Adolescent boys who have high levels of stress hormone 'cortisol' along with some symptoms of depression are at a 14 times higher risk of the condition than their peers, a new study from University of Cambridge found.

For the study, researchers analyzed cortisol levels in saliva samples of teenage boys. They found that raised levels of the hormone along with depressive symptoms were linked with 14 times increased risk of major depression in boys.

In girls, cortisol levels along with depressive symptoms were linked with about four times higher risk of clinical depression.

Occasional feelings of sadness and dejection are normal. Major depression is when the sadness and anxiety begins interfering with everyday activities. Recent research has shown that brains of people with major depression look different than brains of other people. Identification of the biomarker could mean that depression risk can be predicted and hopefully, treated early.

The hormone Cortisol is produced in the body as a primary response to stress. The present study shows that the hormone level could be used to diagnose depression in young boys.

"Through our research, we now have a very real way of identifying those teenage boys most likely to develop clinical depression. This will help us strategically target preventions and interventions at these individuals and hopefully help reduce their risk of serious episodes of depression and their consequences in adult life," Ian Goodyer of the University's Department of Psychiatry, lead author of the study.

The study was based on spit samples from 1,858 teenagers. Participants were even asked to answer a questionnaire that assessed their depressive symptoms, BBC reported.

Researchers found that increased levels of the hormone along with depressive symptoms predicted the risk of major depression in teen boys.

"This new biomarker suggests that we may be able to offer a more personalized approach to tackling boys at risk for depression," said co-author Dr Matthew Owens in a news release.

The study is published in the journal Proceedings of the National Academy of Sciences.