Impact of Parkinson's disease and levodopa on resting state functional connectivity related to speech prosody control

Levodopa may modulate specific speech impairment in Parkinson's disease: an fMRI study

Hypokinetic dysarthria (HD) is a difficult-to-treat symptom affecting quality of life in patients with Parkinson's disease (PD). Levodopa may partially alleviate some symptoms of HD in PD, but the neural correlates of these effects are not fully understood. The aim of our study was to identify neural mechanisms by which levodopa affects articulation and prosody in patients with PD. Altogether 20 PD patients participated in a task fMRI study (overt sentence reading). Using a single dose of levodopa after an overnight withdrawal of dopaminergic medication, levodopa-induced BOLD signal changes within the articulatory pathway (in regions of interest; ROIs) were studied. We also correlated levodopa-induced BOLD signal changes with the changes in acoustic parameters of speech. We observed no significant changes in acoustic parameters due to acute levodopa administration. After levodopa administration as compared to the OFF dopaminergic condition, patients showed task-induced BOLD signal decreases in the left ventral thalamus (p = 0.0033). The changes in thalamic activation were associated with changes in pitch variation (R = 0.67, p = 0.006), while the changes in caudate nucleus activation were related to changes in the second formant variability which evaluates precise articulation (R = 0.70, p = 0.003). The results are in line with the notion that levodopa does not have a major impact on HD in PD, but it may induce neural changes within the basal ganglia circuitries that are related to changes in speech prosody and articulation.

Monitoring the Effect of Levodopa Using Sustained Phonemes in Parkinson's Disease Patients

Parkinson's disease (PD) is a neurological disease identified by multiple symptoms, and levodopa is one of the most effective medications for treating the disease. To determine the dosage of levodopa, it is necessary to meet on a regular basis and observe motor function. The early detection and progression of the disease have been proposed using hypokinetic dysarthria. However, previous studies have not examined the effects of levodopa on speech rigorously and have provided inconsistent results. In this study, three sustained phonemes of PD patients were investigated for the effect of medication. A set of features characterizing vocal fold dynamics as well as the vocal tract coordinators were extracted from the sustained phonemes /of 28 PD patients during levodopa medication off and on states. All the features were statistically investigated and classified using a linear discriminant analysis (LDA) classifier. LDA classifier identified medication on from medication off based on the combined features from phoneme /a/, /o/ and /m/ with the accuracy=82.75% and F1-score=82.18%. Voice recording of PD patients during sustained phonemes /a/, /o/ and /m/ has the potential for identifying whether the patients are in On state or Off state of medication.Clinical Relevance- The outcomes of this study have the potential to monitor the effect and progress of levodopa on PD patients.

Aberrant neurophysiological signaling associated with speech impairments in Parkinson's disease

Difficulty producing intelligible speech is a debilitating symptom of Parkinson's disease (PD). Yet, both the robust evaluation of speech impairments and the identification of the affected brain systems are challenging. Using task-free magnetoencephalography, we examine the spectral and spatial definitions of the functional neuropathology underlying reduced speech quality in patients with PD using a new approach to characterize speech impairments and a novel brain-imaging marker. We found that the interactive scoring of speech impairments in PD (N = 59) is reliable across non-expert raters, and better related to the hallmark motor and cognitive impairments of PD than automatically-extracted acoustical features. By relating these speech impairment ratings to neurophysiological deviations from healthy adults (N = 65), we show that articulation impairments in patients with PD are associated with aberrant activity in the left inferior frontal cortex, and that functional connectivity of this region with somatomotor cortices mediates the influence of cognitive decline on speech deficits.

Reading fluency in Spanish patients with Parkinson's disease: A reading prosody examination

BACKGROUND

The expressiveness during reading is essential for a fluent reading. Reading prosody has been scarcely studied in an experimental manner, owing to the difficulties in taking objective and direct measures of this reading skill. However, new technologies development has made it possible to analyse reading prosody in an experimental way. Prosodic patterns may vary, not being the same at the beginning of the reading learning process as in adulthood. They may also be altered in disorders such as dyslexia, but little is known about the prosodic characteristics and reading fluency of people with neurodegenerative diseases that cause language impairment, such as Parkinson's disease (PD).

