Increase in Plasma S100B Concentration is Associated with Decrements in Spatial Processing During Acute High-Altitude Exposure

Vasogenic edema consequent to blood-brain barrier (BBB) permeability may contribute to cognitive performance decrements during acute exposure to high altitude. S100B is a putative marker of BBB permeability, but S100B responses to high altitude are poorly characterized and the relation to cognitive performance is unknown. To test the hypothesis that S100B increases upon ascent to high altitude and that increase is associated with changes in cognitive performance, 41 healthy Soldiers (mean±SD; age=26±5yr) were tested at their baseline residence (SL, 331m), transported to Taos, NM (2845m), then immediately hiked (n=21) or were driven (n=20) to a high-altitude (HA, 3600m) facility. Plasma S100B was measured at 06:00 throughout the study; twice at SL and again after the first night at HA (16h exposure). The automated neuropsychological assessment metric (ANAM) was administered four times at SL and once at HA to assess sustained attention, working memory, spatial processing, computation, executive function, and reaction time. ANAM performance was assessed using throughput scores, a metric considering both response speed and accuracy. The last SL morning assessment and the HA morning assessment (19h exposure) were used to generate ΔANAM scores. Correlations between ΔS100B and ΔANAM scores were significant for 1 of 9 modules, simultaneous spatial processing (SPD; r=-0.401; p=0.009). S100B increased (5.3%, p=0.02) from SL to HA while SPD scores decreased (8.2%, p=0.05). Using the reliable change index (RCI) to dichotomize individuals into those demonstrating a decrease in performance that exceeded measurement error and day-to-day variability (responders; RCI <-1.64; n=7) and those who did not (non-responders; RCI >-1.64; n=34) revealed that responders experienced a greater increase (+12.3%, p=0.01) in S100B from SL to HA relative to non-responders (+3.4%, p=0.14) Findings suggest that acute exposure to 3600m may increase BBB permeability, as indicated from plasma S100B concentrations, and the increased BBB permeability may be mechanistically associated with spatial processing decrements. Funding: USAMRDC, PRMRP. Authors’ views not offcial U.S. Army or DoD policy. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.