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Bilingualism, aphasia, and Alzheimer’s: What we know and what we’re still learning

Marissa Russell, MS, CCC-SLP | Aphasia, Communication disorders

More than half of the world’s population is bilingual, and this number is rising. With figures this high, it is not surprising that there is a lot of curiosity surrounding how the bilingual brain works. Are there benefits to speaking more than one language? And what does being bilingual mean for someone with a communication disorder, such as aphasia or Alzheimer’s disease? In honor of both Aphasia Awareness Month and Alzheimer’s & Brain Awareness Month, this article explores what we know and what we’re still learning about bilingualism, and how it relates to aphasia, Alzheimer’s, and dementia.

THE FACTS – What do we know?

  • Speaking another language can boost cognitive skills
    Compared to people who only speak one language, bilingual individuals often show stronger attention skills and are better able to switch between tasks.
  • Bilingualism can be protection against cognitive decline
    Being bilingual can help the brain more effectively cope with aging, resulting in the maintenance of cognitive skills such as memory and problem-solving compared to people who are monolingual. This can also delay the onset of symptoms of Alzheimer’s or dementia.
  • It’s not too late to reap the benefits!
    Time to sign up for that language class you’ve been eyeing – research shows that those who learn a second language later in life can still experience the cognitive and aging-related benefits of being bilingual.
  • For bilingual individuals with aphasia, each language may be impacted differently
    Aphasia is a language disorder that can arise after a stroke or brain injury. Often, when someone who speaks two languages is diagnosed with aphasia, both languages are equally impaired. However, sometimes one language is more impacted than the other. This can be influenced by a range of factors, including language ability prior to stroke or brain injury and the age at which each language was learned.
  • In bilingual aphasia, treatment in ONE language can lead to improvements in BOTH
    Studies show that speech-language therapy in one language results in either neutral or positive changes in the second language. For certain language difficulties, a speech-language pathologist can design an effective treatment plan that engages the brain pathways involved in each language, leading to improvements in both (even when only one language is being used in therapy!).

THE QUESTIONS – What’s left to learn?

While research has helped uncover a wealth of information about bilingualism and cognitive-communication disorders such as aphasia and Alzheimer’s, much remains unknown. Here are some of the major questions researchers face today.

  • What does “bilingual” even mean?
    Bilingual ability exists on a continuum. We cannot neatly divide “monolingual” and “bilingual” speakers into two categories because everyone’s language experiences are different. Better understanding this can help inform research studies and treatments for people who speak more than one language.
  • Does being bilingual lower the risk of Alzheimer’s disease?
    While studies show that bilingual individuals show symptoms of Alzheimer’s later than those who only speak one language, we still do not know whether being bilingual can lower the risk of getting Alzheimer’s in the first place.
  • What is the best way to treat bilingual aphasia?
    Researchers and clinicians are still developing effective treatment methods and resources to support the rehabilitation of language skills in this population. Which language(s) should be treated, and in what order? Should treatment be different depending on whether or not the languages are similar (e.g., Spanish and Italian) or different (e.g., English and Mandarin)? How can we create more resources (e.g., therapy tools, apps) to support rehabilitation in other languages?

The number of bilingual individuals in the world continues to increase. As a result, it remains important to provide resources and support for the growing number of multilingual individuals with communication disorders. If you are experiencing challenges after a stroke, brain injury, or diagnosis of a neurological condition such as dementia, ask your doctor if speech-language therapy is a good fit for you. To find a speech-language pathologist who speaks your language, use ASHA ProFind.

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  1. Roberta Francoeur

    I am bilingual French/English with mother tongue being English. My speech therapist and I did not even discuss this. I used Constant Therapy with the therapist. In conversation with my family I seemed to do better in French. Several comments made about this fact with my husband. I find these articles quite fascinating. My stroke was 2 years ago and I do pretty well with my aphasia but still have trouble with some of the words I lost early on. It seems they are harder to bring forth.

    • Carla Gates

      Thank you for your comments, Roberta.

  2. Dan Moser

    My wife, Maria, has svFTD/PPA. She participated in a study of those with PPA who were/are bilingual that was/is being done by the Aphasia Lab at Univ of Texas, Austin. Although she was losing her second language, Spanish, at the time the study was helpful to her (and me) and, hopefully, will result in it helping others with PPA.

    • Carla Gates

      Hi Dan! We did a story on your wife, Maria, a few years back! Thanks for your comment, and we hope you are well.


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