AIMS

The aim of this work was to study reading fluency in PD considering the prosodic characteristics of its reading.

METHODS & PROCEDURES

The participants were 31 Spanish adults with PD and 31 healthy controls, aged 59-88 years. Two experimental texts were designed that included declarative, interrogative, and exclamatory sentences and experimental verbs and nouns. The manipulability level of the nouns and the motor content of the verbs were considered. The reading of the participants was recorded and analysed with Praat software.

OUTCOMES & RESULTS

A longer reading duration and a greater number of pauses, especially in verbs, were found in the PD group, which also showed less pitch variation than the control group in the experimental sentences. The control group showed a big initial rise in declarative and interrogative sentences, as well as a stronger final declination in declarative and exclamatory ones, when compared to the PD group.

CONCLUSIONS & IMPLICATIONS

The use of experimental methodologies for the analysis of reading fluency allows learning more about the prosodic characteristics of people with different pathologies, such as PD. Scarce pitch variability found in the analysis, together with the great number of pauses and the longer reading duration, leads to poorly expressive reading, which compromises fluency in PD. The exhaustive evaluation of the reading fluency of PD patients will make it possible to design more complete assessment methods that will favour the diagnosis and early detection of this pathology.

WHAT THIS STUDY ADDS

What is already known on this subject • The speech of people with Parkinson's disease (PD) is often impaired by the appearance of hypokinetic dysarthria. The language of people with PD is usually affected with the progression of the disease, with lexico-semantic impairment which mainly affects verbs. Previous literature on reading fluency in PD usually considers reading speed and accuracy, neglecting prosody. Other neurodegenerative diseases with language impairment, such as Alzheimer's disease, commonly cause reading fluency problems. What this paper adds to existing knowledge • This study provides direct and objective measures of the reading fluency (speed, accuracy and prosody) in patients with PD, by the design of experimental texts. Reading fluency characteristics were found to be altered in these patients, especially in pitch variations and reading duration. The reading of Parkinson's patients showed a more flattened pitch. In addition, a greater number of pauses and longer reading durations were also found in the reading of verbs compared to the control group. What are the potential or actual clinical implications of this work? • The use of experimentally created texts makes it possible to analyse the influence of different psycholinguistic variables (frequency, length, motor content, manipulability) on reading fluency, and how the processing of these stimuli could be affected in PD. The objective analysis of the reading fluency characteristics in PD allows the design of more specific evaluation and diagnostic tasks. More complete assessment methods may allow the early detection of the disease. In the same way, it may favour a differential diagnosis with other neurodegenerative diseases.

Modulation of cortical resting state functional connectivity during a visuospatial attention task in Parkinson's disease

Visual dysfunction is a recognized early symptom of Parkinson's disease (PD) that partly scales motor symptoms, yet its background is heterogeneous. With additional deficits in visuospatial attention, the two systems are hard to disentangle and it is not known whether impaired functional connectivity in the visual cortex is translative in nature or disrupted attentional modulation also contributes. In this study, we investigate functional connectivity modulation during a visuospatial attention task in patients with PD. In total, 15 PD and 16 age-matched healthy controls performed a visuospatial attention task while undergoing fMRI, in addition to a resting-state fMRI scan. Tensorial independent component analysis was used to investigate task-related network activity patterns. Independently, an atlas-based connectivity modulation analysis was performed using the task potency method. Spearman's rank correlation was calculated between task-related network expression, connectivity modulation, and clinical characteristics. Task-related networks including mostly visual, parietal, and prefrontal cortices were expressed to a significantly lesser degree in patients with PD (p < 0.027). Resting-state functional connectivity did not differ between the healthy and diseased cohorts. Connectivity between the precuneus and ventromedial prefrontal cortex was modulated to a higher degree in patients with PD (p < 0.004), while connections between the posterior parietal cortex and primary visual cortex, and also the superior frontal gyrus and opercular cortex were modulated to a lesser degree (p < 0.001 and p < 0.011). Task-related network expression and superior frontal gyrus–opercular cortex connectivity modulation were significantly associated with UPDRSIII motor scores and the Hoehn–Yahr stages (R = −0.72, p < 0.006 and R = −0.90, p < 0.001; R = −0.68, p < 0.01 and R = −0.71, p < 0.007). Task-related networks function differently in patients with PD in association with motor symptoms, whereas impaired modulation of visual and default-mode network connectivity was not correlated with motor function.

