Current research on the pathogenesis of depression shows that imbalanced inflammatory factors are closely related to Major Depressive Disorder(MDD). As reported, physical exercise, Ω-3 fatty acids, and sulforaphane can be complementary therapies for moderate-to-severe depression. In addition, imaging studies have found changes in the structure and functional connectivity of the brain. Therefore, this study intends to collect clinical and biological information from patients with depression and healthy controls to establish a multi-factor model for early warning and diagnosis of major depressive disorder

The immune imbalance has been reported in patients with unipolar and bipolar depression. There is no unified conclusion in the field and severity of the immune imbalance, and the cause of cognitive impairment is unknown, which may be related to many factors. Omega-3 fatty acids are immune modulators that possess antidepressant effects.

This study includes three steps.

1. We will enroll bipolar and major depressive disorder patients who are in a depressive episode and enroll healthy controls. All subjects will be assessed at baseline
2. We will give omega-fatty acid treatment based on immune indicators
3. The follow-up will last for one year with five sessions.

Inclusion Criteria:

• Outpatients in main-center and sub-centers
• Age between 18-65 years old
• Meet the DSM-IV diagnosis of depressive episode
• HAMD-17 score>17 at baseline
• No antidepressant treatment within 6 weeks prior to enrollment
• Adequate cognition level to complete the tests necessary for the study
• Willing to sign the informed consent form

Exclusion Criteria:

• Have any contraindications to Ω-3 fatty acids
• Severe physical disease
• Diagnosed with schizophrenia, or other mental illness spectra
• Have received physical therapy