Patients randomized to the medication therapy group will receive standardized treatment with antidepressant medications according to clinical guidelines.

The participants will receive standardized IPT treatment for 12 weeks. IPT therapists have received training from IPT workshops in both China and the United States and obtained the corresponding certifications. IPT therapists focus on the interpersonal domains associated with the onset and maintenance of depression. They guide clients in identifying the connections between their emotional changes and interpersonal difficulties, exploring problems, actively seeking potential interpersonal support and assistance, improving interpersonal skills, helping clients alleviate symptoms, enhance their quality of life, and adapt better to society.

Patients randomized to this group will receive standardized treatment with antidepressant medications according to clinical guidelines. The participants will also receive standardized IPT treatment for 12 weeks. IPT therapists have received training from IPT workshops in both China and the United States and obtained the corresponding certifications. IPT therapists focus on the interpersonal domains associated with the onset and maintenance of depression. They guide clients in identifying the connections between their emotional changes and interpersonal difficulties, exploring problems, actively seeking potential interpersonal support and assistance, improving interpersonal skills, helping clients alleviate symptoms, enhance their quality of life, and adapt better to society.

Patients will receive standardized treatment with antidepressant, and their treatment efficacy will be assessed by a blinded psychological assessor using validated rating scales. The assessment will be conducted monthly, and evaluations will be tracked for a period of three months.

The instrument used in this study is a 52-channel Near-Infrared Spectroscopy (fNIRS) brain imaging system. It indirectly calculates the relative changes in levels of oxygenated and deoxygenated hemoglobin in different brain regions by detecting two different wavelengths of near-infrared light (695 nanometers and 830 nanometers). These changes reflect alterations in brain function. The instrument primarily utilizes 17 optical emitters and 16 optical detectors to acquire data. The emitters and detectors are positioned 3.0 centimeters apart, and the measurement area between the probes is defined as a channel. The NIRS probes are arranged in a 3×11 matrix, forming 52 measurement channels. Following the international 10-20 system, the lowest channel is aligned with the Fp1-Fp2 line. The probe coverage of this instrument allows for the measurement of relative changes in oxygenated and deoxygenated hemoglobin signals in bilateral frontal and temporal cortical regions.

The Hamilton Depression Scale (24-items) (HAM-D24), is a 24 item diagnostic questionnaire used to measure the severity of depressive episodes in patients with mood disorders. Higher HAM-D24 score indicates more severe depression, and each item yields a score of 0 to 4.

Remission is defined as HAM-D24 ≤8.

The Patient Health Questionnaire-9 (PHQ-9) is a screening tool used to assess symptoms of depression. It consists of nine questions that are designed to measure the severity of depressive symptoms experienced by an individual. Each question corresponds to one of the nine criteria for major depressive disorder as outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Each question is scored on a scale from 0 to 3, with higher scores indicating greater severity of symptoms. The total score ranges from 0 to 27, with higher scores indicating a higher likelihood of clinical depression. The PHQ-9 is widely used in both clinical and research settings to assess the presence and severity of depressive symptoms, monitor treatment progress, and aid in the diagnosis of depression.

THINC-it is a computerized cognitive screening tool that is designed to assess cognitive function in adults. THINC-it stands for "THINking Clearly," and it includes a series of brief tests that evaluate several cognitive domains, including attention, working memory, executive function, and processing speed. The tool is administered on a tablet or computer, and it takes approximately 20 minutes to complete.