Plasma metabolites associated with biomarker evidence of neurodegeneration in cognitively normal older adults

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that currently has no cure. Identifying biochemical changes associated with neurodegeneration prior to symptom onset, will provide insight into the biological mechanisms associated with neurodegenerative processes, that may also aid in identifying potential drug targets. The current study therefore investigated associations between plasma neurofilament light chain (NF-L), a marker of neurodegeneration, with plasma metabolites that are products of various cellular processes. Plasma NF-L, measured by ultrasensitive Single molecule array (Simoa) technology (Quanterix) and plasma metabolites, measured by mass-spectrometry (AbsoluteIDQ (R) p400HR kit, BIOCRATES), were assessed in the Kerr Anglican Retirement Village Initiative in Ageing Health (KARVIAH) cohort comprising 100 cognitively normal older adults. Metabolites belonging to biogenic amine (creatinine, symmetric dimethylarginine, asymmetric dimethylarginine; ADMA, kynurenine, trans-4-hydroxyproline), amino acid (citrulline, proline, arginine, asparagine, phenylalanine, threonine) and acylcarnitine classes were observed to have positive correlations with plasma NF-L, suggesting a link between neurodegeneration and biological pathways associated with neurotransmitter regulation, nitric oxide homoeostasis, inflammation and mitochondrial function. Additionally, after stratifying participants based on low/high brain amyloid-beta load (A beta +/-) assessed by positron emission tomography, while creatinine, SDMA and citrulline correlated with NF-L in both A beta- and A beta+ groups, ADMA, proline, arginine, asparagine, phenylalanine and acylcarnitine species correlated with NF-L only in the A beta+ group after adjusting for confounding variables, suggesting that the association of these metabolites with neurodegeneration may be relevant to AD-related neuropathology. Metabolites identified to be associated with plasma NF-L may have the potential to serve as prognostic markers for neurodegenerative diseases, however, further studies are required to validate the current findings in an independent cohort, both cross-sectionally and longitudinally.

Automated summary

The study identified associations between plasma neurofilament light chain, a marker of neurodegeneration, and plasma metabolites, suggesting a link between neurodegeneration and biological pathways associated with Alzheimer's disease pathology. Further validation in independent cohorts is needed to explore the potential of these metabolites as prognostic markers for neurodegenerative diseases.