Introduction

The overlap between mood disorders and schizophrenia is a focus of interest in many aspects. Phenomenological and biological issues, including genetic and treatment issues, are the main areas of research in this overlap. One of the most important issues that might have potential clues to help us understand the secrets of the overlap is suicide.

It is well known that suicide is a common and dramatic outcome both in mood disorders and in schizophrenia. The risk for suicide in patients with mood disorders has been reported as significantly higher than in patients with other psychiatric disorders (Henriksson et al., 1993; Mortensen et al., 2000). Rates range from 30 to 70% for mood disorders among all suicides (Goodwin and Jamison, 1990; Tondo et al., 2003). Longitudinal follow-up studies of patients with mood disorders have given more dramatic results despite inconsistencies of the reported rates. There are analyses in literature which resulted in different directions: more suicidal risk for unipolar depressives compared to bipolar disorder patients (Harris and Barraclough, 1997) or vice versa (Rihmer and Kiss, 2002). Beyond the inconsistencies in rates, definitions of suicidal behavior, and differentiation of subtypes of mood disorders, it is obvious that suicidal behavior is the most important feature of these disorders.