Melancholic depression is often considered to be a biologically based and particularly severe form of depression.[3] Treatment involves antidepressants, electroconvulsive therapy, or other empirically supported treatments such as cognitive behavioral therapy and interpersonal therapy for depression.[4] A 2008 analysis of a large study of patients with unipolar major depression found a rate of 23.5% for melancholic features.[3] It was the first form of depression extensively studied, and many of the early symptom checklists for depression reflect this.