Effect of Levodopa on Speech Dysfluency in Parkinson's Disease

Higher Frequency of Stuttered Disfluencies Negatively Affects Communicative Participation in Parkinson's Disease

PURPOSE

Up to 90% of people with Parkinson's disease (PD) develop communication difficulties over the course of the disease. While the negative effect of dysarthria on communicative participation has been well-documented, the impact of the occurrence of acquired stuttered disfluencies on communication in different speech situations is unknown. This study aimed to determine if the frequency of occurrence of stuttered disfluencies affects communicative participation in individuals with PD, and whether such a relationship is mediated by examiner- and self-rated measures of disease severity.

METHOD

Conversational speech samples were collected from 100 people with PD aged 53-91 years to calculate the frequency of occurrence of stuttered disfluencies. Participants completed the Communicative Participation Item Bank to assess participation in communicative situations. Information on overall speech, cognitive, and motor performance was collected using both self-rated and examiner-rated methods.

RESULTS

Participants with PD presented with 0.2%-9.9% stuttered disfluencies during conversation. Overall, participants with PD reported their communicative participation to be impacted "a little" (19.5 ± 7.0), but there was considerable interindividual variation. A higher frequency of stuttered disfluencies was associated with significantly lower communicative participation (ρ = -0.32, p < .01). In addition, examiner-rated frequency of stuttered disfluencies (p < .01), speech (p < .01), and motor severity (p = .04) were all significant predictors of communicative participation. Using self-ratings, speech (p < .01) and cognitive (p < .01) measures significantly predicted communicative participation.

CONCLUSIONS

In people with PD, communicative participation was significantly worse for those with a higher frequency of stuttered disfluencies. Examiner- and self-rated measures of disease severity contributed different information related to communicative constraints. Together, these results highlight the importance of individualized and holistic speech therapy that considers a wide variety of symptoms, including stuttered disfluencies, to ensure positive functional outcomes.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.26850169.

Prosody matters: Preserved prominence marking strategies in people with Parkinson's disease independent of motor status

While many studies focus on segmental variation in Parkinsonian speech, little is known about prosodic modulations reflecting the ability to adapt to communicative demands in people with Parkinson's disease (PwPD). This type of prosodic modulation is important for social interaction, and it involves modifications in speech melody (intonational level) and articulation of consonants and vowels (segmental level). The present study investigates phonetic cues of prosodic modulations with respect to different focus structures in mild dysarthric PwPD as a function of levodopa. Acoustic and kinematic speech parameters of 25 PwPD were assessed in two motor conditions. Speech production data from PwPD were collected before (medication-OFF) and after levodopa intake (medication-ON) by means of 3-D electromagnetic articulography. On the acoustic level, intensity, pitch, and syllable durations were analyzed. On the kinematic level, movement duration and amplitude were investigated. Spatio-temporal modulations of speech parameters were examined and compared across three different prosodic focus structures (out-of-focus, broad focus, contrastive focus) to display varying speech demands. Overall, levodopa had beneficial effects on motor performance, speech loudness, and pitch modulation. Acoustic syllable durations and kinematic movement durations did not change, revealing no systematic effects of motor status on the temporal domain. In contrast, there were spatial modulations of the oral articulators: tongue tip movements were smaller and lower lip movements were larger in amplitude under levodopa, reflecting a more agile and efficient articulatory movement under levodopa. Thus, respiratory-phonatory functions and consonant production improved, while syllable duration and tongue body kinematics did not change. Interestingly, prominence marking strategies were comparable between the medication conditions under investigation, and in fact, appear to be preserved in mild dysarthric PwPD.

No differential effects of subthalamic nucleus vs. globus pallidus deep brain stimulation in Parkinson's disease: Speech acoustic and perceptual findings

Background

Deep Brain Stimulation (DBS) in the Subthalamic Nucleus (STN) or the Globus Pallidus Interna (GPI) is well-established as a surgical technique for improving global motor function in patients with idiopathic Parkinson's Disease (PD). Previous research has indicated speech deterioration in more than 30% of patients after STN-DBS implantation, whilst speech outcomes following GPI-DBS have received far less attention. Research comparing speech outcomes for patients with PD receiving STN-DBS and GPI-DBS can inform pre-surgical counseling and assist with clinician and patient decision-making when considering the neural targets selected for DBS-implantation. The aims of this pilot study were (1) to compare perceptual and acoustic speech outcomes for a group of patients with PD receiving bilateral DBS in the STN or the GPI with DBS stimulation both ON and OFF, and (2) examine associations between acoustic and perceptual speech measures and clinical characteristics.

