The association among plasma p‐tau181, cognitive progression and structural brain change in early Alzheimer’s disease

Abstract

AbstractBackgroundPlasma levels of phosphorylated tau 181 (p‐tau181) is one of the potential blood‐based biomarkers for the diagnosis of Alzheimer’s disease (AD). However, the association among plasma p‐tau181 and cognitive progression and structural brain change still needs to be investigated.MethodAD and mild cognitive impairment (MCI) patients diagnosed with a multidisciplinary consensus meeting were recruited. Cognitive function was assessed at baseline and at annual follow‐ups. Plasma p‐tau181 levels at baseline were measured using Quanterix SIMOA kits. The regional cortical thickness and volumes of baseline brain MRI were measured using the FreeSurfer image analysis suite. T‐tests and multiple regression were used for analyses. FDR tests were performed for multiple comparisons.ResultA total of 162 AD and 19 MCI patients were recruited (mean age = 77.4 ± 7.3 years, 42% male, 37% APOE ɛ4 carrier, and mean MMSE = 20 ± 5.4). There were 137 patients (75.7%) having at least two annual follow‐up and the mean follow‐up time was 2.1 ± 0.4 years. The baseline plasma p‐tau181 levels were correlated with the rates of MMSE decline per year (r = 0.284, p < 0.001). After adjusting for age, gender, education, APOE ɛ4 status and baseline MMSE, the baseline plasma p‐tau181 levels were still correlated with the yearly MMSE decline (β = 0.292, p = 0.001) and was able to predict MMSE decline>3 per year (OR = 4.03, 95% CI 1.47–11.05). There were 152 patients (135 AD and 17 MCI) with valid brain MRI. The cross‐sectional analyses with adjustments of age, gender, education and APOE ɛ4 status showed significant association between plasma p‐tau181 levels and left hippocampus volume (β = ‐0.205, p = 0.010), right hippocampus volume (β = ‐0.213, p = 0.009) and right middle temporal thickness (β = ‐0.292, p < 0.001).ConclusionHigher plasma p‐tau181 levels were associated with the faster rate of MMSE decline in AD and MCI patients as well as the decreased volume and cortical thickness of several AD‐specific brain areas. Our study suggested that the plasma p‐tau181 could be a potential biomarker for tracking cognitive decline and reflecting structural brain changes in AD and MCI patients.