Characterization of Mild and Moderate Dysarthria in Parkinson’s Disease: Behavioral Measures and Neural Correlates

Purpose

Alterations in speech and voice are among the most common symptoms in Parkinson’s disease (PD), often resulting in motor speech disorders such as hypokinetic dysarthria. We investigated dysarthria, verbal fluency, executive functions, and global cognitive function in relation to structural and resting-state brain changes in people with PD.

Methods

Participants with mild-moderate PD (n = 83) were recruited within a randomized controlled trial and divided into groups with varying degrees of dysarthria: no dysarthria (noDPD), mild dysarthria (mildDPD), moderate dysarthria (modDPD), and also combined mildDPD and modDPD into one group (totDPD). Voice sound level and dysphonia, verbal fluency, motor symptoms, executive functions, disease severity, global cognition, and neuroimaging were compared between groups. Gray matter volume and intensity of spontaneous brain activity were analyzed. Additionally, regressions between behavioral and neuroimaging data were performed.

Results

The groups differed significantly in mean voice sound level, dysphonia, and motor symptom severity. Comparing different severity levels of dysarthria to noDPD, groups differed focally in resting-state activity, but not in brain structure. In totDPD, lower scores on semantic verbal fluency, a composite score of executive functions, and global cognition correlated with lower superior temporal gyrus volume.

Conclusion

This study shows that severity of dysarthria may be related to underlying structural and resting-state brain alterations in PD as well as behavioral changes. Further, the superior temporal gyrus may play an important role in executive functions, language, and global cognition in people with PD and dysarthria.

Speech Characteristics of Patients with Parkinson's Disease-Does Dopaminergic Medications Have a Role?

Objective  The present study aimed to investigate the effects of dopaminergic medication on voice, speech motor functions, and motor impairment in patients with Parkinson's disease (PD).

Materials and Methods  Twenty-five individuals (16 males and 9 females) with PD underwent comprehensive assessment of voice, speech, and motor functions in levodopa medication ON and medication OFF conditions. Age- and gender-matched healthy controls were recruited to compare speech and acoustic parameters. Multi-Dimensional Voice Program (MDVP) from Computerized Speech Laboratory (Model: 4500) was utilized for acoustic analysis of voice and the Voice Handicap Index (VHI) for the self-assessment of vocal function. Frenchay Dysarthria Assessment (FDA-2) and Unified Parkinson's Disease Rating Scale-III (UPDRS III) were used to evaluate speech motor and motor functions, respectively.

Statistical Analysis  The mean and standard deviation were used as descriptive statistics measures. Raw scores were obtained for FDA-2, DRS, VHI, MDVP parameters, and UPDRS-III in either medication condition. The Wilcoxon signed-rank test was performed to determine the statistical significance of the above measures in both genders across the medication conditions. Spearman's rank correlation coefficient was used to determine the relationship between motor speech function and motor impairment and between VHI and MDVP parameters across both medication conditions. The interrater reliability rating was established using Cohen's kappa.

