title: School effects on young people's drug use: a systematic review of intervention and observational studies.
abstract: OBJECTIVE
  This systematic review examined the hypothesis that school institutional factors influence young people's use of drugs. We aimed to (1) identify the effect of school-level changes on drug use and (2) explore the possible mechanisms by which school-level influences on individual drug use might occur.
  
  
  METHODS
  Systematic review. Experimental/quasi-experimental studies of "whole-school" drug prevention interventions and longitudinal observational studies on the association between school-level and individual-level school-related exposures and drug use were included. Experimental studies were included because they are the most reliable available source of evidence about causation. Observational studies of school-level and individual-level school-related exposures were included with the aim of providing evidence about a wider range of possible school-level effects and how school-level influences might be mediated by individual-level factors.
  
  
  RESULTS
  Experimental studies suggested that changes to the school social environment that increase student participation, improve relationships and promote a positive school ethos may be associated with reduced drug use. School-level and individual-level observational studies consistently reported that disengagement and poor teacher-student relationships were associated with drug use and other risky health behaviors.
  
  
  CONCLUSIONS
  There is evidence of school effects on young people's drug use. Interventions that promote a positive school ethos and reduce student disaffection may be an effective complement to drug prevention interventions addressing individual knowledge, skills, and peer norms. Such approaches should now be piloted in a wider range of settings. Further research is also needed to explore mechanisms by which schools may influence young people's drug use.
authors.affiliation: The Centre for Research on Drugs and Health Behaviour, London School of Hygiene and Tropical Medicine, London, United Kingdom. adam.fletcher@lshtm.ac.uk
authors.forename: Adam
authors.initials: A
authors.lastname: Fletcher
authors.forename: Chris
authors.initials: C
authors.lastname: Bonell
authors.forename: James
authors.initials: J
authors.lastname: Hargreaves
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D017677:Age Distribution; D000428:Alcohol Drinking / Q000453:epidemiology / Q000517:prevention & control; D001315:Australia / Q000453:epidemiology; D002648:Child; D004522:Educational Status; D005178:Faculty; D005260:Female; D015438:Health Behavior; D006801:Humans; D007398:Interpersonal Relations; D008137:Longitudinal Studies; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D019370:Observation; D012307:Risk Factors; D012574:Schools / Q000706:statistics & numerical data*; D012907:Smoking / Q000453:epidemiology; D000074606:Smoking Prevention; D012924:Social Conditions; D019966:Substance-Related Disorders / Q000453:epidemiology* / Q000517:prevention & control; D014481:United States / Q000453:epidemiology