there is some cognitive impairment in patients with unipolar and bipolar depression. There is no unified conclusion in the field and severity of cognitive impairment, and the cause of cognitive impairment is unknown, which may be related to many factors. The THINC-it is a simple, fast and free cognitive assessment tool for cognitive impairment screening of unipolar and bipolar depression.~This study includes three steps.~baseline: demographic data, theTHINC-it tool , clinical scales（HAMD-17,HAMA、YMRS、PSQI） evaluation and Laboratory examination（blood glucose, blood lipids, BMI）~follow-up (4 week): Clinical scales and THINC-it tool were evaluated in unipolar and bipolar depression.~follow-up (12 weeks): all patients with bipolar depression were evaluated by clinical scales, THINC-it test.
Cognitive impairment is the core symptom of unipolar and bipolar depression, which seriously affects the prognosis of the disease and the rehabilitation of social function. There is no unified conclusion in the field and severity of cognitive impairment, and the cause of cognitive impairment is unknown, which may be related to many factors. In this study,the THINC-it tool was used to study the characteristics of cognitive impairment in unipolar and bipolar depression by longitudinal follow-up, which provides a theoretical basis for the differential diagnosis of unipolar and bipolar depression. Early identification and intervention of risk factors can improve the prognosis of the disease.