AQP4 and Cognitive impairment: Despite being not able to demonstrate any significant difference between CAA-ICH patients and controls, this study showed a very interesting association between serum AQP4 levels and the load of cerebral haemorrhages in the CAA cohort; AQP4 levels were lower in the serum of patients suffering cognitive impairment, implying a very important link between Aβ clearance and AQP4 expression.