Qualitative review and quantitative effect size meta-analyses in brain regions identified by cue-reactivity addiction studies

Objective: Various brain regions have been identified as involved in addictions, yet inconsistencies remain regarding the primary regions that may underlie addictive behaviors. To address this, we conducted a meta-analysis investigating cue-reactivity functional MRI studies for different addictions. Method: We explored 8 different addiction-related brain regions in 27 studies (29 samples) using homogeneity tests of effect sizes. Results: An initial qualitative review failed to identify consistent activations in any brain region. We subsequently explored possible moderators related to either the addiction, participants, or study design, and found addiction type to be a relevant moderator, suggesting that different addictions may not necessarily involve the same brain regions. Successive quantitative analyses found that internet gaming addiction and heroin dependence modulated neural activation in the right dorsolateral prefrontal cortex and heroin dependence further in the right orbitofrontal cortex. Our analyses also demonstrated the expected mean effect sizes in each region when conducting cue-reactivity experiments on addictions. Conclusions: It appears that distinct addiction types may manifest differently in the brain and may moderate cue reactivity to a greater extent than previously suggested factors. This study underscores the need for additional research comparing the neural mechanisms underlying different addiction types.