The feasibility of using a blood test to identify depression has been demonstrated recently by researchers at Medical University of Vienna.
Although blood tests for detection of mental illnesses have mostly been looked on as impossible, this study plainly indicates that, theoretically depression can be diagnosed this way. In the not too distant future it may even become reality.
Serotonin transporter 5-HTT, a protein in the cell membrane, facilitates movement of the neurotransmitter serotonin into the cell. In the brain, serotonin transporter, or SERT for short, regulates neural depression networks.
Depressive conditions may often be caused by a lack of serotonin. Consequently, the serotonin transporter is also the focus for the major antidepressant drugs.
Serotonin and the Default Mode Network
But SERT also is present in large amounts in various other organs like the intestines or the blood. Recent studies have shown that the serotonin transporter in the blood works in precisely the same way as in the brain. In the blood, it ensures that blood platelets keep the correct concentration of serotonin in the blood plasma.
The researchers took advantage of functional magnetic resonance imaging of the brain and pharmacological analysis to demonstrate that there is a close relationship between the speed of the serotonin uptake in blood platelets and the function of a depression network in the brain.
The network is known as the default mode network, since it is mainly active at rest and processes content with strong self-reference. Recent findings have also shown that it is actively suppressed during complex thought processes, essential for adequate levels of concentration.
Diagnosis of Depression via Blood Test
Interestingly, patients with depression find it difficult to suppress the default mode network during thought processes, leading to negative thoughts, ruminations and poor concentration.
“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. 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 reality in the not too distant future," said study leader Lukas Pezawas.
These results indicate that the diagnosis of depression through blood tests could become reality in the not too distant future.
Scharinger C, Rabl U, Kasess CH, Meyer BM, Hofmaier T, et al. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity. PLoS ONE, 2014; 9 (3): e92543 DOI:10.1371/journal.pone.0092543