Profiling spontaneous speech decline in Alzheimer's disease: a longitudinal study

Abstract

Objective: This study aims to document the nature and progression of spontaneous speech impairment suffered by patients with Alzheimer's disease (AD) over a 12-month period, using both cross-sectional and prospective longitudinal design.

Methods: Thirty one mild-moderate AD patients and 30 controls matched for age and socio-cultural background completed a simple and complex oral description task at baseline. The AD patients then underwent follow-up assessments at 6 and 12 months.

Results: Cross-sectional comparisons indicated that mild-moderate AD patients produced more word-finding delays (WFDs) and empty and indefinite phrases, while producing fewer pictorial themes, repairing fewer errors, responding to fewer WFDs, produce shorter and less complex phrases and produce speech with less intonational contour than controls. However, the two groups could not be distinguished on the basis of phonological paraphasias. Longitudinal follow-up, however, suggested that phonological processing deteriorates over time, where the prevalence of phonological errors increased over 12 months. Discussion Consistent with findings from neuropsychological, neuropathological and neuroimaging studies, the language deterioration shown by the AD patients shows a pattern of impairment dominated by semantic errors, which is later joined by a disruption in the phonological aspects of speech.