It's like sitting under a cloud when everyone else is in the sun. Or watching a movie in black and white when all your friends are seeing color. Depression takes the pleasure out of life and interferes with living. It jeopardizes jobs, marriages and parenting and can lead to suicide or illness.
Because about twice as many women as men suffer from depression, most studies of the disorder's inheritance have focused on women. Researchers in St. Louis, Chicago and Australia now have studied depression in a community sample of 2,662 pairs of same-gender and mixed-gender twins. Stressful events such as the death of a spouse or loss of a job were the major causes of depression in both the men and the women, they found. However, genetic factors were more likely to have contributed to depression in the women than in the men. Surprisingly, this appeared to be true for mild as well as severe depression.
"So women who are related to a person with major depression seem to be more vulnerable to developing depression themselves than men who come from a family with depression," says Laura J. Bierut, M.D., assistant professor of psychiatry at Washington University School of Medicine in St. Louis. "And the transmission of depression appears to be due to the genes a family shares rather than to the family environment. It's not that a mother who is depressed teaches a daughter how to be depressed."
Bierut was lead author of the report, which appeared in the June 1999 issue of Archives of General Psychiatry. Grants from the National Institutes of Health, the U.S. Public Health Service and the Australian National Health and Medical Research Council funded the research.
Studying the incidence of a disorder in twins is one way to tease out genetic factors from environmental influences. Genes are likely to play a role if a disorder occurs more often in both members of identical twins, who have the same genes, than in both members of frater
Contact: Linda Sage
Washington University in St. Louis