KNG1 and dementia: Factor XIIa levels in blood and CSF elevate progressively as the disease worsens, cleaved HK levels correlate with clinical dementia and neuritic plaque scores, and an antibody to HK prevents its cleavage by Aβ, while an antibody that blocks binding of prekallikrein and factor XI to HK inhibits intrinsic coagulation induced by Aβ.