Altered long-range temporal correlations in delta oscillatory amplitude dynamics in gambling disorder.

Understanding the neural oscillations underlying gambling disorder (GD) is essential for developing effective prevention and treatment strategies. While the spatial coordination of neural activity in GD patients has been extensively studied, the temporal dynamics of neural activity have not yet been investigated. In this study, we aim to investigate the long-range temporal correlations (LRTC) of the instantaneous amplitude of resting-state Electroencephalography (EEG) in GD patients. EEG activity was recorded during eyes-closed wakeful rest in 87 patients with GD and 40 age-, gender-, and education-matched healthy controls. LRTC in amplitude fluctuations was quantified using detrended fluctuation analysis (DFA) to estimate Hurst exponents across delta (1-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), and gamma (30-45 Hz) frequency bands. Participants also completed measures of impulsivity and gambling severity. Group differences were assessed using parametric or non-parametric statistical tests, depending on data distribution. Compared with healthy controls, the GD group exhibited significantly higher LRTC in the delta band over middle-frontal and parietal regions (p < .001, rank-biserial correlation = 0.44), whereas no significant group differences were observed in the theta, alpha, beta, or gamma bands. Additionally, GD participants also showed higher scores on the "motor impulsivity" construct of impulsivity (p < .001, Cohen's d = 1.35), which was positively associated with higher LRTC in the delta band in the GD group (p = .034). These increased LRTC in the delta band effectively differentiated individuals with GD from healthy controls (p < .001). We identified disrupted temporal correlations in the brain networks of GD patients, suggesting that elevated delta-band LRTC may represent a candidate electrophysiological marker warranting further replication and longitudinal validation.