Plasma Beta-Amyloid and Metabolic Biomarkers: Age- and Sex-Stratified Analyses Suggest Limited Population-Level...

Background and Objectives: This study examined the relationships between plasma beta-amyloid levels and systemic inflammatory, thyroid, and lipid biomarkers using complementary analytical approaches in a cross-sectional cohort undergoing plasma OAβ and laboratory testing. Materials and Methods: Plasma beta-amyloid, high-sensitivity C-reactive protein (hsCRP), thyroid hormones (TSH and FT4), and lipid profiles (HDL, LDL, and TG) were analyzed. Pearson correlation analyses assessed continuous associations, and one-way analysis of variance (ANOVA) compared biomarker distributions across plasma beta-amyloid categories (low, boundary, high), with additional stratification by age and sex. Multivariable linear regression models adjusted for age and sex evaluated the independence of observed associations. Results: Overall, plasma beta-amyloid showed limited associations with metabolic biomarkers at the population level. A weak inverse correlation with hsCRP was observed in unadjusted analyses in the low group and in males, whereas other biomarkers showed no consistent associations. Additional correlations emerged in selected subgroups but were heterogeneous, based on small samples, and interpreted as exploratory. ANOVA-based comparisons showed no significant differences across plasma beta-amyloid categories in the overall cohort or major strata. Although HDL showed subgroup-specific variation, these associations were not retained after adjustment. Conclusions: Assay-based plasma beta-amyloid categorization was not associated with uniform systemic metabolic alterations. Common inflammatory, thyroid, and lipid biomarkers were not robust population-level correlates and, when present in subgroups, likely reflected context-dependent rather than stable associations.