A saliva test for teenage boys with mild symptoms of depression could help identify those who will later develop major depression, a new study says.

Researchers measured the stress hormone cortisol in teenage boys and found that ones with high levels coupled with mild depression symptoms were up to 14 times more likely to suffer clinical depression later in life than those with low or normal cortisol levels.

The test was tried on teenage boys and girls, but found to be most effective with boys. Experts suggested that cortisol might affect boys and girls differently.

The study observed more that 1,800 teenagers aged 12 to 19 and examined their cortisol levels with saliva tests. The researchers also collected the teens' own reports of depression symptoms and tracked diagnoses of mental health disorders in them for up to three years later.

The boys who had high cortisol levels and mild depression symptoms were up to 14 times more likely to suffer from clinical depression when compared to other teens with normal levels, while girls with similarly elevated cortisol levels were only up to four times more likely to develop the condition.

The study appeared in the journal Proceedings of the National Academies of Science.

Source: Businessweek
http://www.businessweek.com/ap/2014-02-18/test-could-predict-which-teen-boys-get-depression