A rare acquired speech disorder known as foreign accent syndrome (FAS) causes a person's spoken accent to be perceived as "foreign." As the term implies, it appears to others that you have adopted a foreign accent.
There are two main types of foreign accent syndrome:
Structural: Damage to the parts of your brain that regulate the muscles you use to speak can result in FAS.
Functional: This type of FAS arises when medical professionals are unable to identify a cause. It may be associated with mental health disorders that involve disordered activity or hyperactivity in specific brain regions, or it may occur after seizures or migraines. This is commonly referred to by medical professionals as "psychogenic" FAS, indicating that it has no structural origin.
FAS primarily impacts your speech rhythm. The following are some examples of these disruptions:
Pace of speech
Tone and pitch
The ability to accurately produce sounds (articulation)
Emphasizing certain syllables while ignoring others (syllable stressing)
Sound duration, volume, or loudness
Inflections (such as how a statement changes into a question if you raise your voice at the end)
According to a 2019 study [4] of 49 individuals with foreign accent syndrome, the following conditions were most frequently linked:
15 people with severe migraines or headaches
12 with strokes
6 individuals with oral or facial surgery
5 with seizures
More than 100 cases have been documented in medical literature, despite their rarity. Multiple sclerosis (MS), severe injury, stroke, and vascular dementia are among the brain conditions that can cause FAS. In some cases, FAS may manifest as a form of functional neurological disorder (FND), where speech impairment occurs without visible brain injury. One helpful analogy is that neurogenic FAS (the first type) is caused by "hardware" abnormalities in the brain, whereas functional FAS (the second type) is caused by "software" issues. Furthermore, there are "mixed" cases where people have both neurogenic and functional speech challenges.
In one study [5], researchers identified 25 reported cases of acquired neurogenic FAS without aphasia. They projected each lesion volume onto a reference brain and used a connectome dataset from normal subjects to determine the network of brain regions functionally associated with each FAS lesion. To find common network sites among the lesions, network maps were then superimposed.
Consistent with earlier findings, classical lesion overlap analysis revealed variation in lesion anatomical locations. However, network overlap was observed in the medial frontal cortex and the bilateral lower and middle regions of the precentral gyrus in at least 80% of cases. The middle part of the precentral gyrus is thought to be a larynx-specific motor area linked to the production of vowels and stop/nasal consonants, as well as the assessment of pitch accent, while the lower left portion is believed to be the site of lesions causing apraxia of speech (AOS).
MedBound Times reached out to Dr. Mohammed Dhilber PK, MBBS, MD (General Medicine), to learn his opinion on foreign accent syndrome. Here’s what Dr. Dhilber had to say:
Foreign Accent Syndrome is a unique and intriguing reminder that the human brain is a labyrinth of mysteries, where even the simplest speech may turn into a voyage into unexplored realms of sound and identity.Dr MOHAMMED DHILBER PK MBBS, MD (General Medicine) Assistant Professor, Dept. of Internal Medicine MES Medical College, Perinthalmanna, Malappuram district, Kerala
Although it is still debated whether this is a crucial element of functional FAS, some patients report that their symptoms begin or worsen during times of emotional or psychological stress.
An early instance of Foreign Accent Syndrome was documented by Norwegian neurologist Georg Herman Monrad-Krohn (1884–1964).
The tempo, intonation, and positioning of the tongue can all change in speech, making it sound foreign. Speech does not always become disorganized and often remains highly comprehensible. Reported cases of FAS include accent changes such as:
Spanish to "Hungarian"
British English to "French"
American English to "British English"
Japanese to "Korean"
Predictable errors
Unusual prosody, particularly in multi-syllabic words
Consonant substitution, deletion, or distortion
Voicing errors (e.g., "pike" instead of "bike")
Difficulty with consonant clusters
Vowel distortions, prolongations, or substitutions (e.g., "yeah" pronounced as "yah")
Insertion of "uh" into words
Karen Butler, an American woman, underwent a dental procedure. In addition to experiencing numb gums afterward, she also developed a noticeable foreign accent. Born in Bloomington, Illinois, Butler relocated to Oregon as a baby. She claims to be an American who was "born and bred" in the United States and has never visited Europe or lived abroad.
However, she no longer sounds American. Her accent now combines elements of Irish, English, and possibly other European languages.
"I just fell asleep, and when I woke up, my mouth was swollen and hurt, and I made a funny noise. 'You'll talk normally after the swelling goes down,' the dentist stated," Butler recalls.
The foreign accent persisted, even though the swelling quickly subsided. She was later diagnosed with foreign accent syndrome by neurologist Ted Lowenkopf, head of the Providence Stroke Center in Portland.
It's usually the result of a brain injury, which can come from stroke, head trauma, or other diseases that can damage brain tissue, like multiple sclerosis.Dr. Ted Lowenkopf, Neurologist, Head of the Providence Stroke Center, Portland
Other examples include a British woman from Devon who had a stroke and now sounds French and another British woman who had a migraine and then gained a Chinese accent.
According to Lowenkopf, only the pattern and intonation of speech are affected by FAS. Brain trauma and strokes typically result in significant brain damage, causing speech issues that extend beyond a change in accent.
Butler won't know for sure until she has a brain scan, but it's possible that she suffered a minor stroke while under anesthesia. According to Lowenkopf, comparing a recent scan with an older one Butler obtained years ago may provide insight into what transpired.
Foreign accent syndrome itself is not a health threat. However, it can indicate serious underlying conditions such as multiple sclerosis (MS), dementia, brain tumors, or lesions. Therefore, treatment focuses on addressing the underlying cause of FAS.
Although medication can help manage symptoms, many causes of foreign accent syndrome have no cure. To help patients regain their normal speech patterns, doctors often recommend speech therapy. In cases where the cause is unknown—such as Butler’s case after dental surgery—speech therapy may be the only available treatment option.
Cleveland Clinic. "Foreign Accent Syndrome." Cleveland Clinic, May 1, 2024. https://my.clevelandclinic.org/health/diseases/25242-foreign-accent-syndrome-fas.
Greenhalgh, Jane. "A Curious Case of Foreign Accent Syndrome." NPR, June 1, 2011. https://www.npr.org/sections/health-shots/2011/06/01/136824428/a-curious-case-of-foreign-accent-syndrome.
The University of Texas at Dallas. "Home - Foreign Accent Syndrome (FAS)." University of Texas at Dallas. Accessed February 20, 2025. https://sites.utdallas.edu/fas/.
Villines, Zawn. "What Is Foreign Accent Syndrome?" Medical News Today, April 28, 2020. https://www.medicalnewstoday.com/articles/foreign-accent-syndrome#treatment.
Higashiyama, Yuichi, Tomoya Hamada, Asami Saito, Keisuke Morihara, Mitsuo Okamoto, Katsuo Kimura, Hideto Joki, et al. "Neural Mechanisms of Foreign Accent Syndrome: Lesion and Network Analysis." NeuroImage Clinical 31 (January 2021): 102760. https://doi.org/10.1016/j.nicl.2021.102760.