ABSTRACT
Major depressive disorder (MDD) is among the most prevalent of medical ill-
nesses. Recent epidemiological studies have highlighted the similarity in preva-
lence rates of depression in different countries (Figure 1.1). For many patients,
depression is a chronic and recurrent illness. In follow-up studies, up to
30% of patients with MDD are still depressed after one year, 18% are ill after
two years and 12% remain ill after five years. Many patients treated for MDD
still have residual and subsyndromal symptoms that result in poor outcomes,
including higher risk for relapse and suicide, poor psychosocial function and
higher mortality from other medical diseases. Among patients who recover
from a depressive episode, over 50% will have a recurrence.