Methods

Ten individuals with PD receiving STN-DBS and eight individuals receiving GPI-DBS were audio-recorded reading a passage. Three listeners blinded to neural target and stimulation condition provided perceptual judgments of intelligibility and overall speech severity. Speech acoustic measures were obtained from the recordings. Acoustic and perceptual measures and clinical characteristics were compared for the two neural targets and stimulation conditions.

Results

Intelligibility and speech severity were not significantly different across neural target or stimulation conditions. Generally, acoustic measures were also not statistically different for the two neural targets or stimulation conditions. Acoustic measures reflecting more varied speech prosody were associated with improved intelligibility and lessened severity. Convergent correlations were found between UPDRS-III speech scores and perceptual measures of intelligibility and severity.

Conclusion

This study reports a systematic comparison of perceptual and acoustic speech outcomes following STN-DBS and GPI-DBS. Statistically significant differences in acoustic measures for the two neural targets were small in magnitude and did not yield group differences in perceptual measures. The absence of robust differences in speech outcomes for the two neural targets has implications for pre-surgical counseling. Results provide preliminary support for reliance on considerations other than speech when selecting the target for DBS in patients with PD.

A neurocomputational view of the effects of Parkinson's disease on speech production

The purpose of this article is to review the scientific literature concerning speech in Parkinson's disease (PD) with reference to the DIVA/GODIVA neurocomputational modeling framework. Within this theoretical view, the basal ganglia (BG) contribute to several different aspects of speech motor learning and execution. First, the BG are posited to play a role in the initiation and scaling of speech movements. Within the DIVA/GODIVA framework, initiation and scaling are carried out by initiation map nodes in the supplementary motor area acting in concert with the BG. Reduced support of the initiation map from the BG in PD would result in reduced movement intensity as well as susceptibility to early termination of movement. A second proposed role concerns the learning of common speech sequences, such as phoneme sequences comprising words; this view receives support from the animal literature as well as studies identifying speech sequence learning deficits in PD. Third, the BG may play a role in the temporary buffering and sequencing of longer speech utterances such as phrases during conversational speech. Although the literature does not support a critical role for the BG in representing sequence order (since incorrectly ordered speech is not characteristic of PD), the BG are posited to contribute to the scaling of individual movements in the sequence, including increasing movement intensity for emphatic stress on key words. Therapeutic interventions for PD have inconsistent effects on speech. In contrast to dopaminergic treatments, which typically either leave speech unchanged or lead to minor improvements, deep brain stimulation (DBS) can degrade speech in some cases and improve it in others. However, cases of degradation may be due to unintended stimulation of efferent motor projections to the speech articulators. Findings of spared speech after bilateral pallidotomy appear to indicate that any role played by the BG in adult speech must be supplementary rather than mandatory, with the sequential order of well-learned sequences apparently represented elsewhere (e.g., in cortico-cortical projections).

Identifying Medications Underlying Communication Atypicalities in Psychotic and Affective Disorders: A Pharmacovigilance Study Within the FDA Adverse Event Reporting System

PURPOSE

Communication atypicalities are considered promising markers of a broad range of clinical conditions. However, little is known about the mechanisms and confounders underlying them. Medications might have a crucial, relatively unknown role both as potential confounders and offering an insight on the mechanisms at work. The integration of regulatory documents with disproportionality analyses provides a more comprehensive picture to account for in future investigations of communication-related markers. The aim of this study was to identify a list of drugs potentially associated with communicative atypicalities within psychotic and affective disorders.

METHOD

We developed a query using the Medical Dictionary for Regulatory Activities to search for communicative atypicalities within the FDA Adverse Event Reporting System (updated June 2021). A Bonferroni-corrected disproportionality analysis (reporting odds ratio) was separately performed on spontaneous reports involving psychotic, affective, and non-neuropsychiatric disorders, to account for the confounding role of different underlying conditions. Drug-adverse event associations not already reported in the Side Effect Resource database of labeled adverse drug reactions (unexpected) were subjected to further robustness analyses to account for expected biases.

RESULTS

A list of 291 expected and 91 unexpected potential confounding medications was identified, including drugs that may irritate (inhalants) or desiccate (anticholinergics) the larynx, impair speech motor control (antipsychotics), or induce nodules (acitretin) or necrosis (vascular endothelial growth factor receptor inhibitors) on vocal cords; sedatives and stimulants; neurotoxic agents (anti-infectives); and agents acting on neurotransmitter pathways (dopamine agonists).

