The Relationships Between Components of Metabolic Syndrome and Mild Cognitive Impairment Subtypes: A Cross-Sectional Study of Japanese Older Adults

Background: The associations between components of metabolic syndrome (MetS) and mild cognitive impairment (MCI) subtypes remain unclear. Objective: The study aim was to identify the prevalence of MetS for MCI subtypes and to investigate sex differences in the association between MetS and MCI subtypes in older Japanese adults. Methods: The study analyzed data from 3,312 men and women aged 70 years or more. MetS was diagnosed according to International Diabetes Federation criteria. Participants completed cognitive tests and were categorized into normal cognition, amnestic MCI (aMCI), and non-amnestic MCI (naMCI). The associations between MetS and its components and MCI subtypes were analyzed using multiple logistic regression. Results: MetS prevalence was greater in participants with naMCI (men: p = 0.030; women: p = 0.040). Participants with naMCI showed higher odds ratios (OR) of MetS (men: 2.45, 95% confidence intervals (CI): 1.13-5.32; women: OR: 1.94, 95% CI: 1.12-3.39) compared with participants with normal cognition. MetS was not associated with aMCI. Analysis of MetS components showed that raised glucose (OR: 1.62, 95% CI: 1.19-2.22) and reduced high-density lipoprotein cholesterol (OR: 1.97, 95% CI: 1.25-3.12) were associated with naMCI in men. In women, raised blood pressure (OR: 1.42, 95% CI: 1.03-1.94) and raised glucose (OR: 1.32, 95% CI: 1.02-1.71) were associated with naMCI. Conclusion: MetS was associated only with naMCI regardless of sex, which suggests etiologic differences in MCI subtypes. We also found sex differences in the relationship between naMCI risk and MetS and its components.