Depression is a potentially life -threatening disorder that affects hundreds of millions of people all over the world. It can occur at any age from childhood to late life and is a tremendous cost to society as this disorder causes severe distress and disruption of life and, if left untreated, can be fatal. The psychopathological state involves a triad of symptoms with low or depressed mood, anhedonia, and low energy or fatigue. Other symptoms, such as sleep and psychomotor disturbances, feelings of guilt, low self-esteem, suicidal tendencies, Inhibitors,research,lifescience,medical as well as autonomic

and gastrointestinal disturbances, are also often present. Depression is not a homogeneous disorder, but a complex phenomenon, which has many subtypes and probably more than one etiology. It includes a predisposition to Inhibitors,research,lifescience,medical episodic and often progressive mood disturbances, differences in symptomatology ranging

from mild to severe symptoms with or without psychotic features, and interactions with other psychiatric and somatic disorders. Classification, prevalence, and course of depression At present, the NVP-AUY922 purchase essence of major depressive disorder is a clinical course that is characterized by one or more major depressive episodes without a history of manic, mixed, or hypomanic episodes, according to the criteria of the Diagnostic and Statistical Manual of Menial Health, Inhibitors,research,lifescience,medical Fourth Edition (DSM.-IV).1For an appropriate diagnosis, five of the following nine DSM-IVsymptoms must be present continuously for a minimum 2-week period: (i) depressed mood; (ii) loss of interest or pleasure; (iii) significant weight or appetite alteration; (iv) insomnia or Inhibitors,research,lifescience,medical hyposomnia; (v) psychomotor agitation or retardation; (vi) fatigue or loss of energy; (vii) feelings of worthlessness; (viii) diminished ability

to think or concentrate or indccisiveness; and (ix) suicidal ideation. Historically, there has been lengthy discussion on the basis and classification of depression. Two different concepts, Emil Kraepelin’s formulation of depression as a disease and Sigmund Freud’s view of depression as a manifestation of internalized anger and loss, were the two opposite points PD184352 (CI-1040) Inhibitors,research,lifescience,medical of view at the beginning of the 20th century. It was the merit of Sir Martin Roth and the Newcastle Group that contributed to the understanding of depression: they classified the clinical manifestations of depression (from mild to severe psychotic) in a categorical manner, separating them into distinct groups of “endogenous” and “reactive” subtypes of depression.2 This concept was used for decades in biological psychiatric research in order to identify etiologically different subtypes of the disorder. The recent editions of DSM-IV 1 and the International Statistical Classification of Diseases, 10th Revision (ICD-10) 3 follow the results from collaborative projects“-5 in the USA and the UK and distinguish unipolar (depression) from bipolar (manic depressive) disorder.