Changes in apparent diffusion coefficient (ADC) for acute mountain sickness (AMS) and no-AMS groups across different cerebral regions (basal ganglia, gray matter, white matter, splenium of corpus callosum, genu of corpus callosum—see text for details. Panels (A), (B), and (C) are same time periods as Figure 1). The no-AMS group shows a broadly similar pattern in all regions with increased ADC at 2 days hypoxia relative to normoxia (A), which is still elevated at 7 days hypoxia (B). The AMS group show decreased ADC when symptomatic at 2 days hypoxia in basal ganglia, gray matter, and white matter (A), with normalization or increased ADC at 7 days when asymptomatic (B). Different pattern of ADC change is seen in the AMS group in corpus callosum: in the splenium (CC splen.) ADC is initially increased despite symptoms of AMS (A), which increases further at 7 days (B). In the genu (CC Genu), the ADC is initially reduced at 2 days hypoxia relative to normoxia, and shows no change by 7 days despite recovery of symptoms (B, C). Data are mean changes. Error bar=1s.d. Significant differences in ADC at both 2 days and 7 days hypoxia relative to normoxia (P<0.05, main effect of AMS), and between regions at 7 days (P<0.01, AMS × region interaction).