The addition of a second PET scan resulted in a further change in the etiological diagnosis in 9% (4/43; χ2 = 0.25, p = 0.617) of dementia patients both after amyloid-PET and after tau-PET (Table 2), with no difference between the two exams (χ2 = 0, p = 1.00). This evidence concerns the gene MAPT and dementia.