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.