Institutet, Department of Public Health Sciences, SE-171 77, Stockholm, Sweden. Electronic address: anna-karin.danielsson@ki.se.
authors.forename: Anna-Karin
authors.initials: AK
authors.lastname: Danielsson
authors.affiliation: Karolinska Institutet, Department of Public Health Sciences, SE-171 77, Stockholm, Sweden; Centre for Epidemiology and Community Medicine, Stockholm County Council, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Lundin
authors.affiliation: Karolinska Institutet, Department of Public Health Sciences, SE-171 77, Stockholm, Sweden.
authors.forename: Emilie
authors.initials: E
authors.lastname: Agardh
authors.affiliation: Karolinska Institutet, Department of Public Health Sciences, SE-171 77, Stockholm, Sweden; Centre for Epidemiology and Community Medicine, Stockholm County Council, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Allebeck
authors.affiliation: Karolinska Institutet, Department of Public Health Sciences, SE-171 77, Stockholm, Sweden; Centre for Epidemiology and Community Medicine, Stockholm County Council, Sweden.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Forsell
mesh_terms: D000328:Adult; D001007:Anxiety / Q000453:epidemiology*; D003863:Depression / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology / Q000523:psychology*; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Anxiety; Cannabis; Depression; General population; Longitudinal