Dysarthria vs. Aphasia

The ability to communicate is essential to the human experience. With it we are able to express our ideas, emotions, thoughts, and feelings. Speech and language disorders such as dysarthria and aphasia, however, can disrupt this essential ability, making both speech and understanding others a challenge.

In this comprehensive graphic, we break down the differences between dysarthria and aphasia, and explain their symptoms, causes, and treatments.

What Is the Difference Between Aphasia and Dysarthria?

While dysarthria and aphasia are both communication disorders, they affect different aspects of communication. Aphasia is a language disorder caused by damage to parts of the brain that control language functions. This condition can impair an individual’s ability to speak, understand, read, or write. It usually occurs after a stroke or traumatic brain injury (TBI) and can vary in severity depending on how much of the brain was damaged.

Dysarthria, on the other hand, is a motor speech disorder. It happens when the muscles used for speaking—such as those in the lips, tongue, vocal cords, and diaphragm—become impaired due to damage to the nervous system (e.g., become weak, become too tight, do not move enough, move too much, etc.). Unlike aphasia, dysarthria doesn’t affect a person’s ability to understand language or find words. Rather, it makes it difficult for them to articulate and speak clearly.

You can have dysarthria without aphasia. Since dysarthria is a motor speech disorder, it only affects the muscles that control speech, not the brain’s language centers. A person with dysarthria may fully understand language, but their ability to communicate verbally is impaired because of difficulty controlling the movements of their mouth, tongue, or vocal cords.
For example, someone with Myasthenia gravis might develop dysarthria due to muscle weakness but retain their ability to understand and write fluently. Alternatively, people with aphasia may have no physical problems with the muscles required for speech but struggle to find words or make sense of sentences due to brain damage.