Objective: In this study, we explored speech characteristics of Korean Parkinson’s disease (PD) patients and their usefulness as a biomarker.

Background: Previous studies have shown that speech disorders in PD reflect motor and non-motor cognitive dysfunctions. Yet, many studies have only focused on English-speaking patients without considering that languages differ in many ways from pronunciation to word order in sentences.

Method: Healthy controls (HC; n=13) and PD patients with a Hoehn and Yahr scale of 2 or less, a disease duration of less than 5 years, and without motor fluctuations or dyskinesia (n=58) were enrolled at baseline. We examined participants’ speech, motor, and cognitive functions in a medication-off state. Speech tasks included a sustained phonation task (pronouncing the vowel /a/ as long as possible), a diadochokinetic task (repeating /pa-ta-ka-/ more than 7 times as quickly as possible), a paragraph reading task, and picture description tasks. Speech parameters were automatically extracted using a speech activity detector, openSMILE, and the DDKtor package in Python. Differences between the two groups were assessed using the non-parametric Mann-Whitney U test. The Spearman’s correlation coefficient was used to examine the correlation between speech measures and clinical assessments. Receiver operating characteristic (ROC) analyses were performed to assess the prediction accuracy of speech index for PD.

Results: Almost all patients did not show any noticeable speech problems when measured in MDS-UPDRS item 2.1 (0, n=57 (98.3%)). However, PD patients showed increased jitter variability (p=0.039) and decreased diadochokinetic rate (DDKR; p=0.017), compared to HC. PD patients also produced fewer conjunctions per 100 words than HC (p=0.031). When the composite speech index was calculated by combining normative jitter variability and DDKR, the index correlated with the MDS-UPDRS part 3 score (r_s=0.269, p=0.043), depression scale (r_s=0.363, p=0.006), and verbal disfluency (r_s=−0.315, p=0.018), showing good discriminatory power in distinguishing PD patients from HC (Area under the ROC curve=0.776; p=0.002).

Conclusion: Features of voice quality, articulation, and fluency in the speech of Korean PD patients significantly differed from those of HC. The composite speech index obtained from these measures may be used for screening and monitoring PD patients as it correlates with motor function, depression, and cognition.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/speech-features-in-korean-parkinsons-disease-patients-a-prospective-cohort-study/