CONCLUSIONS

We provide a list of medications to account for in future studies of communication-related markers in affective and psychotic disorders. The current test case illustrates rigorous procedures for digital phenotyping, and the methodological tools implemented for large-scale disproportionality analyses can be considered a road map for investigations of communication-related markers in other clinical populations.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.23721345.

Acquired Stuttering in Parkinson's Disease

Background

Parkinson's disease frequently causes communication impairments, but knowledge about the occurrence of new-onset stuttering is limited.

Objectives

To determine the presence of acquired neurogenic stuttering and its relationship with cognitive and motor functioning in individuals with Parkinson's disease.

Method

Conversation, picture description, and reading samples were collected from 100 people with Parkinson's disease and 25 controls to identify the presence of stuttered disfluencies (SD) and their association with neuropsychological test performance and motor function.

Results

Participants with Parkinson's disease presented with twice as many stuttered disfluencies during conversation (2.2% ± 1.8%SD) compared to control participants (1.2% ± 1.2%SD; P < 0.01). 21% of people with Parkinson's disease (n = 20/94) met the diagnostic criterion for stuttering, compared with 1/25 controls. Stuttered disfluencies also differed significantly across speech tasks, with more disfluencies during conversation compared to reading (P < 0.01). Stuttered disfluencies in those with Parkinson's disease were associated with longer time since disease onset (P < 0.01), higher levodopa equivalent dosage (P < 0.01), and lower cognitive (P < 0.01) and motor scores (P < 0.01).

Conclusion

One in five participants with Parkinson's disease presented with acquired neurogenic stuttering, suggesting that speech disfluency assessment, monitoring and intervention should be part of standard care. Conversation was the most informative task for identifying stuttered disfluencies. The frequency of stuttered disfluencies was higher in participants with worse motor functioning, and lower cognitive functioning. This challenges previous suggestions that the development of stuttered disfluencies in Parkinson's disease has purely a motoric basis.

Artificial Intelligence-Based Voice Assessment of Patients with Parkinson's Disease Off and On Treatment: Machine vs. Deep-Learning Comparison

Parkinson's Disease (PD) is one of the most common non-curable neurodegenerative diseases. Diagnosis is achieved clinically on the basis of different symptoms with considerable delays from the onset of neurodegenerative processes in the central nervous system. In this study, we investigated early and full-blown PD patients based on the analysis of their voice characteristics with the aid of the most commonly employed machine learning (ML) techniques. A custom dataset was made with hi-fi quality recordings of vocal tasks gathered from Italian healthy control subjects and PD patients, divided into early diagnosed, off-medication patients on the one hand, and mid-advanced patients treated with L-Dopa on the other. Following the current state-of-the-art, several ML pipelines were compared usingdifferent feature selection and classification algorithms, and deep learning was also explored with a custom CNN architecture. Results show how feature-based ML and deep learning achieve comparable results in terms of classification, with KNN, SVM and naïve Bayes classifiers performing similarly, with a slight edge for KNN. Much more evident is the predominance of CFS as the best feature selector. The selected features act as relevant vocal biomarkers capable of differentiating healthy subjects, early untreated PD patients and mid-advanced L-Dopa treated patients.

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

The effect of dopaminergic medication on speech has rarely been examined in early-stage Parkinson's disease (PD) and the respective literature is inconclusive and limited by inappropriate design with lack of PD control group. The study aims to examine the short-term effect of dopaminergic medication on speech in PD using patients with good motor responsiveness to levodopa challenge compared to a control group of PD patients with poor motor responsiveness. A total of 60 early-stage PD patients were investigated before (OFF) and after (ON) acute levodopa challenge and compared to 30 age-matched healthy controls. PD patients were categorised into two clinical subgroups (PD responders vs. PD nonresponders) according to the comparison of their motor performance based on movement disorder society-unified Parkinson's disease rating scale, part III. Seven distinctive parameters of hypokinetic dysarthria were examined using quantitative acoustic analysis. We observed increased monopitch (p > 0.01), aggravated monoloudness (p > 0.05) and longer duration of stop consonants (p > 0.05) in PD compared to healthy controls, confirming the presence of hypokinetic dysarthria in early PD. No speech alterations from OFF to ON state were revealed in any of the two PD groups and speech dimensions investigated including monopitch, monoloudness, imprecise consonants, harsh voice, slow sequential motion rates, articulation rate, or inappropriate silences, although a subgroup of PD responders manifested obvious improvement in motor function after levodopa intake (p > 0.001). Since the short-term usage of levodopa does not easily affect voice and speech performance in PD, speech assessment may provide a medication state-independent motor biomarker of PD.

