Sept. 15, 2000 — Researchers may be a step closer to understanding the biological underpinnings of depression. A new study finds that in children at high risk for depression, the body’s response to a growth hormone stimulation test may predict which of those kids will later go on to develop depression.
The high-risk group in the study had a “significantly decreased release of growth hormone” when stimulated by another hormone that prompts the release, says study author Boris Birmaher, MD, associate professor of psychiatry at the University of Pittsburgh Medical School.
Birmaher’s hope, he tells WebMD, is that the study will help convince the public at large — including school and insurance company officials — “that depression is indeed a biological illness, at least in part, as is diabetes … so that schools will realize it’s not that he’s lazy or that parents are bad parents, [but] that this is something that runs in families. You’re not going to tell a parent that he’s a bad parent because the kid has diabetes. This will help people to address this illness as any other illness and treat it.”
The study, published in the latest issue of the Archives of General Psychiatry, focused on 119 children and adolescents between 8 and 16 years old. Sixty-four of the children were considered at high risk for major depressive disorder because of family history. Another 50 children were at low risk for depression because of no depressive disorders in their family.
In the study, the children were given injections of a substance called growth hormone-releasing hormone, which naturally stimulates the release of growth hormone. Injections were given at intervals during the daytime and night; then the children’s growth hormone levels were measured. Researchers found “markedly less” levels of growth hormone in the high-risk children, says Birmaher.
This does not mean that children are developing abnormally, Birmaher hastens to add. “All children in the study were secreting normal amounts of growth hormone and were growing completely normally. But in tests that stimulate the response, their levels were lower. This is what is important here.”
Previous studies have shown that children and adults secrete less growth hormone after they have had major depression. “We wanted to know if this exists before they develop depression. This means that a low secretion of growth hormone after stimulation exists before, during, and after depression. That’s what we call a true biological marker,” Birmaher tells WebMD.
Whether this will become a test for depression, Birmaher tells WebMD, “it’s too early to say. We’re going to follow these kids over time and see how many with low growth hormone response become depressed. Only then will we talk about whether this is a good test or not. Our objective was not to create a test, but to understand the mechanisms of depression in kids. Now we’re studying the mechanisms of why these kids are secreting less growth hormone. Then we will be able to understand the biology of depression in kids.
“Family history is still the most important risk factor in diagnosing depression,” says Birmaher. However, he adds, “Even with family history, your kids can be affected or not; you don’t know. It’s the same with diabetes. It would be good to know who is definitely at risk.”
Similar findings — reduced growth hormone response — have also been shown with panic disorder and social phobia, Ronald Pies, MD, clinical professor of psychiatry at Tufts University School of Medicine, tells WebMD. In this study, researchers “haven’t shown that this is specific for mood disorders. … If people think this is a highly specific test for depression, they would be way off base.” Pies is a medical adviser for WebMD.
In fact, “Over the years, a lot of biological markers have shown an association with depression: elevated [blood] cortisol and abnormal thyroid function,” says Pies. He tells WebMD a careful personal and family history remains the best diagnostic tool for depressive disorder.