AIF1 and Alzheimer disease: Aside from two studies considering risk variants [14, 37], prior studies investigating the relationship of IBA1 and AD predominately categorized patient samples based on a broad clinical diagnosis of AD and did not consider individual patient demographics, such as AAO (defined herein as the age at first clinical presentation of symptoms), AAD, symptom duration, the Aβ(1–42)/Aβ(1–40) ratio, which is used as a putative diagnostic of disease [46–48], or sex, which has been implicated as a risk factor for certain types of AD [28, 49].