Speech and language in healthy ageing and Alzheimer’s dementia

Healthy ageing involves cognitive and functional declines, including changes in speech and language abilities, many of which intensify in Alzheimer’s dementia. In this Review, I survey speech and language research in older adults with and without Alzheimer’s dementia, considering reception (listening, reading) and production (speaking). First, I introduce approaches to measuring speech and language, including neuropsychological tests, psycholinguistic paradigms, clinical linguistic assessments, and automated speech and language analysis. Second, I synthesize findings on speech and language in healthy older adults, typified by minor difficulties with motor speech, phonology and morphosyntax; reduced word-processing speed and pragmatic and discursive skills; and increases in vocabulary size. Third, I summarize results from patients with Alzheimer’s dementia, which reveal partial sparing of motor speech and phonological and morphosyntactic abilities alongside reduced vocabulary, slower word processing, and pragmatic and discursive deficits. Fourth, I highlight the potential of automated speech and language analysis for early and preclinical detection, syndrome differentiation and severity estimation in Alzheimer’s dementia. Fifth, I consider methodological shortcomings and the impact of inequitable language coverage across these studies. Last, I outline multicentric, transdisciplinary, intersectoral efforts to tackle such gaps. Healthy ageing involves cognitive and functional declines, many of which intensify in Alzheimer’s dementia. In this Review, Garcia outlines key age-related changes in speech and language abilities and how these typical changes differ from changes observed in Alzheimer’s dementia.