A blood test that can show the effectiveness of drug therapy in individual patients is one step closer to being developed.
A new proof of concept study led by Mark Rasenick, University of Illinois Chicago distinguished professor of physiology and biophysics and psychiatry, has identified a biomarker in human platelets that tracks the extent of depression.
Several investigators have shown in humans and animal models that depression is related to a small molecule inside the cell that is made in response to neurotransmitters.
Adenylyl cyclase is low when you are depressed. The reason adenylyl cyclase is not functioning is because the Gs alpha is stuck in a cholesterol-rich matrix of the membranes.
The new study, "A Novel Peripheral Biomarker for Depression and Antidepressant Response", was published in the journal, Molecular Psychiatry. A blood test can be used to identify the biomarker.
"We have developed a test that can show the presence of depression but also show the response with a single biomarker, which is something that has not existed to date," said Rasenick, who is also a research career scientist at Jesse Brown VA Medical Center.
The researchers think they will be able to use the blood test to determine if the therapies are working as soon as one week after starting treatment. The Gs alpha was out of the raft when patients showed improvement in their depression symptoms. The Gs alpha was still stuck in the raft in patients who took antidepressants but showed no improvement in their symptoms.
A blood test may be able to show if the Gs alpha was still in the raft after a week.
You would see a change in people who were going to get better when platelets turn over. You would be able to see the biomarker that should tell you if your treatment is successful.
Patients and their doctors have to wait several weeks, sometimes months, to find out if antidepressants are working, and if they aren't, different therapies are tried.
About 30% of people don't get better. Both doctors and patients make the assumption that nothing will work when they fail. Most depression is diagnosed in primary care doctor's offices. The doctor could say that they look like they are depressed, but their blood doesn't show it. Maybe we need to re-examine this.
After further research, the screening test will be developed by Pax Neuroscience.
The research was supported by the National Institutes of Health and the U.S. Department of Veterans Affairs.
Additional researchers include Jeffrey Schappi, Athanasia Koutsouris, Runa Bhaumik, Steven Targum, Mark Rapaport, and Natalie Rasgon.
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