Increased systemic inflammatory interleukin‐1ß and interleukin‐6 during agitation as predictors of Alzheimer's disease

Abstract

Identification of biomarkers for Alzheimer's disease (AD) is important for its early diagnosis and prevention and a key in advancing our understanding of its pathophysiology. The aim of this study was to determine whether systemic inflammatory interleukin-1ß (IL-1ß) and interleukin-6 (IL-6) as well as hypertension (HT), diabetes mellitus (DM), and body mass index (BMI) are predictors of AD. We performed a 10-year follow-up study on 133 elderly who were institutionalized in a nursing home. The associations of IL-1ß and IL-6 at both rest and agitation, as well as HT, DM, and BMI at baseline, were analyzed with the incidences of vascular dementia (VD) and AD during a 10-year follow-up period. The Kaplan-Meier method with log-rank test and Cox regression analyses for the total of 133 subjects showed significantly higher incidences of both VD and AD in subjects with DM or HT at baseline. Resting IL-1ß or IL-6 value, or agitation score, was not significantly associated with the subsequent development of VD or AD. The analyses of 40 subjects who had shown agitation at least once in the previous 3 months demonstrated that IL-1ß and IL-6 values at the agitation stage were significantly associated with AD, but not with VD. Our results indicate that systemic inflammatory IL-1ß and IL-6 at the agitation stage are risk factors for the development of AD, but not VD. Inflammatory mechanisms for AD seem to be causal and specific to the development of AD.