The quest within scientific research to identify new biomarkers for a wide spectrum of diseases and disorders is something that we at Medical News Today report on frequently.
In recent months we have looked at studies investigating biomarkers that can be used to test concussion severity, the relationship between Alzheimer's biomarkers and severity of symptoms, and biomarkers as a fast, non-invasive test for brain cancer.
But can biomarkers be used to diagnose or improve treatment for patients with psychiatric disorders?
Mental health problems are often perceived as being "ethereal" in origin, compared with more visible and quantifiable health problems.
Depression, for instance, is not considered to have a specific root cause but is believed to be influenced by a combination of stressful life events, genetic susceptibility, chemical changes in the brain or other underlying medical conditions.
Yet, in the past couple of years, there has been a drive in research to locate biomarkers for depression and to develop reliable tests that detect these biomarkers in depressed patients.
Only last week, it was announced that the world's biggest scanning project - UK Biobank - is currently analyzing the DNA of half a million participants in order to identify biomarkers for conditions including not just the likes of cancer, stroke and heart disease, but also depression.
What are biomarkers?
Biomarkers are "biological clues" that doctors can look for in patients to confirm the presence or risk of disease. These clues are usually found in changes in blood, urine or body tissue. Fasting glucose, for example, can be used to diagnose diabetes, and the presence of liver enzymes in the blood can indicate liver disease.
Biomarkers are a popular area of study. A 2012 article in Massachusetts General Hospital's Proto magazine calculated that out of 150,000 published papers announcing the discovery of thousands of new biomarkers for a range of conditions, from Loyola University Health System (resource no longer available at protomag.com) in Illinois listed corticotropin-releasing hormone antagonists, ketamine, partial adrenalectomy, benzodiazepines, anesthetics, deep brain stimulation and transcranial magnetic stimulation as new or forthcoming depression treatments.
The new theories behind the development of these depression therapies "should not be viewed as separate entities because they are highly interconnected," the authors write. "Integrating them provides for a more expansive understanding of the pathophysiology of depression and biomarkers that are involved."
Explaining that it can take months to recover from depression, the researchers suggest that existing depression treatment programs averaging 6 weeks are not long enough for adequate recovery. They hope the new biomarker-led research will not only enhance treatment, but open doors for a new understanding of depression.