Silence speaks volumes a fine-frained analysis of pause production reveals group differences on the spectrum of cognitive decline
Year: 2024
Type: dissertation
Study design: Observational Study
Abstract: Previous evidence suggests that increased pause production in spontaneous speech can indicate cognitive decline in Alzheimer’s disease (AD), and that this may depend on the linguistic context of the pause, such as syntactic location. This study aimed to further characterize pauses in AD by examining their context related to syntactic boundaries, lexical demands, and disfluencies. The research consists of three independent studies, involving two cohorts in three different languages. Speech samples were obtained from picture description tasks, in groups across different cross sections of the cognitive decline spectrum. The first data set included English descriptions from healthy controls (n=40), mild AD (n=21), and moderate AD (n=19). The second data set included Spanish and Catalan descriptions from healthy controls (n=19), subjective cognitive decline (SCD) (n=31), mild cognitive impairment (MCI) (n=39), and AD (n=31). Pauses were analyzed based on their location relative to syntactic constituents: utterance, clause, and phrase. Pairwise group comparisons were conducted, and significant differences were correlated with neuropsychological data. In the first study, AD groups showed increased pause rates compared to healthy controls, with mild AD having more within-clause pauses and moderate AD more clauseboundary pauses. The second study found that temporal speech production measures varied more across groups than pitch measures, with AD producing the longest pauses and SCD the shortest. The third study separated pauses before fluent speech from pauses before disfluencies. In the fluent pause analysis, AD groups had the longest utterance-boundary and phrase-boundary pauses, while SCD again had the shortest. In the analysis of pauses before disfluencies, there were also fewer self-repairs in SCD and increased word repetition in AD. Correlations showed a positive association between processing speed/executive function and the duration of word-finding pauses, and a negative association with pauses before disfluencies. SCD deviated from the positive correlation pattern seen in other groups. The results suggest early word-finding difficulties in mild AD, progressing to challenges in organizing thoughts into utterances, as suggested by pauses in major boundary positions. A pattern of hyperfluency (as indexed by increased speech rate and decreased pauses) in SCD may be due to internal performance pressure, leading to faster speech at the cost of monitoring. Increased pausing and repetition in AD may reflect early working memory decline, resulting in smaller speech chunks. These results underscore the need and utility of integrating syntactic context measures into fluency investigations to provide further insight into the nature of linguistic decline on the spectrum of cognitive decline in association with AD dementia.
Author: Lofgren, Mary
Language: English
Subfield: Psychiatry and Mental health
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7110580423
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