Which mental health condition is characterized by periods of hypomania and depressive episodes lasting at least two years?

The mental health condition characterized by periods of hypomania and depressive episodes lasting at least two years is cyclothymic disorder. This disorder involves chronic mood fluctuations where individuals experience numerous periods of hypomanic symptoms, which are less severe than those seen in full manic episodes, along with periods of depressive symptoms that do not meet the criteria for a major depressive episode.

For a diagnosis of cyclothymic disorder, these symptoms must persist for at least two years in adults (or one year in children and adolescents), indicating a long-standing pattern of mood instability rather than acute episodes. This distinguishes cyclothymic disorder from other mood disorders that may involve hypomanic or depressive episodes, but do not have the same duration or continuity.

In contrast, major depressive disorder is defined primarily by episodes of significant depression without the hypomanic phases. Bipolar I disorder requires the presence of at least one manic episode, while Bipolar II disorder is characterized by at least one major depressive episode and one hypomanic episode, but does not include the chronicity and mildness of symptoms seen in cyclothymic disorder. Thus, the specific time frame and types of mood symptoms present support the classification of cyclothymic disorder as the correct answer