Scientists identify biomarker in human platelets that tracks the extent of depression

Scientists have identified a biomarker in human platelets that tracks the extent of depression in a new study.

The research called "A Novel Peripheral Biomarker for Depression and Antidepressant Response," has been published in Molecular Psychiatry.

The study aims at developing a blood test that provides a simple biochemical hallmark for depression and the efficacy of drug therapy in individual patients.

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A spike in suicide rates worldwide has cast fresh light on the need for more effective treatments for major depression, with researchers saying it is a tricky development area that has largely been abandoned by big pharmaceutical companies.

The new research builds off of previous studies by several investigators that have shown that depression is consistent with decreased adenylyl cyclase in humans and animal models.

Adenylyl cyclase is a small molecule inside the cell that is made in response to neurotransmitters such as serotonin and epinephrine.

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According to the study's lead author Mark Rasenick from the University of Illinois Chicago, "When you are depressed, adenylyl cyclase is low. The reason adenylyl cyclase is attenuated is that the intermediary protein that allows the neurotransmitter to make the adenylyl cyclase, Gs alpha, is stuck in a cholesterol-rich matrix of the membrane, a lipid raft, where they don't work very well."

"What we have developed is a test that can not only indicate the presence of depression but it can also indicate therapeutic response with a single biomarker, and that is something that has not existed to date," said Rasenick, who is also a research career scientist at Jesse Brown VA Medical Center.

More than 4 percent of the world’s population lives with depression, and women, youth and the elderly are the most prone to its disabling effects as per the World Health Organization (WHO).

Global economic losses exceed $1 trillion a year, it said, referring to lost productivity due to apathy or lack of energy that lead to an inability to function at work or cope with daily life.

Rasenick explains that "Because platelets turn over in one week, you would see a change in people who were going to get better. You'd be able to see the biomarker that should presage successful treatment."

"About 30 per cent of people don't get better, their depression doesn't resolve. Perhaps, failure begets failure and both doctors and patients make the assumption that nothing is going to work," Rasenick said. 

"Most depression is diagnosed in primary care doctor's offices where they don't have sophisticated screening. With this test, a doctor could say, 'Gee, they look like they are depressed, but their blood doesn't tell us they are. So, maybe we need to re-examine this.'"

(With inputs from agencies)