Cognitive and Physiological Assessment of Prefrontal Cortex Neuromodulation in Low and High Risk Gambling

Gambling disorder (GD) is the most widely studied behavioural addiction (BA), however there is still an unmet need for more effective treatment strategies. With the aim to improve the understanding of transcranial direct current stimulation (tDCS) as a potential treatment intervention for GD, four experiments were conducted using different protocols and participant samples to measure neuromodulation effects during gambling-related task performance. In Experiments I and II, the effects of tDCS were investigated in low impulsive (LI) and high impulsive (HI) participants. Different high definition (HD) tDCS montages were used to target right dorsolateral prefrontal cortex (rDLPFC) and ventromedial prefrontal cortex (vmPFC), brain areas associated with decision-making and reward processing, respectively. Results revealed effects of tDCS on gambling task performance, but no difference on tDCS effects between rDLPFC and vmPFC targets, or between participant groups. In Experiment III, the potential cumulative effects of rDLPFC tDCS combined with cognitive behavioural therapy (CBT) were investigated across eight sessions, in two patients diagnosed with GD. The intervention combining tDCS and CBT resulted in reductions in gambling severity and cravings, but this effect was also seen in the sham tDCS case. In Experiment IV, physiological data, including electrodermal activity (EDA), electrocardiogram (ECG) and electroencephalogram (EEG), was used to investigate rDLPFC tDCS effects on the autonomous nervous system (ANS), in LI and HI gamblers. Results showed that real stimulation was associated with increased sympathetic activation compared with sham, which was higher during gambling-related wins compared with losses, and in HI compared with LI. There were significant correlations between gambling severity, cognitive outcomes and physiological variables, which helped to identify biological markers associated with GD. These results helped refine the knowledge of specific cognitive and physiological underpinnings of reward processing in different participant samples, and contributed to the development of novel treatment interventions for GD.