New study identifies depression biomarker in human platelets

New study identifies depression biomarker in human platelets

A new study has found biomarkers for depression in platelets that track the extent of the disorder.

A biomarker has been identified in human platelets that tracks the extent of depression, according to a new proof of concept study by researchers led by Mark Rasenick, University of Illinois Chicago distinguished professor of physiology and biophysics and psychiatry.

The research builds off of previous studies by several investigators that have shown in humans and animal models that depression is associated with decreased adenylyl cyclase, a small molecule inside the cell that is made in response to neurotransmitters such as serotonin and epinephrine.

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, Rasenick said.

The new study has identified the cellular biomarker for translocation of Gs alpha from lipid rafts. A blood test can identify a biomarker.

Researchers at the Jesse Brown VA Medical Centre said that the test that we developed can not only indicate the presence of depression but also indicate the therapeutic response with a single biomarker.

The researchers hypothesized that they could use this blood test to determine if antidepressant therapies are working, perhaps as soon as one week after beginning treatment. Previous research shows that when patients showed improvement in their depression symptoms, the Gs alpha was out of the lipid raft. However, in patients who took antidepressants but showed no improvement in their symptoms, the Gs alpha was still stuck in the raft, meaning that simply having antidepressants in the bloodstream was not good enough to improve symptoms.

A blood test may be able to determine whether or not the Gs alpha was out of the lipid raft.

After a week.

Because platelets turned over in a week, you would see a change in people who were going to get better. You can see the biomarker that should predate successful treatment, according to Rasenick.

Patients and their doctors have to wait several weeks, sometimes months, to determine if antidepressants are working, and when it is determined they aren't working, different therapies are tried.

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

Most people with depression are 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 who they are. He said that we need to re-examine this.