Stroke: the leading cause of aphasia
A stroke happens when blood flow to part of the brain is cut off, either because a clot blocks a blood vessel (an ischemic stroke) or because a blood vessel leaks or bursts (a hemorrhagic stroke). Without blood, brain cells start to die within minutes. If the stroke hits the language areas, usually on the left side of the brain, it can cause aphasia.
About one in three stroke survivors has aphasia. That is why sudden trouble speaking or understanding is one of the main warning signs of a stroke, and why fast emergency care matters so much.
Other causes of aphasia
| Cause | How it usually starts |
|---|---|
| Stroke | Suddenly |
| Head injury (traumatic brain injury) | Suddenly, after a fall, crash or blow to the head |
| Brain surgery | Right after surgery near the language areas |
| Brain infection, such as encephalitis | Over hours to days, often with fever, headache or confusion |
| Brain tumor | Gradually, over weeks to months; treatment can affect language too |
| Primary progressive aphasia and other dementias | Slowly, over months to years, and keeps getting worse |
When the cause is a head injury, an infection or a progressive disease, aphasia often comes with other changes, such as trouble with memory or attention.
Causes that come and go
Some language problems last only minutes or hours. They still need a doctor:
- Transient ischemic attack (TIA), sometimes called a mini-stroke. Blood flow is blocked for a short time and then returns. Language usually comes back, but a TIA is a warning that a stroke may be coming. Call 911.
- Seizures can cause short episodes of language trouble.
- Migraines can sometimes cause short-lived trouble speaking.
It is not possible to tell these apart from a stroke at home. Treat sudden trouble speaking as an emergency every time.
Sudden or gradual: what to do
- Sudden trouble finding words, speaking or understanding: call 911 now and note the time it started. Read more about sudden difficulty finding words.
- Gradual trouble that builds over weeks or months: make an appointment with a doctor and bring someone who has noticed the changes.
Lowering the risk of stroke
Because stroke is the leading cause of aphasia, lowering stroke risk also lowers the risk of aphasia. The CDC names a past stroke or TIA, high blood pressure, high cholesterol, heart disease, diabetes, smoking, obesity and not being active among the risk factors. Ask a doctor which ones apply to you and what you can do about them.
Common questions
What is the most common cause of aphasia?
Stroke. A stroke happens when a blood clot blocks blood flow in the brain or a blood vessel in the brain leaks or bursts. About one in three stroke survivors has aphasia.
Can aphasia come on suddenly?
Yes. Aphasia from a stroke or head injury starts suddenly. Sudden trouble speaking, finding words or understanding is an emergency: call 911 right away, even if it goes away.
Can aphasia come on gradually?
Yes. A brain tumor or primary progressive aphasia can cause language problems that build slowly over months or years. Word-finding trouble that keeps getting worse should be checked by a doctor.
Can a mini-stroke (TIA) cause aphasia?
A transient ischemic attack, or TIA, can cause aphasia that lasts minutes to hours and then goes away. A TIA is a warning sign that a stroke may follow, so it needs emergency care right away, even if the person feels fine again.
Can stress or anxiety cause aphasia?
Stress, tiredness and anxiety can make anyone search for words more than usual, but aphasia itself comes from damage to the brain. Word-finding trouble that starts suddenly is an emergency even if you feel stressed, and trouble that keeps getting worse should be checked by a doctor.
How ExpressAgain can help
Whatever caused the aphasia, the person still has things to say. ExpressAgain gives them words to read and choose, from pain and basic needs to questions for the doctor, and says them out loud. It is built for aphasia after a stroke and is also used after a brain injury, with a brain tumor and with dementia.
Keep reading
More about aphasia
- Understanding aphasia: the overview
- Sudden difficulty finding words: When word-finding trouble starts suddenly, call 911. What it can mean, and when slower changes need a doctor.
- Types of aphasia: Broca's, Wernicke's and global aphasia, plus anomic, conduction, transcortical and primary progressive aphasia.
- Can aphasia be cured?: Recovery, speech-language therapy and what to expect, including primary progressive aphasia.
- ExpressAgain for aphasia: how the app's aphasia mode works
- ExpressAgain after a stroke: communication through recovery
Sources
- NIDCD (National Institutes of Health): Aphasia
- CDC: Signs and Symptoms of Stroke
- CDC: About Stroke
- CDC: Stroke Risk Factors
- NINDS (National Institutes of Health): Transient Ischemic Attack
- Mayo Clinic: Aphasia, symptoms and causes
- National Aphasia Association: Acquired Aphasia from Stroke/Brain Injury
- American Stroke Association: Aphasia and Stroke
Last reviewed . This page is general information written in plain language from the sources above. It is not medical advice and cannot diagnose anyone. Talk with a doctor or a speech-language pathologist about your own situation. If speaking or understanding suddenly becomes hard, call 911.