Novel Blood Test to Diagnose Depression and Bipolar Disorder

The researchers worked hard to identify blood biomarkers for neuropsychiatric disorders — and they were successful.
Derya Ozdemir

Depression is a common condition, which affects more than 264 million people of all ages globally. When you're feeling ill, a doctor may run tests to figure out the reason why, with a simple blood test in many cases, revealing the possible answer. 

However, when it's a mental condition that's causing your distress, diagnosis and treatment can be a painful process relying on largely trial and error with no guarantees. Now, a breakthrough study by Indiana University School of Medicine researchers is ushering in a blood test that aims to support a precision-medicine approach to treatment, according to a press release. In very welcome news, the researchers have found a biological basis for these mood disorders which affect millions.

Published in the journal Molecular Psychiatry, the team's work centers around the development of a blood test that is composed of RNA biomarkers. This way, the researchers can distinguish how severe a patient's depression is, the risk of them developing severe depression in the future, and the risk of future bipolar disorder.

Choosing the right medicine for each person has always been a challenging task, and this test also informs tailored medication choices for patients.

"Through this work, we wanted to develop blood tests for depression and for bipolar disorder, to distinguish between the two and to match people to the right treatments," said Dr. Alexander B. Niculescu, research lead and professor of psychiatry at the IU School of Medicine.

The study explained

The study has been ongoing for more than four years, with the researchers studying over 300 participants in the process. By using a careful four-step approach of discovery, prioritization, validation, and testing, their high and low moods were studied, and the differences in their biomarkers between these moods were recorded.

Then, the findings were cross-validated and prioritized by looking at the previous studies in the field. The researchers confirmed the top 26 candidate biomarkers in independent groups of clinically severe people with depression or mania. Lastly, the biomarkers were tested in additional independent cohorts to see how good they were at predicting who is ill and who will become ill in the future. 

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"Blood biomarkers are emerging as important tools in disorders where subjective self-report by an individual, or a clinical impression of a health care professional, are not always reliable," said Niculescu. "These blood tests can open the door to precise, personalized matching with medications, and objective monitoring of response to treatment."

Moreover, the researchers found that mood disorders were affected by circadian clock genes which control our day-to-day and seasonal sleep-wake cycles. "That explains why some patients get worse with seasonal changes and the sleep alterations that occur in mood disorders," said Niculescu.

"Blood biomarkers offer real-world clinical practice advantages. The brain cannot be easily biopsied in live individuals, so we've worked hard over the years to identify blood biomarkers for neuropsychiatric disorders," added Niculescu. "Given the fact that one in four people will have a clinical mood disorder episode in their lifetime, the need for and importance of efforts such as ours cannot be overstated."