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Depression

Depression is a topic covered in the 5-Minute Clinical Consult.

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Basics

Description

  • A primary mood disorder characterized by a sustained feeling of sadness and/or decreased interest in all or most activities once enjoyed (anhedonia), which represents a change from previous functioning
  • Variants: disruptive mood dysregulation disorder, major depressive disorder (MDD), persistent depressive disorder (dysthymia), premenstrual dysphoric disorder, substance/medication-induced depressive disorder, depressive disorder due to another medical condition, other specified depressive disorder, unspecified depressive disorder

Epidemiology

Incidence
In United States, 6.9% of 18 years of age or older in past year


Prevalence
  • 16.2% lifetime risk of having MDD
  • Patients can relapse; risk decreases with longer remission period but increases in patients with severe episodes, episodes at a younger age, and multiple episodes.
  • Predominant age
    • Low risk before early teens but highest prevalence in teens and young adults
  • Predominant gender
    • Females > males (2:1)

Etiology and Pathophysiology

There are diverse theories on the pathophysiology of depression.

  • Monoamine-deficiency hypothesis: symptoms related to decreased levels of norepinephrine (dullness and lethargy) and serotonin (irritability, hostility, and suicidal ideation) in multiple regions of the brain; other neurotransmitters involved include dopamine, acetylcholine, γ-aminobutyric acid (GABA), glutamate.
  • Stress/hypothalamic–pituitary–adrenal axis: Abnormalities in cortisol response lead to depression; elevated cortisol levels can be associated with depression, but cortisol tests are not indicated for diagnosis.
  • Depression as inflammatory disorder: Proinflammatory marker levels are reported to be elevated in depressed patients. Examples of these markers are C-reactive protein (CRP), interleukin (IL)-6, IL-1, and tumor necrosis factor-α (TNF-α).
  • Hormones and depression: Reduction in thyroid hormone, estrogen levels, and elevation in vasopressin has been seen in people with depression.
  • Other areas of research interest: abnormal circadian rhythms; impaired synthesis/metabolism of neurotransmitters
  • Environmental factors and learned behavior may affect neurotransmitters and/or have an independent influence on depression.

Genetics
Multiple gene loci place a person at increased risk when faced with environmental stressor; twin studies suggest 37% concordance (1).

Risk Factors

  • Female > male (2:1)
  • Severity of first episode
  • Persistent sleep disturbances
  • Presence of chronic disease(s), recent myocardial infarction (MI), cardiovascular accident (CVA)
  • Strong family history (depression, bipolar, suicide, substance abuse), spouse with depression
  • Childhood trauma/maltreatment
  • Substance abuse and dependence, domestic abuse/violence
  • Losses, stressors, unemployment
  • Single, divorced, or unhappily married

Commonly Associated Conditions

  • Bipolar disorder, cyclothymic disorder, grief reaction, anxiety disorders, somatoform disorders, schizophrenia/schizoaffective disorders
  • Medical comorbidity
  • Substance abuse

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Citation

Stephens, Mark B., et al., editors. "Depression." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116171/all/Depression.
Depression. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116171/all/Depression. Accessed April 24, 2019.
Depression. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116171/all/Depression
Depression [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 April 24]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116171/all/Depression.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - Depression ID - 116171 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116171/all/Depression PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -