Dysarthria in Parkinson's Disease: Lusophony vs. Francophony Comparison

Overview

Parkinson's disease (PD) affects between 1% and 2% of the world's population aged 60 and older; in Europe the prevalence is around 150 PD patients per 100,000 individuals. PD is classically characterized by a symptomatic triad that includes rest tremor, akinesia and hypertonia and although the motor expression of the symptoms involves mainly the limbs, the muscles implicated in speech production are also subject to specific dysfunctions. Motor speech disorders, so-called dysarthria, can thus be developed by PD patients. The main objective of our project is to evaluate the physiological parameters (acoustics), perceptual markers (intelligibility) and psychosocial impact of dysarthric speech in PD, in the context of language (French vs. Portuguese) modulations. Acoustic parameters are expected to be physiologically-based, linked with the motoric aspects of dysarthric speech. The same degree of impairment of such parameters should be associated with the pathology and be present universally in all patients, even if they speak different languages; that should be also the case of prosodic markers, whereas impairment of speech intelligibility may participate to the psychosocial impact in communication alteration. PD patients will be enrolled in the study in Aix-en-Provence (N = 60) and Lisbon (N = 60). Their global motor disability will be assessed with dedicated clinical rating scales, without (off) and with (on) pharmacological treatment. Two groups of 60 healthy age-matched volunteers will provide the normal reference for between-group comparisons. Along with the off and on medication clinical examinations, several speech tasks will be recorded. Moreover, speech organ functions will also be assessed during the same examination. The psychosocial impact of dysarthria will be evaluated via self-questionnaires; it will be analysed a posteriori, as well as the speech intelligibility evaluation, and both will strengthen the overall speech assessments. This global investigation will represent a unique opportunity to provide the most precise and reliable description of PD patients' speech and its impacts on intelligibility and quality of life. Challenging and interdisciplinary aspects are combined in our project, which original cross-linguistic approach involves an international collaboration definitely new in the field of motor speech disorders.

Background - Individuals with Parkinson's disease (PD) have to deal with several aspects that contribute to voice and speech decline and thus, alteration of communication ability during the course of the disease: (i) The orofacial motor dysfunction, so-called dysarthria, which depends on the neurodegenerative processes; (ii) The effects of the medical treatment, which vary according to the disease stage; and (iii) The particular speech modifications that can be language-specific, i.e. dependent on the language spoken by the patients. The main objective of the FralusoPark project is to evaluate changes in dysarthric speech in PD as a result of medical treatment and disease duration using acoustic parameters (voice and prosody), perceptual markers (intelligibility), and patient-based outcomes (the psychosocial impact on quality of life) in two different languages (French vs. European Portuguese). Methods - Individuals with PD will be enrolled in the study in Aix-en-Provence, France (N = 60) and Lisbon, Portugal (N = 60). Their global motor disability and orofacial motor functions will be assessed with specific clinical rating scales, without (OFF) and with (ON) medical treatment. Two groups of 60 healthy age-matched volunteers will provide the reference for between-group comparisons. Along with the clinical examinations, several speech tasks will be recorded to obtain acoustic and perceptual measures. Self-evaluation questionnaires will be used to assess the psychosocial impact of dysarthria on quality of life. Discussion - Our three a priori hypotheses are the following: (i) Global acoustic features are altered similarly in French and Portuguese individuals with PD; (ii) Language-specific prosodic patterns might be altered differently according to the language spoken by the patients; and (iii) The impact of speech disorders on intelligibility and quality of life depends on the cultural and linguistic environment. The study combines an interdisciplinary and cross-linguistic approach to study motor speech disorders and will allow for a better understanding of the progression of speech symptoms in PD and their response to medical treatment. It will provide recommendations on how to assess speech and voice disorders in individuals with PD in order to monitor symptom progression and management.