title: Deficits in behavioural inhibition in substance abuse and addiction: a meta-analysis.
abstract: OBJECTIVE
  Deficits in behavioural inhibitory control are attracting increasing attention as a factor behind the development and maintenance of substance dependence. However, evidence for such a deficit is varied in the literature. Here, we synthesised published results to determine whether inhibitory ability is reliably impaired in substance users compared to controls.
  
  
  METHODS
  The meta-analysis used fixed-effects models to integrate results from 97 studies that compared groups with heavy substance use or addiction-like behaviours with healthy control participants on two experimental paradigms commonly used to assess response inhibition: the Go/NoGo task, and the Stop-Signal Task (SST). The primary measures of interest were commission errors to NoGo stimuli and stop-signal reaction time in the SST. Additionally, we examined omission errors to Go stimuli, and reaction time in both tasks. Because inhibition is more difficult when inhibition is required infrequently, we considered papers with rare and equiprobable NoGo stimuli separately.
  
  
  RESULTS
  Inhibitory deficits were apparent for heavy use/dependence on cocaine, MDMA, methamphetamine, tobacco, and alcohol (and, to a lesser extent, non-dependent heavy drinkers), and in pathological gamblers. On the other hand, no evidence for an inhibitory deficit was observed for opioids or cannabis, and contradictory evidence was observed for internet addiction.
  
  
  CONCLUSIONS
  The results are generally consistent with the view that substance use disorders and addiction-like behavioural disorders are associated with impairments in inhibitory control. Implications for treatment of substance use are discussed, along with suggestions for future research arising from the limitations of the extant literature.
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney 2052, NSW, Australia. Electronic address: janette.smith@unsw.edu.au.
authors.forename: Janette L
authors.initials: JL
authors.lastname: Smith
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney 2052, NSW, Australia.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Mattick
authors.affiliation: Monash Biomedical Imaging & School of Psychological Sciences, Monash University, Melbourne 3800, VIC, Australia.
authors.forename: Sharna D
authors.initials: SD
authors.lastname: Jamadar
authors.affiliation: National Drug and Alcohol Research Centre, University of New South Wales, Sydney 2052, NSW, Australia.
authors.forename: Jaimi M
authors.initials: JM
authors.lastname: Iredale
mesh_terms: D000435:Alcoholic Intoxication / Q000175:diagnosis / Q000523:psychology; D032763:Behavior Control / Q000523:psychology*; D016739:Behavior, Addictive / Q000175:diagnosis / Q000523:psychology*; D005715:Gambling / Q000175:diagnosis / Q000523:psychology*; D006801:Humans; D007266:Inhibition, Psychological; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000523:psychology*
keywords: Behavioural control; Inhibition; Meta-analysis; Pathological gambling; Review; Substance abuse