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 are
- ischemic: blockage that disrupts blood flow to a region of the brain
- hemorrhagic: a ruptured blood vessel that damages surrounding brain tissue
- traumatic brain injury
- brain tumors
- brain surgery
- brain infections
- other neurological diseases (e.g., dementia).
Stroke is the most common cause of aphasia. According to the National Aphasia Association (2011), about 25% to 40% of stroke survivors experience aphasia. Approximately 35%-40% of adults 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, Raaschou, & Olsen, 1995).