- patients suffering from major depression according to DSM-IV with a MADRS score of at least 25 and not treated by an antidepressant at the time of inclusion with the exception of non-responders to antidepressant for a period of at least 6 weeks or not tolerating an ongoing antidepressant necessitating a change of the antidepressant(excluding fluoxetine and irreversible MAOI)