Aphasia is a disorder that results from damage to portions of the brain that are responsible for language. For most people, these areas are on the left side of the brain. Aphasia usually occurs suddenly, often following a stroke or head injury, but it may also develop slowly, as the result of a brain tumor or a progressive neurological disease. The disorder impairs the expression and understanding of language as well as reading and writing. Aphasia may co-occur with speech disorders, such as dysarthria or apraxia of speech, which also result from brain damage.

Aphasia affects areas of the brain that control your ability to speak and the words you use or how you understand them.


Causes of aphasia

Aphasia is caused by damage to one or more of the language areas of the brain. Most often, the cause of the brain injury is a stroke. A stroke occurs when a blood clot or a leaking or burst vessel cuts off blood flow to part of the brain. Brain cells die when they do not receive their normal supply of blood, which carries oxygen and important nutrients. Other causes of brain injury are severe blows to the head, brain tumors, gunshot wounds, brain infections, and progressive neurological disorders, such as Alzheimer's disease.

Types of Aphasia


Global aphasia

This is the most severe form of aphasia, and is applied to patients who can produce few recognizable words and understand little or no spoken language. Persons with Global Aphasia can neither read nor write. Global aphasia may often be seen immediately after the patient has suffered a stroke and it may rapidly improve if the damage has not been too extensive. However, with greater brain damage, severe and lasting disability may result.

Broca’s aphasia (non-fluent aphasia)

In this form of aphasia, speech output is severely reduced and is limited mainly to short utterances of less than four words. Vocabulary access is limited and the formation of sounds by persons with Broca's aphasia is often laborious and clumsy. The person may understand speech relatively well and be able to read, but be limited in writing. Broca's aphasia is often referred to as a 'non fluent aphasia' because of the halting and effortful quality of speech.

Mixed non fluent aphasia

This term is applied to patients who have sparse and effortful speech, resembling severe Broca's aphasia. However, unlike persons with Broca's aphasia, they remain limited in their comprehension of speech and do not read or write beyond an elementary level.

Wernicke’s aphasia (fluent aphasia)

In this form of aphasia the ability to grasp the meaning of spoken words is chiefly impaired, while the ease of producing connected speech is not much affected. Therefore Wernicke's aphasia is referred to as a 'fluent aphasia.' However, speech is far from normal. Sentences do not hang together and irrelevant words intrude-sometimes to the point of jargon, in severe cases. Reading and writing are often severely impaired.

Anomic aphasia

This term is applied to persons who are left with a persistent inability to supply the words for the very things they want to talk about-particularly the significant nouns and verbs. As a result their speech, while fluent in grammatical form and output is full of vague circumlocutions and expressions of frustration. They understand speech well, and in most cases, read adequately. Difficulty finding words is as evident in writing as in speech.

Other forms of aphasia

Other conditions that involve or look like aphasia





Broca’s aphasia

You know what you want to say and can understand others. However, speech is difficult and requires great effort. Short phrases are often used, such as “Want food.” Some weakness or paralysis of the limbs on one side of the body may also be present.


global aphasia

This is the most severe aphasia. You can’t produce and sometimes can’t understand language. However, you’ll still have normal cognitive ability in areas not related to language and communication.


transcortical motor aphasia

You can understand language but can’t communicate fluently. You may use short phrases, have a delay in response time, and frequently repeat things.


Wernicke’s aphasia

You can speak in long sentences. However, these sentences have no obvious meaning and can contain unnecessary or even made up words. Trouble with understanding language and with repeating things is also present.


conduction aphasia

You can still speak fluently and can understand language but have trouble with repetition and finding words.


anomic aphasia

This is a more mild aphasia. Your speech is fluent and you can understand others. However, you’ll often use vague or filler words. You may often feel like a word is on the tip of your tongue and may use other words to help describe the word you’re looking for.


transcortical sensory aphasia

You have trouble comprehending language, although you can communicate fluently. Like Wernicke’s aphasia, your sentences may have no obvious meaning. But unlike Wernicke’s aphasia, you’re able to repeat things, although echolalia may occur in some cases.



Aphasia can happen with any condition that damages the brain. It can also happen with problems that disrupt your brain’s functions. Possible causes for this include: