Inflammation Markers May Reveal Best Patients for Ketamine
Patients with major depression who show signs of systemic inflammation have elevated levels of glutamate in regions of the brain linked with motivation, according to a study in the online Molecular Psychiatry.
Consequently, they may respond best to antidepressant treatments that target the brain chemical glutamate, such as the anesthetic ketamine, researchers noted.
"Our results suggest that inflammation markers can guide us to which depressed patients respond best to glutamate blockers," said lead author Ebrahim Haroon, MD, assistant professor of psychiatry and behavioral sciences at Emory University School of Medicine and Winship Cancer Institute in Atlanta. "This could be an important step toward personalizing treatment for depression."
To investigate a potential link between elevated inflammation and glutamate levels in patients with major depression, Dr. Haroon and colleagues evaluated 50 outpatients with depression who were not taking antidepressant medication. They determined inflammation by a blood test for C-reactive protein.
Meanwhile, an imaging technique called magnetic resonance spectroscopy measured patients’ glutamate levels in the basal ganglia, a region of the brain important for motor control, motivation, and decision making. Researchers also measured levels of myo-inositol, a marker of glial health.
High glutamate and myo-inositol levels in the basal ganglia, they found, were associated with patient reports of anhedonia, or an inability to feel pleasure, and slow motor function.
“We focused on the basal ganglia,” Dr. Haroon explained, “because we had previously seen that a treatment for hepatitis C virus that arouses inflammation and can trigger depressive symptoms could also increase glutamate levels there.”
—Jolynn Tumolo
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