title: Evaluating the drug use "gateway" theory using cross-national data: consistency and associations of the order of initiation of drug use among participants in the WHO World Mental Health Surveys.
abstract: BACKGROUND
  It is unclear whether the normative sequence of drug use initiation, beginning with tobacco and alcohol, progressing to cannabis and then other illicit drugs, is due to causal effects of specific earlier drug use promoting progression, or to influences of other variables such as drug availability and attitudes. One way to investigate this is to see whether risk of later drug use in the sequence, conditional on use of drugs earlier in the sequence, changes according to time-space variation in use prevalence. We compared patterns and order of initiation of alcohol, tobacco, cannabis, and other illicit drug use across 17 countries with a wide range of drug use prevalence.
  
  
  METHODS
  Analyses used data from World Health Organization (WHO) World Mental Health (WMH) Surveys, a series of parallel community epidemiological surveys using the same instruments and field procedures carried out in 17 countries throughout the world.
  
  
  RESULTS
  Initiation of "gateway" substances (i.e. alcohol, tobacco and cannabis) was differentially associated with subsequent onset of other illicit drug use based on background prevalence of gateway substance use. Cross-country differences in substance use prevalence also corresponded to differences in the likelihood of individuals reporting a non-normative sequence of substance initiation.
  
  
  CONCLUSIONS
  These results suggest the "gateway" pattern at least partially reflects unmeasured common causes rather than causal effects of specific drugs on subsequent use of others. This implies that successful efforts to prevent use of specific "gateway" drugs may not in themselves lead to major reductions in the use of later drugs.
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052, Australia. l.degenhardt@unsw.edu.au
authors.forename: Louisa
authors.initials: L
authors.lastname: Degenhardt
authors.forename: Lisa
authors.initials: L
authors.lastname: Dierker
authors.forename: Wai Tat
authors.initials: WT
authors.lastname: Chiu
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Medina-Mora
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Neumark
authors.forename: Nancy
authors.initials: N
authors.lastname: Sampson
authors.forename: Jordi
authors.initials: J
authors.lastname: Alonso
authors.forename: Matthias
authors.initials: M
authors.lastname: Angermeyer
authors.forename: James C
authors.initials: JC
authors.lastname: Anthony
authors.forename: Ronny
authors.initials: R
authors.lastname: Bruffaerts
authors.forename: Giovanni
authors.initials: G
authors.lastname: de Girolamo
authors.forename: Ron
authors.initials: R
authors.lastname: de Graaf
authors.forename: Oye
authors.initials: O
authors.lastname: Gureje
authors.forename: Aimee N
authors.initials: AN
authors.lastname: Karam
authors.forename: Stanislav
authors.initials: S
authors.lastname: Kostyuchenko
authors.forename: Sing
authors.initials: S
authors.lastname: Lee
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Lépine
authors.forename: Daphna
authors.initials: D
authors.lastname: Levinson
authors.forename: Yosikazu
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Jose
authors.initials: J
authors.lastname: Posada-Villa
authors.forename: Dan
authors.initials: D
authors.lastname: Stein
authors.forename: J Elisabeth
authors.initials: JE
authors.lastname: Wells
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Kessler
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000437:Alcoholism / Q000453:epidemiology; D015331:Cohort Studies; D016208:Databases, Factual; D017831:Diagnosis, Dual (Psychiatry); D018450:Disease Progression; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology; D001523:Mental Disorders / Q000453:epidemiology; D008875:Middle Aged; D012907:Smoking / Q000453:epidemiology; D019966:Substance-Related Disorders / Q000453:epidemiology* / Q000523:psychology; D014944:World Health Organization; D055815:Young Adult