Interleukin-6, IL-1 receptor antagonist (IL-1RA), and tumor necrosis factor–alpha (TNF-alpha) activity was associated with inflammation and neurodegeneration in patients with chronic bipolar disorder, according to Sercan Karabulut, MD, of Kepez State Hospital in Antalya, Turkey, and associates.

In a study published in the Turkish Journal of Psychiatry, the investigators collected enzyme-linked immunosorbent assays from 30 patients with early-stage bipolar disorder, 77 with chronic disease, and 30 healthy controls. Early-stage disease patients were significantly younger than chronic patients (25.3 years vs. 37.8 years). TNF-alpha, IL-6, IL-1RA, neuron-specific enolase, and S100 calcium-binding protein B (S100B) were measured, reported Dr. Karabulut and associates.

Patients with chronic bipolar disorder had significantly increased levels of all measured markers, compared with those with early-stage disease and the healthy controls. IL-6 and IL-1RA levels correlated with neuron-specific enolase and S100B, biomarkers that are associated with glial alterations and neuronal damage. TNF-alpha correlated with scores on the Clinical Global Impressions Scale and other measures.

“The present findings support in part the hypothesis that inflammation starts at later stages of [bipolar disorder], presumably as an associated effect of gliosis and neuronal loss, which appear to be particularly associated with IL-1RA and IL-6 activity,” the investigators wrote. “TNF-alpha ... might be a useful prognostic marker in patients with [bipolar disorder].”

No conflicts of interest were reported.

SOURCE: Karabulut S et al. Turk Psikiyatri Derg. 2019 Winter;30(2):75-81.