Voice handicap Index in Parkinson's patients: Subthalamic versus globus pallidus deep brain stimulation

PURPOSE

Subthalamic nucleus (STN) and globus pallidus interna (GPI) are the two most common sites for deep brain stimulation (DBS) in people with Parkinson's disease (PWP). Voice impairments are a common symptom of Parkinson's disease and information about voice outcomes with DBS is limited. Most studies in speech-language pathology have focused on STN-DBS and few have examined the effects of GPI-DBS. This was an initial effort to examine the impact of DBS location on Vocal Handicap Index (VHI) scores, which assess the impact of a voice disorder on an individual.

METHOD

Twenty-four gender-matched PWP (12 STN-DBS and 12 GPI-DBS) completed the VHI post-DBS implantation. Two-tailed independent samples t-tests were used to compare each VHI scale score (physical, functional, emotional, total) and patient factors between the two groups.

RESULTS

No significant differences in total or subscale VHI scores were identified between the two DBS groups. A trend toward greater impairment in PWP with GPI-DBS was noted. An association between higher VHI scores and DBS settings was found.

CONCLUSIONS

Studies directly comparing speech outcomes for different DBS targets are lacking. The current findings provide new insights concerning voice outcomes following DBS by adding to the limited literature directly comparing speech outcomes in multiple DBS targets. Limitations and directions for future research are discussed.

Speech dysfunction, cognition, and Parkinson's disease

Communication difficulties are a ubiquitous symptom of Parkinson's disease and include changes to both motor speech and language systems. Communication challenges are a significant driver of lower quality of life. They are associated with decreased communication participation, social withdrawal, and increased risks for social isolation and stigmatization in persons with Parkinson's disease. Recent theoretical advances and experimental evidence underscore the intersection of cognition and motor processes in speech production and their impact on spoken language. This chapter overviews a growing evidence base demonstrating that cognitive impairments interact with motor changes in Parkinson's disease to negatively affect communication abilities in myriad ways, at all stages of the disease, both in the absence and presence of dementia. The chapter highlights common PD interventions (pharmacological, surgical, and non-pharmacological) and how cognitive influences on speech production outcomes are considered in each.

Linguistic features of dysfluencies in Parkinson Disease

PURPOSE

The purpose of this study was to examine dysfluency characteristics of individuals with Parkinson Disease (PD) relative to linguistic features of grammatical class and position within word. Few studies have reported dysfluency characteristics of PD relative to these characteristics. Those that do report on these characteristics include one case study and a study of six individuals with PD. No previous research is known to have examined dysfluency related to grammatical class and position within words for a large sample of individuals with PD.

METHOD

Dysfluencies from 32 individuals with PD were analyzed according to position within a word and grammatical class.

RESULTS

Participants produced significantly more dysfluencies in the initial position of words compared to medial or final positions, and a significantly higher percent dysfluency for content words versus function words.

CONCLUSION

Effects of linguistic features of grammatical class and position within a word on dysfluencies are present within a population with PD and are similar to the linguistic features associated with developmental stuttering. Clinical implications of the effect of linguistic features on speech dysfluencies in PD are discussed.

Variation in Speech Intelligibility Ratings as a Function of Speech Rate Modification in Parkinson's Disease

Purpose The aim of this study was to quantify changes in speech intelligibility in two cohorts of people with Parkinson's disease (PD; those with and without deep brain stimulation [DBS]) across a broad range of self-selected speech rate alterations in (a) read sentences and (b) extemporaneous speech (monologues). Method Four speaker groups participated in this study: younger and older controls, people with PD undergoing standard pharmaceutical treatment, and people with PD and DBS. Naïve listeners rated the intelligibility of read sentences and extemporaneous monologues, spoken by participants at seven self-selected speech rates from very slow to very fast. Intelligibility was modeled as a function of group, speech rate condition, and speech task. Results Overall, compared to habitual speech rate, slower speech rate conditions were not associated with changes in speech intelligibility, whereas faster-than-habitual conditions were associated in declines in intelligibility. Results were mediated by group and task effects, such that talkers with PD and DBS were more likely to see intelligibility benefits at slower self-selected speech rates and less likely to see detriments at faster rates, and these differences were amplified in monologues compared to sentences. Conclusion Findings suggest differences in the ways in which slower and faster speech rate adjustments impact speech intelligibility in people with PD with and without DBS, with the latter demonstrating greater magnitudes of change.

