What does "unipolar" refer to in psychological terms?

In psychological terms, "unipolar" specifically refers to a condition that is characterized by one phase of mood disturbance, which can be either manic or depressive, but not both. In the context of mood disorders, unipolar depression denotes a state where an individual experiences episodes of depression without the occurrence of manic episodes. This is distinct from bipolar disorder, in which an individual experiences alternating phases of depression and mania.

The term "unipolar" is used to highlight this absence of manic episodes, emphasizing that the individual is functioning within a single mood spectrum. This differentiates it from conditions where both depressive and manic episodes are present, as seen in bipolar disorders. Therefore, the understanding of "unipolar" is crucial as it shapes the treatment approaches and diagnostic criteria associated with mood disorders.