AQP4 and neurodegenerative disease: The patients were later organised into a dichotomised classification depending on the AQP4 concentrations compared to the median: AQP4-High and AQP4-Low groups were defined, and there was a significant association between neurodegenerative patients and the AQP4-High group (AQP4-High: 42 patients with neurodegenerative disease and 21 subjects without neurodegenerative disease; AQP4-Low: 28 patients with neurodegenerative disease and 33 subjects without neurodegenerative disease; chi-squared test: χ2 = 5.44, p = 0.020) (Fig. 2).