Depression News:

Depressed Patients Have Persistent Serotonin System Abnormality

Depressed patients have a persistent serotonin system abnormality, according to researchers at the University of North Carolina at Chapel Hill.

Previous research has shown that depressed people show a weakened hormonal response to a test that boosts serotonin, a neurotransmitter chemical in the brain.

"This neuroendocrine challenge test, which involved giving depressed volunteer patients a medicine called clomipramine, indicated that depressed patients' serotonin systems were sluggish in response and not working efficiently," said Dr. Robert Golden, professor and chair of psychiatry at the UNC School of Medicine and author of the study. "An analogy I use is that their serotonin 'engine' needs a tune-up because they aren't getting much mileage out of the gas being burned."

New research is showing that people suffering from depression have the abnormality even when they are not depressed.

"We believe this work is an important step forward in our understanding of depression because it demonstrates an ongoing trait that distinguishes patients who have had the illness from the rest of the population," said Golden. "It is strong evidence that depression reflects a genetic trait, which clinicians have believed for a long time because depression tends to run in families."

Serotonin helps regulate many emotional and physiologic functions that are disturbed when people suffer from depression, said Golden.

In 20 patients with depression and a control group, researchers measured changes in the levels of prolactin and other hormones released by the pituitary gland in response to the serotonin challenge test. The goal was to find out if the abnormality was always present or detectable only when patients were depressed and disappeared like fevers do when infections end.

The patients were treated and were then tested again at the end of their initial acute therapy, at the end of a year and again a month after completing their treatment.

"To our surprise, in that medication-free state of remission, most of them still demonstrated a blunted hormonal response to serotonin challenge," reported Golden. "That means that even when they are well, their serotonin systems still do not work as efficiently as in people who don't have a history of depression. It may also mean that those patients with this persistent abnormality need to stay on medication longer."

Investigators are continuing their research to identify specific genetic components of the serotonin system that may account for their findings. They are also studying former depression patients and first-degree relatives to learn more about depression's genetic complexities.

Source: Depression Week of June 9, 2002