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.
Other common symptoms reported included memory problems, limb weakness, daily pain, and tremor or abnormal limb movements.
Study investigators, led by neuropsychiatrist Dr Laura McWhirter, noted that recent research has examined the role of attention in functional symptoms.
“Here, perhaps transient changes in awareness or perception following facial injury, migraine, stroke, functional disorder presenting similarly to a stroke, or dissociative seizure produce abnormal attentional focus on the voice or mechanics of speech, disrupting normally automatic speech processes.”
“We propose that features of functional FAS can occur in those with structural lesions because FAS may in some cases have a functional basis even when it starts after neurological injury.”
“Identifying features which can indicate functional FAS with more certainty would help in developing treatments and reducing iatrogenic harm.”
The study authors added that in their clinical experience, most people who develop FAS after a neurological injury recover within weeks.
“While acoustic and physiological speech changes may persist, the period of sounding ‘foreign’ is typically short. It seems likely that, where FAS persists, a functional disorder is largely responsible for a chronic change in accent.”