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

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.