Aphasia is an acquired language disorder caused by damage to the brain's language networks. It affects the ability to speak, understand, read, and write. It does not affect intelligence.
Key Takeaways
- ✓ASHA estimates aphasia affects approximately 1 in 3 stroke survivors.
- ✓It is a language disorder, not a cognitive one. Intelligence, personality, and memories remain intact.
- ✓Four main types exist, each with a different communication profile and a different therapy approach.
- ✓Recovery is possible at any stage, including years after the initial injury.
What causes aphasia?
Stroke is the most common cause, accounting for roughly 80% of cases. Other causes include traumatic brain injury, brain tumours, and progressive neurological conditions such as primary progressive aphasia. In all cases, the underlying mechanism is damage to the perisylvian language network in the left hemisphere, the region responsible for processing language.
Is aphasia the same as a speech disorder?
No. Speech disorders affect the physical production of sound. Aphasia affects language itself: the system of words, grammar, and meaning. A person with aphasia may struggle to find words, form sentences, understand spoken language, read, or write, depending on which part of the language network was damaged. Some people with aphasia also have co-occurring motor speech disorders such as apraxia or dysarthria, but these are separate conditions with separate treatment approaches.
What are the main types of aphasia?
- •Broca's aphasia: effortful, telegraphic speech with relatively preserved comprehension. The person understands much of what is said but struggles to produce fluent sentences.
- •Wernicke's aphasia: fluent but often meaningless speech with significantly impaired comprehension. The person may not be aware of their errors.
- •Global aphasia: severe impairment of both expression and comprehension, typically following large left hemisphere strokes.
- •Anomic aphasia: difficulty finding specific words, with otherwise relatively preserved language. This is the mildest and most common type across all aphasia presentations.
For a detailed breakdown of each type, its communication profile, and what therapy looks like, see our complete guide to types of aphasia.
How common is aphasia?
The National Aphasia Association estimates that aphasia is more common than Parkinson's disease, cerebral palsy, or muscular dystrophy, yet far less recognised by the general public. In the United States alone, roughly 2 million people live with aphasia, and approximately 180,000 new cases occur each year.
What does recovery look like?
Most recovery occurs in the first three to six months post-stroke, driven partly by spontaneous neurological healing and partly by speech-language therapy. Meaningful improvement is documented well beyond that window in patients who maintain active therapy. The NIDCD states directly that some people continue to improve for years after a stroke.
The factors most consistently associated with better outcomes are smaller lesion size, early initiation of therapy, high therapy intensity, and consistent home practice between sessions.
