The issue of language disorders is quite huge which is the reason why you need to choose what aspect you want to dwell upon. To begin with, there are child language disorders and adult language disorders. Child language disorders include selective mutism, preschool language disorder and language-based learning disabilities. Speaking about adult language disorders, the most common one is aphasia.
Aphasia is a communication disorder. It usually results from damage to one or several parts of the brain. Typically, the left part of the brain has to be damaged so that to cause a language disorder. Aphasia causes difficulties with speaking, reading, listening and writing but it does not affect intellectual abilities of the person. Quite often aphasia is caused by stroke. Yet, brain tumors, progressive neurological disorders and traumatic brain injury can cause aphasia as well. The most common signs of aphasia include difficulties with understanding others, difficulties producing language and difficulties writing and reading. Speaking about the statistic data, it has been estimated that nearly 1 million people suffer from aphasia in the United States of America.