Researchers learned that depression is influenced by genetics by studying patterns of depression in twins and families. No single gene is thought responsible for determining the risk for developing depression. Instead, multiple genes are probably interacting to create what amounts to a genetic baseline level of risk. On top of that baseline, environmental factors are likely mixed in as well, things such as non-genetic physiological problems or psychological traumas.
Some 10 to 15 percent of people suffer from severe depression at some point in their lives, and 3 to 5 percent have it more than once. Women are twice as likely to develop depression as men, although the reason is not yet known.
"We don't think depression is entirely genetic, by any means, but there are important genetic factors," said Levinson. "If we can succeed in finding one or more genes in which there are specific DNA sequence variations that affect one's risk of depression, then we would be able to understand what type of gene is it, what it does in the brain and by what mechanism it could make one more or less predisposed to depression."
Knowing more about which genes are the major factors causing a predisposition for depression would also help researchers sort out the environmental factors that contribute to depression, Levinson said. And knowing more about either genetic or environmental factors could help in developing more effective therapies to treat depression. "The treatments we have now are lifesavers for some people, but there are others who have only a partial response or no response at all," he said. "Understanding the biology would help the search for better treatments."
The next phase of the consortium's research is already under way. This phase is an even more detailed lo
Source:Stanford University Medical Center