Effect of High-Intensity Transcranial Alternating Current Stimulation on Gambling Disorder: A Randomized Controlled Trial

Gambling symptom severity will be measured by the Pathological Gambling Yale-Brown Obsessive Compulsive Scale (PG-YBOCS). The total score of PG-YBOCS ranges from 0 to 40, in which higher scores indicate more severe pathological gambling symptoms.

Depressive symptoms will be measured by the 17-item Hamilton Depression Rating Scale (HAMD-17). The total score of HAMD-17 ranges from 0 to 52, in which higher scores mean a higher severity of depressive symptoms.

Anxiety symptoms will be measured by the 14-item Hamilton Anxiety Rating Scale (HAMA-14). The total score of HAMA-14 ranges from 0 to 56, in which higher scores mean a higher severity of anxiety symptoms.

Sleep quality will be measured by the Pittsburgh Sleep Quality Index (PSQI). The total score of PSQI ranges from 0 to 21, in which higher scores mean poorer sleep quality.

Gambling craving will be measured by the gambling craving Visual Analog Scale (VAS). The total score of VAS ranges from 0 to 10, in which higher scores mean a higher level of gambling craving.

Side effects will be assessed using a standardized adverse reaction evaluation form. The total score varies depending on symptom severity, with higher scores indicating more significant adverse reactions.

Self-control ability will be measured by the Self-Control Scale (SCS). Higher scores of SCS indicate better self-regulation and impulse control.

Gambling symptom severity will be measured by the Gambling Symptom Assessment Scale (G-SAS). The total score of G-SAS ranges from 0 to 48, in which higher scores mean more severe gambling-related symptoms.

Risky decision-making performance will be assessed using the Balloon Analogue Risk Task (BART). Higher average pumps in the BART indicate greater risk-taking propensity. Electroencephalography (EEG) will be used to measure neural electrical signals, where increases in relevant electrophysiological indicators may reflect heightened individual sensitivity to negative feedback.

Pig dice game will be administered during functional magnetic resonance imaging (fMRI) scanning to assess risk-taking decision-making. Higher frequency of continued dice rolls indicates greater risk propensity. Neural activity features related to the task will be analyzed, with specific patterns associated with risk evaluation and reward processing.

The stop-signal task (SST) will be employed to measure inhibitory control, with longer stop-signal reaction times (SSRT) indicating poorer response inhibition. Concurrent EEG recording will be performed, and changes in relevant electrophysiological indicators can serve as electrophysiological markers of increased cognitive conflict and reduced inhibitory processing efficiency.

Resting-state functional magnetic resonance imaging (rsfMRI) will be used to assess intrinsic brain connectivity. Resting-state electroencephalography (rsEEG) will be employed to measure spontaneous neural oscillations.

Structural magnetic resonance imaging (sMRI) with T1-weighted imaging, along with diffusion tensor imaging (DTI), will be employed to construct individualized head models for simulating the electric field distribution of HI-tACS. This approach will allow us to estimate the individualized stimulation intensity and assess the optimal dose for each participant.

SPICE fast spectroscopic imaging will be employed to measure molecular-level neurochemical metabolites. This technique enables simultaneous acquisition of spatial distribution and concentration changes of multiple metabolites and neurotransmitter-related indicators within a single clinically acceptable scan time, allowing for assessment of brain molecular metabolic spectrum remodeling before and after the intervention.