Results  An improvement in lip and laryngeal functioning was found in the medication ON over medication OFF state in both males and females with PD. A few frequency and amplitude-related measures improved in the medication-ON state over the medication-OFF state. UPDRS-III scores reduced from the OFF state to the ON state, and no change in dysarthria severity or VHI was found in either gender or medication condition. No correlation was found between speech motor function and motor function or between VHI and acoustic parameters of voice in either medication condition.

Conclusions  Improvement in motor symptoms with levodopa was predominantly observed when compared with the minor improvements in a few aspects of speech motor function and vocal parameters. The results of this study suggest the need for speech therapy as a nonpharmacological treatment method for speech impairments in PD.

(Dys)Prosody in Parkinson's Disease: Effects of Medication and Disease Duration on Intonation and Prosodic Phrasing

The phonology of prosody has received little attention in studies of motor speech disorders. The present study investigates the phonology of intonation (nuclear contours) and speech chunking (prosodic phrasing) in Parkinson’s disease (PD) as a function of medication intake and duration of the disease. Following methods of the prosodic and intonational phonology frameworks, we examined the ability of 30 PD patients to use intonation categories and prosodic phrasing structures in ways similar to 20 healthy controls to convey similar meanings. Speech data from PD patients were collected before and after a dopaminomimetic drug intake and were phonologically analyzed in relation to nuclear contours and intonational phrasing. Besides medication, disease duration and the presence of motor fluctuations were also factors included in the analyses. Overall, PD patients showed a decreased ability to use nuclear contours and prosodic phrasing. Medication improved intonation regardless of disease duration but did not help with dysprosodic phrasing. In turn, disease duration and motor fluctuations affected phrasing patterns but had no impact on intonation. Our study demonstrated that the phonology of prosody is impaired in PD, and prosodic categories and structures may be differently affected, with implications for the understanding of PD neurophysiology and therapy.

Altered Spontaneous Neural Activity and Functional Connectivity in Parkinson's Disease With Subthalamic Microlesion

Background

Transient improvement in motor symptoms are immediately observed in patients with Parkinson's disease (PD) after an electrode has been implanted into the subthalamic nucleus (STN) for deep brain stimulation (DBS). This phenomenon is known as the microlesion effect (MLE). However, the underlying mechanisms of MLE is poorly understood.

Purpose

We utilized resting state functional MRI (rs-fMRI) to evaluate changes in spontaneous brain activity and networks in PD patients during the microlesion period after DBS.

Method

Overall, 37 PD patients and 13 gender- and age-matched healthy controls (HCs) were recruited for this study. Rs-MRI information was collected from PD patients three days before DBS and one day after DBS, whereas the HCs group was scanned once. We utilized the amplitude of low-frequency fluctuation (ALFF) method in order to analyze differences in spontaneous whole-brain activity among all subjects. Furthermore, functional connectivity (FC) was applied to investigate connections between other brain regions and brain areas with significantly different ALFF before and after surgery in PD patients.

Result

Relative to the PD-Pre-DBS group, the PD-Post-DBS group had higher ALFF in the right putamen, right inferior frontal gyrus, right precentral gyrus and lower ALFF in right angular gyrus, right precuneus, right posterior cingulate gyrus (PCC), left insula, left middle temporal gyrus (MTG), bilateral middle frontal gyrus and bilateral superior frontal gyrus (dorsolateral). Functional connectivity analysis revealed that these brain regions with significantly different ALFF scores demonstrated abnormal FC, largely in the temporal, prefrontal cortices and default mode network (DMN).

Conclusion

The subthalamic microlesion caused by DBS in PD was found to not only improve the activity of the basal ganglia-thalamocortical circuit, but also reduce the activity of the DMN and executive control network (ECN) related brain regions. Results from this study provide new insights into the mechanism of MLE.

Non-invasive brain stimulation for speech in Parkinson's disease: A randomized controlled trial

BACKGROUND

Hypokinetic dysarthria is a common but difficult-to-treat symptom of Parkinson's disease (PD).

