Associations of plasma metabolites with protein biomarkers linked to Alzheimer’s disease pathology in the Rotterdam Study

BACKGROUND: Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder characterized by amyloid-β (Aβ) and tau pathology, neuroaxonal damage, and neuroinflammation. While blood biomarkers, such as tau, neurofilament light chain (NfL), and Aβ isoforms, reflect AD pathology, the systemic metabolic alterations contributing to the disease remain poorly defined. This study aims to explore associations between plasma metabolites and key protein biomarkers linked to AD pathology in a large, population-based cohort. METHODS: Plasma levels of Aβ40, Aβ42, total-tau (t-tau), and NfL were measured using the highly sensitive Simoa NF-light and N3PA assays (Quanterix platform) among over 3,000 participants from the Rotterdam Study. Plasma metabolites were quantified using the Nightingale NMR-based (n = 2,871) and Metabolon MS-based (n = 1,491) platforms. Multivariable linear regression models, adjusted for demographic, lifestyle, and genetic factors, were applied. Analyses were stratified by sex and APOE genotype. Sensitivity analyses excluded participants with dementia, stroke, or impaired kidney function. RESULTS: Triglyceride-rich lipoproteins across VLDL, LDL, and HDL subclasses were positively associated with both Aβ isoforms. Among them, Triglyceride-rich lipoproteins in small VLDL showed the strongest association with Aβ40 (β = 0.168, FDR = 4.362e-16). Conversely, HDL cholesterol fractions showed inverse associations with Aβ. GlycA (β > 0.097, FDR < 2.092e-05) and creatinine (β > 0.253, FDR < 3.371e-24) were positively associated with all Alzheimer's disease biomarkers, while albumin was inversely related to tau (β = -0.094, FDR = 1.924e-04) and NfL (β = -0.079, FDR = 4.210e-05). On the Metabolon platform, S-adenosylhomocysteine (β > 0.206, FDR < 1.303e-09) was positively associated with all biomarkers, while uridine and 2'-deoxyuridine showed inverse associations with Aβ40, t-tau, and NfL. Stratified analyses indicated stronger GlycA-tau associations in APOE ε2 carriers and sex-specific effects for amino acids and ApoA1. CONCLUSIONS: Our findings highlight metabolites involved in lipid transport, inflammation, amino acid metabolism, and methylation as being linked to AD-related protein biomarkers. These results provide novel insights into systemic metabolic pathways underlying AD and suggest that certain metabolites may serve as potential biomarkers for early detection and risk stratification in AD.