The purpose of this study was to investigate the reliability and validity of the bipolar index (BPX) to diagnosis bipolar disorder, and to verify the stability of it in identifying bipolar disorder; the secondary purpose was to understand the dynamic changes of bipolar disorder in natural status.

Inclusion Criteria:

1. Age 18-65 years old；
2. Be able to understand the content of assessment and cooperate；
3. Currently patients are depressive episode, and / or manic / hypomanic episode, also can be mood stable；
4. Currently according to diagnostic criteria of the U.S Diagnostic and Statistical Manual Fourth Edition of Mental Disease (DSM-IV) of bipolar disorder (Type I, II, rapid cycling, mixed episodes)；
5. Currently according to diagnostic criteria of the U.S Diagnostic and Statistical Manual Fourth Edition of Mental Disease (DSM-IV) of depressive disorder；
6. No other mental illness or a history of physical disease，or patients with physical disease;
7. Not received modified ECT at least four weeks or more before entering the group.

Exclusion Criteria:

1. Can not understand the content of assessment and cooperate；
2. Meet the diagnosis criteria of schizophrenia and other psychotic disorders;
3. Meet the diagnosis criteria of Diagnosis of mental retardation or pervasive developmental disorder;
4. Clinically significant neurological disease or loss of consciousness more than one hour of traumatic brain injury；

The cases were selected from the Sixth Hospital of Peking University and other eight hospitals, and they must meet the diagnosis inclusion criteria of un-bipolar and bipolar disorders. The control group of non-mood disorders will be selected from heathy population who met the following inclusion criteria of healthy controls. Informed consent must be obtained.