Aphasia is an umbrella term for any type of language impairment that affects speaking, comprehension, or the ability to read or write. According to the National Aphasia Association, approximately 80,000 people acquire a form of aphasia each year. However, in this video we see an example of a specific form of aphasia, known as Wernicke's aphasia (fluent aphasia).

While the most common cause of aphasia is a stroke, the condition can also be induced by a head injury or brain tumor. When the Wernicke's area of the brain, the part of the brain responsible for speech comprehension, is damaged, Wernicke’s aphasia can ensue. When this happens, as it did for stroke survivor Byron Peterson, patients lose the ability to understand the meaning of spoken words. Despite this, their speech fluency is left unaffected, hence the condition’s name.

Often, patients with this form of aphasia will speak nonsensically, using unnecessary or made-up words. Because patients with this form of aphasia have damaged the area of their brain responsible for language comprehension, they often have difficulty both understanding others’ speech and realizing the mistakes in their own speech. Thus, they are oblivious to how nonsensical their speech actually is. Reading and writing are also severely impaired in patients with fluent aphasia.

Unlike other forms of aphasia normally associated with body movement paralysis, such as Broca’s aphasia, Wernicke’s aphasia does not cause any problems with movement. Although there is no cure for aphasia, the condition can be treated with therapy.