Depression increases stress hormones in adolescent boys and girls, but can lead to excess weight only in girls, says a new study.

Early treatment of depression may help reduce stress and control obesity - a major health issue.

"This is the first time, cortisol reactivity was identified as a mediator between depressive mood and obesity in girls," said Elizabeth J. Susman, professor of bio-behavioral health at Penn State University (PSU).

"We have not really seen this connection in children before, but it tells us that biological risk factors, which are similar to obesity and depression," Susman added.

Cortisol, a hormone that regulates various metabolic functions in the body and is released in response to stress.

Researchers have long known that depression and cortisol are linked to obesity, but they had not mapped the precise biological mechanisms.

Although it is not clear why translate high cortisol responses in obesity for girls, scientists believe it could cope on physiological and behavioral differences - estrogen release and stress eating among girls - in the way of the two sexes are in fear.

"The effects are beginning to treat depression early, because we know that depression, cortisol and obesity in adults have to do," said Susman.

If depression were treated at an earlier time, she noted, they contribute to the levels of cortisol could, and thereby help to reduce obesity.

"We know that stress is a critical factor in many psychological and physical health problems," said Susman. "We shared the biology of stress, emotions, and a better understanding of clinical disease, a major public health problem."

Susman and colleagues Lorah D. Dorn, professor of pediatrics, Cincinnati Children's Hospital Medical Center and Samantha Dockray, Postdoctoral Fellow, University College London, uses a child behavior checklist to 111 boys and girls aged 8 to 13 for the symptoms of to assess depression.

Next, they measured the children's obesity and the levels of cortisol in saliva before and after various stress tests, said release a power supply.