Associations of Serum Neurofilament Light Chain Concentration with Able Life and Healthy Life in Older Adults: The Cardiovascular Health Study

Abstract

Serum neurofilament light chain (NfL) is a sensitive biomarker of brain injury, which has been increasingly used to prognosticate and monitor disease activity and treatment response in neurological diseases. Neural injury impacts the ability to live independently and maintain long-term health. These analyses aimed to examine the association of serum NfL concentrations with able life and healthy life among older adults. We used data from the Cardiovascular Health Study (CHS), a longitudinal cohort study of adults aged 65 and older. Eligible participants in our analyses were free of stroke or transient ischemic attack (TIA) and had serum NfL measured. Over 13 years of follow-up, outcomes were years of life (YOL), years of able life (YAL), years of healthy life (YHL), YAL/YOL%, and YHL/YOL%. “Able” was defined by independence in activities of daily living (ADLs), and “healthy” was defined by self-reported health status. Associations of serum NfL with each outcome were assessed using linear regression and spline linear regression models. A total of 1,957 participants (mean age 77.8) were included. In the fully adjusted linear model, each doubling of NfL concentration was associated with 1.0 fewer YOL, 1.2 fewer YAL, 0.9 fewer YHL, 4.9% lower YAL/YOL% and 3.1% lower YHL/YOL%. Spline analysis showed the strongest associations at NfL concentration of 19.7–33.8 pg/mL (between the 25th-75th percentiles), where each doubling of NfL concentration was associated with 11.2% lower YAL/YOL% and 9.5% lower YHL/YOL%. Although women lived longer than men, they spent a smaller proportion of follow-up able and healthy. Serum NfL concentration might serve as a valuable predictor of able and healthy life among older adults free of stroke or TIA. The goal of incorporating this biomarker into routine examination would be to enable earlier interventions to preserve ADLs and extend both able and healthy life expectancy.