Background To examine the patterns of longitudinal tau accumulation and cortical atrophy and their association in patients with mild cognitive impairment (MCI). Methods We collected 23 participants (60-89 years old, 11 male/12 female) with MCI from the Alzheimer's Disease Neuroimaging Initiative database. All participants underwent 18 F flortauirpir (FTP) positron emission tomography (PET) and structural magnetic resonance imaging (MRI) scans at the baseline and follow-up visits (12-36 months).

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... General linear models with covariates (baseline age, sex) were used to detect brain areas of significant tau accumulation and atrophy over time. The mediation analysis was employed to explore the potential reason for sequential biomarker changes in MCI progression, adjusting for baseline age, sex, education.Results Voxelwise tau accumulation in MCI patients was predominantly located in inferior temporal, middle temporal, parietal cortex, posterior cingulate, precuneus as well as temporo-parietal regions ( P < 0.001), and MRI atrophy included inferior-middle temporal, parietal lobe, cerebellum and precuneus ( P < 0.001). Longitudinal FTP accumulation was moderately associated with MRI cortical atrophy ( r = 0.409, 95% CI: 0.405-0.414, P < 0.01). Regional analyses indicated significant bivariate associations between MRI cortical atrophy and FTP accumulation (baseline FTP cortical uptake and longitudinal FTP change). The result of the mediation analysis showed the relationship between baseline FTP uptake and longitudinal cortical atrophy was partly mediated by the longitudinal FTP cortical change (indirect effect: 0.0107, P = 0.04).Conclusions Our finding provides a preliminary description of the patterns of longitudinal FTP accumulation and cortical atrophy in MCI progression, and MCI patients with high tau binding level show increase risk of longitudinal tau accumulation, atrophy and cognitive decline.