Medically Reviewed By William C. Lloyd III, MD, FACS

What is aphasia?

Aphasia is an impairment of the brain’s ability to process language, affecting speech, comprehension, reading, or writing. Aphasia is usually due to damage on the left side of the brain, which controls most language functions. Common causes of aphasia are typically stroke, head injuries like traumatic brain injury (TBI), and neurological disease, but aphasia can also be due to a tumor or infection.

Aphasia is most common in older people due to increased risk of stroke, but the condition can affect anyone. Stroke causes aphasia to come on suddenly, but if aphasia is due to disease or infection, the symptoms can develop more gradually. The effects of aphasia vary and the symptoms depend on the location and extent of the damage. In mild cases, people may search for words or find it difficult to read or write. In severe cases, people may be completely unable to speak, read, write or understand language.

People with aphasia from stroke may recover all or some function spontaneously. Treatment for aphasia varies according to the symptoms. It can seek to restore function or teach people to compensate for abilities they have lost.

If you notice difficulty speaking or comprehending language, or you see it in someone you know, seek immediate medical care (call 911), as aphasia can be due to a life-threatening condition. Doctors may be able to treat the source of the aphasia and lessen the amount of brain damage that occurs, and the sooner treatment begins the better the chances for maximum recovery.

What are the different types of aphasia?

Aphasia has two main categories. One is expressive, or nonfluent, in which people have difficulty speaking but comprehend language. The other is receptive, or fluent, in which people speak though it is not always understandable, but their comprehension is limited.

Within the two categories, forms of aphasia include:

  • Broca’s, a common form of expressive aphasia, named after the affected area in the brain’s left frontal lobe critical to speech. The person can usually speak in short phrases only and may drop connecting words such as “is,” and “the.” “Sherry is feeding the dog” becomes “Sherry feeding dog,” for example. People with Broca’s aphasia may be able to read, but writing is generally difficult. 
  • Wernicke’s, a form of receptive aphasia caused by damage to the brain’s left temporal lobe. People can form sounds and words but their speech may not be logical, though they are unaware of it. People with Wernicke’s have limited comprehension of language generally, including speech, reading and writing. 
  • Global, in which affected people have both expressive and receptive challenges. It is difficult for them to form recognizable words as well as understanding others. The ability to read and write is also affected. Global aphasia can occur immediately after a stroke but it may improve quickly, even without speech therapy. In some people, however, part or all of the disability is permanent.
  • Primary progressive (PPA), a form of aphasia that advances gradually, making it increasingly difficult for the person to speak, understand language, read or write. It is caused when brain tissue atrophies from degenerative neurological diseases like Alzheimer’s disease and other types of dementia.
  • Anomic, in which the person’s ability to make sounds is unaffected, but they cannot find the correct words to express their thoughts. They may have the same difficulty when they write, though they typically retain the ability to read and understand speech.

People with aphasia can have different combinations of symptoms, and the severity of the impairment varies. People may lose the ability to read, which is called alexia, or have agraphia, an inability to write. Still others may not be able to speak but can calculate math problems, and some cannot do calculations but can speak.

What are the symptoms of aphasia?

The most common symptoms of aphasia include:

  • Difficulty finding words 
  • Speaking slowly and with effort
  • Speaking only single words 
  • Speaking in short, fragmented phrases and omitting connecting words like “of” or “was”
  • Speaking words in the wrong order or illogically
  • Difficulty comprehending speech
  • Difficulty reading or writing   

Aphasia is often caused by stroke, which can be life-threatening. If you notice yourself or someone else suddenly having difficulty speaking or understanding, seek immediate medical care (call 911). Quick action can limit the damage and save lives. The sooner aphasia is diagnosed, the better the chances the person will recover some or all speech ability.

What causes aphasia?

The most common cause of aphasia is brain damage from a stroke, when a blood vessel in the brain is blocked or ruptures. Brain cells are damaged or die due to the loss of blood in areas that handle language processing. Sometimes people have a temporary episode of aphasia due to a migraine headache, seizure, or a transient ischemic attack (TIA). A TIA occurs when blood flow is temporarily blocked to an area of the brain. People who have had a TIA are at higher risk of stroke.

Aphasia can also be due to traumatic brain injury, tumor, infection or degenerative neurological disease, when it is often accompanied by memory loss or confusion. Primary progressive aphasia (PPA) is due to the degeneration of brain cells over time, and progresses to severe dementia.

What are the risk factors for aphasia?

While aphasia is most common among older people due to increased risk of stroke, it can occur in people of any age, gender, race, or nationality. If you are at high risk for stroke, you are at increased risk of aphasia, which affects up to 40% of people who have a stroke. Not all people with risk factors will have a stroke and acquire aphasia, but risk factors for stroke include:

  • Age
  • Heavy alcohol use

Reducing your risk of aphasia

You may be able to lower your risk of acquiring aphasia by lowering your risk of stroke:

  • Stay at a healthy weight.
  • Exercise regularly.
  • Eat a healthy diet.
  • Don’t smoke.
  • Avoid heavy alcohol use.

Aphasia affects about a million people in the United States, with some 180,000 people diagnosed each year. If you are at high risk for stroke, see your doctor regularly and work together to lower your stroke risk, which in turn will reduce your risk of developing aphasia.

What are some conditions related to aphasia?

