Depression

BASICS

DESCRIPTION

Primary mood disorder characterized by a sustained feeling of sadness and/or decreased interest in all or most activities once enjoyed, which represents a change from previous state.

EPIDEMIOLOGY

Prevalence

Lifetime prevalence of major depressive disorder (MDD) is 20.6% (1).
Low risk before early teens; highest prevalence in teens and young adults; average age of onset is 30 years.

ETIOLOGY AND PATHOPHYSIOLOGY

Pathophysiology is poorly understood.

Genetics

Twin studies suggest 37% concordance.

RISK FACTORS

Female > male (2:1)
Adverse life events (2)
First-degree relative or spouse with depression, bipolar, suicide, substance abuse
Presence of comorbid medical conditions including neurodegenerative diseases

GENERAL PREVENTION

Physical activity lowers risk for depression (3).

COMMONLY ASSOCIATED CONDITIONS

Bipolar disorder, cyclothymic disorder, grief reaction, anxiety disorders, somatoform disorders, schizophrenia/schizoaffective disorders, conduct disorder, substance abuse

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