Aphasia primarily causes difficulties with speech, listening, reading and writing, according to the American Speech-Hearing-Language Association. The disorder may also cause apraxia, dysarthria, or difficulties swallowing, but it does not typically affect intelligence. The specific symptoms and their severity vary greatly, depending on the location and extent of the brain damage.
Expressive, or non-fluent, aphasia causes difficulties with communicating thoughts into speech or writing, according to WebMD. Receptive, or fluent, aphasia distorts a person's understanding of speech. Primary progressive aphasia is a rare type in which a person slowly loses the ability to communicate and understand language over time. Global aphasia, the most severe type, takes away the ability to speak, understand words, read and write, and it often shows up right after a severe stroke.
Aphasia is most commonly caused by stroke, occurring in about 25 to 40 percent of stroke patients, states the National Aphasia Association. It can also occur as the result of a head injury, a brain tumor or a neurological disorder. Aphasia affects about one in 250 people in America, with 180,000 people acquiring the condition annually. It is more common than cerebral palsy, muscular dystrophy and Parkinson's disease, and it can occur in people of all races, genders and ages.