Suicide is a major health problem that causes annually a million death worldwide. Loneliness is known to be associated with suicidal ideation in minors and to be related with suicidal risk in elderly people. However little is known about this association in a middle-aged population. Loneliness is a modifiable factor with suitable psychotherapeutic measures, it is essential to improve the scientific and medical knowledge about the link between this feeling and suicide risk in a population of depressed patients in middle age.

The main objective is the study of the relationship between loneliness and the occurrence of suicidal behavior (SB) in major depressed adult population over 12 months.

The secondary objectives are:

• Identification of risk factors (clinical, neuropsychological and biological) of the occurrence of SB within a clinical population and their interaction;
• Identification of predictive factors (clinical, neuropsychological, biological) therapeutic response to antidepressant in the context of depression.

This project is based on clinical, neuropsychological and biological data routinely collected in the Department of Emergency Psychiatry and Post Acute Care. This is a one year follow-up prospective study.

Over three years, 600 depressed patients will be recruited.

• First visit (inclusion): clinical, biological and neuropsychological assessment
• Follow up visits (3, 6 and 12 months): clinical assessment only

Inclusion criteria:

Main diagnosis of major depressive disorder according to Diagnostic and Statistical Manual of Mental DisordersIV (DSM IV) Having signed informed consent Able to understand nature, aims, and methodology oh the study

Exclusion criteria:

Participation in another clinical trial Patient on protective measures (guardianship or trusteeship)