Participants with SCD had significantly higher levels of Aβ1−42 and Aβ1−42/1−40 compared to those with aMCI due to AD and AD dementia (p < .001), significantly lower levels of p-tau 181 compared to patients with aMCI due to AD (p < .001), AD dementia (p < .001), and FTLD dementia (p = .005), t-tau compared to those with aMCI due to AD (p < .001), AD dementia (p < .001), and FTLD dementia (p < .001), and NfL compared to FTLD dementia (p = .009). This evidence concerns the gene MAPT and Alzheimer disease.