Chronic foreign accent syndrome appears to be largely a functional disorder, even when a structural neurological lesion is present.
A case series of 49 English-speaking adults who self-report speaking with a foreign accent found 71% were probably functional and 28% were probably or possibly structural.
Participants in the study led by the Centre for Clinical Brain Sciences, University of Edinburgh, were classified on the basis of responses to an online survey and analysis of recorded speech samples.
The study found the onset of symptoms was typically sudden after significant events including migraine or severe headache, stroke, physical injury or surgery to the mouth, face or jaw, or a seizure.
The most common ‘foreign’ accents were Italian, Eastern European, French, German, Indian and ‘Asian’. Some English speakers adopted a different accent in their own language such as Scottish, Australian or Jamaican. And almost a third (31%) said they also developed ‘national characteristics’ they associated with their accent such as hand movements or inappropriate interpersonal behaviour (‘…become loud, arrogant and sneering’).
Investigations carried out typically included MRI and CT but also PET, EEG and lumbar puncture. Only five structural lesions were reported based on imaging.
Positive features of functional foreign accent syndrome (FAS) included periods of remission, the ability to copy other accents, and behavioural features associated with a stereotype.
However these features were also found in the probably or possibly structural group.