Aphasia is the inability to express or understand words due to damage to the brain. Some types of dementia, such as Alzheimer’s, share a connection with a certain kind of aphasia, known as primary progressive aphasia.

Aphasia is a disorder that affects a person’s ability to understand, read, write, and speak words. The primary cause is damage to the part of the brain that controls speech, usually the left hemisphere.

Aphasia typically occurs due to a stroke or acute brain damage. However, a certain type of aphasia called primary progressive aphasia may develop due to the slow degeneration of the brain from some types of dementia, such as Alzheimer’s.

This article reviews how aphasia relates to dementia. It also explores primary progressive aphasia symptoms, causes, and more.

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Some forms of dementia may cause aphasia. Dementia describes a range of neurological degenerative disorders that affect the brain.

The most common form of dementia in the United States is Alzheimer’s, which accounts for 60–80% of all cases. Alzheimer’s typically begins by affecting the area of the brain that is responsible for learning.

As the condition progresses, it can cause more severe symptoms that can include confusion, mood changes, unfounded suspicions of family members or caregivers, disorientation, and behavioral changes, among others.

Alzheimer’s disease causes an unusual buildup of two proteins, called amyloid plaques and neurofibrillary tangles, in the brain. In most people, the condition affects areas responsible for memory. However, in some cases, the proteins may gather in areas related to speech and language.

When this occurs, it can lead to the clinical diagnosis of a condition called primary progressive aphasia.

Primary progressive aphasia

Primary progressive aphasia is a type of degeneration of the brain’s frontal or temporal lobes. It can cause changes in a person’s ability to speak, write, read, and understand language.

As it progresses, the condition will impact a person’s daily life and their ability to communicate with others.

Primary progressive aphasia has three variants, which include:

  • Semantic: A person with this variant may have trouble remembering the correct words, such as names, or understanding their meaning.
  • Nonfluent agrammatic: A person with this variant may have difficulty speaking fluently with correct words or grammar.
  • Logopenic variant: A person with this variant may have trouble coming up with the right words and may pause frequently while they speak.

Alzheimer’s can cause primary progressive aphasia to occur. In these cases, a person may notice speech changes first and only notice symptoms of dementia as the condition progresses.

Alzheimer’s Research UK notes that the symptoms a person may experience depend on the variant of primary progressive aphasia:

Semantic variant

Those with the semantic variant can forget the meaning of words, objects, and concepts. Instead, they may use vague terms such as “thing” to describe what they mean.

This can begin with words and names they do not use very often. As the condition progresses, a person may have difficulty with words they use more commonly.

People with this variant may also:

  • forget the function of everyday items
  • talk about subjects in a vague or repetitive manner or at great length
  • have difficulty understanding what others are saying
  • have difficulties with reading and spelling

Nonfluent agrammatic variant

Those with the nonfluent agrammatic variant may find it challenging to produce speech. They may have trouble producing words even when they know what they want to say, and it can take a lot of effort to speak.

People with this variant may also:

  • stutter
  • speak more slowly
  • find it challenging to use the correct grammar when speaking or writing
  • have difficulty understanding long sentences

Over time, a person may:

  • develop hearing difficulties
  • find reading, spelling, and writing more challenging
  • find it more difficult to make plans and decisions
  • have trouble understanding some words
  • develop mood and behavioral changes
  • have difficulty swallowing

Logopenic variant

Those with the logopenic variant can speak and understand others. However, they may find it difficult to find the right words.

A person may:

  • pause while they try to remember words
  • speak hesitantly and slowly
  • have difficulty understanding and remembering complex verbal information
  • become frustrated and agitated

The primary cause of aphasia is damage to the parts of the brain responsible for language and speech. Over time, dementia causes the cells in the brain to become damaged and lost.

Although the exact cause of primary progressive aphasia is unclear, researchers believe the unusual buildup of proteins inside the brain cells may be a cause, suggesting that:

  • the semantic variant may occur due to a build of proteins called TDP-43
  • the nonfluent agrammatic variant may develop as a result of a buildup of tau protein
  • the logopenic variant may occur due to a build of up the amyloid protein

Alzheimer’s and other forms of dementia have several potential risk factors, including:

There are ethnic and racial disparities in Alzheimer’s rates. According to the Alzheimer’s Association, African Americans are about twice as likely as white people to develop the condition, and Latin Americans are about 1.5 times as likely.

Genetics is also a potential risk factor for both primary progressive aphasia and Alzheimer’s. However, the genes involved vary.

In primary progressive aphasia, the primary gene responsible is the progranulin gene. In Alzheimer’s disease dementia, the primary genetic risk factor is ApoE4.

ApoE4 is not a risk factor for primary progressive aphasia, even in cases that develop as a result of Alzheimer’s disease.

Aphasia can cause challenges in interacting with others.

In some cases, this may lead to:

Treatment for aphasia can vary greatly based on a person’s needs. It can often involve a range of specialists, from neurologists to physical therapists.

Treating aphasia often involves therapy with a speech-language pathologist. Sessions may be individual or include family members.

When aphasia is the result of a degenerative condition, treatment will focus more on what a person can do rather than trying to improve their language skills. Doctors and therapists may focus on finding ways to cope, such as using pictures or other forms of communication.

Managing aphasia can involve several steps, including:

  • using assistive devices that can range from a sheet of paper with pictures on it to assistive technology, such as pads or computers
  • having caregivers attend therapy sessions and important appointments
  • using gestures, body language, miming, and facial expressions
  • making sure to get a person’s attention before attempting communication

For behavioral changes, a doctor may prescribe medications such as antidepressants or low dose antipsychotic drugs to help if needed.

When speaking with a person who has primary progressive aphasia, it is important to:

  • avoid finishing their words or sentences unless they ask for help
  • be patient and understanding
  • speak clearly
  • engage in one-to-one conversations

Over time, a person with primary progressive aphasia will require additional help. At this point, it is important to think about any changes that family or caregivers may need to make in the home.

People may also wish to consider creating a power of attorney for healthcare, home care, and driving safety.

Learn more about dementia and setting up a power of attorney for healthcare.

Below are answers to some common questions about aphasia.

Is aphasia common in dementia?

The United Kingdom’s National Health Service (NHS) states that those with the most common types of dementia usually have a mild form of aphasia. This usually involves having difficulty finding words and remembering names. However, primary progressive aphasia is rare.

Dementia, like Alzheimer’s, typically affects the part of the brain that affects memory, not speech. As a result, it is not a common cause of aphasia.

How is aphasia different from dementia?

Aphasia affects the part of the brain responsible for speech and language. Dementia affects the parts of the brain responsible for memory and high level thinking.

What is the life expectancy for someone with primary progressive aphasia dementia?

Studies suggest that life expectancy varies between the variants of primary progressive aphasia. According to a retroactive study from 2021, once symptoms start, life expectancy may be:

  • 12 years for the semantic variant
  • 7.1 years for nonfluent variant
  • 7.6 years for logopenic variant

However, these are estimates only. A person’s actual life expectancy following the onset of aphasia can vary.

Will aphasia get better in a person with dementia?

In the case of primary progressive aphasia, the condition will not improve and can worsen over time. Therapies and treatment may help improve a person’s overall quality of life.

Aphasia affects a person’s ability to communicate, while dementia affects the areas of the brain responsible for memory and thinking. Although aphasia is often the result of a stroke or brain injury, dementia can also cause it.

A certain form of aphasia, primary progressive aphasia, is a type of degenerative disease that affects the speech and language portion of the brain. In some cases, it may be a form of atypical Alzheimer’s disease.