Monday, May 20, 2013

What Causes Depression?

Table of Contents

Causes


The causes of depression are not fully known. Most likely a combination of genetic, biologic, and environmental factors play a role.

Genetic Factors

Because depression often runs in families, it appears that a genetic component is involved. Studies have found that close relatives of patients with depression are two to six times more likely to develop the condition than individuals without a family history.

Biologic Factors

The basic biologic causes of depression are strongly linked to abnormalities in the delivery of certain key neurotransmitters (chemical messengers in the brain). These neurotransmitters include:

  • Serotonin. Perhaps the most important neurotransmitter in depression is serotonin. Among other functions, it is important for feelings of well being. Imbalances in the brain’s serotonin levels can trigger depression and other mood disorders.
  • Other Neurotransmitters. Other neurotransmitters possibly involved in depression include acetylcholine and catecholamines, a group of neurotransmitters that consists of dopamine, norepinephrine, and epinephrine (also called adrenaline). Corticotropin-releasing factor (CRF), a stress hormone and neurotransmitter, may be involved in depression and anxiety disorders.
Endocrine glands
Endocrine glands release hormones into the bloodstream that are transported to various organs and tissues throughout the body. For instance, the pancreas secretes insulin, which allows the body to regulate levels of sugar in the blood. The thyroid gets instructions from the pituitary gland to secrete hormones that determine the pace of chemical activity in the body. The more thyroid hormone in the bloodstream, the faster the chemical activity; the less hormone, the slower the metabolism.

The degree to which these chemical messengers are disturbed may be affected by other factors such as genetic susceptibility.

Reproductive Hormones. In women, the female hormones estrogen and progesterone may play a role in depression.

Environmental Factors

Medications. Many prescription drugs can affect brain chemicals and trigger depression. These medications include certain types of drugs used for acne, high blood pressure, contraception, Parkinson’s disease, inflammation, gastrointestinal relief, and other conditions.


Review Date: 01/27/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)