OBJECTIVES

We evaluated the long-term effects of multiple-session repetitive transcranial magnetic stimulation on hypokinetic dysarthria in PD. Neural mechanisms of stimulation were assessed by functional MRI.

METHODS

A randomized parallel-group sham stimulation-controlled design was used. Patients were randomly assigned to ten sessions (2 weeks) of real (1 Hz) or sham stimulation over the right superior temporal gyrus. Stimulation effects were evaluated at weeks 2, 6, and 10 after the baseline assessment. Articulation, prosody, and speech intelligibility were quantified by speech therapist using a validated tool (Phonetics score of the Dysarthric Profile). Activations of the speech network regions and intrinsic connectivity were assessed using 3T MRI. Linear mixed models and post-hoc tests were utilized for data analyses.

RESULTS

Altogether 33 PD patients completed the study (20 in the real stimulation group and 13 in the sham stimulation group). Linear mixed models revealed significant effects of time (F(3, 88.1) = 22.7, p < 0.001) and time-by-group interactions: F(3, 88.0) = 2.8, p = 0.040) for the Phonetics score. Real as compared to sham stimulation led to activation increases in the orofacial sensorimotor cortex and caudate nucleus and to increased intrinsic connectivity of these regions with the stimulated area.

CONCLUSIONS

This is the first study to show the long-term treatment effects of non-invasive brain stimulation for hypokinetic dysarthria in PD. Neural mechanisms of the changes are discussed.

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

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.

Articulatory network reorganization in Parkinson's disease as assessed by multimodal MRI and acoustic measures

INTRODUCTION

Hypokinetic dysarthria (HD) is common in Parkinson's disease (PD). Our objective was to evaluate articulatory networks and their reorganization due to PD pathology in individuals without overt speech impairment using a multimodal MRI protocol and acoustic analysis of speech.

METHODS

A total of 34 PD patients with no subjective HD complaints and 25 age-matched healthy controls (HC) underwent speech task recordings, structural MRI, and reading task-induced and resting-state fMRI. Grey matter probability maps, task-induced activations, and resting-state functional connectivity within the regions engaged in speech production (ROIs) were assessed and compared between groups. Correlation with acoustic parameters was also performed.

RESULTS

PD patients as compared Tto HC displayed temporal decreases in speech loudness which were related to BOLD signal increases in the right-sided regions of the dorsal language pathway/articulatory network. Among those regions, activation of the right anterior cingulate was increased in PD as compared to HC. We also found bilateral posterior superior temporal gyrus (STG) GM loss in PD as compared to HC that was strongly associated with diadochokinetic (DDK) irregularity in the PD group. Task-induced activations of the left STG were increased in PD as compared to HC and were related to the DDK rate control.

CONCLUSIONS

The results provide insight into the neural correlates of speech production control and distinct articulatory network reorganization in PD apparent already in patients without subjective speech impairment.

Dysarthria and Speech Intelligibility Following Parkinson’s Disease Globus Pallidus Internus Deep Brain Stimulation

Background: Although earlier studies reported variable speech changes following subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson’s disease (PD) patients, the effects of globus pallidus internus (GPi) DBS on speech performance in PD remain largely unknown. Objective: We aimed to characterize speech changes following PD GPi-DBS. Methods: We retrospectively analyzed clinical and speech outcomes of 25 PD patients treated with bilateral GPi-DBS at a single center. Outcome measures included the Unified Parkinson’s Disease Rating Scale (UPDRS), speech subsystem domains (respiratory, laryngeal, resonance, orofacial, rate, prosody, rhythm, and naturalness), and overall speech intelligibility. Scores at baseline were compared with those at 6 months, 1 year, and the longest clinical follow-up available. Results: In the off-medication state, activities of daily living and motor function based on UPDRS II and III significantly improved postoperatively. We observed unique patterns of speech changes in patients with PD following GPi-DBS in the short- (n = 25) and longer-term (n = 8) follow-up periods. Velopharyngeal (resonance), laryngeal components, and prosody worsened after bilateral GPi-DBS (p < 0.015). Speech intelligibility did not worsen after GPi-DBS in the short-term, but there was a trend to deteriorate at long-term follow-up (e.g., one year and beyond). We observed worsening of hypokinetic dysarthria in individual patients. Also, a minority of patients developed stuttering, spastic dysarthria, or ataxic dysarthria. Conclusion: Bilateral GPi-DBS worsened several modalities of parkinsonian speech without compromising overall speech intelligibility. GPi-DBS can potentially worsen or induce hypokinetic dysarthria, stuttering, spastic dysarthria, or ataxic dysarthria. GPi-DBS may have different and variable effects on speech function when compared to STN-DBS.

