I have recently been diagnosed with depression. What are the risks that my children will inherit it?
Anne’s comment: My husband has suffered from depression much of his adult life and has a history of depression in his family. We watched our children closely, as we were concerned about the possibility of an inherited predisposition to the illness. To date, two of our four children have been diagnosed with and are being treated for bipolar disorder. Many different studies have been conducted to examine the influence of genetics on the development of depression.
First-degree relatives of persons with major depression are two to three times more likely to have major depression than are the first-degree relatives of non-depressed persons. In adoption studies the biologic children of affected (depressed) parents remain at an increased risk for a mood disorder even when adopted by nonaffected (nondepressed) parents. Identical twins (who share 100% of genetic material) have concordance rates for depression of approximately 50%, and nonidentical twins have concordance rates of 10% to 25%. If depression were a strictly genetic illness, identical twins would both be affected.
This number, however, is significantly greater than the rate in nonidentical twins, thereby demonstrating that there is at least some genetic contribution to development of this disorder but also that environmental influences also have a role in precipitating a depressive episode.
Life circumstances, or environmental influences, often precipitate a depressive episode in affected individuals. Trauma, financial distress, death of a loved one, and relationship problems are some types of stressors that may be associated with development of depression. No matter how extreme, however, no specific environmental situation will cause a depressive episode in all persons. Therefore, environmental conditions alone are not usually sufficient to explain a depression. The specific event more typically will precipitate a depression in one who is vulnerable to its development at that time.
Putting together genetic and environmental factors as contributors to the onset of depression means that with a family history of depression, an individual has a higher relative risk than the general population for developing depression. In fact, the greater number of mood disorders that are present in a person’s family, the higher the risk becomes for development of depression. Stressful life events, specific environmental circumstances, or certain psychological processes may serve as a trigger of a depressive episode in someone with a genetic predisposition for the disorder.