WEDNESDAY, May 29, 2002 (HealthDayNews) -- People who suffer from depression have persistent problems with an important brain chemical called serotonin, even when they're not depressed.
These people have sluggish and inefficient serotonin systems compared to people who don't have a history of depression, say University of North Carolina researchers in a new study published in the May issue of the journal Neuropsychopharmacology.
The finding offers strong evidence that depression has genetic causes, the researchers say.
Serotonin is one of the body's most important neurotransmitters, helping regulate many emotional and physiologic functions that are disrupted when a person suffers from depression.
The study included 20 depressed people and a control group of depression-free people. The researchers looked at differences between the two groups by doing a "serotonin challenge." They measured hormones released by the pituitary gland when the test volunteers were given a special medicine.
The test was repeated after the depressed people completed therapy. Even in remission, the people with a history of depression had a blunted hormonal response. The researchers are now trying to identify specific genetic parts of the serotonin system that may account for the findings.
Depression affects about 10 percent of Americans at some point in their lives. It can be triggered by upsetting events, such as the death of a loved one, loss of a job, or stress.
More information
To learn more about serotonin, visit California State University, Chico. New York University School of Medicine offers an online depression screening test.
