Aphasia is a language disorder where people have problems speaking and writing. In some cases, people with aphasia also find it difficult to understand the spoken and written word.

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

• stroke, which is thought to be the most common cause, as around 1 in 3 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)

Types of aphasia

The three most common types of aphasia are:

• Broca's aphasia
• Wernicke's aphasia
• global aphasia

These are described below.

Broca's aphasia

Broca's aphasia, also known as non-fluent aphasia, is where 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, "Want...coffee... no...milk".

Wernicke's aphasia

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

One example of speech recorded by a researcher was, “Mother is away here working her work out of here to get her better, but when she's looking, the two boys looking in other part”.

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

Global aphasia

Global aphasia is the most 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. 

See Aphasia - symptoms for more information.

How common is aphasia?

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

Most people affected by asphasia are 65 or over. This is because stroke and common progressive neurological conditions, such as Alzheimer’s disease or other types of dementia, tend to affect people who are 65 or over.

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

Speech and language therapy (SLT)

Speech and language therapy (SLT) is the main type of treatment for people with aphasia. SLT is a general term used to describe a range of different treatments that can help people who have problems with speech and language.

See Aphasia - treatment for more information about SLT.

Outlook

The outlook for people with aphasia depends on the cause of the condition, the extent of the initial brain injury and the severity of symptoms. Depending on these factors, the outlook can range from good to very poor.

However, most people with aphasia will make at least some degree of recovery and many will recover fully. Even if aphasia persists, it does not necessarily mean that a person is unable to live an independent and meaningful life.

The outlook for people with aphasia related to progressive neurological conditions is poor because there is currently no effective method of repairing or preventing the ongoing injury to the brain that is associated with these types of conditions.

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

In cases where aphasia has been caused by a sudden brain injury, such as a stroke or a severe head injury, the symptoms will usually develop straight after the injury.

In cases where there is gradual damage to the brain as a result of a condition that gets worse over time, such as dementia or a brain tumour, the symptoms may develop gradually.

Broca's aphasia

Someone with Broca's aphasia will usually have the following signs and symptoms:

• slow and halting speech
• they may struggle to get certain words out, such as the names of objects, places or people
• the content of their speech is usually stripped down to the barest elements and only contains some basic nouns and verbs, for example, "want drink" or "go town today"
• their writing ability is often similarly affected

A person with Broca's aphasia may be able to understand spoken language to some degree, but have difficulty understanding grammar. For example, they may be unable to tell the difference in meaning between, "Maureen slapped the naughty boy" and "the naughty boy slapped Maureen."

Their ability to read is usually affected. For example, they may assign different meanings to written words, such as reading ‘symphony’ when the word is actually ‘concert’. They may also lose the ability to sound out written words in their head.

Additional symptoms that are not directly connected to speech and language but can occur in people with Broca's aphasia include:

• an inability to control facial muscles and one or both limbs
• weakness down one side of their body (usually the right side)

Wernicke's aphasia

A person with Wernicke's aphasia will usually have the following signs and symptoms.

• They may be able to speak fluently using long sentences, but their speech contains a lack of meaning and often includes nonsense words. For example, they might say “That was just like time for the next week when the bait”.
• People with Wernicke's aphasia are often unaware of their language problems, especially soon after a stroke, and become frustrated that other people are unable to understand them. However, they may recognise their problems if presented with evidence, such as a video or audio recording of them speaking.
• They may have difficulty understanding spoken language.
• Some people also have similar difficulties with reading written language.
• Their ability to write is affected in a similar way to their speaking ability in that they can write fluently but what they write makes little or no sense.

Additional symptoms can include:

• some loss of vision
• difficulties with arithmetic, such as  adding, subtracting, multiplying or dividing numbers
• difficulties with spatial orientation, which is the ability to judge accurately where you are positioned in relation to other physical objects, and is often referred to as your sense of direction
• loss of voluntary limb control

Global aphasia

People with global aphasia usually have more brain damage, so they often have symptoms of both Broca’s aphasia and Wernicke’s aphasia. This can cause problems with all aspects of communication, including:

• speaking
• understanding the speech of others
• naming objects, people and places
• repeating other people’s speech
• reading and writing

Additional symptoms can include:

• paralysis of the right side of the body
• some loss of vision
• loss of voluntary control of their limbs
• problems pronouncing certain sounds and words, which is due to difficulties controlling the mouth, tongue and voice box (so it is not specifically associated with aphasia)

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Aphasia is caused by damage to the parts of the brain that are responsible for:

• speaking
• understanding others
• reading and writing

Collectively, these parts of the brain are known as the brain’s language centre.

