title: Steep delay discounting and addictive behavior: a meta-analysis of continuous associations.
abstract: To synthesize continuous associations between delayed reward discounting (DRD) and both addiction severity and quantity-frequency (QF); to examine moderators of these relationships; and to investigate publication bias.
  
  
  
  Meta-analysis of published studies examining continuous associations between DRD and addictive behaviors. Published, peer-reviewed studies on addictive behaviors (alcohol, tobacco, cannabis, stimulants, opiates and gambling) were identified via PubMed, MEDLINE and PsycInfo. Studies were restricted to DRD measures of monetary gains. Random-effects meta-analysis was conducted using Pearson's r as the effect size. Publication bias was evaluated using fail-safe N, Begg-Mazumdar and Egger's tests, meta-regression of publication year and effect size and imputation of missing studies.
  
  
  
  The primary meta-analysis revealed a small magnitude effect size that was highly significant (r = 0.14, P < 10-14). Significantly larger effect sizes were observed for studies examining severity compared with QF (P = 0.01), but not between the type of addictive behavior (P = 0.30) or DRD assessment (P = 0.90). Indices of publication bias suggested a modest impact of unpublished findings.
  
  
  
  Delayed reward discounting is associated robustly with continuous measures of addiction severity and quantity-frequency. This relation is generally robust across type of addictive behavior and delayed reward discounting assessment modality.
authors.affiliation: Peter Boris Centre for Addictions Research, McMaster University/St Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada.
authors.forename: Michael
authors.initials: M
authors.lastname: Amlung
authors.affiliation: Peter Boris Centre for Addictions Research, McMaster University/St Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada.
authors.forename: Lana
authors.initials: L
authors.lastname: Vedelago
authors.affiliation: Center for Integrated Healthcare, Syracuse VA Medical Center, Syracuse, NY, USA.
authors.forename: John
authors.initials: J
authors.lastname: Acker
authors.affiliation: Peter Boris Centre for Addictions Research, McMaster University/St Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada.
authors.forename: Iris
authors.initials: I
authors.lastname: Balodis
authors.affiliation: Peter Boris Centre for Addictions Research, McMaster University/St Joseph's Healthcare Hamilton, Hamilton, Ontario, Canada.|Homewood Research Institute, Homewood Health Centre, Guelph, Ontario, Canada.
authors.forename: James
authors.identifier: 0000-0003-4118-9500
authors.initials: J
authors.lastname: MacKillop
mesh_terms: D016739:Behavior, Addictive / Q000503:physiopathology* / Q000523:psychology*; D065786:Delay Discounting / Q000502:physiology*; D006801:Humans; D017594:Publication Bias; D012201:Reward; D012720:Severity of Illness Index
keywords: Addiction; behavioral economics; delayed reward discounting; meta-analysis; publication bias; quantity-frequency; severity