Depression is a serious condition, and can impact a person's life in multiple ways. Now, though, scientists have found a new way to possibly detect depression--through a person's blood.

When it comes to detecting depression, it's all about proteins and chemicals. Serotonin transporter (SERT) is a protein in the cell membrane the helps transport the neurotransmitter serotonin, which is popularly known as the "happiness hormone," into the cell. In the brain, SERT regulates neural depression networks; a lack of serotonin can actually cause depressive conditions.

The SERT doesn't only occur in the brain, though; it also occurs in large quantities in numerous other organs, including in the blood. It's possible that by taking blood samples and testing for SERT, scientists could detect whether or not a person is at risk for depression.

The researchers used functional magnetic resonance imaging of the brain to reveal that there is a close relationship between the speed of the serotonin uptake in blood platlets and the function of a depression network in the brain. The network, called the default mode network, is primarily active at rest and processes content with strong self-reference.

"This is the first study that has been able to predict the activity of a major depression network in the brain using a blood test," said Lukas Pezawas, one of the researchers, in a news release. "While blood tests for mental illnesses have until recently been regarded as impossible, this study clearly shows that a blood test is possible in principle for diagnosing depression and could become a reality in the not too distant future."

The findings reveal a new way to examine depression. This, in turn, could pave the way for future studies, and help those suffering from depression.

The findings are published in the journal PLOS One.