As mentioned earlier, the typical victim of FAS has experienced some form of brain damage, which could be from head trauma, a stroke or a disease like multiple sclerosis. In these cases, researchers find that the damage sustained has occurred in the parts of the brain related to speech, such as the left hemisphere or in the middle cerebral artery. The creation of speech is wildly complex and involves multiple areas of the brain, so damage caused to one area could alter speech without impeding it. People with FAS are often entirely coherent and articulate, although some can have difficulty with speech elements like word order or pronunciation [source: Stollznow].
All of these causes are what researchers would call "neurogenic." Until recently it was thought that FAS was entirely neurogenic in origin. It is now acknowledged that people can develop FAS through psychogenic means. In other words, foreign accent syndrome can be a symptom of different forms of mental illness. Bipolar disorder, conversion disorder or schizophrenia have all been found to correlate with rare cases of foreign accent syndrome [source: Keulen].
In one recent case, an American woman in her mid-30s began speaking in a British accent. This was a relatively minor element of her case file because she ended up in a psychiatric emergency room after attacking her mother's landlady. The attack was precipitated by her belief that said landlady was using voodoo to curse her. It turned out there was a history of schizophrenia in the patient's family and that she herself had experienced psychotic episodes in the past. In fact, the British accent had shown up in her previous episodes as well. And, as often seems to happen in cases of psychogenic FAS, her accent faded away when she recovered from her episodes [source: Beck].
It's all very well to say that neurogenic cases of FAS are caused by damage to certain areas of the brain and that the psychogenic variants are caused by mental health issues, but what do either of these explanations really mean? Why would such factors make people sound like they've suddenly switched nationalities?