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Symptoms – Speech Difficulties or Changes

Parkinson’s disease (PD) affects approximately one million Americans and can cause several motor and non-motor symptoms. One of the secondary motor symptoms that people with PD may experience is a change in speech, or speech difficulty. Not everyone with PD experiences the same symptoms, and not all patients will have changes in their speech. However, for those who are affected, it can be a significant problem, causing difficulties in communication and possibly leading to reduced social interactions.1

There are several ways PD may affect speech:

  • The voice may get softer, breathy, or hoarse, causing others difficulty hearing what is said.
  • Speech may be slurred.
  • Speech may be mumbled or expressed rapidly.
  • The tone of the voice may become monotone, lacking the normal ups and downs.
  • The person may have difficulty finding the right words, causing speech to be slower.
  • The person may have difficulty participating in fast-paced conversations.1

Some of the medical terms that describe the speech changes that can occur with PD include:

  • Dysarthria, which is a motor speech disorder or impairment in speaking due to PD affecting the muscles required for speech
  • Hypophonia, which means soft speech, is an abnormally weak voice caused by the weakening muscles
  • Tachyphemia, also known as cluttering, is characterized by an excessively fast speed of talking and a rapid stammering that makes it difficult to understand the person speaking2,3

How does Parkinson’s cause speech difficulties?

PD causes damage to the nerves in the brain and in the body. The motor symptoms of PD, including speech changes, are caused by damage to the part of the brain called the substantia nigra pars compacta. The neurons (nerve cells) in the substantia nigra produce dopamine, a neurotransmitter (chemical messenger) that transmits signals from the substantia nigra to other parts of the brain to produce smooth, purposeful movement. Damage to the neurons in the substantia nigra causes a reduction in dopamine, creating the motor symptoms seen in people with PD, including the movement needed by the muscles in the face and mouth to generate speech. Communication may be further impaired in people with PD who experience a mask-like expression, in which the face has less movement and appears less animated.1,4

Treating speech difficulties in Parkinson’s disease

Treatment is customized to the individual’s needs, as well as the difficulties they are experiencing. Speech therapy has been shown to help people with PD who experience speech difficulties. A speech therapist, or speech language pathologist, can evaluate and treat a number of speech difficulties. One program, with exercises specifically for people with PD, is called the Lee Silverman Voice Treatment (LSVT), and it has shown improvements that can last up to two years.5,6

Other options include assistive communication devices, such as a portable voice amplifier or an electronic device for stuttering (Speech Easy). Some people with PD get a procedure where collagen is injected into the vocal folds, which may help in cases where the vocal cords don’t close completely when talking.6

Other symptoms of Parkinson’s disease

The primary motor symptoms of PD are tremor, rigidity, postural instability (impaired balance), and bradykinesia (slowing down and loss of spontaneous movement). PD also causes many secondary motor symptoms, including micrographia (small or cramped handwriting), changes in gait (way of walking), stooped posture, dystonia (muscle contractions that cause twisting), cramping, difficulty swallowing, sexual dysfunction, impaired fine motor dexterity, and akathisia (restless movement). In addition to these motor symptoms, PD can cause non-motor symptoms such as depression, difficulty swallowing or chewing, urinary problems, constipation, skin problems, sleep problems, pain, and cognitive problems, such as memory problems or slow thinking.1,7

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Written by: Emily Downward | Last reviewed: March 2017
  1. Parkinson’s Disease Foundation. Accessed online on 12/21/16 at
  2. Accessed online on 12/21/16 at
  3. Taber’s Medical Dictionary. Accessed online on 12/21/16 at
  4. Alexander GE. Biology of Parkinson's disease: pathogenesis and pathophysiology of a multisystem neurodegenerative disorder. Dialogues Clin Neurosci. 2004 Sep; 6(3): 259–280.
  5. MacDonald DC. Speech deficits in Parkinson’s disease. Aging Well; 3(4):12. Accessed online on 12/21/16 at
  6. National Parkinson Foundation. Accessed online on 12/21/16 at
  7. Parkinson’s Disease. NIH Publication No. 15-139. Dec 2014. National Institute of Neurological Disorders and Stroke, National Institutes of Health.