Science //

Reading the blood

Felicity Nelson reports on a recent breakthrough that could change how we see mental illness.

Photograph by Patrick Lauke via Flickr.

Mental illnesses are as real as a broken leg and are often just as debilitating. Yet, until recently, diagnosis has relied almost entirely on the testimony of the patient – on words alone.

This has strengthened the myth that mental illness is not a real disease, discouraged people from seeking help early and made it very difficult to diagnose disease with the precision and objectivity demanded by the medical profession.

All that could be about to change. Recent studies suggest we will soon be able to diagnose depression, suicidal tendencies, schizophrenia and even paedophilia with a lab test or a brain scan. Being able to detect mental illness with the prick of a finger will immediately and radically alter the situation for patients and the perception of mental illness in society. It could, very possibly, be the most important development in psychiatry in this century.

Seven people commit suicide every day in Australia. It is a shocking statistic and every single one of these deaths is preventable. It is difficult to reach people at that stage in their depression or anxiety. Many people in the depths of despair remain completely silent out of fear of stigma, fear of forced hospitalisation or, worse, fear that their plans will be thwarted.

We desperately need a method of detecting suicidal tendencies that do not rely on the capacity of the individual to recognize their own problems. This is where blood biomarkers come in.

In a paper published in Molecular Psychiatry last year, six biomarkers carried in the blood were identified as predictors of suicide risk, the strongest being a protein encoded by a gene called SAT1. When combined with clinical measures of mental state, the tests went from 65 per cent to 80 per cent accuracy in prediction of short and long-term suicide risk.

In 2010, VeriPsych became the first blood-based diagnostic aid for schizophrenia. More recently, a team at the Medical University of Vienna developed a reliable blood test for clinical depression. They discovered that the uptake speed of the ‘happy hormone’, serotonin, in blood cells directly reflected the function of a depression network in the brain.

The use of biomarkers in diagnosing these mental illnesses builds on a decade-worth of research into blood tests for Alzheimer’s disease. It now seems possible to identify Alzheimer’s in healthy individuals with 90 per cent accuracy five years before they develop symptoms with a simple blood test.

Tendencies towards paedophilia are highly stigmatized in society – with good reason – but study shows that some people are simply hard-wired to have warped sexual preferences. Recently, MRI brain scans have revealed a pattern of brain activity in paedophiles that differs strongly to people who are attracted to adults. We may one day be able to detect paedophilic tendencies before crimes are committed and help people become less of a threat.

One in five Australians will suffer from mental illness this year. The relief that a certain and early diagnosis gives a person cannot be overstated. Proving a physical basis for mental diseases will validate cries for help in a way that education and public health campaigns cannot. These advances will revolutionize the way we think about mental illness and are absolutely certain to save lives in the future.