AQP4 and dementia: An important observation in the patients with IIH is that the perivascular expression of AQP4 was not reduced, as opposed to the dementia subtype idiopathic normal pressure hydrocephalus (iNPH), which presented with loss of perivascular AQP4 expression (Eide and Hansson, 2018; Hasan-Olive et al., 2019a).