Changes in Blood Biomarkers of Brain Injury and Degeneration Following Long-Duration Spaceflight

Abstract

This study investigates the longitudinal course of blood-based biomarkers representing the brain parenchyma in long-duration spaceflight.

Figure.. Timeline for Neurofilament Light Chain, Glial Fibrillary Acidic Protein, Total Tau, and Aβ₄₂/Aβ₄₀ Ratio Response

A, Neurofilament light chain protein showed a 33% increase on day 1 and a 50% increase 1 week after return from a long-duration mission compared with preflight measurements. This may represent an axonal injury. B, Glial fibrillary acidic protein showed an increase of 20% and 27% for the same comparisons in time, pointing to a concurrent and sustained astrocytic response. C, Total tau protein as a surrogate for the neuronal tissue showed nonsignificant elevation for the first week postflight with a significant drop of more than 50% below baseline levels 3 weeks after return to Earth. D, Amyloid β (Aβ)₄₀ and Aβ₄₂ increased significantly postflight (Table) with the stronger relative elevation in Aβ_40. Therefore, the course for the ratio of the 2 amyloid proteins, Aβ₄₂/Aβ₄₀, showed a decreasing trajectory after return to Earth from a long-duration mission. This kind of downward trajectory is often viewed as unfavorable with respect to long-term brain health in the general population. The solid line represents the mean group response, while dashed lines show the individual’s parameter course. Error bars give the standard error of mean for each time point. Actual percentage change from preflight baseline indicated for the greatest deviation for the respective parameter.