Related Experiment Video
Updated: Jun 17, 2026

MALDI Imaging Mass Spectrometry of Neuropeptides in Parkinson's Disease
Published on: February 14, 2012
Effect of Levodopa on Speech Dysfluency in Parkinson's Disease
Hannah Im1, Scott Adams1,2,3, Anita Abeyesekera1,2
1School of Communication Sciences and Disorders, Western University, Elborn College 1201 Western Road, London ON Canada N6G 1H1.
Objective:
To examine the effect of levodopa medication on speech dysfluency in Parkinson's disease.
Methods:
Fifty-one individuals with Parkinson's disease (IWPD) read aloud during off- and on- medication states. Total speech dysfluencies were calculated from transcriptions of recorded speech samples.
Results:
Severity of speech dysfluency was not significantly related to the severity of motor symptoms, duration of disease, levodopa equivalent dosage, or age. When the IWPD were divided into two groups based on dysfluency severity, there was a significant group-by-medication state interaction. There was a significant correlation between the medication-related change in speech dysfluency and the off-medication severity of speech dysfluency measure (r = -0.46).
Conclusions:
The results of this study indicate that levodopa medication can have a significant effect on speech dysfluency. The beneficial levodopa effect appears to be related to the severity of the off-medication speech dysfluency. Results did not provide strong support for the excess dopamine theory of stuttering in IWPD. A dualistic model of the effects of dopamine on speech fluency in PD is proposed.
Related Concept Videos
Parkinson's Disease: Overview
Parkinson's Disease: Treatment
Parkinson's Disease is primarily a result of the loss of dopaminergic neurons in the substantia nigra pars compacta. The cornerstone of its...
Drugs Affecting GI Tract Motility: Dopamine Receptor Antagonists
Parkinson Disease l: Introduction
Parkinson Disease ll: Pathophysiology
Alterations in Muscle Tone lll

