Why are certain people more susceptible to depression?
Women are clearly at greater risk for developing depression than men. This may be due to two factors. First, women are physiologically different, which may explain some of the variance. More importantly, women are psychologically different, and this psychology is shaped by both their different physiology and the different cultural expectations placed on them. They are expected to express their feelings more, and it is more socially acceptable for them to admit to being depressed, although formal studies have demonstrated that men and women are equally likely to report their depressive symptoms. Depression often leads to withdrawal, which can be interpreted as passivity in women, which is also more culturally acceptable. Withdrawal in men is generally interpreted as a sign of weakness. When men withdraw they usually describe it as a choice without any change in mood. Thus it is interpreted more as an independent act and is recharacterized in more socially acceptable terms such as stoicism. Social factors likely play a large roll in the higher rates of depression in women as well (see Question 80).
Certain ethnic groups are more susceptible. A correlation appears to exist between latitude and susceptibility to depression. Northern Europeans are the most susceptible, with Scandinavians suffering from the highest rates and Mediterraneans suffering from the lowest rates. Certain races also appear to be more susceptible, with whites suffering greater rates than blacks. Recently, a cultural shift has occurred in Japan as a result of the introduction of safe and effective antidepressants used to treat milder forms of depression. Because Buddhism has heavily influenced Japanese society, the notion that life is filled primarily with suffering has been the accepted paradigm. In contrast, Western culture tends to be more positive and hopeful. Thus feeling sad about one's lot in life in Japan was considered the norm, whereas in Western culture it is considered abnormal. As Japan has become more Westernized and Buddhism less valued, the notion of treatable depression has become more accepted.
Obesity plays a role in the development of depression, counteracting the myth of Falstaff or "Jolly Old St. Nick." Studies are beginning to demonstrate that significant weight loss in patients with clinical obesity can lead to remission of their depression. Depression appears to be linked with obesity in a manner similar to hypertension, heart disease, sleep apnea, joint pain, and diabetes. There may be some correlation with obesity, female gender, and suffering higher rates of depression. Females have, on average, higher percentages of body fat than males, and body fat has higher estrogen levels, the hormone involved in female development.
Certain personality styles are more susceptible to depression, with shy, reserved, or dependent people at higher risk than outgoing, sociable, or independent people. This is truer for males than females, again because being shy, reserved, or dependent is more culturally acceptable in females than males. Body fat and personality style have a significant biologic basis, although both are clearly shaped by environmental factors.
I have recently been diagnosed with depression. What are the risks that my children will inherit it?
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 nondepressed 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.
-  immediate biologically related family member, such as biologic parents or full siblings.
-  a scientific study designed to control for genetic relatedness and environmental influences by comparing siblings adopted into different families.
-  in genetics, a similarity in a twin pair with respect to presence or absence of illness.
-  a ratio of incidence of a disorder in persons exposed to a risk factor to the incidence of a disorder in persons not exposed to the same risk factor.