The language centre

The language centre is not a single area of the brain. It is a network of specific sections of the brain that work together in a similar way to a computer network.

The language centre is made up of the following areas:

• Broca’s area, which is responsible for the production of speech
• Wernicke's area, which is responsible for understanding spoken and written language
• the sensory cortex, which is responsible for processing the various signals that the body receives, such as sounds (for language) and images (for reading)
• the auditory cortex, which is responsible for converting the actual physical sounds of spoken language into meaningful information
• the motor cortex, which is responsible for controlling the various parts of the body that are used to generate speech, such as the muscles, tongue and voice box

In the past it was thought that damage to a specific part of the brain would always result in a specific type of aphasia, for example, damage to the Broca’s area would always result in Broca’s aphasia. However, the way the language centre works is now thought to be less straightforward than this.

Damage to specific areas of the language centre does not always lead to the expected symptoms. Also, the after effects of brain damage can vary considerably from person to person, making them unpredictable.

Damage to many sections of the brain will usually result in more severe types of aphasia, such as global aphasia.

Brain damage

Ways that the brain can become damaged include the following.

• stroke: during a stroke the brain is deprived of blood and oxygen, which leads to the death of brain tissue
• severe head injury: for example, the sort of injury that occurs as a result of a road traffic accident or following a serious fall from height
• brain tumour: where an abnormal growth of cells develops inside the brain
• health conditions that cause progressive damage to the brain, such as Alzheimer’s disease, other forms of dementia or rarer conditions, such as progressive supranuclear palsy or corticobasal degeneration (two related conditions that are associated with both physical and mental disabilities as a result of brain damage)
• infections that affect the brain, such as meningitis (an infection of the outer layer of the brain) and encephalitis (an infection of the brain itself), although this is a much rarer cause of aphasia

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Communication assessment

Aphasia will usually be diagnosed by a speech and language therapist. There are several tests, including the Boston Diagnostic Aphasia Examination test, that can be used to assess all aspects of an individual’s communication skills.

These types of tests involve simple exercises, such as asking a person to name as many words as they can think of beginning with the letter F, or asking them to name objects in the room. The results can then be used to build up a detailed picture of a person’s language capabilities.

Imaging

Imaging techniques can be used to assess the extent of any brain damage. The two most widely used types of imaging that are used to diagnose aphasia are:

• a computerised tomography (CT) scan, which is where a series of X-rays are taken to build up a detailed, 3D image of the brain
• magnetic resonance imaging (MRI) scan, which is where strong fluctuating magnetic fields are used to produce a detailed image of the inside of the brain

Much less commonly, a type of scan known as a positron emission tomography (PET) scan may be used to assess the state and functionality of the brain. PET scans are usually only used to carry out clinical research at specialist centres.

A PET scan works by detecting the energy that is produced by positrons (positively charged particles). This allows researchers to study a number of processes inside the brain, such as blood flow, inflammation and the release of dopamine (a chemical that is associated with physical pleasure). Therefore, a PET scan can provide an insight into how the brain is functioning, as well as simply seeing what it looks like.

This type of information can be useful in diagnosing aphasia that is associated with progressive damage to the brain, such as the type of damage that is caused by Alzheimer’s disease.

Most cases of aphasia can be improved with treatment, even severe cases of global aphasia. However, a complete return to pre-aphasia communication levels is not always possible.

Speech and language therapy (SLT) is the main treatment for aphasia. SLT is a general term that is used to describe a number of different techniques that can help improve a person’s ability to communicate.

