To compare the clinical efficacy of XingpiJieyu formula or its placebo combined with Escitalopram (ESC) in the treatment of moderate and severe MDD, and to explore a new method of integrated traditional Chinese and western medicine for the treatment of moderate and severe MDD with severe liver depression and spleen deficiency, as well as its neurological mechanism for regulating the relative power (RP) of resting-state EEG spectra.

MDD patients, especially severe MDD patients have heavy burden of disease, high risk of suicide, difficulty in single drug treatment, and poor compliance with combined western medicine treatment. It is urgent to explore new methods of integrated traditional Chinese and western medicine in the treatment of moderate and severe MDD to enhance efficacy and reduce toxicity. A double-blind, randomized, controlled Trial (RCT) was conducted to compare the efficacy of XingpiJieyu formula or its placebo combined with escitalopram in the treatment of MDD with severe liver depression and spleen deficiency. We aim to explore the clinical efficacy of XingpiJieyu formula combined with escitalopram and its possible multi-target neural mechanism.

Inclusion Criteria:

1. outpatient/inpatient, age 18-45 years old, right-handed;
2. western medical diagnosis meets the diagnostic criteria of MDD in DSM-5, without psychiatric features;
3. In accordance with the diagnostic criteria of depression and liver-stagnation and spleen-deficiency in the "Guidelines for Diagnosis and Treatment of Internal Diseases in Traditional Chinese Medicine" issued by the China Association of Chinese Medicine in 2008;
4. 17-item Hamilton Depression Scale score ≥18;
5. educational experience ≥5 years;
6. The current episode has not used antidepressants, antipsychotics, mood stabilizers, or other medications that can act on the central nervous system for at least 4 weeks;
7. Have not received physical therapy, such as MECT, rTMS, etc., in the past 6 months;
8. The total duration of the disease ≤10 years.

Exclusion Criteria:

1. Any current or previous mental disorder other than MDD according to DSM-5;
2. Diagnosis of syndromes other than depression and liver-stagnation and spleen-deficiency in the "Guidelines for Diagnosis and Treatment of Internal Diseases in Traditional Chinese Medicine" issued by the China Association of Chinese Medicine in 2008;
3. Suicidal ideation or suicidal behaviour (HAMD-17 item 3 > 2);
4. Drinking alcohol in the week prior to the enrollment;
5. Patients with neurological disorders, somatic disorders, organic brain diseases, and tumour;
6. Sleep disorders other than insomnia disorders currently diagnosed according to DSM-5, such as obstructive sleep apnea syndrome, periodic limb movement disorder, restless legs syndrome, etc.