To investigate the intervention effect of high definition transcranial direct current stimulation (HD-tDCS) on somatic symptoms in patients with depressive disorder and its underlying neural mechanism by MRI.

Depressive disorder is a major public health and safety problem around the world. Patients with depression often performe symptoms such as anhedonia, lack of motivation, somatic symptoms, and even suicidal ideation and behavior. The purpose of this study was to study the relieving effect of high definition transcranial direct current stimulation (HD-tDCS) on the symptoms of depression.

60 patients with depressive disorder diagnosed by DSM-5 were recruited from the fourth people's Hospital of Hefei and the first affiliated Hospital of Anhui Medical University. All participants underwent a structured interview and routine laboratory examination before and after receiving HD-tDCS. After meeting the inclusion criteria and obtaining informed consent. Each participant will complete the clinical evaluation, functional magnetic resonance imaging (fMRI) and HD-tDCS treatment conducted by trained researchers at the Neuropsychological Synergetic Innovation Center of Anhui Medical University. All the participants were randomized (1:1) to receive "active" or "sham" treatment protocol. The anode was placed over Fz with return electrodes placed at Fpz, Cz, F3 and F4. Fourteen 2-mA sessions (ramp-up and ramp-down periods of 30 and 30 seconds, respectively) were applied for 20 minutes each day over 14 consecutive sessions. Sham HD-tDCS was delivered using the same protocol and current intensity, but the period of active stimulation was only during the ramp-up and ramp-down periods of 30 and 30 seconds.

Before and after the HD-tDCS treatment, the patients had receiving a battery measure of neuropsychological tests and Magnetic resonance imaging scan in multimodalities. Neuropsychological assessment included MoCA, Stroop Test, VFT, DST, AVLT, HAMD, HAMA, PHQ15, BSS(Beck scale for suicide ideation),ISI,SDS, RRS, TEPS, AES, FPQ, PVAQ and AAS. Multimodal fMRI includes 3D-T1, rs-fMRI, DTI and ASL.

Neuropsychological evaluation and magnetic resonance imaging data were obtained again 24 hours after the last treatment. The symptoms of the patients were followed up one month after the end of treatment.They were instructed to focus their answers on the past week. Afterwards, they were unblinded by the study coordinator.

Inclusion Criteria:

• the patients were diagnosed by more than 2 psychiatrists and met the diagnostic criteria of DSM-5 for depression, and HAMD>17, PHQ-15>5.
• the age ranged from 18 to 60 years old
• right-handed
• stable dose of medication for at least 4 weeks or no history of antidepressive drugs before intervention

Exclusion Criteria:

• accompanied by severe somatic diseases, such as severe heart, liver, renal insufficiency and so on.
• accompanied by other neurological diseases, such as stroke, epilepsy and so on.
• accompanied by other mental disorders, such as drug abuse, schizophrenia, schizophrenic affective disorder, hysteria, autism and so on.
• patients with MRI taboos or factors affecting imaging quality, such as cardiac pacemaker, cochlear implant, cardio-cerebrovascular metal stent, metal denture, etc.
• pregnancy and breastfeeding.
• previous physical treatment (electroconvulsive therapy or tDCS).