Stuttering and Parkinson's disease - what can we learn from looking at both

A Multimodal approach: Comparisons between developmental stuttering and speech disfluencies in Parkinson’s Disease.

People with Parkinson’s disease (PD) often exhibit dysfluent speech, which appears stuttering-like. This project aims to understand the similarities and differences in speech-motor control between Developmental Stuttering (DS) and Parkinson’s disease.

The two populations appear to have similar motor symptoms, and therefore theoretical assumptions have been made about their underlying mechanisms. However, very limited research has investigated these assumptions. Both conditions involve motor control and speech production difficulties, including tremors, freezes, repetitions, and coordination difficulties, whether in speech and/or gross body motor control. 

This project will combine state-of-the art Magnetic Resonance Imaging methods to compare the two populations.

We will look at how speech is produced, and take a detailed look at dysfluencies. Vocal tract Magnetic Resonance Imaging (VtMRI) is a method used in the lab that provides an unobstructed view of the vocal tract as people speak, enabling us to observe key characteristics of stuttering movements. This project will use previously collected data from DS and collect PD data to compare similarities and differences in speech apertures during speech dysfluency. See “Research Summary: Looking inside the vocal tract during stuttering” for more information.

We will also look at very small details within the brain. The similarities of symptoms between the two conditions create theoretical interest in the possible overlapping (and important differing) neural pathways. Both have differences rooted in the basal-ganglia-cortical system, predominantly via dopaminergic pathways, which act on motor control and timing. Dopamine is an important aspect of both DS and PD neural components. However, Positron Emission Tomography (PET) scans are necessary for imaging dopamine in-vivo, which are invasive and involve radiation. Therefore, limited research has been conducted on dopamine and stuttering (Wu et al., 1995). Within the brain, dopamine and iron must be balanced and create a homeostatic environment, therefore we can use a new type of imaging which captureds iron content, as a proxy for dopamine. This study will use multi-parameter mapping (MPM) MRI as a method to investigate iron deposits in the speech-motor network, including the inferior frontal gyrus and basal ganglia (building upon the lab’s work with stuttering: Cler et al., 2021). 

This is a really exciting project in its early stages and is collaborating with the Speech Biosignal Processing Lab at the University of Groningen. If you would like to know more about this project, including collaboration, would be interested in participating, or know someone who would, please do not hesitate to get in contact! Get in contact here or by emailing Abigail Grant at bgg22slv@bangor.ac.uk.