People with aphasia may also have some movement disorder, typically on the right side of their body. This is because aphasia is due to damage to the left side of the brain, which controls movement on the right side. If the cause of aphasia is severe injury, tumor, infection or disease, people may also lose memory and experience confusion.

How do doctors diagnose aphasia?

If a doctor suspects aphasia, he or she will perform a physical and neurological exam and ask questions to assess speech and comprehension skills, including asking the patient to:

  • Name common objects.
  • Engage in conversation.
  • Answer questions about content after reading or listening. 
  • Repeat words and sentences and follow instructions.
  • Answer yes or no questions.
  • Respond to open-ended questions.
  • Demonstrate ability to read and write.

If people show symptoms of aphasia, the doctor typically will order an MRI or CT scan to confirm the occurrence and location of a stroke or brain injury. If necessary, further tests can be ordered to detect disease or infection.

After a diagnosis of aphasia, the patient will likely see a speech-language pathologist who can perform a thorough assessment of the degree and categories of impairment.

What are the treatments for aphasia?

When brain tissue begins to die following a stroke or brain injury, the body springs into action, sending a molecule known as GDF10 to the area to begin the repair process. It encourages healthy neurons (nerve cells) to sprout new axons, nerve fibers that can reestablish connections in the brain. The brain’s ability to repair itself, called plasticity, can be dramatic.

People with aphasia often see spontaneous improvement in their ability to speak and communicate within the first few months. If symptoms last beyond several months, a complete recovery is unlikely, but with treatment some people continue to improve for many years.

Speech and language therapy can be geared toward restoring function or compensating for lost function, depending on the extent of the damage and the remaining ability.

Treatments to restore function include:

  • Constraint-induced language therapy (CILT), which restricts the use of nonverbal communication, such as gestures, to encourage the person to use speech. This therapy typically is for people who retain some ability to speak.
  • Melodic intonation therapy (MIT), in which patients “sing” words and phrases. This activates the part of the brain used in singing, which can also stimulate parts of the brain involved in language processing and speech formation. 

Treatments to enhance nonverbal communication include:

  • Alternative communication, learning to use pictures, symbols, gestures, and finger-spelling to replace or add to speech. 
  • Visual action therapy (VAT), training in the use of gestures to help people with global aphasia communicate. 

Treatment to improve the ability to read include:

  • Multiple oral reading (MOR), in which people who can speak and read relatively easily practice reading aloud
  • Supported reading comprehension, which utilizes easy-to-read text with drawings, familiar photographs, and simple layouts to improve comprehension. 

Speech and language therapists offer many other forms of therapy to help people regain or replace the use of language. Story completion can help people form sentences with the words in the correct order, and word-finding and word retrieval therapy can prompt people to learn to respond more fully.

Newer research avenues for aphasia treatment include stimulating the brain through electrical or magnetic devices in combination with speech and language therapy. Family and friends can contribute to recovery and lessen frustration by take these steps:

  • Using short, uncomplicated sentences in a natural, conversational way
  • Repeating or writing down key words
  • Allowing plenty of time for the person to express himself or herself or comprehend language
  • Avoiding distractions like loud TV, video games, or music when communicating
  • Encouraging communication and not correcting errors in speech

How does aphasia affect quality of life?

Aphasia does not affect intelligence. However, studies have shown that it is a greater cause of depression and low quality of life than cancer or other severe illness, due to social isolation and frustration. Depression is also more common in stroke patients with aphasia than in other people who have had a stroke. Aphasia can be extremely frustrating for the patient.

In recent years, book clubs, classes, and technology groups have formed to help people with aphasia participate in life outside the home. These activities can boost confidence and improve the ability to communicate. There are support groups in most cities for people who have had a stroke.

Family involvement is important in treating aphasia. Participating in therapy sessions and exploring communication avenues at home supports the person with aphasia and helps maintain social and emotional relationships.

Does aphasia shorten life expectancy?

It is not known if aphasia from stroke or injury affects life expectancy in and of itself, though the underlying condition can affect a person’s overall prognosis. For example, if aphasia is due to Alzheimer’s disease, the aphasia itself does not affect longevity, but Alzheimer’s patients have an average life expectancy from 3 to 10 years.

People with primary progressive aphasia (PPA), which typically begins in middle age, tend to retain memory and personality, even when speech and language are disrupted, until the advanced stages of the condition.

Aphasia disrupts the ability to communicate, but people can recover some or even all their language processing skills, either spontaneously or with therapy, over the short or even the long term.

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  2. Aphasia Therapy Guide. National Aphasia Association. https://www.aphasia.org/aphasia-resources/aphasia-therapy-guide/
  3. Aphasia. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/aphasia/symptoms-causes/syc-20369518
  4. Aphasia. National Institutes of Health. https://www.nidcd.nih.gov/health/aphasia
  5. Speech and Language. Memory and Aging Center, UCSF Weill Institute for Neurosciences. https://memory.ucsf.edu/symptoms/speech-language
  6. Aphasia: A More Common Disorder Than You Think. Baptist Health South Florida. https://baptisthealth.net/baptist-health-news/aphasia-disorder-common-realize/
  7. Scientists identify main component of brain repair after stroke. National Institutes of Health. https://www.nih.gov/news-events/news-releases/scientists-identify-main-component-brain-repair-after-stroke
Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jun 16
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