Language disturbances in schizophrenia: the relation with antipsychotic medication

Language disturbances are key aberrations in schizophrenia. Little is known about the influence of antipsychotic medication on these symptoms. Using computational language methods, this study evaluated the impact of high versus low dopamine D₂ receptor (D2R) occupancy antipsychotics on language disturbances in 41 patients with schizophrenia, relative to 40 healthy controls. Patients with high versus low D2R occupancy antipsychotics differed by total number of words and type-token ratio, suggesting medication effects. Both patient groups differed from the healthy controls on percentage of time speaking and clauses per utterance, suggesting illness effects. Overall, more severe negative language disturbances (i.e. slower articulation rate, increased pausing, and shorter utterances) were seen in the patients that used high D2R occupancy antipsychotics, while less prominent disturbances were seen in low D2R occupancy patients. Language analyses successfully predicted drug type (sensitivity = 80.0%, specificity = 76.5%). Several language disturbances were more related to drug type and dose, than to other psychotic symptoms, suggesting that language disturbances may be aggravated by high D2R antipsychotics. This negative impact of high D2R occupancy drugs may have clinical implications, as impaired language production predicts functional outcome and degrades the quality of life.

Brain morphological changes in hypokinetic dysarthria of Parkinson's disease and use of machine learning to predict severity

Background

Up to 90% of patients with Parkinson's disease (PD) eventually develop the speech and voice disorder referred to as hypokinetic dysarthria (HD). However, the brain morphological changes associated with HD have not been investigated. Moreover, no reliable model for predicting the severity of HD based on neuroimaging has yet been developed.

Methods

A total of 134 PD patients were included in this study and divided into a training set and a test set. All participants underwent a structural magnetic resonance imaging (MRI) scan and neuropsychological evaluation. Individual cortical thickness, subcortical structure, and white matter volume were extracted, and their association with HD severity was analyzed. After feature selection, a machine‐learning model was established using a support vector machine in the training set. The severity of HD was then predicted in the test set.

Results

Atrophy of the right precentral cortex and the right fusiform gyrus was significantly associated with HD. No association was found between HD and volume of white matter or subcortical structures. Favorable and optimal performance of machine learning on HD severity prediction was achieved using feature selection, giving a correlation coefficient (r) of .7516 and a coefficient of determination (R²) of .5649 (P < .001).

Conclusion

The brain morphological changes were associated with HD. Excellent prediction of the severity of HD was achieved using machine learning based on neuroimaging.

Attention/memory complaint is correlated with motor speech disorder in Parkinson's disease

BACKGROUND

The mechanisms underlying the online modulation of motor speech in Parkinson's disease (PD) have not been determined. Moreover, medical and rehabilitation interventions for PD-associated motor speech disorder (MSD) have a poor long-term prognosis.

METHODS

To compare risk factors in PD patients with MSD to those without MSD (non-MSD) and determine predictive independent risk factors correlated with the MSD phenotype, we enrolled 314 PD patients, including 250 with and 64 without MSD. We compared demographic, characteristic data, as well as PD-associated evaluations between the MSD group and non-MSD group.

