Phonetic and phonological aspects of speech in Alzheimer’s disease

ABSTRACT

Background: Alzheimer’s disease (AD) can involve changes in communication and can lead to mutism in severe cases. Oral communication may be impaired by phonetic-motor disorders, such as apraxia of speech (AOS), or by language disorders, such as aphasia. Therefore, the identification of manifestations of AOS and phonemic paraphasias in patients with AD is critical to understanding the communication changes and determining the therapeutic planning.

Aims: To identify the distribution of phonetic–phonological manifestations in older patients with AD and healthy older subjects and assess whether these manifestations indicate the origin of the changes, including a predominantly phonetic-motor origin, a predominantly phonological–linguistic origin, or both.

Methods & Procedures: This cross-sectional study evaluated 90 patients with AD and 30 healthy older volunteers. All of the participants underwent the same repetition task for phonetic and phonological assessments using the current classification of phonetic–phonological manifestations; this classification distinguishes characteristics that are mostly related to AOS from other signs that are mostly related to aphasia. Negative binomial regression analysis was conducted to compare the amount of each manifestation presented by the two groups.

Outcomes & Results: The patients with AD showed significantly more signs of aphasia (self-correction, and vowel and consonant substitutions), AOS (prolonged intervals and extended vowel duration), and AOS or aphasia (distortion, omission, attempts at the syllable level, distorted substitutions, and additions) than the healthy older volunteers.

Conclusions: Older adults with AD presented phonetic and phonological changes of aphasia and AOS and, consequently, limitations in symbolic–linguistic planning and motor planning.

KEYWORDS:

• Speech-language pathology
• Alzheimer’s disease
• speech
• language
• aging

Acknowledgments

The authors are grateful to the participants for their time and effort. We also thank Tamy Tsujimoto for the statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors gratefully acknowledge the funding for this project provided by the State of São Paulo Research Foundation (FAPESP 2008/52670-1), the National Council for Scientific and Technological Development (CNPq 132979/2008-0), and the Coordination for the Improvement of Higher Education Personnel (CAPES). Thaís Minett is funded as an Academic Clinical Fellow from the National Institute for Health Research.