Together with medial temporal lobe atrophy on MRI [114–118] or FDG-PET [119] and presence of the APOE ɛ4 allele, these markers predict dementia in mild cognitive impairment or higher risk for developing AD [83, 89, 120] as does rCBF-SPECT [121] and cerebral hypoperfusion induced by fMRI [122] and plasma Aβ-42, medial temporal lobe atrophy and homocysteine [123]. This evidence concerns the gene APOE and Alzheimer disease.