Language deficits across PET-based Braak stages of tau accumulation in Alzheimer's disease

INTRODUCTION. Widespread language complaints in the cognitively unimpaired (CU) may reflect Alzheimer's Disease (AD) pathology and future objective impairments. METHODS. 138 CU, 45 mild cognitive impairment and 28 dementia participants from the TRIAD cohort underwent 18F-MK-6240 tau-PET and 18F-AZD-4694 amyloid-PET. Word-finding complaints, confrontation naming, semantic and phonemic fluency and word-knowledge were evaluated. Covariance, direct and stepwise discriminant, and voxel-wise regression analyses were conducted. RESULTS. Word-finding complaints appeared in early tau stages (Braak 1-2), followed by naming difficulties (Braak 3-4), and widespread language impairments in later stages (Braak 5-6). Complaints over forgetting the names of objects, naming, and APOE significantly improved classification of early AD pathology. In CU, complaints over forgetting names of objects were linked to left fusiform and inferior temporal gyri tau accumulation. DISCUSSION. Language measures are useful in detecting and tracking AD-related pathophysiologies. Results encourage refinement of clinical tools for early detection and disease monitoring.