Longitudinal speech rate in progressive AOS (Utianski et al., 2021)

Purpose: Individuals with primary progressive apraxia of speech (PPAOS) have apraxia of speech (AOS) in which disruptions in articulation or prosody predominate the speech pattern, referred to, respectively, as phonetic or prosodic subtypes. Many develop aphasia and/or dysarthria. Past research has demonstrated that simple temporal acoustic measures are sensitive to the presence of AOS. The aim of this study was to describe the change in temporal acoustic measures over time and assess if specific patterns of AOS or co-occurring aphasia or dysarthria impact the rate of change over time.

Method: Durations for multiple productions of the words cat, catnip, catapult, and catastrophe, in an imitative speech task, were recorded for 73 patients, with two to six visits each. A linear mixed-effects model was used to assess the cross-sectional differences and longitudinal influence of AOS subtype and presence of aphasia/dysarthria on speech rate. Pearson correlations were calculated between rate measures and performance on other clinical measures.

Results: Cross-sectionally, patients with prosodic-predominant PPAOS produced words more slowly than those with phonetic-predominant PPAOS. Patients with either aphasia or dysarthria produced words more slowly than those without. Longitudinally, the speech rate of patients with phonetic-predominant PPAOS had a reduction of 0.5 syllables per second per year. Patients with prosodic-predominant AOS changed less quickly, as did those who developed aphasia. Dysarthria did not impact rate of change. There were strong associations between speech rate measures and other clinical indices of speech and language functioning.

Conclusion: Simple temporal acoustic measures may reflect the subtype of AOS (phonetic or prosodic predominant), serve as an index of progression of AOS, and inform prognostication relative to the presenting combination of speech and language features.

Supplemental Material S1. Correlations between the baseline rate (syllables/second) of production of the word catastrophe with Apraxia of Speech Rating Scale-3 (ASRS-3) Total score, and Phonetic and Prosodic subscores. The correlation is calculated across all patients; AOS subtype is shown for demonstrative purposes. Not surprisingly, the correlation is strongest with the prosodic subscore, in which one item specifically rates the overall speech rate.

Utianski, R. L., Martin, P. R., Hanley, H., Duffy, J. R., Botha, H., Clark, H. M., Whitwell, J. L. & Josephs, K. A. (2021). A longitudinal evaluation of speech rate in primary progressive apraxia of speech. Journal of Speech, Language, and Hearing Research. Advance online publication. https://doi.org/10.1044/2020_JSLHR-20-00253