Larger Neural Responses to Reward in Gambling Disorder: Relationships with Depression and Gambling Severity.

Abstract

Background: For most people, gambling is a type of entertainment that engages pleasure, risk, and reward drives. However, some individuals develop gambling disorder (GD), a behavioral addiction involving continued gambling despite negative consequences. Disturbances in reward neurocircuitry have been implicated in GD, but are not well-characterized, including how neural alterations relate to clinical symptomatology of GD and commonly co-occurring presentations such as depression.

Methods: EEG was recorded while participants with GD (n=26) and comparison subjects (HCs=54) completed a slot machine task. Event-related potential components (ERPs) reflecting reward anticipation (stimulus preceding negativity: SPN) and reward outcome evaluation (reward positivity: RewP; late positive potential: LPP) were assessed. Within GD, we examined associations between reward ERPs and a clinical summary score that reflected greater problem-gambling and depressive symptoms, and lower global functioning.

Results: Compared to HCs, GD participants had larger (more negative) SPN amplitudes to possible wins vs. total-miss losses (t=2.45, p=.017), equivalent RewP amplitudes, and higher LPP amplitudes (F=9.08, p=.003) to both wins (t=2.90, p=.004) and near-miss losses (t=2.69, p=.004). More severe clinical symptomatology covaried with more negative SPN amplitudes (Spearman's rho=-.523, p=.021, FDR-corrected), but not with RewP or LPP.

Conclusions: Individuals with GD show larger neural responses during reward anticipation (SPN) and late-stage processing of reward outcomes (LPP). Exaggerated neural responses during reward anticipation are most pronounced among individuals with more severe clinical symptomatology. These findings suggest that excessive reward anticipation as well as heightened salience to outcomes, regardless of valence, are potential mechanisms underlying GD.