Articulatory and phonological performance in people with mild cognitive impairment and Alzheimer's disease: A scoping review

Background: Markers of phonological and articulatory processing, though at times difficult to identify, may be useful for the assessment of changes in the speech of people with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Objective: To review the evidence on phonological and articulatory speech processing in older adults with MCI and AD and identify the most sensitive speech assessment tasks for detecting impairments in these abilities. Methods: This scoping review of the PubMed, Scopus, Lilacs, Web of Science, Google Scholar, ProQuest, and Embase databases was updated in April 2024. Studies of older adults with MCI and AD that evaluated articulatory or phonological aspects of speech were included in the review. Two independent reviewers used EndNote and Rayyan software to evaluate search results in a two-phase process, consisting of (1) title and abstract screening, and (2) full-text review. Results: Of the 163 studies retrieved, 41 were selected in Phase 1. At the end of Phase 2, 29 studies were included in the review. All studies included individuals with AD and only one also included participants with MCI. Normal phonological and articulatory performance was observed in MCI. In AD, phonological or articulatory alterations were associated with the speech assessment method, sample size, and diagnosis of atypical dementia. Conclusions: Phonological and articulatory changes may occur in AD but may be difficult to identify. Single repetition or naming tasks may be more sensitive for detecting these impairments.