Neuropsychopharmacology. 2019 Jul;44(8):1354-1361. doi: 10.1038/s41386-019-0393-9.
Ioannidis K1,2, Hook R1, Wickham K1, Grant JE3, Chamberlain SR4,5.
Gambling Disorder is a prevalent psychiatric condition often linked to dysfunction of cognitive domains regulating impulsive behavior. Despite the centrality of impulsivity to neurobiological models of Gambling Disorder, a comprehensive meta-analysis of all impulsive cognitive domains has yet to be conducted. It is also not clear whether cognitive deficits in Gambling Disorder extend to those with problem (at-risk) gambling. A systematic review was undertaken of case-control studies examining the following cognitive domains in Gambling Disorder or in at-risk (problem) gambling: attentional inhibition, motor inhibition, discounting, decision-making, and reflection impulsivity. Case-control differences in cognition were identified using meta-analysis (random-effects modeling). Moderation analysis explored potential influences of age, gender, presence/absence of comorbidities in cases, geographical region, and study quality on cognitive performance. Gambling Disorder was associated with significant impairments in motor (g = 0.39-0.48) and attentional (g = 0.55) inhibition, discounting (g = 0.66), and decision-making (g = 0.63) tasks. For problem gambling, only decision-making had sufficient data for meta-analysis, yielding significant impairment versus controls (g = 0.66); however, study quality was relatively low. Insufficient data were available for meta-analysis of reflection impulsivity. There was evidence for significant publication bias only for the discounting domain, after an outlier study was excluded. Study quality overall was reasonable (mean score 71.9% of maximum), but most studies (~85%) did not screen for comorbid impulse control and related disorders. This meta-analysis indicates heightened impulsivity across a range of cognitive domains in Gambling Disorder. Decision-making impulsivity may extend to problem (at-risk) gambling, but further studies are needed to confirm such candidate cognitive vulnerability markers.