Abstract
BACKGROUND: Serum neurofilament light chain (NfL) is a biomarker of brain injury. We examined the associations of serum NfL concentration with able life and healthy life among older adults.
METHODS: We analyzed Cardiovascular Health Study participants with measured NfL and no history of stroke or transient ischemic attack (TIA). Over 13 years' follow-up, outcomes were years of life (YOL), years of able life (YAL), years of healthy life (YHL), and proportion of follow-up spent able (YAL/YOL%) or healthy (YHL/YOL%). "Able" was defined by independence in all activities of daily living, and "healthy" was defined by self-reported health status. Linear regression and linear spline regression models were used to estimate the difference in each outcome associated with a 50% increment in serum NfL, an increment within the range of the observed data.
RESULTS: Among 1957 participants (mean age 77.8; 61% female), in the adjusted linear model, each 50% increment in NfL was associated with 0.6 fewer YOL (95% CI: -0.7, -0.4), 0.7 fewer YAL (-0.8, -0.5), 0.5 fewer YHL (-0.7, -0.4), 2.9% lower YAL/YOL% (-4.0%, -1.7%) and 1.8% lower YHL/YOL% (-3.1%, -0.6%). Spline analysis showed the strongest associations at NfL of 19.7-33.9 pg/mL, where each 50% increment in NfL was associated with 6.5% lower YAL/YOL% (-9.4%, -3.6%) and 5.6% lower YHL/YOL% (-8.8%, -2.4%).
CONCLUSIONS: Higher serum NfL concentration was associated with less able and healthy life among older adults free of stroke or TIA. Further investigation of NfL, including longitudinal evaluation, is needed to understand its relationship with functional status.