Voice Analysis to Differentiate the Dopaminergic Response in People With Parkinson's Disease

Humans' voice offers the widest variety of motor phenomena of any human activity. However, its clinical evaluation in people with movement disorders such as Parkinson's disease (PD) lags behind current knowledge on advanced analytical automatic speech processing methodology. Here, we use deep learning-based speech processing to differentially analyze voice recordings in 14 people with PD before and after dopaminergic medication using personalized Convolutional Recurrent Neural Networks (p-CRNN) and Phone Attribute Codebooks (PAC). p-CRNN yields an accuracy of 82.35% in the binary classification of ON and OFF motor states at a sensitivity/specificity of 0.86/0.78. The PAC-based approach's accuracy was slightly lower with 73.08% at a sensitivity/specificity of 0.69/0.77, but this method offers easier interpretation and understanding of the computational biomarkers. Both p-CRNN and PAC provide a differentiated view and novel insights into the distinctive components of the speech of persons with PD. Both methods detect voice qualities that are amenable to dopaminergic treatment, including active phonetic and prosodic features. Our findings may pave the way for quantitative measurements of speech in persons with PD.

The clinical meaning of levodopa equivalent daily dose in Parkinson's disease

Levodopa (L-dopa) remains the basis of pharmacological treatment of Parkinson's disease (PD). However, L-dopa therapy is associated with the development of complications and presents major challenges in the long-term treatment. Thus, other medications may be suggested to delay and/or reduce the doses of L-dopa in order to prevent complications. The interpretation of treatment evolution reported in clinical trials on PD may be tricky, especially due to some variability in medications and dose regimens. Some authors have suggested a conversion factor to generate a total L-dopa equivalent daily dose (LEDD), calculated as a sum of each parkinsonian medication. Therefore, LEDD provides an artificial summary of the total daily medication a patient is receiving, and to date, there is no report focusing on the clinical interpretation of this parameter. Thus, based on a 3-year, multi-center retrospective study assessing the impact of second-line therapy initiation on LEDD in PD patients, the aim of our article was to discuss LEDD as a quantitative outcome to estimate the impact of second-line therapies on medication regimens; and in the second part of the discussion, to provide a narrative review of the clinical outcomes associated with LEDD in the literature.

Estimation of Parkinson's disease severity from voice features of vowels and consonant

This study has investigated the efficiency of voice features in estimating the motor Unified Parkinson's Disease Rating Scale (UPDRS) score in Parkinson's disease (PD) patients. A total of 26 PD patients (mean age = 72) and 22 control subjects (mean age = 66.91) were recruited for the study. The sustained phonation /a/, /u/ and /m/ were collected in both off-state and on-state of Levodopa medication. The average motor UPDRS for PD off-state patients was 27.31, on-state was 20.42 and that of controls was 2.63. Voice features were extracted from the phonation tasks and were reduced to the most relevant 6 features for each phonation task using the Least Absolute Shrinkage and Selection Operator (LASSO) feature ranking method. The correlation between the reduced features and motor UPDRS was tested using the Spearman correlation coefficient test. AdaBoost regression learner was trained and used for automatically estimating the motor UPDRS score using the voice features. The results show that the vocal features for /m/ performed best by estimating the motor UPDRS score for PD off-state with the mean absolute error (MAE) of 3.52 and 5.90 for PD on-state. This study shows that assessment of voice can be used for day to day remote monitoring of PD patients.

Speech-based characterization of dopamine replacement therapy in people with Parkinson's disease

People with Parkinson's (PWP) disease are under constant tension with respect to their dopamine replacement therapy (DRT) regimen. Waiting too long between doses results in more prominent symptoms, loss of motor function, and greater risk of falling per step. Shortened pill cycles can lead to accelerated habituation and faster development of disabling dyskinesias. The Unified Parkinson's Disease Rating Scale (MDS-UPDRS) is the gold standard for monitoring Parkinson's disease progression but requires a neurologist to administer and therefore is not an ideal instrument to continuously evaluate short-term disease fluctuations. We investigated the feasibility of using speech to detect changes in medication states, based on expectations of subtle changes in voice and content related to dopaminergic levels. We calculated acoustic and prosodic features for three speech tasks (picture description, reverse counting, and diadochokinetic rate) for 25 PWP, each evaluated "ON" and "OFF" DRT. Additionally, we generated semantic features for the picture description task. Classification of ON/OFF medication states using features generated from picture description, reverse counting and diadochokinetic rate tasks resulted in cross-validated accuracy rates of 0.89, 0.84, and 0.60, respectively. The most discriminating task was picture description which provided evidence that participants are more likely to use action words in ON than in OFF state. We also found that speech tempo was modified by DRT. Our results suggest that automatic speech assessment can capture changes associated with the DRT cycle. Given the ease of acquiring speech data, this method shows promise to remotely monitor DRT effects.