Objective: This study aims to improve understanding of festinating speech as a potential source of intraspeaker variability by comparing speakers with and without Parkinson’s disease (PD), and to examine the effects of deep-brain stimulation (DBS) by comparing on and off conditions within individuals who underwent DBS.

Background: Festination refers to a pattern of increasingly rapid and poorly coordinated movement during repetitive movements and is often observed in PD. First described in gait, the concept has since been extended to handwriting and speech behaviors [1,2]. Festinating speech is characterized by progressively increasing articulation rate and breakdown, particularly in advanced stages [3]. Despite frequent use of the term, systematic investigations of repetition-to-repetition changes in festinating speech remain limited, especially in connected speech [4]. This study also extends ongoing efforts to characterize the complex and multifaceted effects of DBS on speech.

Method: Twenty-seven adult participants were included: 10 with idiopathic PD and without DBS, 9 with idiopathic PD with DBS, and 8 healthy controls. They repeated a syntactically complex sentence 10 times consecutively. Acoustic analyses targeted variables representing phonation, articulation, and prosody. For each variable and participant, a best-fit slope across repetitions was estimated using linear regression. Statistical analyses were conducted using linear mixed-effects models.

Results: Speakers with PD showed steeper downward trends than healthy controls for some, but not all, acoustic parameters across 10 repetitions, including vowel articulation and articulation rate. This festinating pattern was observed in approximately half of the participants, consistent with prior diadochokinetic findings [4]. However, although an overall decline across repetitions was observed, DBS status did not affect these performance trends, consistent with previous reports showing minimal to no speech changes associated with DBS [5,6].

Conclusion: Festinating speech appears to contribute to both intraspeaker and interspeaker variability in PD and does not seem to be influenced by DBS status. In this presentation, we will highlight the importance of speech-stimulus selection in PD research and discuss the possibility that festination may help identify clinically meaningful PD subtypes.

References: [1] Giladi, N., Shabtai, H., Rozenberg, E., & Shabtai, E. (2001). Gait festination in parkinson’s disease. Parkinsonism & Related Disorders, 7(2), 135-138.
[2] Morris, M. E., Iansek, R., & Galna, B. (2008). Gait festination and freezing in parkinson’s disease: pathogenesis and rehabilitation. Movement Disorders, 23(S2), S451-S460.
[3] Ho, A. K., Iansek, R., Marigliani, C., Bradshaw, J. L., & Gates, S. (1999). Speech impairment in a large sample of patients with Parkinson’s disease. Behavioural neurology, 11(3), 131-137.
[4] Moreau, C., Ozsancak, C., Blatt, J. L., Derambure, P., Destee, A., & Defebvre, L. (2007). Oral festination in Parkinson’s disease: biomechanical analysis and correlation with festination and freezing of gait. Movement disorders: official journal of the Movement Disorder Society, 22(10), 1503-1506.
[5] Nip, I. S., Burke III, M. M., & Kim, Y. (2023). The effects of deep brain stimulation on speech motor control in people with Parkinson’s disease. Journal of Speech, Language, and Hearing Research, 66(3), 804-819.
[6] Kim, Y., Thompson, A., & Nip, I. S. (2024). Effects of deep-brain stimulation on speech: perceptual and acoustic data. Journal of Speech, Language, and Hearing Research, 67(4), 1090-1106.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/festinating-speech-in-parkinsons-disease-effects-of-deep-brain-stimulation-and-interspeaker-variability/