Motor speech and non-motor language endophenotypes of Parkinson’s disease

ABSTRACT

Introduction: Idiopathic Parkinson’s Disease (PD) results in a range of motor and non-motor impairments. Clinical diagnosis commonly occurs after substantial neurophysiological damage limiting the opportunity for neuroprotective treatments. Uncovering sensitive objective markers with the capacity to detect pre-symptomatic disease and track disease progression is therefore a priority. Speech may provide an ideal proxy marker for PD; a quantifiable biometric that displays salient changes in early disease and appears to evolve with disease progression.

Areas covered: This review describes the endophenotype of speech, voice, cognition and language modalities in PD and investigates the speech as a ‘proxy marker’ of PD disease state.

Expert opinion: Detailed characterization at different disease stages are needed and must incorporate longitudinal assessment to capture small but significant changes in speech, voice, cognition and language modalities within patient changes over time. Advances in technology are leading to new opportunities for acquiring data remotely and more frequently, offering more ecologically valid testing environments. Combined with automated signal processing and analysis, symptoms may also be tracked in-home readily. Features extracted may provide a ‘proxy marker’ for early identification of PD and objective monitoring of disease progression.

KEYWORDS:

• Parkinson’s
• dysarthria
• acoustic
• voice
• language
• communication

Article highlights

• Dysarthria, a neuromuscular speech disorder, can be the first and most prominent manifestation of PD.

• Alongside changes in speech, PD is associated with impaired morphosyntactic, lexical-semantic, and high-level language comprehension and production.

• Pharmaceutical and surgical interventions for PD may improve certain modalities of speech production, but effects vary between individuals.

• Longitudinal research designs are needed to evaluate the complex interplay between motor speech, language, and cognition.

• Speech acoustics may serve as a valuable proxy marker of PD ‘risk’, disease progression and treatment efficacy.

Declaration of interest

A Vogel has been funded by a National Health and Medical Research Council, Australia Dementia Fellowship (#1135683) and is Chief Science Officer of Redenlab. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or conflict with the subject matter or materials discussed in this manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was funded in part by National Health and Medical Research Council Australia Dementia Fellowship (#1135683), Australia