American researchers have discovered a new biomarker of depression in blood platelets. They are now working on the development of a blood test to better detect it and better adapt the drug treatments of each patient.
- Antidepressants do not always have the expected effects on patients, who do not always react positively to drug treatment.
- A blood test, which measures a protein present in the blood, could help determine the effectiveness of antidepressant treatment early on.
Affecting more than 300 million people worldwide according to the World Health Organization (WHO), depression is a mental illness that is still difficult to treat today. Existing antidepressants have little or no effect in nearly one in two patients. And it also takes a while – about three to five weeks – for the treatment to start having an effect on mood and anxiety.
Hence the need to identify personalized approaches for each patient and to be able to verify the effectiveness of the drug treatments they receive.
A discovery made by researchers at the University of Illinois at Chicago seems to be on the right track. In a study published in the journal in Molecular Psychiatrythey explain that they have identified in blood platelets a biomarker allowing the extent of depression to be monitored.
A biomarker identifying depression
This finding builds on previous studies that have shown, in humans and animal models, that depression is linked to a decrease in adenylyl cyclase – a small molecule inside the cell that is made in response to neurotransmitters such as serotonin and epinephrine.
“When you’re depressed, adenylyl cyclase is low. The reason adenylyl cyclase is attenuated is that the intermediate protein that allows the neurotransmitter to make adenylyl cyclase, Gs alpha, is stuck in a cholesterol-rich matrix of the membrane – a lipid raft – where they don’t work very well”says Mark Rasenick, who led the study.
With his team, he developed a blood test identifying the cellular biomarker of Gs alpha translocation of Rasenick lipid rafts. This test not only identifies the presence of depression, but also the appropriate therapeutic response.
Better cure depression thanks to the blood test
Researchers hope to be able to use this blood test to determine if antidepressant therapies are working as early as a week after starting treatment. Indeed, previous studies have shown that when patients showed improvement in their symptoms of depression, the Gs alpha protein was released from the lipid raft. In contrast, in patients who were taking antidepressants but whose symptoms did not improve, the Gs alpha protein remained stuck in the raft, meaning that the mere presence of antidepressants in the blood is not enough to improve symptoms. .
A blood test could therefore make it possible to know whether or not Gs alpha has left the lipid raft after one week.
“As the platelets turn over within a week, you would see a change in people who will improve. You would be able to see the biomarker that should predict treatment success”hopes Professor Rasenick.
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