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Blood Test Could Distinguish Between Schizophrenia, Depression

The A procedure that uses a blood test to measure levels of the hormone arginine vasopressin (AVP) can distinguish between depression and schizophrenia, suggests a proofof-concept study published online in Experimental Physiology.

“This is the first objective, physiological marker for 2 major psychiatric disorders that, once fully developed into a clinical test, can allow for earlier and more accurate diagnosis, and selection of more appropriate medications for patients,”said researcher Handan Gunduz-Bruce, MD, of Yale University in New Haven, Connecticut. The procedure identifies patients whose depression or schizophrenia involves N-methyl-D-aspartate (NMDA) receptor malfunction. Depression, according to previous research, is linked with increased NMDA receptor signaling, while schizophrenia is linked with decreased NMDA receptor signaling.

Animal studies have shown that NMDA receptor signaling affects the release of the hormone AVP. Consequently, for their study, researchers infused patients with depression,
patients with schizophrenia, and healthy controls with a high concentration of saline solution to trigger the release of AVP. Then they measured the level of AVP in the blood.

Patients with depression had an AVP level that was significantly increased compared with patients with schizophrenia, whose AVP level was abnormally low, researchers found.
The level of AVP for healthy controls was not statistically different from either group. Researchers are hopeful their findings are the first step toward producing a simple test to identify certain forms of depression and schizophrenia early on in illness progression. 

Gunduz-Bruce H, Kenney J, Changlani S, et al. A translational approach for NMDA receptor profiling as a vulnerability biomarker for depression and schizophrenia. Experimental Physiology. 2017 March 13.First physiological test for schizophrenia and depression [press release]. London, England: The Physiological Society; March 14, 2017.