The study participants were measured for their levels of the stress hormone cortisol using a saliva test, as well as asked to self-report their symptoms of sadness, stress, and anxiety over a period of 12 months. After tracking the teenagers for three years, scientists found that the group of boys who presented with both high levels of cortisol and self-reported "pre-depressive" symptoms were 14 times more likely to have developed clinical depression. Scientists believe that these findings will allow for earlier detection of depression or "pre-depression" — thus enabling preventative treatment.
Cortisol levels may be elevated for many reasons — genetics, a stressful home environment, bullying in school, etc. — and the relationship between stress and depression is well-established. Also, it makes sense that teenagers who have depressive symptoms would be likely to become more depressed as the years pass. So, the fact that these boys with both high cortisol and sadness developed depression isn't exactly surprising.
However, the study is an interesting reflection of the growing consensus that preventatively addressing mental illness in teenagers is important. More research is needed to investigate whether a similar test could be administered to adults to predict depression. And, as women are nearly twice as likely as men to develop major depression, more research is definitely needed to see if similar tests can help at-risk women. Depression is a costly and debilitating disease, so here's hoping that a spit test can help predict and prevent it. (Reuters)