Aphasia is a loss of the ability to use and understand language. It results from damage to the part of the brain that is associated with language. The most common cause of aphasia is stroke.

Aphasia may be classified in several ways. When people with brain damage forget words and experience difficulty communicating with others, they have expressive aphasia. Aphasia characterized by problems understanding spoken or written words is called receptive aphasia. Receptive and expressive aphasia often occur simultaneously.

Some physicians also describe aphasia as either fluent or non-fluent. Aphasia is considered fluent if the patient is able to speak at a volume, speed and intonation that is similar to normal speech. If the patient has problems producing sentences or words, the aphasia is considered non-fluent.

Aphasia can be further categorized according to the location of damage in the brain:

• Broca’s aphasia. Caused by damage to the frontal lobe of the brain and results in a highly simplified language system that is reliant on interpretation by the listener.
  
  
• Wernicke’s aphasia. Caused by damage to the temporal lobe of the brain and results in the patient using nonsense words in fluent-sounding sentences.
  
  
• Global aphasia. Caused by damage to various parts of the brain and may result in severe difficulties speaking and understanding words.

Often mistaken for aphasia, apraxia (loss of motor function, particularly in the mouth and tongue) is another symptom of brain damage that may accompany aphasia. People with aphasia may also experience depression, paralysis and memory loss.

Although the most common cause of aphasia is stroke, it may also be caused by other conditions, such as:

• Alzheimer's disease
• Traumatic brain injury
• Brain tumors or lesions
• Landau-Kleffner syndrome

Treatment of aphasia typically focuses on rehabilitation of the patient’s language ability through individual or group therapy with a speech-language therapist. Although prevention of aphasia may not always be possible, taking measures to reduce the risk of stroke may be the most effective way to prevent aphasia.

Aphasia can make simple attempts to communicate difficult. There are certain steps that people with aphasia can take to ease their ability to communicate, such as carrying a pen and paper with them at all times. It is important for friends and family members of individuals with aphasia to remain patient and supportive.