Aphasia is a neurological disorder caused by damage to the portions of the brain that are responsible for language. Primary signs of the disorder include difficulty in expressing oneself when speaking, trouble understanding speech, and difficulty with reading and writing. Aphasia is not a disease, but a symptom of brain damage. Most commonly seen in adults who have suffered a stroke, aphasia can also result from a brain tumor, infection, head injury, or dementia that damages the brain. It is estimated that about 1 million people in the United States today suffer from aphasia. The type and severity of language dysfunction depends on the precise location and extent of the damaged brain tissue. Generally, aphasia can be divided into four broad categories: (1) Expressive aphasia involves difficulty in conveying thoughts through speech or writing. The patient knows what he wants to say, but cannot find the words he needs. (2) Receptive aphasia involves difficulty understanding spoken or written language. The patient hears the voice or sees the print but cannot make sense of the words. (3) Patients with anomic or amnesia aphasia, the least severe form of aphasia, have difficulty in using the correct names for particular objects, people, places, or events. (4) Global aphasia results from severe and extensive damage to the language areas of the brain. Patients lose almost all language function, both comprehension and expression. They cannot speak or understand speech, nor can they read or write.

In some instances, an individual will completely recover from aphasia without treatment. In most cases, however, language therapy should begin as soon as possible and be tailored to the individual needs of the patient. Rehabilitation with a speech pathologist involves extensive exercises in which patients read, write, follow directions, and repeat what they hear. Computer-aided therapy may supplement standard language therapy.

The outcome of aphasia is difficult to predict given the wide range of variability of the condition. Generally, people who are younger or have less extensive brain damage fare better. The location of the injury is also important and is another clue to prognosis. In general, patients tend to recover skills in language comprehension more completely than those skills involving expression.

Prepared by the National Institutes of Health