Aphasia is caused by damage to the language centers of the brain. In most people, these language centers are located in the left hemisphere, but aphasia can also occur as a result of damage to the right hemisphere; this is often referred to as crossed aphasia, to denote that the right hemisphere is language dominant in these individuals.

Common causes of aphasia include the following:

  • Stroke
    • Ischemic—caused by a blockage that disrupts blood flow to a region of the brain
    • Hemorrhagic—caused by a ruptured blood vessel that damages surrounding brain tissue
  • Traumatic brain injury
  • Brain tumors
  • Brain surgery
  • Brain infections
  • Progressive neurological diseases (e.g., dementia)

Stroke is the most common cause of aphasia. According to the National Aphasia Association (n.d.), about 25%–40% of stroke survivors experience aphasia. Approximately 35%–40% of adults who are admitted to an acute-care hospital with a diagnosis of stroke are diagnosed with aphasia by the time they are discharged (Dickey et al., 2010; Pedersen, Jorgensen, Nakayama, Raaschou, & Olsen, 1995).

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