<unk>  is often considered to be a biologically based and particularly severe form of depression. Treatment involves antidepressants, electroconvulsive therapy, or other empirically supported treatments such as cognitive behavioral therapy and interpersonal therapy for depression. A 2008 analysis of a large study of patients with unipolar major depression found a rate of 23.5% for<unk>  features. It was the first form of depression extensively studied, and many of the early symptom checklists for depression reflect this.
Melancholic depression
Collective depression
Masked depression
Double depression
Depression 
Psychotic depression
Retarded depression
Late life depression