In findings that could open the door to people seeking a diagnosis, or who want to better understand their condition, scientists have discovered a biological basis for mood disorders

Depression is an incredibly common condition, with one in four people experiencing a depressive episode in their lifetime. And yet, despite this, current diagnosis and treatment plans are mostly trial and error – leading some people to feel uncertain and excluded, while others are overlooked completely.

But now, researchers from the Indiana University School of Medicine have found a biological basis for mood disorders, and have developed a blood test that aims to support a precision-medicine approach to treatment.

The blood test, which is composed of RNA biomarkers, is able to establish how severe an individual’s depression is, what their risk of depression, bipolar disorder, or manic-depressive illness in the future could be, and can inform the best course of medication.

It’s been more than four years since the study began, and in that time researchers looked at over 300 participants, studying their high and low moods and recorded the differences in their biomarkers between these moods.

"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," research lead, Dr Alexander B. Niculescu, professor of psychiatry at the IU School of Medicine, said.

"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. These blood tests can open the door to precise, personalised matching with medications, and objective monitoring of response to treatment."

But in addition to the biomarkers, the team also found that mood disorders were affected by circadian clock genes, which regulate our sleep-wake cycles – which Dr Niculescu notes explains why some people experience seasonal depression, and why our mood affects our sleep.

It’s research that will bring hope to many who would like to better understand or treat their depression and is another step to understanding the complexity of mental illnesses.

"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," Dr Niculescu said. "Given the fact that 1 in 4 people will have a clinical mood disorder episode in their lifetime, the need for and importance of efforts such as ours cannot be overstated."

Hero photo | Dr. Alexander B. Niculescu by Liz Kaye, Indiana University

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