Aims of SLT

SLT for people with aphasia has three main goals:

• to help the person to relearn any communication skills that have been lost or damaged (if this is possible)
• to make the best use of the person’s remaining communication abilities
• to find new ways of communicating

Principles of SLT

There is no single way to treat aphasia, but most experts agree that a course of SLT tends to be more successful if it is based on the principles that are described below.

Intensive

Research has found that a short-term course of intensive SLT, for example, eight to ten hours a week over the course of two months, is usually more effective than a longer, less intensive course, for example, one to two hours a day for five or six months. However, not everyone has the energy to participate in intensive therapy, particularly elderly people who are recovering from a stroke.

Cumulative

SLT works best when the therapist sets relatively modest goals and then moves on to more complex goals. For example, they might start with naming a specific person, before describing their relationship with that person.

Personalised

Research has found that using teaching material and aids that have a personal significance to the person being treated produces a more engaged response than using generic materials.

For example, using photographs of people or situations that a person would remember is more effective than using stock photographs.

Provide alternatives

Spoken and written language is not the only way that a person with aphasia can communicate. Therefore, it is important that a therapist discusses potential alternative communication methods, such as simple gestures, more complex sign language, or technology, such as electronic speech synthesisers.

Group work

It can be beneficial for someone with aphasia to work in a group with other people with the condition. As well as providing a non-threatening opportunity to practise communication skills, it can also lessen the feelings of loneliness and isolation experienced by many people with aphasia.

In addition, research carried out in 2010 suggested that SLT does not always have to be provided by a fully qualified therapist to be successful. Trained and supervised volunteers can also provide effective treatment or they can work with professional therapists to improve the effects of therapy.

The Stroke Association provides training for volunteers. See The Stroke Association website for details about how to volunteer.

SLT techniques

Promoting Aphasics' Communicative Effectiveness (PACE)

Promoting Aphasics' Communicative Effectiveness (PACE) is a type of SLT that uses conversation to improve a person’s communication skills.

The therapist will use a picture or drawing to stimulate a conversation, while the person with aphasia is encouraged to use any means of communication to respond.

Early PACE sessions will focus on relatively simple topics of conversation, such as where the person was born. As the sessions progress, the topics of conversation become more complex and abstract, including, for example, the person’s favourite film and why they like it.

Melodic intonation therapy (MIT)

Melodic intonation therapy (MIT) is a type of SLT that is often used in the treatment of non-fluent forms of Broca's aphasia.

MIT is based on a common observation that many people with aphasia who have speaking difficulties do not have similar difficulties when singing. This may be because the parts of the brain that are used when singing are different to those that are used when speaking, so the singing areas of the brain and the associated ability may remain undamaged.

During MIT sessions, a person with non-fluent aphasia is encouraged to hum and to sing words or phrases that they find difficult to recall, while tapping out a rhythm. This technique has been shown to increase the number of words a person can recall.  

Computerised script training (CST)

Computerised script training (CST) is a type of SLT that involves using a computer. CST uses scripts that simulate real-life conversations and social activities, allowing a person with aphasia to practise their communication skills and to relearn abilities.

Constraint-induced aphasia therapy (CIAT)

Constraint-induced aphasia therapy (CIAT) is a type of SLT that is designed for people with chronic (long-term) aphasia (usually defined as aphasia that lasts longer than two years).

CIAT is based on a type of physical therapy, known as constraint-induced motor therapy (CIMT), which is sometimes used to help people recovering from a stroke.

People recovering from a stroke often have weakness on one side of their body. This causes them to use the other side of their body more. CIMT uses equipment, such as splints, to prevent them from relying on the stronger side of their body, and forces them to make use of the weakened side in an effort to get them to relearn how to use it.

CIAT is based on a similar premise. People with chronic aphasia may adopt a number of basic compensatory strategies to help them to communicate, for example:

• pointing
• gesturing (but not complex sign language)
• making sound effects, such as saying "brrrrm" for car

These strategies may be useful in the short to medium term, but relying on them can cause a person with aphasia to forget previously learnt communication skills and delay their recovery. 

