After The Rensselaer Polytechnic Institute in New York announced last week the development of a blood test to identify autism in children, there have been reports of yet another advancement in diagnostic technology, this time from scientists at Yale, the John B. Pierce Laboratory, and the VA Medical Center in West Haven, Connecticut.

The team has worked on an early diagnosis tool for depression and schizophrenia and created a blood test that can differentiate between the two conditions. Their procedure focuses on a new biomarker that hasn't been tested before, making timely detection more possible and providing a valid diagnosis at any stage of either ailment.

The researchers published a paper in the journal Experimental Physiology, detailing how their proof-of-concept diagnostic test works and what success rates can be expected by employing this technique. Their work is all the more valuable, considering the two conditions are difficult to detect early on by simply measuring behavioral changes.

Just like the blood test for autism, this is the first physiological diagnostic tool available for depression and schizophrenia patients whose symptoms lack consistency from one case to another and can be easily mistaken for other comorbid conditions.

The Importance Of Early Diagnosis

According to the National Institute of Mental Health, schizophrenia is a chronic and debilitating disorder that affects 1.1 percent of adults in the United States, whereas depression is among the most prevalent mental health problems Americans are currently facing.

Studies have indicated that only a third of patients (35 percent) exhibiting early symptoms develop schizophrenia in the following 2.5 years, while a comparable proportion of cases results in mood disorders.

In some instances, patients are known to overcome these early symptoms, whose ambiguous and moderate nature cumbers detection and proper diagnosis.

Lead author Dr. Handan Gunduz-Bruce, from the Department of Psychiatry at Yale School of Medicine, says early intervention in these types of cases in paramount.

As she explains, "a physiological or biological marker that will give us some indication as to which direction a particular young person is heading toward" would be tremendously valuable.

How The Novel Diagnostic Tool Works

The newly developed blood test does just that and is designed to detect a specific hormone called arginine-vasopressin (AVP), whose levels are distinct among patients suffering from depression and schizophrenia. This hormone regulates blood vessel constriction and body water retention and is produced in the body via NMDA (altered N-methyl-D-aspartate) signaling — a pathway though which nervous system cells communicate.

In the study, Dr. Gunduz-Bruce's team stimulated AVP production through saline solution injections and measured the hormone levels in seven schizophrenia patients, eight unipolar depression patients, and a 10-member control group.

Previous studies suggested NMDA signaling manifests differently among people suffering from the two conditions. In depression patients, NMDA signaling is increased, showing elevated levels of the AVP hormone. In contrast, schizophrenia patients report a decreasing NMDA pattern, resulting in lower presence of AVP in the bloodstream.

Comparative analysis revealed NMDA receptors were "hyperactive" in people with depression and "not functioning very well" in people with schizophrenia. Results showed study participants with depression had a concentration of AVP three times higher than the schizophrenia group, proving the blood test can successfully differentiate between the two conditions based on the chosen biomarker.

"We hope that this will lead to a very useful biological marker in the clinic to help us distinguish between schizophrenia and depression in young people," said Dr. Gunduz-Bruce.

She added this new diagnosis tool could also help "select the right medicines" and course of treatment for the two disorders and mentioned several drug makers are developing NMDA blockers for depression and NMDA stimulants for schizophrenia.

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