Comprehensive assessment of speech physiology and acoustics in Parkinson's disease progression - Project Summary Parkinson’s disease (PD) is a progressive neurological condition affecting up to 1% of older adults, over 90% of whom experience speech problems. These speech problems cause reductions in quality of life, as measured by patient-centered outcomes (PCOs) of communicative participation, speech intelligibility, and naturalness, with further declines as the disease progresses. Decrements in PCOs can be attributed to changes in underlying physiological mechanisms of speech (i.e., the respiratory, laryngeal, and articulatory subsystems), yet the relative contributions of changes in speech physiology to PCOs are unknown. Without this knowledge, precious therapy time may be wasted on addressing physiological changes that do not matter to the patient experience. Defining the relationships between speech physiology and PCOs would allow clinicians to focus on physiological changes that are important to the patient. Furthermore, since many clinical settings do not have the resources to implement physiological measures, research is needed to determine which clinically accessible acoustic assessments are related to the individualized changes in speech physiology that drive changes in PCOs. We propose a comprehensive, longitudinal study of PCOs, physiology, and acoustics in a large sample, which should provide novel outcomes for clinical translation. In Aim 1, we will compare longitudinal changes in PCOs in PD to concomitant changes in speech physiology. Regardless of whether we see group-level changes, this aim will provide physiological targets that are tied to PCOs in the individuals who decline during the study period. In Aim 2, we will develop and evaluate a refined set of acoustic correlates of speech decline in PD based on their relationships with respiratory, laryngeal, and articulatory physiology. Finally, in Aim 3, we will psychometrically assess the sensitivity to change of the measures of speech physiology and the acoustic correlates. The ability of a measure to appropriately reflect change over time is a critical characteristic, essential for measures to be used for clinical or research applications. To comprehensively assess sensitivity to change, we will examine both decreasing (due to disease progression) and increasing (due to improvement with behavioral cueing – clear speech) function. Our results will provide a roadmap for future evidence-based treatment. Based on a physiological or acoustic evaluation, clinicians will be able to target specific speech subsystems to improve PCOs. This work will guide the future development of personalized treatment for individuals with PD.
