Blood test offers new hope to people with depression

A blood test using RNA markers is offering new hope to people with mood disorders such as depression in what could be a significant breakthrough in the diagnosis of mental health conditions.

A team from the US’s Indiana University School of Medicine launched the blood test in April, claiming it to be psychiatry’s first-ever biological answer to diagnosing a mood disorder.

“Our study shows that it is possible to have a blood test for depression and bipolar disorder, that have clinical utility, can distinguish between the two, and match people to the right medications,” said psychiatrist and geneticist Dr Alexander Niculescu, who led the research.

“This avoids years of trials and error, hospitalisations, and side-effects. As these are very common disorders, we think we can do a lot of good with this and other tests and apps we have developed.”

The study delved into the biological basis of mood disorders, developing a tool to distinguish which type of mood disorder a person has – depression or bipolar disorder.

To develop the test, Dr Niculescu’s team drew on its 15 years of previous research into how psychiatry relates to blood gene expression biomarkers – measurable indicators of a biological state in the form of RNA, DNA, proteins or other molecules.

Every system in the body – the brain, the nervous system, the immune system – has a common developmental route, says Dr Niculescu.

In the first stage of the study, the team identified a list of RNA biomarkers that could track mood states over a period of time. After validating them in an independent cohort of subjects with clinically severe depression and clinically severe mania, they finalised 26 biomarkers, which they whittled down to 12 through further testing.

With these findings, doctors would be able to send patients to a lab for bloodwork to indicate the causes of their symptoms, just as they would for a physical illness, says Dr Niculescu.

The biomarkers could also help with treatment because some of them were found to be affected by Selective Serotonin Reuptake Inhibitors (SSRIs), a class of antidepressants.  Three others were identified in previous work to be affected by lithium carbonate – a mood stabiliser used in the treatment of bipolar disorder.

“Depending on which of those biomarkers are changed in [a patient], we have a list of medications … ranked by how tightly they match [the patient’s] biological profile,” Dr Niculescu said.

The blood tests developed by Dr Niculescu and his team are now available as CLIA tests for physicians to order, via a company set up by Niculescu and other experts in the field. CLIA are a set of US government standards for laboratories that test human specimens for health assessment or to diagnose, prevent, or treat disease

But according to Alexander Talkovsky, a programme officer in the Division of Translational Research at the National Institute of Mental Health (NIMH) in the United States, there is still research to be done. The key issue is whether the findings are replicated by independent researchers, he adds.

This process has been done to some extent within the study itself, says Dr Niculescu, through several steps of testing and validation in independent cohorts. According to the study, promising findings were also generated by independent large scale genetic studies released after the study was complete.

But what if the study’s premise is in itself incorrect?

Professor Ian Hickie, co-director of health and policy at the University of Sydney’s Brain and Mind Centre, and a former national mental health commissioner in Australia, argues that finding one algorithm which applies to all mood disorder patients is unlikely because the disorders are so individual and are based on clinical presentation at different stages of life.

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