title: Effectiveness of traditional meditation retreats: A systematic review and meta-analysis.
abstract: An increasing number of studies are investigating traditional meditation retreats. Very little, however, is known about their effectiveness.
  
  
  
  To evaluate the effectiveness of meditation retreats on improving psychological outcomes in general population.
  
  
  
  A systematic review of studies published in journals or as dissertations in PSYCINFO, PUBMED, CINAHL or Web of Science from the first available date until October 22, 2016.
  
  
  
  A total of 20 papers (21 studies, N=2912) were included.
  
  
  
  Effect-size estimates of outcomes combined suggested that traditional meditation retreats are moderately effective in pre-post analyses (n=19; Hedge's g=0.45; 95% CI [0.35, 0.54], p<0.00001) and in analyses comparing retreats to controls (n=14; Hedge's g=0.49; 95% CI [0.36, 0.61], p<0.00001). Results were maintained at follow-up. No differences were observed between meditation styles. Results suggested large effects on measures of anxiety, depression and stress, and moderate effects on measures of emotional regulation and quality of life. As to potential mechanisms of actions, results showed large effects on measures of mindfulness and compassion, and moderate effects on measures of acceptance. In addition, changes in mindfulness levels strongly moderated clinical effect sizes. However, heterogeneity was significant among trials, probably due to differences in study designs, types and duration of the retreats and assessed outcomes, limiting therefore the implications of the results.
  
  
  
  Meditation retreats are moderately to largely effective in reducing depression, anxiety, stress and in ameliorating the quality of life of participants.
authors.affiliation: Department of Educational and Counselling Psychology, McGill University, Quebec, Canada; Department of Psychology, Harvard University, MA, United States. Electronic address: bassam.el-khoury@mcgill.ca.
authors.forename: Bassam
authors.initials: B
authors.lastname: Khoury
authors.affiliation: Department of Psychology, McGill University, Quebec, Canada.
authors.forename: Bärbel
authors.initials: B
authors.lastname: Knäuper
authors.affiliation: Department of Psychology, University College London, London, United Kingdom.
authors.forename: Marco
authors.initials: M
authors.lastname: Schlosser
authors.affiliation: Department of Psychology, McGill University, Quebec, Canada.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Carrière
authors.affiliation: Department of Biomedical and Neuromotor Science, University of Bologna, Bologna, Italy; Associazione di Psicologia Cognitiva - Scuola di Psicoterapia Cognitiva, Roma, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Chiesa
mesh_terms: D006801:Humans; D019122:Meditation / Q000379:methods* / Q000523:psychology; D011584:Psychology
keywords: Compassion; Meta-analysis; Mindfulness; Traditional meditation retreat; Vipassana