Increased concentrations of phosphorylated tau in the brain have been connected to a progressive reduction in cognitive function, and research has shown that p-tau concentrations in the CSF are 3.4 times larger in AD patients than in healthy controls, while elevated t-tau is not connected to the course of the disease (Toledo et al., 2011; Laske et al., 2017; Müller et al., 2017; Clark et al., 2021; Frank et al., 2022). This evidence concerns the gene MAPT and Alzheimer disease.