Aphasia is a condition that affects the brain and leads to problems using language correctly.

People with aphasia make mistakes in the words they use, sometimes using the wrong sounds in a word, choosing the wrong word, or putting words together incorrectly.

Aphasia also affects speaking and writing in the same way. Many people with the condition find it difficult to understand words and sentences they hear or read.

Why does aphasia happen?

Aphasia is caused by damage to parts of the brain responsible for understanding and using language. Common causes include:

  • stroke, thought to be the most common cause, around one in three people experience some degree of aphasia after having a stroke
  • severe head injury
  • brain tumour
  • progressive neurological conditions (conditions that over time cause progressive brain and nervous system damage, such as Alzheimer’s disease)

Read more about the causes of aphasia.

Types of aphasia

Some more common types of aphasia are:

  • Broca's aphasia
  • Wernicke's aphasia
  • global aphasia
  • aphasia in Alzheimer's disease
  • primary progressive aphasia (PPA)

These are described below.

Broca's aphasia

In Broca's aphasia, also known as non-fluent or expressive aphasia, a person has great difficulty speaking and can only manage to string a small number of words together in short, halting sentences. However, it is usually possible to understand the meaning of their speech. For example, a person with Broca's aphasia might say, " no...milk".

Wernicke's aphasia

In Wernicke's aphasia, also known as fluent aphasia, a person is able to speak normally and use long, complex sentences, but the actual words they use do not make sense, or they include nonsense words in their speech.

Many people with Wernicke's aphasia are often unaware their spoken language makes no sense to others and can become angry or frustrated by the lack of understanding shown by others.

Global aphasia

Global aphasia is a severe form of aphasia. Someone with the condition has difficulty with all forms of communication, including speaking, reading, writing, correctly naming objects or people, and understanding other people’s speech.

Aphasia in Alzheimer's disease

People with Alzheimer's disease usually have trouble thinking of the right word, or remembering people's names. This is called anomia or anomic aphasia. As the condition gets worse, people may have difficulty putting a sentence together and making themselves understood. People usually develop problems with memory and understanding at the same time, which can also make communication more difficult.

Primary progressive aphasia

Sometimes a progressive brain disease causes aphasia but doesn't affect memory or other thought processes for a long time, possibly for several years. This is called primary progressive aphasia (PPA).

Read more about the symptoms of aphasia.

How is aphasia treated? 

A speech and language therapist (SLT) usually diagnoses the condition by testing your language capabilities. They can also help arrange treatment.

Speech and language therapy is the main type of treatment for people with aphasia. This aims to help restore some of your ability to communicate and also help you develop alternative ways of communicating, if necessary.

The effectiveness of treatment is different for everyone, but most people with aphasia make at least some degree of recovery and some recover fully. Even if aphasia persists, it does not necessarily mean a person is unable to live an independent and meaningful life.

However, the chances of recovery for people with aphasia related to progressive neurological conditions is poor because there is no way of repairing or preventing the ongoing injury to the brain associated with these types of conditions.

When aphasia is caused by a progressive condition, treatment focuses on making the most of what people can still do, and on developing other ways of communicating, to prepare for a time when speaking will be more difficult.

Read more about diagnosing aphasia and treating aphasia.


Due to the challenges of living with aphasia, some people with the condition develop further problems.

People may experience what are sometimes called "catastrophic reactions". These are sudden and overwhelming outbursts of frustration and anxiety, often in the form of aggression or screaming. However, these reactions are only temporary and should pass.

Losing the ability to communicate effectively can understandably also lead to depression in many people with aphasia. Discussing feelings openly or taking medication can be helpful in managing this.

Read more about complications of aphasia.

Speech and language therapy

A speech and language therapist explains how the therapy works and who can benefit from it.

Media last reviewed: 11/07/2013

Next review due: 11/07/2015

Who is affected?

Aphasia is one of the most common disorders to affect the brain. Speakability, a leading charity for people affected by aphasia, estimates there are currently 250,000 people in the UK with aphasia, with 20,000 new cases occurring each year.

Most people affected by aphasia are 65 or over. This is because stroke and common progressive neurological conditions, such as dementia, tend to affect people who are 65 or over.

Aphasia triggered by a brain tumour or a severe head injury can affect people of all ages, including children.

Page last reviewed: 13/11/2012

Next review due: 13/11/2014