RESULTS

Univariate analysis showed that demographic characteristics, including occupation, educational level, monthly income and speaking background; clinical characteristics, including lesions in the frontal and temporal lobes, and concurrent dysphagia; and PD-associated evaluations, including the activity of daily living (ADL) score, non-motor symptoms scale (NMSS) domain 4 score (perceptual problem), and NMSS domain 5 score (attention/memory) were all significantly different between the MSD and non-MSD group (all P < 0.05). Multivariate logistic regression analysis showed that educational level, frontal lesions, and NMSS domain 5 score (attention/memory) were independent risk factors for PD-associated MSD (all P < 0.005).

CONCLUSIONS

We determined an association between MSD phenotype and cognitive impairment, reflected by low-level education and related clinical profiles. Moreover, attention and memory dysfunction may play key roles in the progression of MSD in PD patients. Further studies are required to detail the mechanism underlying abnormal speech motor modulation in PD patients. Early cognitive intervention may enhance rehabilitation management and motor speech function in patients with PD-associated MSD.

Speech difficulties in early de novo patients with Parkinson's disease

INTRODUCTION

Speech difficulties are a common debilitating feature of Parkinson's disease and we aimed to investigate whether speech difficulties are associated with striatal dopaminergic deficits and faster disease progression.

METHODS

Using the Parkinson's Progression Markers Initiative database, 143 early de novo Parkinson's disease patients with speech difficulties were identified and matched 1:1 with 143 Parkinson's disease patients without speech difficulties for age, disease duration and motor symptom severity. We investigated differences in clinical features and striatal [¹²³I]FP-CIT single photon emission computed tomography (SPECT) uptake in Parkinson's disease patients with and without speech difficulties. Cox proportional hazards analysis was carried out to investigate whether speech difficulties were predictive of a faster motor progression and cognitive decline.

RESULTS

Speech difficulties were more common in patients with an akinetic-rigid motor phenotype compared to those with a tremor-dominant phenotype. Parkinson's disease patients with speech difficulties had lower resting tremor (P = 0.027), higher autonomic dysfunction (P = 0.034), increased daytime sleepiness (ESS; P = 0.048), and a higher prevalence of REM sleep behaviour disorder (RBD) symptoms (P = 0.007) compared to those without speech difficulties. Parkinson's disease patients with speech difficulties had significantly lower [¹²³I]FP-CIT uptake in the striatum (P < 0.001), caudate (P = 0.003) and putamen (P = 0.003) compared to those without speech difficulties. The presence of speech difficulties was a predictor of cognitive decline [Hazard Ratio (HR): 0.341, 95% Confidence Interval (CI): 0.153-0.759; Wald: 6.945; P = 0.008), whereas it had no influence on motor progression (HR: 0.885, 95% CI: 0.662-1.183; Wald: 0.680; P > 0.10).

CONCLUSION

Speech difficulties are associated with greater autonomic dysfunction, sleep disturbances and striatal dopaminergic deficit, and can serve as a predictor of faster cognitive decline in early Parkinson's disease.

Changes in Phonation and Their Relations with Progress of Parkinson’s Disease

Hypokinetic dysarthria, which is associated with Parkinson’s disease (PD), affects several speech dimensions, including phonation. Although the scientific community has dealt with a quantitative analysis of phonation in PD patients, a complex research revealing probable relations between phonatory features and progress of PD is missing. Therefore, the aim of this study is to explore these relations and model them mathematically to be able to estimate progress of PD during a two-year follow-up. We enrolled 51 PD patients who were assessed by three commonly used clinical scales. In addition, we quantified eight possible phonatory disorders in five vowels. To identify the relationship between baseline phonatory features and changes in clinical scores, we performed a partial correlation analysis. Finally, we trained XGBoost models to predict the changes in clinical scores during a two-year follow-up. For two years, the patients’ voices became more aperiodic with increased microperturbations of frequency and amplitude. Next, the XGBoost models were able to predict changes in clinical scores with an error in range 11–26%. Although we identified some significant correlations between changes in phonatory features and clinical scores, they are less interpretable. This study suggests that it is possible to predict the progress of PD based on the acoustic analysis of phonation. Moreover, it recommends utilizing the sustained vowel /i/ instead of /a/.

