Aphasia

Aphasia, also known as dysphasia, is an impairment in a person's ability to comprehend or formulate language because of damage to specific <a href="/facts/Brain/EKla9NkJ">brain</a> regions. The major causes are <a href="/facts/Stroke/DwpjdzY0">stroke</a> and head trauma; prevalence is hard to determine, but aphasia due to stroke is estimated to be 0.1–0.4% in <a href="/facts/Developed_country/sqwTSDHm">developed countries</a>. Aphasia can also be the result of <a href="/facts/Brain_tumor/avjI5Nhm">brain tumors</a>, <a href="/facts/Epilepsy/wawyp56a">epilepsy</a>, autoimmune neurological diseases, brain infections, or <a href="/facts/Neurodegenerative_disease/HTDrVEqc">neurodegenerative diseases</a> (such as <a href="/facts/Dementia/T0MRDE9I">dementias</a>).
To be diagnosed with aphasia, a person's language must be significantly impaired in one or more of the four aspects of communication. In the case of progressive aphasia, a noticeable decline in language abilities over a short period of time is required. The four aspects of communication include spoken language production, spoken language comprehension, <a href="/facts/Written_language/QQ5DlfoK">written language</a> production, and written language comprehension. Impairments in any of these aspects can impact functional communication.
The difficulties of people with aphasia can range from occasional trouble finding words, to losing the ability to speak, read, or write; intelligence, however, is unaffected. Expressive language and receptive language can both be affected as well. Aphasia also affects <a href="/facts/Visual_language/KfbsWqmb">visual language</a> such as <a href="/facts/Sign_language/Wjfl9Db6">sign language</a>. In contrast, the use of <a href="/facts/Formulaic_language/u0fUkXaJ">formulaic expressions</a> in everyday communication is often preserved. For example, while a person with aphasia, particularly <a href="/facts/Expressive_aphasia/Ne6dMC37">expressive aphasia</a> (<a href="/facts/Broca%2527s_area/lV3X3Yb6">Broca's</a> aphasia), may not be able to ask a loved one when their birthday is, they may still be able to sing "Happy Birthday". One prevalent deficit in all aphasias is <a href="/facts/Anomic_aphasia/cGUeXp1c">anomia</a>, which is a difficulty in finding the correct word.: 72 
With aphasia, one or more modes of communication in the brain have been damaged and are therefore functioning incorrectly. Aphasia is not caused by damage to the brain resulting in motor or sensory deficits, thus producing <a href="/facts/Dysarthria/UQFqqkvH">abnormal speech</a> — that is, aphasia is not related to the mechanics of <a href="/facts/Speech/WEelhfTs">speech</a>, but rather the individual's language cognition. However, it is possible for a person to have both problems, e.g. in the case of a hemorrhage damaging a large area of the brain. An individual's language abilities incorporate the socially shared set of rules, as well as the thought processes that go behind communication (as it affects both verbal and nonverbal language). Aphasia is not a result of other peripheral motor or sensory difficulty, such as <a href="/facts/Paralysis/Sh1Rqr8R">paralysis</a> affecting the speech muscles, or a general hearing impairment.
<a href="/facts/Neurodevelopmental_disorder/vfBhK1S6">Neurodevelopmental</a> forms of <a href="/facts/Auditory_processing_disorder/b5p1GHuV">auditory processing disorder</a> (APD) are differentiable from aphasia in that aphasia is by definition caused by acquired brain injury, but acquired epileptic aphasia has been viewed as a form of APD.

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Aphasia