HMGB1 and Alzheimer disease: Notably, while some studies have reported elevated levels of HMGB1 in the CSF or sera of AD patients [16,30] or mouse models [31], the total amount of HMGB1 protein in brain tissue—for example, in the hippocampus—is inconsistent; in some studies, the levels were increased [30,32,33], whilst in others there was no difference [34].