Altered resting-state functional connectivity of the putamen and internal globus pallidus is related to speech impairment in Parkinson's disease

INTRODUCTION

Speech impairment in Parkinson's disease (PD) is pervasive, with life-impacting consequences. Yet, little is known about how functional connections between the basal ganglia and cortex relate to PD speech impairment (PDSI). Whole-brain resting-state connectivity analyses of basal ganglia nuclei can expand the understanding of PDSI pathophysiology.

METHODS

Resting-state data from 89 right-handed subjects were downloaded from the Parkinson's Progression Markers Initiative database. Subjects included 12 older healthy controls ("OHC"), 42 PD patients without speech impairment ("PDN"), and 35 PD subjects with speech impairment ("PDSI"). Subjects were assigned to PDN and PDSI groups based on the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III speech item scores ("0" vs. "1-4"). Whole-brain functional connectivity was calculated for four basal ganglia seeds in each hemisphere: putamen, caudate, external globus pallidus (GPe), and internal globus pallidus (GPi). For each seed region, group-averaged connectivity maps were compared among OHC, PDN, and PDSI groups using a multivariate ANCOVA controlling for the effects of age and sex. Subsequent planned pairwise t-tests were performed to determine differences between the three groups using a voxel-wise threshold of p < 0.001 and cluster-extent threshold of 272 mm3 (FWE<0.05).

RESULTS

In comparison with OHCs, both PDN and PDSI groups demonstrated significant differences in cortical connectivity with bilateral putamen, bilateral GPe, and right caudate. Compared to the PDN group, the PDSI subjects demonstrated significant differences in cortical connectivity with left putamen and left GPi. PDSI subjects had lower connectivity between the left putamen and left superior temporal gyrus compared to PDN. In addition, PDSI subjects had greater connectivity between left GPi and three cortical regions: left dorsal premotor/laryngeal motor cortex, left angular gyrus, and right angular gyrus.

CONCLUSIONS

The present findings suggest that speech impairment in PD is associated with altered cortical connectivity with left putamen and left GPi.

Speech and Voice Response to a Levodopa Challenge in Late-Stage Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) patients are affected by hypokinetic dysarthria, characterized by hypophonia and dysprosody, which worsens with disease progression. Levodopa's (l-dopa) effect on quality of speech is inconclusive; no data are currently available for late-stage PD (LSPD).

OBJECTIVE

To assess the modifications of speech and voice in LSPD following an acute l-dopa challenge.

METHOD

LSPD patients [Schwab and England score <50/Hoehn and Yahr stage >3 (MED ON)] performed several vocal tasks before and after an acute l-dopa challenge. The following was assessed: respiratory support for speech, voice quality, stability and variability, speech rate, and motor performance (MDS-UPDRS-III). All voice samples were recorded and analyzed by a speech and language therapist blinded to patients' therapeutic condition using Praat 5.1 software.

RESULTS

24/27 (14 men) LSPD patients succeeded in performing voice tasks. Median age and disease duration of patients were 79 [IQR: 71.5-81.7] and 14.5 [IQR: 11-15.7] years, respectively. In MED OFF, respiratory breath support and pitch break time of LSPD patients were worse than the normative values of non-parkinsonian. A correlation was found between disease duration and voice quality (R = 0.51; p = 0.013) and speech rate (R = -0.55; p = 0.008). l-Dopa significantly improved MDS-UPDRS-III score (20%), with no effect on speech as assessed by clinical rating scales and automated analysis.

CONCLUSION

Speech is severely affected in LSPD. Although l-dopa had some effect on motor performance, including axial signs, speech and voice did not improve. The applicability and efficacy of non-pharmacological treatment for speech impairment should be considered for speech disorder management in PD.