ABO and Alzheimer disease: Compared to the brains of subjects in control groups, increased AβO levels in AD brains are associated with severe cognitive impairment and loss of synaptic markers 37; plasma AβOs are negatively correlated with Aβ42 concentrations in cerebrospinal fluid and Mini-Mental State Examination (MMSE) scores (Babapour Mofrad et al., 2021).