Researchers today announced that the first biomarker for clinical depression has been identified. A new study, published in the Proceedings of the National Academy of Sciences, has linked cortisol and depressive symptoms to clinical depression. This biomarker is especially strong in indicating whether young men may develop clinical depression.

Cortisol is a hormone sometimes known as the ‘stress hormone.’ The study’s authors hope that the identification of a biomarker for depression could help medical professionals better assess the risk of clinical depression in patients, allowing for earlier intervention.

The study looked at saliva samples from over 1,800 teenagers, surveying these same teens about any current symptoms of depression. The teens were then separated into four groups based on their cortisol levels (normal or high) and their level of depression symptoms (low or high). Researchers found that the teens who had high cortisol levels in addition to high depression symptoms were a full seven times more likely to develop clinical depression that those who had both normal cortisol levels and low depression symptoms.

In addition to this the researchers found a significant split among genders in the study. Males with high cortisol and depressive symptoms were 14 times as likely to develop clinical depression than those with low cortisol and depressive symptoms. Girls with high cortisol and depressive symptoms were only four times as likely to develop clinical depression than those with low cortisol and depressive symptoms.

“This new biomarker suggests that we may be able to offer a more personalized approach to tackling boys at risk for depression,” said Matthew Owens, lead author of the study and a researcher at the University of Cambridge. “This could be a much needed way of reducing the number of people suffering from depression, and in particular stemming a risk at a time when there has been an increasing rate of suicide amongst teenage boys and young men.”