Dopaminergic Treatment Effects on Dysarthric Speech: Acoustic Analysis in a Cohort of Patients With Advanced Parkinson's Disease

Abstract

Importance: The effects of dopaminergic treatment on speech in patients with Parkinson's disease (PD) are often mixed and unclear. The aim of this study was to better elucidate those discrepancies.Methods: Full retrospective data from advanced PD patients before and after an acute levodopa challenge were collected. Acoustic analysis of spontaneous monologue and sustained phonation including several quantitative parameters [i.e., maximum phonation time (MPT); shimmer local dB] as well as the Unified Parkinson's Disease Rating Scale (UPDRS) (total scores, subscores, and items) and the Clinical Dyskinesia Rating Scale (CDRS) were performed in both the defined-OFF and -ON conditions. The primary outcome was the changes of speech parameters after levodopa intake. Secondary outcomes included the analysis of possible correlations of motor features and levodopa-induced dyskinesia (LID) with acoustic speech parameters. Statistical analysis included paired t-test between the ON and OFF data (calculated separately for male and female subgroups) and Pearson correlation between speech and motor data.Results: In 50 PD patients (male: 32; female: 18), levodopa significantly increased the MPT of sustained phonation in female patients (p < 0.01). In the OFF-state, the UPDRS part-III speech item negatively correlated with MPT (p = 0.02), whereas in the ON-state, it correlated positively with the shimmer local dB (p = 0.01), an expression of poorer voice quality. The total CDRS score and axial subscores strongly correlated with the ON-state shimmer local dB (p = 0.01 and p < 0.01, respectively).Conclusions: Our findings emphasize that levodopa has a poor effect on speech acoustic parameters. The intensity and location of LID negatively influenced speech quality.

Voice in Parkinson's Disease: A Machine Learning Study

“…We here demonstrated that L-Dopa exerts significant improvement of voice in mid-advancedstage patients. Furthermore, our clinical evaluation allowed us to demonstrate that L-Dopa improved voice less than other motor symptoms, a finding pointing to the weaker clinical effect of L-Dopa on axial signs in PD, as also shown by the correlations between LEDDs and VHI as well as UPDRS-III-v (1,27,30). By using an objective and automatic voice analysis, we demonstrated the significant effect of L-Dopa on voice in PD as suggested by high diagnostic accuracy in the comparison of patients OFF and ON therapy.…”

“…Another important finding in this study concerns the effect of L-Dopa on voice abnormalities in PD which is still a matter of debate given previous reports on beneficial ( 28 , 29 , 31 – 33 ) or null effect ( 27 , 30 ). We here demonstrated that L-Dopa exerts significant improvement of voice in mid-advanced-stage patients.…”

“…Also, it is relevant to verify whether machine learning can recognize the effect of disease severity by discriminating patients in different stages of the disease. Still, given that the symptomatic effect of L-Dopa on voice is still largely a matter of debate (1,10,(27)(28)(29)(30)(31)(32)(33), it is relevant to compare the instrumental voice analysis with machine learning in patients under and not under L-Dopa treatment.…”

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

“…Although dopaminergic treatment provides beneficial effects on motor manifestations, mixed results have been reported regarding the effect of levodopa challenge on speech in PD 5 – 20 . 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.…”

“…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.…”