Increased delta connectivity within brain networks as a biomarker of adherence to a rTMS-based treatment program in a sample of cocaine use disorder patients

Objective: We have investigated the association between the adherence to a repetitive transcranial magnetic stimulation (rTMS)-based treatment program and resting-state (RS) functional connectivity within two large-scale networks [i.e., the Frontoparietal Network (FPN) and the Default Mode Network (DMN)] in a sample of patients with cocaine use disorder (CUD; N= 33, 32 males). Method: Each participant underwent a psychopathological assessment and a RS electroencephalography (EEG) recording before starting the treatment protocol. EEG connectivity analysis was performed using the exact Low-Resolution Brain Electromagnetic Tomography (eLORETA) software comparing dropout patients (i.e., treatment program abandonment within 3 months) and adherence patients. Results: Compared to dropout group, the adherence group showed increased pre-treatment delta connectivity within the FPN (T= 4.562, p= 0.010, Cohen's d= 0.819) and the DMN (T= 4.045, p= 0.036, Cohen's d= 0.726). Multivariable Cox proportional hazard models showed that both DMN (HR= 0.41, p= 0.015) and FPN connectivity data (HR= 0.54, p= 0.007) were significantly related to prolonged treatment adherence. Increased functional connectivity within the FPN decreased the probability of dropout before the first 12 weeks of treatment (OR= 0.36, p= 0.019). Conclusions: Our results may reflect enhanced goal-driven cognitive integration in adherence patients. Providing effective neurophysiological predictors of treatment outcomes, such as relapse and dropout, could allow the timely implementation of additional support measures for CUD patients.