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Turning Down the 'Heat'

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Depression and inflammation may be closely related

One-third of people with depression fail to respond to conventional drug therapy, posing a treatment challenge.

Researchers at Emory have found in a new study that depressed patients who have not responded to multiple antidepressants show evidence of increased inflammation.

Previous studies among laboratory animals have shown that inflammation has effects on the brain that can undermine the effectiveness of common antidepressants. This is one of the first studies in humans that confirms these findings.

“Measuring inflammatory markers and targeting inflammation or its downstream effects on the brain may benefit patients with multiple failed antidepressant treatment trials during their current depressive episode,” says researcher Andrew Miller, William P. Timmie Professor of Psychiatry and Behavioral Sciences at Emory.

Levels of inflammation can be easily measured by simple blood tests like C-reactive protein (CRP). If a patient’s inflammation level is high (CRP>3mg/L), drugs that affect dopamine, such as bupropion, may be more effective than drugs that affect serotonin, the usual antidepressants prescribed.

“Ways to reduce inflammation include weight loss and exercise. Anti-inflammatory drugs are being tested for depression with some early promising results, but they are not approved for that use at this time,” says researcher Ebrahim Haroon, assistant professor of psychiatry and biomedical engineering at Emory.

During the study, researchers measured blood concentrations of inflammatory molecules in 98 unmedicated patients with depression who had experienced varying numbers of failed antidepressant trials.

“Stress-induced inflammatory signals can be transmitted to the brain,” says Miller. “We may be looking at a new era of therapeutics that target the immune system to treat depression.”

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