The connection between stuttering and Parkinson’s disease (PD) has long been discussed and is the source of speculation. Many in online PD communities have raised the question when talking about speech difficulties. But data is scarce due to the absence of extensive research.
Parkinson’s is a neurodegenerative motor disorder with no known cause or cure. Damage to neurons in the substantia nigra portion of the brain leads to a reduction in the production of dopamine. Dopamine is a neurotransmitter produced by nerve cells that signal to produce smooth, purposeful movements. This disruption is most commonly associated with the motor symptoms of tremor, rigidity, postural instability (balance), and bradykinesia (slowness of movement). It also affects the facial muscles used to produce smooth, productive speech.2
Parkinson’s affects each person differently. Not all symptoms are experienced by everyone with the disorder. Changes in speech are known as hypokinetic dysarthria, and common symptoms include2:
Decreased breath support resulting in breathy or soft volume of speech (Hypophonia)
Slurred, mumbled, or rapid speech (Tachyphemia) making speech difficult to understand
A loss of inflection, pitch and volume resulting in speaking in monotone (Monopitch)
Difficulty in finding the right words
Stuttering and palilalia
Stuttering is a speech fluency/rhythm disorder resulting in the involuntary repetition of sounds or words that has two fundamental types: developmental and acquired stuttering. In general, stuttering is characterized as instability in the language loops of the brain resulting in disruptions in speech production.3 Palilalia is a condition with similar-presenting symptoms typically associated with advanced PD.
Developmental stuttering is the most frequent form of stuttering. It typically develops in children between the ages of 2 and 5 during language acquisition and development. The speech hesitation is most commonly in the repetition of the first word in a sentence or thought. Anxiety can contribute to the development of stuttering. Children generally grow out of their stuttering, but research has shown that it can reoccur in some people after a neurological illness or injury.
Neurogenic stuttering is a relatively rare speech fluency disorder that develops during adulthood in people with no prior history of stuttering after the occurrence of a neurological event, injury, or ongoing illness.1 An acquired form of stuttering, it affects the rhythm of speech and can initiate at any part of saying a word.7 It involves the involuntary prolongation, cessation or repetition of a sound.5 Speech can sound halting or fragmented characterized by frequent interruptions and difficulty producing words.7
The exact cause of neurogenic stuttering is not known. It is associated with several neurological conditions and possible locations of basal ganglia in the brain’s nervous system, which may result from a disruption in dopamine levels.4,5 People who have experienced a stroke, traumatic brain injury, epilepsy, multiple sclerosis, and Parkinson’s are among those who may develop neurogenic stuttering.5,7
Psychogenic stuttering is another acquired form. It is connected to behavioral dysfunction, which may occur after trauma or emotional, or physical stress.5,7
Unlike stuttering, which has not generally been linked to Parkinson’s, palilalia is more common.3 It is a speech disorder that can resemble neurogenic stuttering.5 Associated with PD and other Parkinsonian conditions, palilalia presents as an involuntary repetition of syllables, words or phrases with increased speed and decreased volume and clarity.1,3 The presence of palilalia is likely to be found in older people with advanced stages of Parkinson’s.
The treatment approach for developmental and neurogenic stuttering can be the same. Most often, people who stutter are under the care of a speech pathologist, someone who treats communication and swallowing disorders. They are expert in addressing the needs of people who have experienced neurological conditions including stroke, brain injury, hearing loss, and Parkinson’s disease.
Success in treatment of those with PD is often limited because respiration and breath support is affected by decreasing muscle strength. Vocal exercise is one approach, but its success is strongly correlated with the severity of other Parkinson’s symptoms. Speech pathologists work to help people with Parkinson’s coordinate their breathing and muscle movements in order to eliminate the stutter.
There have been limited studies evaluating stuttering in people with PD and even those studies have very few participating subjects. There is therefore not sufficient data to make a direct correlation between stuttering and Parkinson’s disease. However, there is an association reported by some people with Parkinson’s.4 To find out more about the stuttering, and what may be causing it, consider making an appointment with a speech pathologist to get a clear diagnosis and therapeutic plan.
Casagrande Brabo, N., Soares, T. et al. Fluency in Parkinson’s disease: disease duration, cognitive status and age. Available at: https://pdfs.semanticscholar.org/386b/104d3cadc0db3afda4d5026d6132c96e359b.pdf. Accessed 1.7.19.
Downward, E. Symptoms – Speech Difficulties or Changes. Available at: https://parkinsonsdisease.net/symptoms/speech-difficulties-changes/. Accessed 1.9.19.
Anderson, J., Hughes, JD et al. Developmental stuttering and Parkinson’s disease: the effects of levodopa treatment. Available at: https://jnnp.bmj.com/content/jnnp/66/6/776.full.pdf. Accessed 1.7.19.
Gregg, BA, Zraick, RI, Smith-Olinde, L. Stuttering-like Dysfluencies in the Speech of Patients with Parkinson’s Disease. Available at: https://www.asha.org/Events/convention/handouts/2009/2237_Gregg_Brent/. Accessed 1.6.19.
Cruz, C., Amorim, H. et al. Neurogenic stuttering: a review of the literature. Available at: https://www.neurologia.com/articulo/2017151/eng. Accessed 1.7.19.
Shahed, J., Jankovic, J. Re-emergence of childhood stuttering in Parkinson's disease: a hypothesis. Available at: https://www.ncbi.nlm.nih.gov/pubmed/11215569. Accessed1.7.19.
Neurogenic Stuttering. Available at: https://www.stutteringhelp.org/neurogenic-stuttering. Accessed 1.7.19.
Benkea, Th. Hohensteina, C. et al. Repetitive speech phenomena in Parkinson's disease. Available at: https://jnnp.bmj.com/content/69/3/319. Accessed 1.9.19.