Oxidative stress in older patients with bipolar disorder

Abstract

Objective: Increases in oxidative stress have been consistently reported in younger patients with bipolar disorder (BD) in postmortem brain and blood samples studies. Changes in oxidative stress are also associated with the natural aging process. Thus, the investigation of oxidative stress across the life span of patients with BD is crucial.

Methods: We compared the levels of oxidative damage to proteins and lipids in plasma from 110 euthymic older patients with BD I or II (mean±SD age: 63.9±9.7 years) and 75 older healthy individuals (66.0±9.6 years). To assess protein oxidation, we measured the plasma levels of protein carbonyl (PC) and 3-nitrotyrosine (3-NT) using the ELISA technique. To assess lipid peroxidation, we measured plasma levels of lipid hydroperoxide (LPH) and 4-hydroxynonenal (4-HNE) using spectrophotometric assays.

Results: LPH levels were higher in patients than in the comparison healthy individuals, whereas there were no significant differences for PC, 3-NT, and 4-HNE between the two groups.

Conclusions: The increased levels of an early component of the peroxidation chain (LPH) in euthymic older patients with BD support the hypothesis of a persistent effect of reactive species of oxygen in patients with BD into late life.

Keywords: Bipolar disorder; aging; lipid peroxidation; oxidative stress; protein oxidation.