Shortening of telomere length may be associated with inflammatory cytokine levels in patients with bipolar disorder

Background: Bipolar disorder (BD) is hypothesized to be associated with accelerated biological aging. Telomere length (TL) is a biomarker of aging, and although TL decreases with each cell division, the rate of telomere shortening may be affected by inflammation. We aimed to investigate whether TL is decreased in BD patients and to determine the association between TL and inflammatory markers in such patients. Methods: 137 BD patients and 118 healthy controls (HCs) were recruited. Leukocyte TL and plasma levels of cytokines [tumor necrosis factor (TNF)-alpha, interleukin (IL)-8, IL-6, IL-10, transforming growth factor (TGF)-beta 1], Creactive protein (CRP), and brain-derived neurotrophic factor (BDNF) were assessed. Results: TL did not differ significantly between the BD patients and HCs after adjustment for potential confounding factors (P = 0.79). TL was significantly negatively associated with age (beta = -0.007, P < 0.001). In addition, log TNF-alpha levels were significantly negatively associated with TL (P = 0.009), in both the BD patients (P = 0.02) and HCs (P = 0.05). Conclusion: We found a significant association between TNF-alpha levels and TL shortening in both BD patients and HCs. However, BD patients did not display increased TL shortening relative to HCs. Studies that involve larger sample sizes and control for the heterogeneity of BD participants will be needed.