Are People Born With Depression?

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While it is possible that people may be born with depression, the causes of this condition are believed to be a bit more complex than simply being born with it.  It is thought that depression is most likely caused by a combination of genetic, environmental and biological factors.

Genetic Factors

While no studies so far have been able to identify a specific gene or gene combination that is responsible for depression, there is evidence that such a link does exist.

  For example, those who have a close relative (parent, sibling or child) with major depression are about two to four times more likely to have depression than other people. In addition, twin studies have shown that if a fraternal (non-identical) twin has depression his or her twin has a 20 percent chance of also developing depression.  For identical twins, the risk is over 50 percent.  Finally, studies have also shown than people with certain inherited personality traits like neuroticism seem to be at greater risk for developing depression.  People with this type of personality are more likely to respond to stressful situations in a negative way and to interpret events as being threatening or hopeless.

Environmental Factors

Evidence also exists, however, which points to the role that environmental stressors can play in depression causation.  It has been shown that people who experience extremely stressful events during their childhoods - such as physical and/or sexual abuse or parental divorce - are more likely that other people to experience depression later in life.

  It is not understood why these early experiences could predispose people to depression, but it is thought that perhaps these experiences make their brains become more sensitive to stress. 

Current environmental stress - such as grief or marital conflicts - can also make an individual more prone to depression, perhaps by keeping the stress hormone cortisol chronically elevated.

  It is believed that cortisol has an influence on levels of the mood-regulating substance called serotonin.

Biological Factors

Finally, certain biological factors may play a role in causing depression.  For example, female sex hormones have been implicated in causing depression by possibly affecting the neurotransmitters which regulate mood, with women being about twice as likely as men to suffer from depression, especially at times when a woman's hormone levels are in flux, such as during menstruation, childbirth and perimenopause.  In addition, the hormone cortisol may impact serotonin levels, causing depression to occur during times of chronic stress.

Sources:

Espejo, E.P. et. al. "Stress sensitization and adolescent depressive severity as a function of childhood adversity: a link to anxiety disorders." Journal of Abnormal Child Psychology. 23.2 (2007): 287-99.

Heina, A., et. al. "Relationship between cortisol and serotonin metabolites and transporters in alcoholism (correction of alcolholism)." Pharmacopsychiatry 35.4 (2002):127-34.

Katz, Vern L. et. al., eds. Comprehensive Gynecology. 5th ed. Philadelphia: Mosby, 2007.

Moore, David P. and James W. Jefferson. Handbook of Medical Psychiatry. 2nd Ed. Philadelphia: Mosby, Inc., 2004.

Stern, Theodore A. et. al. eds. Massachusetts General Hospital Comprehensive Clinical Psychiatry. 1st ed. Philadelphia: Mosby Elsevier, 2008.

Tafet, G.E., et. al. "Correlation between cortisol level and serotonin uptake in patients with chronic stress and depression." Cognitive, Affective, & Behavioral Neuroscience 1.4 (2001) :388-393(6).

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