The essential feature of Cyclothymic Disorder is a chronic, fluctuating mood disturbance involving numerous periods of hypomanic symptoms and numerous periods of depressive symptoms (Criterion A). The hypomanic symptoms are of insufficient number, severity, pervasiveness, or duration to meet full criteria for a Manic Episode, and the depressive symptoms are of insufficient number, severity, pervasiveness, or duration to meet full criteria for a Major Depressive Episode. However, it is not necessary that any of the periods of hypomanic symptoms meet either the duration or symptom threshold criterion for a Hypomanic Episode.
During the 2-year period (1 year for children or adolescents), any symptom-free intervals last no longer than 2 months (Criterion B). The diagnosis of Cyclothymic Disorder is made only if the initial 2-year period of cyclothymic symptoms is free of Major Depressive, Manic, and Mixed Episodes (Criterion C). After the initial 2 years of the Cyclothymic Disorder, Manic or Mixed Episodes may be superimposed on the Cyclothymic Disorder, in which case both Cyclothymic Disorder and Bipolar I Disorder are diagnosed. Similarly, after the initial 2 years of Cyclothymic Disorder, Major Depressive Episodes may be superimposed on the Cyclothymic Disorder, in which case both Cyclothymic Disorder and Bipolar II Disorder are diagnosed.
The diagnosis is not made if the pattern of mood swings is better accounted for by Schizoaffective Disorder or is superimposed on a Psychotic Disorder, such as Schizophrenia, Schizophreniform Disorder, Delusional Disorder, or Psychotic Disorder Not Otherwise Specified (Criterion D), in which case the mood symptoms are considered to be associated features of the Psychotic Disorder. The mood disturbance must also not be due to the direct physiological effects of a substance (e.g., a drug of abuse, a medication) or a general medical condition (e.g., hyperthyroidism) (Criterion E). Although some people may fnction particularly well during some of the periods of hypomania, overall there must be clinically significant distress or impairment in social, occupational, or other important areas of functioning as a result of the mood disturbance (Criterion F).
The impairment may develop as a result of prolonged periods of cyclical, often unpredictable mood changes (e.g., the person may be regarded as temperamental, moody, unpredictable, inconsistent, or unreliable).