A meta-analysis of functional brain activity during valence processing in internet gaming disorder and gambling...

The intersection of gaming and gambling has gained increasing attention due to their role in addictive behaviours and their effects on brain function. Disadvantageous decision-making, involving continued engagement despite adverse consequences, may reflect dysregulations in positive and negative valence processing common to both gaming and gambling disorders. After conducting a thorough literature search (3773 records identified), we included 56 studies focusing on valence-related processes during functional magnetic resonance imaging (fMRI) with a total of 952 individuals with Internet Gaming Disorder (IGD) and 469 with Gambling Disorder (GD). We performed several meta-analyses using GingerAle software to identify patterns of task-related functional brain activity within IGD and GD (IGD vs controls: 22 experiments, 562 IGD and 530 control participants; GD vs controls: 18 experiments, 341 GD and 365 control participants) and to conduct exploratory comparisons between disorders. Our analysis identified spatial convergence of case-control activation in the right putamen across IGD studies, as well as in the caudate and globus pallidus across GD studies. Exploratory cross-disorder contrast identified shared spatial convergence in the right caudate head across IGD and GD studies while greater spatial convergence was found in the right globus pallidus and left caudate in GD. However, systematic comparison of the two literatures identified substantial differences in reporting conventions, diagnostic approaches, participant characteristics and task paradigms. Consequently, the exploratory between-literature contrast cannot establish disorder-specific basal-ganglia differences and should be regarded as hypothesis-generating. Future studies would benefit from harmonised diagnostic criteria and reporting conventions to enable more robust transdiagnostic comparisons.