Contribution of Alzheimer's disease pathology to biological and clinical progression: A longitudinal study across two cohorts.

ABSTRACT

INTRODUCTION: Amyloid beta (Aß) deposition, tau accumulation, and brain atrophy occurr in sequence, but the contribution of Alzheimer's disease (AD) pathology to biological and clinical progression remains unclear. METHODS: We included 290 and 70 participants with longitudinal assessment on Aß-positron emission tomography (PET), tau-PET, magnetic resonance imaging, and cognitive function from the Harvard Aging Brain Study (HABS) and Alzheimer's Disease Neuroimaging Initiative (ADNI) datasets, respectively. Partial least squares structural equation modeling (PLS-SEM) was used to determine the contribution of AD pathology to the biological and clinical longitudinal changes. RESULTS: Imaging biomarkers and cognitive function were significantly associated in cross-sectional and longitudinal analyses. At the final time point, the percentage of variance explained by PLS-SEM was 27% for Aß, 30% for tau (Aß accounted for 61%), 29% for brain atrophy (tau accounted for 37%), and 37% for cognitive decline (brain atrophy accounted for 35%). DISCUSSION: This study highlights distinctive contributing proportions of AD pathology to biological and clinical progression. Treatments targeting Aß and tau may partially block AD progression.