Progressive Neurological Disorders

Many progressive neurological disorders can affect speech, language, voice, swallowing, and cognition.

Parkinson's disease (PD) can be associated with changes in voice, particularly a decrease in volume, and a fast rate of speech which can make it difficult to be understood. Many people with Parkinson's disease can also experience changes in cognition, including trouble with memory, paying attention, or recalling words. Dysphagia, or trouble swallowing, can also occur.


Multiple sclerosis (MS) can result in slurred or unclear speech and decreased volume. Cognitive changes also occur in over 50% of people with MS, including difficulty processing information, learning and remembering new information, organizing and problem-solving, and paying attention. Swallowing problems can also result from damage to the nerves that control the muscles in the mouth and throat.

Amyotrophic lateral sclerosis (ALS) can make it difficult to communicate clearly due to weakening and loss of control of the muscles in the mouth and throat. Some people with ALS may use a communication device to help them speak. This can also impact the ability to swallow safely; eventually, swallowing enough food and drink to stay healthy may become impossible or impractical.

Dementia is not a specific disease but is a term for a collection of symptoms that can be caused by a number of disorders that affect the brain. These symptoms include loss of memory, language, problem-solving and other thinking abilities that are severe enough to interfere with daily life.

Primary progressive aphasia (PPA) is a type of dementia that affects the ability to communicate. Unlike aphasia that results from a stroke, Primary progressive aphasia is caused by neurodegenerative diseases, such as Alzheimer’s disease or Frontotemporal lobar degeneration. People with primary progressive aphasia can lose the ability to speak and write and, eventually, to understand written or spoken language.

Speech therapy can help restore or maintain many of these abilities for people with progressive neurological diseases.