Therefore, CIAT usually involves a short course of intensive therapy where the therapist will work with the person with aphasia to identify these types of basic compensatory strategies and encourage them to adopt more complex ways of communicating. This may not necessarily be full speech, but may include methods that force the person’s brain to make use of its language centre, such as drawing or using communication tools, such as a speech synthesiser.

Transcranial stimulation

Transcranial stimulation is a type of painless treatment that may benefit some people with aphasia.

There are two types of transcranial stimulation:

• transcranial direct current stimulation (tDCS), which is where electrodes (small metallic discs) are placed on the surface of the scalp and a small electrical current is passed through them
• transcranial magnetic stimulation (TMS), which is where magnetic coils are placed above the scalp and used to generate magnetic fields, which create short-lasting electrical currents in the brain below the stimulation site

It has been suggested that both tDCS and TMS may help to stimulate parts of the language centre that have been damaged and encourage a certain degree of recovery and repair. For example, initial research has found that these types of treatment may help people to improve their ability to remember the names of certain objects, people and places.

As transcranial stimulation is a new method of treatment, access is currently limited to people who are willing to take part in a clinical trial. A clinical trial is where researchers compare a new treatment against an existing treatment or a dummy treatment (placebo) to see whether the new treatment is effective and safe.

See the Health A-Z topic about Clinical trials and Aphasia - clinical trials for more information.

Medication

Researchers have also been studying the effects of medication for improving the language skills of people with aphasia.

One type of medication that has proved reasonably effective in some people with Broca's aphasia, when used in combination with SLT, is called bromocriptine.

It is thought that bromocriptine may help stimulate some sections of the brain’s language centre, leading to an improvement in communication skills.

Another medication that has proved reasonably effective in improving language skills, particularly the ability to name objects, people and places correctly, is called donepezil.

Donepezil increases the levels of a chemical called acetylcholine in the brain. This is thought to lead to an increase in cognitive ability (the ability to think, reason and plan).

Again, it is likely that access to these sorts of treatment will only be available in clinical trials. 

Communicating with a person with aphasia

If you live with, or care for, a person with aphasia, you may be unsure about the best way to communicate with them. You may find the advice listed below helpful.

• After speaking, allow the person plenty of time to respond. If a person with aphasia feels rushed or pressured to speak, they may become anxious, which can affect their ability to communicate.
• Use short, uncomplicated sentences and do not change the topic of conversation too quickly.
• Avoid asking open ended questions. Closed questions that have a yes or no answer are better.
• Avoid finishing a person’s sentences or correcting any errors in their language. This may cause resentment and frustration for the person with aphasia.
• Keep any possible distraction to a minimum, such as background radio or TV noise.
• Use paper and a pen to write down any key words, diagrams or pictures to help reinforce your message.
• If you do not understand something that a person with aphasia is trying to communicate, do not pretend that you do understand. The person may find this type of behaviour patronising and upsetting. It is always best to be honest about your lack of understanding.
• Try to remember that despite their change in speech pattern, the person’s personality is unchanged. They may appear emotionally distant or abrupt, but how they speak to you does not necessarily reflect how they feel about you.

Brain

The brain controls thought, memory and emotion. It sends messages to the body controlling movement, speech and senses.

Depression

Depression

Depression is when you have feelings of extreme sadness, despair or inadequacy that last for a long time.

There is no guaranteed method of preventing aphasia. However, there is some general lifestyle advice that can reduce your risk of developing conditions that are associated with aphasia, such as Alzheimer’s disease (or other forms of dementia) or stroke.

For example, you should:

• stop smoking (if you smoke)
• avoid drinking large amounts of alcohol
• eat a healthy, balanced diet that includes at least five portions of fruit and vegetables every day
• use a combination of exercise and a calorie controlled diet to achieve a healthy weight, which is particularly important if you are overweight or obese
• exercise for at least 30 minutes each day because this will improve both your physical and mental health
• stay mentally active, for example, by reading, writing or taking an adult education course

Below is a list of topics that provide more detailed information and advice about the conditions that are associated with aphasia.

• Alzheimer’s disease - prevention
• Dementia - prevention 
• Healthy eating 
• Lose weight 
• Quitting smoking 
• Stroke - prevention