Rate and significance of hypomanic switches in unipolar melancholic depression

Summary One hundred and sixteen patients with RDC unipolar recurrent depressive disorder, melancholic subtype, were treated with imipramine or phenelzine and followed-up for six months. None of the patients had a first-degree relative with bipolar I disorder. Twenty-six patients (22.4%) presented an hypomanic episode (‘hypomanic group’). This group of patients, when depressed, had a significantly lower age of onset of the disorder and higher response to antidepressant therapy than patients who did not present an hypomanic episode. Significantly more patients (88%) of the ‘hypomanic group’ had at least one first-degree relative with a history of major depressive disorder. These patients displayed some of the typical features of bipolar II disorder. Overall results support the continuum in clinical phenomena between unipolar and bipolar disorders.