Foreign Accent Syndrome is a rare side effect that causes people to speak their native language in a foreign accent

Foreign Accent Syndrome is a real thing where people talk in their native language with a foreign accent. An example of this would be an American person speaking English with a French accent. Foreign Accent Syndrome - or FAS - is a possible side-effect of a head injury, stroke, or anything else that causes serious brain damage. It was originally thought of as a made-up symptom of a brain injury, but research has concluded that it is real and points towards serious brain trauma.