MAPT and Alzheimer disease: Previous studies have demonstrated that higher concentrations of p-tau are associated with cognitive decline and memory impairment.34 Yet p-tau begins to accumulate during the mild cognitive impairment stage, so it cannot be reliably used as a predictor of AD, only as a diagnosis.34 Additionally, lower plasma Aβ42/40 ratios have been linked to an increased risk of Alzheimer's disease incident and greater cognitive decline.32 Our negative findings could be attributed to our limited sample size as well as shorter follow-up times.