Detecting Effect of Levodopa in Parkinson’s Disease Patients Using Sustained Phonemes

Abstract

Background: Parkinson’s disease (PD) is a multi-symptom neurodegenerative disease generally managed with medications, of which levodopa is the most effective. Determining the dosage of levodopa requires regular meetings where motor function can be observed. Speech impairment is an early symptom in PD and has been proposed for early detection and monitoring of the disease. However, findings from previous research on the effect of levodopa on speech have not shown a consistent picture. Method: This study has investigated the effect of medication on PD patients for three sustained phonemes; /a/, /o/, and /m/, which were recorded from 24 PD patients during medication off and on stages, and from 22 healthy participants. The differences were statistically investigated, and the features were classified using Support Vector Machine (SVM). Results: The results show that medication has a significant effect on the change of time and amplitude perturbation (jitter and shimmer) and harmonics of /m/, which was the most sensitive individual phoneme to the levodopa response. /m/ and /o/ performed at a comparable level in discriminating PD- off from control recordings. However, SVM classifications based on the combined use of the three phonemes /a/, /o/, and /m/ showed the best classifications, both for medication effect and for separating PD from control voice. The SVM classification for PD- off versus PD- on achieved an AUC of 0.81. Conclusion: Studies of phonation by computerized voice analysis in PD should employ recordings of multiple phonemes. Our findings are potentially relevant in research to identify early parkinsonian dysarthria, and to tele-monitoring of the levodopa response in patients with established PD.

Short-term effect of dopaminergic medication on speech in early-stage Parkinson’s disease

“…Interestingly, probably the most effort has been put into the investigation of the short-term effect of levodopa on voice quality; however, the results remain inconclusive. Whereas some authors found jitter, shimmer, HNR, cepstral peak prominence or pitch breaks to be unresponsive to short-term dopaminergic stimulation 5 , 6 , 9 , others were pointing to a dopamine-related amelioration in phonatory parameters 13 , 15 , 17 . Cushnie-Sparrow et al 6 divided patients into two groups based on voice quality severity perceptually evaluated by three listeners and found that only PD patients with poor voice quality off-medication showed improvements in voice quality on-medication, while those with better voice quality did not.…”

“…Yet, the available evidence about the effect of levodopa on speech in PD is limited due to small sample sizes, heterogeneity of studied population, lack of concise and valid speech recording and analysis methodology, and lack of motor scores. After levodopa intake, improvements in voice quality 13 , 15 , 17 , loudness 11 , 19 , speaking rate 14 , speech dysfluency 12 , respiration 5 , 8 and overall speech intelligibility 8 have been reported, while other studies found no significant changes in voice quality 5 , 6 , 9 , loudness 5 , 10 , 18 , speaking rate 7 , 9 , 18 , vowel articulation 11 , 18 , consonant articulation 20 , monopitch 5 , 9 , 18 or respiration 9 , 16 . This inconsistency may be caused, at least partially, by different disease duration and motor severity of investigated PD patients.…”

“…This inconsistency may be caused, at least partially, by different disease duration and motor severity of investigated PD patients. While most of the studies focused on advanced 5 – 10 , 12 , 19 or mixed 11 , 13 , 15 – 17 , 20 stages, little is known about the acute effect of levodopa on speech in early PD patients 14 , 18 . Nevertheless, the stage of the disease may play an important role in a short-term levodopa response 21 , 22 .…”

Phonemes based detection of parkinson’s disease for telehealth applications

“…Table 2 provides the demographics of the subjects. The detailed information can be found in 22 , 32 .…”

“…Most of the studies were focused on the parameters that are closely related to impairments in vocal cord vibration. The pitch frequency variation, number of pulses, jitter (perturbation of the glottal vibration period), shimmer (amplitude perturbation of glottal vibration), autocorrelation, and harmonics to noise ratio (HNR/NHR) were used in the authors previous work 22 , as well as in the work of Orozco-Arroyave 23 , Behroozi et al 24 , Tsanas and Little 25 , Ali et al 26 , Sakar et al 19 , and Rusz et al 6 .…”