Study of tDCS Intervention on Motivational Anhedonia of Major Depressive Disorder

All patients underwent a medical evaluation that included physical examination and routine laboratory studies before and after transcranial direct current stimulation (tDCS) treatment. Patients were randomly allocated to real group , sham group or control group. A threshold of 3 points on the Hamilton Depression scale has been specified by the National Institute for Health and Care Excellence to determine a clinically meaningful difference between active pharmacotherapy and placebo. We plan to enroll minimum total sample size of 37 participants in real, sham or control group respectively according to the Power and Sample Size program. The decision to enroll a patient was always made prior to randomization. The tDCS administrators had access to the randomization list. They had minimal contact with the patients, and no role in assessing depression. Each patient would be treated for continuous 14 days by tDCS in real and sham group. The control group was evaluated by clinical symptom scale, behavioral evaluation before and after 14 days.

Before the tDCS treatment, depression symptom of each participant was assessed by the Hamilton Depression Scale and the Beck Depression Self-Rating Scale. The anhedonia severity was evaluated by The Temporal Experience of Pleasure Scale, the Self-Report Apathy Evaluation Scale, Dimensional Anhedonia Rating Scale, the Motivation and Pleasure Scale.The neuroimaging data was collected using event-related potentials during monetary incentive delay task. After the last treatment, the same scales and neuroimaging scan were used again to assess the treatment effect of the tDCS and the underlying brain mechanism. Each participant was interviewed in detail about the adverse event of the tDCS intervention during the past 14 days.Every participant should take part in the study in voluntary and sign an informed consent form before the study.