Speech biomarkers in rapid eye movement sleep behaviour disorder and Parkinson's disease

OBJECTIVE This multi-language study employed simple speech recording and high-end pattern analysis to provide sensitive and reliable non-invasive biomarkers of prodromal vs. manifest alpha-synucleinopathy in patients with idiopathic rapid eye movement sleep behaviour disorder (iRBD) and early-stage Parkinson's disease (PD). METHODS We performed a multicentre study across the Czech, English, German, French and Italian languages at seven centres in Europe and North America. A total of 448 participants (337 males) including 150 with iRBD (mean duration of iRBD across language groups 0.5-3.4 years), 149 with PD (mean duration of disease across language groups 1.7-2.5 years), and 149 healthy controls were recorded; 350 of the participants completed the 12-month follow-up. We developed a fully-automated acoustic quantitative assessment approach for the seven distinctive patterns of hypokinetic dysarthria. RESULTS No language differences that impacted clinical parkinsonian phenotypes were found. Compared to the controls, we found significant abnormalities of an overall acoustic speech severity measure via composite dysarthria index for both iRBD (p = 0.002) and PD (p < 0.001). By contrast, only PD (p < 0.001) was perceptually distinct in a blinded subjective analysis. We found significant group differences between PD and controls for monopitch (p < 0.001), prolonged pauses (p < 0.001) and imprecise consonants (p = 0.03); only monopitch was able to differentiate iRBD patients from controls (p = 0.004). At the 12-month follow-up, a slight progression of overall acoustic speech impairment was noted for the iRBD (p = 0.04) and PD (p = 0.03) groups. INTERPRETATION Automated speech analysis may provide a useful additional biomarker of parkinsonism for the assessment of disease progression and therapeutic interventions. This article is protected by copyright. All rights reserved.