How Genetics Can Factor Into Depression

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No one knows exactly what causes it, but depression does appear to have a genetic component. While your genetic makeup can certainly factor into whether or not you end up with depression, this only means that you are potentially more susceptible to developing depression, not that you necessarily will.

How Genetics Factor Into Depression

First-degree relatives, that is, parents, siblings, and children, of people with major depression have been found to have a two to three times higher prevalence of major depression than their normal counterparts.

Twin studies, which look at how frequently pairs of twins have the same trait, also provide evidence of a genetic link. Pairs of fraternal (non-identical) twins were found to have major depression at a rate of 20%. However, with pairs of identical twins, which means they share the same genetic material, the rate rose to about 50%.

Thus far, no genetic studies have identified what specific genes are associated with major depression. It is likely that major depression is a genetically complex condition involving multiple genes and possibly multiple modes of inheritance.

Other Causes of Depression

Genetics are not the only potential cause of depression. Other factors may include:

  • Brain chemistry. People who are depressed seem to have lower levels and decreased functioning of neurotransmitters, which are the chemicals in the brain that affect mood and well-being.
  • Different brain structure. Studies have shown that people with depression may have physical differences in their brains. Research is still being done on this.
  • Hormones. When hormones are out of whack for reasons like pregnancy, thyroid conditions or menopause, this can trigger depression, particularly in people who are already susceptible.
  • Extreme stress. Some people develop what's called situational depression, also known as adjustment disorder with depressed mood, in response to a highly stressful situation or trauma. 

Any of these factors can be exacerbated by a genetic predisposition to depression, but conversely, someone who has no genetic predisposition to depression can still develop it as well.


Depressive symptoms may vary from person to person, but in general, to be officially diagnosed with major depressive disorder, you must have five or more of these symptoms and have been experiencing them for at least two weeks:

  • Loss of pleasure in activities you once enjoyed
  • Eating more or less than you used to, which may include weight loss or gain
  • Feeling fatigued and/or lacking energy
  • Either sleeping too much or too little
  • Feeling hopeless, worthless, and/or guilty
  • Thoughts of suicide or death
  • Feeling sad, anxious or upset often
  • Being irritable and/or restless
  • Physical symptoms, such as headache or stomachache


Depression is typically treated with medication, psychotherapy, or a combination of the two. It can take some time to figure out the best treatment plan for each person, so try to be patient if you have recently been diagnosed with depression. Make sure to keep an open line of communication with your mental health professional as far as any side effects you may be experiencing, as well as other medications, vitamins or herbs that you are taking that could interfere with your depression medication.

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Article Sources

  • "Depression (major depressive disorder)." Mayo Clinic (2015).
  • Moore, David P., and James W. Jefferson. Handbook of Medical Psychiatry. 2nd Ed. Philadelphia: Mosby, Inc., 2004.
  • U.S. Department of Health and Human Services, National Institutes of Health, National Institute of Mental Health. (2015). Depression (NIH Publication No. 15-3561). Bethesda, MD: U.S. Government Printing Office.