To explore if the associations with t-tau, p-tau and Aβ42 concentration change in the preclinical stage of AD, the individuals were dichotomized into two groups based on CSF Aβ42/Aβ40 ratio denoted as either amyloid-positive (A+) or amyloid-negative (A−) (Table 1). This evidence concerns the gene MAPT and Alzheimer disease.