What is multilingual aphasia?

Multilingual aphasia is a type of aphasia where someone often misspeaks by saying something in her/his native language that is semantically similar to what the person intended to say. People with this type of aphasia do not necessarily misspeak as often in languages that are foreign to them as they do in their native language. This type of aphasia is probably caused by learning and/or acquiring too many foreign languages.

Multilingual aphasia is contrasted with mathematician's aphasia, wherein a person says the exact opposite of what she/he intended to say. Mathematician's aphasia is probably caused by being good at math and/or studying math.

Neither of these types of aphasia are caused by physiological damage to the language-processing hemisphere of the brain, in contrast to the two main types of aphasia and to most miscellaneous types.