Primary Progressive Aphasia Causes Language—Not Memory—Loss

The recent issue (January 13, 2021) of the journal Neurology contains research finding that while primary progressive aphasia causes a loss of language, it does not cause a loss of memory in people who also have Alzheimer’s disease.

The Progression of Primary Progressive Aphasia

Up until this point, scientists knew that PPA affected language first whereas Alzheimer’s affected memory first. As we wrote in our overview of PPA:

Is PPA the Same as Alzheimer’s Disease? No, though both are neurodegenerative diseases. PPA affects language first, while Alzheimer’s disease affects memories early on. PPA begins in the frontotemporal area of the brain, which is responsible for language. As the two diseases progress, they begin to resemble each other in the sense that people with PPA may lose memories as well as the ability to care for themselves, much like Alzheimer’s disease. But the first signs of PPA are language-based, and the first signs of Alzheimer’s disease are memory-based.

That loss of language made it difficult to know for certain whether PPA also affected memories or whether memories were intact but unable to be expressed due to loss of language. A doctor looked at people with primary progressive aphasia and underlying Alzheimer’s disease as well as people who solely had Alzheimer’s disease. According to U.S. News & World Report, “about 40% of people who have [PPA] have underlying Alzheimer’s disease.”

Researching Primary Progressive Aphasia

U.S. News & World Report wrote about Dr. M. Marsel Mesulam’s study. “For the study, Mesulam’s team assessed 17 people with primary progressive aphasia associated with Alzheimer’s disease and 14 people with typical Alzheimer’s disease and memory loss … While participants with aphasia showed no decline in memory skills during the study, they had significant language-skill declines. The patients with typical Alzheimer’s, meanwhile, had equally severe declines in verbal memory and language skills.”

Moreover, autopsies performed on the brains after the study revealed “similar amounts of Alzheimer’s-related plaques and tangles” in both people with PPA and people with Alzheimer’s.

Mesulam states that more research is needed to determine how people with PPA can hold onto their memories, even when their brains contain Alzheimer’s-like damage in the brain.

You can read the research in Neurology or a summary in U.S. News & World Report.