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

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 that involves 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 the clinical symptomatology of GD and commonly co-occurring presentations such as depression.

Electroencephalography (EEG) was recorded while participants with GD (n = 26) and healthy control participants (HCs) (n = 54) completed a slot machine task. Event-related potential (ERP) components 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.

Compared with HCs, participants with GD had larger (more negative) SPN amplitudes to possible wins versus total-miss losses (t₇₈ = 2.45, p = .017), equivalent RewP amplitudes, and higher LPP amplitudes (F_1,78 = 9.08, p = .003) to both wins (t₇₈ = 2.90, p = .004) and near-miss losses (t₇₈ = 2.69, p = .004). More severe clinical symptomatology covaried with more negative SPN amplitudes (Spearman's rho = -0.523, p = .021, false discovery rate corrected) but not with RewP or LPP.

Individuals with GD showed larger neural responses during reward anticipation (SPN) and late-stage processing of reward outcomes (LPP). Exaggerated neural responses during reward anticipation were 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.