Now depression can be diagnosed by a blood test

American scientists have developed a new blood test for depression, Psych Central reports. The researchers, from Northwestern University’s Feinberg School of Medicine, say this is the first unbiased scientific way to diagnose the illness. This is a huge breakthrough given that depression is the most common mental illness in the world and the second biggest cause of disability, after back pain. It affects around 1 in 4 people in the UK.

The Northwestern team’s study was made up of 32 patients aged 21 to 79, all of whom had been assessed by independent doctors as depressed , plus 32 people, also aged 21 to 79, who had no personal experience of depression. The researchers found that the people with depression had significantly different levels of nine different markers in the blood when compared with the control group.

They also found that even after the depressed patients recovered following treatment, three biomarkers remained different from people with no history of the disease. This means that in future, doctors may be able to spot people at risk of depression and be more alert to potential symptoms. The co-head of the study, Eva Redei, a professor of psychiatry and behavioural sciences at the university, says, ‘This clearly indicates that you can have a blood-based laboratory test for depression.’ She’d previously developed a blood test to detect depression in teenagers, but found that the blood markers for the disease in adults are different.

Scientists have been looking for a biological rather than purely psychological test for depression for decades, because diagnosis depends on a doctor being sensitive to the symptoms plus an ill person’s ability to convey how they’re feeling at a time when they’re  likely to be struggling to communicate. Some of the symptoms of depression can also overlap with a lot of other health problems, so this test should be helpful when doctors are unsure of a diagnosis.

Clearly, there are lots of positives to this news, including the potential for more personalised treatment in future. However, let’s hope that GPs continue to listen to patients’ experiences and offer them support when they’re in distress, whatever their blood tests say.

Image via University of Michigan’s School of Natural Resources & Environment’s Flickr.