MAPT and Cognitive impairment: According to recent research, patients with AD dementia have higher serum P-tau-181 levels (Mielke et al., 2018), which correlate with the levels of tau protein in the cerebrospinal fluid and can also predict the progression of the disease in participants with normal cognitive function and in patients with mild cognitive impairment (Janelidze et al., 2020; Thijssen et al., 2020; Karikari et al., 2021).