Philadelphia, PA, October 11, 2017 - A new study of young people experiencing a first episode of psychosis reports elevations in the brain chemicals glutamate and glycine. Published in Biological Psychiatry, the study led by Dr. Dost Öngür of Harvard Medical School provides the first ever measurement of glycine levels in patients with psychotic disorders.
Abnormal brain activity in psychotic disorders, such as schizophrenia and bipolar disorder, is thought to stem in part from impaired function of the NMDA receptor. Glutamate and glycine activate the receptor, which is an important mediator of brain signaling for processes such as learning and memory. According to Dr. Öngür, the findings may serve as a marker in the development of future treatments aimed at restoring function of NMDA receptors.
Reliable detection of glycine in the human brain has previously been very challenging--if not impossible--with conventional techniques, as an overlapping signal interferes with its detection. But first author Dr. Sang-Young Kim and colleagues applied a new method of the brain imaging technique called MR spectroscopy to suppress the interfering signal and reveal the hidden glycine signal.
Glycine levels were higher in 46 patients with first-episode psychosis, compared with 50 healthy participants. "Our findings suggest that glycine abnormalities may play a role in the earliest phases of psychotic disorders," said Dr. Öngür. The researchers also measured increased glutamate levels in patients, which lines up with strong support for elevated glutamate reported in other studies of first-episode psychosis. The elevations in glutamate and glycine indicate that NMDA receptors receive abnormal stimulation in psychotic disorders.
The increased glycine level was the opposite of what the authors expected to find -- researchers have actually tried raising glycine levels in patients to compensate for the underperforming NMDA receptors. The new findings revealing higher levels early on in the disease might help to explain why glycine supplementation hasn't worked as well as researchers hoped.
"This study supports the notion of different developmental phases in the biology of schizophrenia. These phases might require somewhat different treatments," said Dr. John Krystal, Editor of Biological Psychiatry.
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Notes for editors
The article is "In Vivo Brain Glycine and Glutamate Concentrations in Patients with First-Episode Psychosis Measured by Echo-Time-Averaged Proton MR Spectroscopy at 4 Tesla," by Sang-Young Kim, Marc J. Kaufman, Bruce M. Cohen, J. Eric Jensen, Joseph T. Coyle, Fei Du and Dost Öngür (http://dx.doi.org/10.1016/j.biopsych.2017.08.022). It appears in Biological Psychiatry, published by Elsevier.
Copies of this paper are available to credentialed journalists upon request; please contact Rhiannon Bugno at Biol.Psych@UTSouthwestern.edu or +1 214 648 0880. Journalists wishing to interview the authors may contact Dost Öngür, M.D., Ph.D., at dongur@partners.org or +1 617 855 3922.
The authors' affiliations and disclosures of financial and conflicts of interests are available in the article.
John H. Krystal, M.D., is Chairman of the Department of Psychiatry at the Yale University School of Medicine, Chief of Psychiatry at Yale-New Haven Hospital, and a research psychiatrist at the VA Connecticut Healthcare System. His disclosures of financial and conflicts of interests are available here.
About Biological Psychiatry
Biological Psychiatry is the official journal of the Society of Biological Psychiatry, whose purpose is to promote excellence in scientific research and education in fields that investigate the nature, causes, mechanisms and treatments of disorders of thought, emotion, or behavior. In accord with this mission, this peer-reviewed, rapid-publication, international journal publishes both basic and clinical contributions from all disciplines and research areas relevant to the pathophysiology and treatment of major psychiatric disorders.
The journal publishes novel results of original research which represent an important new lead or significant impact on the field, particularly those addressing genetic and environmental risk factors, neural circuitry and neurochemistry, and important new therapeutic approaches. Reviews and commentaries that focus on topics of current research and interest are also encouraged.
Biological Psychiatry is one of the most selective and highly cited journals in the field of psychiatric neuroscience. It is ranked 6th out of 142 Psychiatry titles and 10th out of 258 Neurosciences titles in the Journal Citations Reports® published by Thomson Reuters. The 2016 Impact Factor score for Biological Psychiatry is 11.412.
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