PPA is caused by loss of brain cells in the front and sides of the brain, called the frontal and temporal lobes. However, the reasons for this loss are not yet clear.

We know that there is an unusual build-up of certain proteins inside brain cells. These proteins include TDP-43 and tau but it’s a complicated picture. Researchers are working hard to find out why this happens and how it damages brain cells.

Most people with logopenic aphasia have the same kind of damage in their brains as people with Alzheimer’s disease. This includes the build-up of a protein called amyloid in the brain. Therefore, in most cases logopenic aphasia is an unusual form of early-onset Alzheimer’s.

In a small number of people semantic dementia or primary non-fluent aphasia may be caused by a faulty gene that can be passed down in families. The genes involved are called MAPT, progranulin (or GRN) and C9ORF72. These genes are also associated with other forms of frontotemporal dementia. Find out more about genes and dementia.

What is Primary progressive aphasia?

Information in this booklet is for anyone who wants to know more about primary progressive aphasia (PPA). This includes people living with PPA, their carers, families and friends.


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This information was written in April 2019 and is due for review in April 2021. Please contact us if you would like a version with references.

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