Background: Neurological symptoms are common in acute mountain sickness (AMS); however, the extent of neuroaxonal damage remains unclear. Neurofilament light chain (NfL) is an established blood biomarker for neuroaxonal damage.
Objective: To investigate whether plasma (p) NfL levels increase after simulated altitude exposure, correlate with the occurrence of AMS, and might be mitigated by preacclimatization.
Methods: Healthy subjects were exposed to simulated high altitude (4500 m) by the use of a normobaric hypoxic chamber at the University of Innsbruck two times, that is, within Cycle 1 (C1) over 12 h, and within Cycle 2 (C2) for another 12 h but with a random assignment to prior acclimatization or sham acclimatization. Before each cycle (measurement [M] 1 and 3) and after each cycle (M2 and M4), clinical data (arterial oxygen saturation [SaO2], heart rate, and Lake Louise AMS score [LLS]) and plasma samples were collected. pNfL was measured using single-molecule array (Simoa) technique.
Results: pNfL levels did not significantly change within each study cycle, but increased over the total study period (M1: 4.57 [3.34-6.39], M2: 4.58 [3.74-6.0], M3: 5.64, and M4: 6.53 [4.65-7.92] pg/mL, p < 0.001). Subjects suffering from AMS during the study procedures showed higher pNfL levels at M4 (6.80 [6.19-8.13] vs. 5.75 [4.17-7.35], p = 0.048), a higher total pNfL increase (2.88 [1.21-3.48] vs. 0.91 [0.53-1.48], p = 0.022) compared to subjects without AMS. An effect of preacclimatization on pNfL levels could not be observed.
Conclusions: pNfL increases alongside exposure to simulated altitude and is associated with AMS.
Keywords: acute mountain sickness; biomarker; headache; high altitude; neurofilament light chain.
© 2024 The Author(s). Brain and Behavior published by Wiley Periodicals LLC.