Study of the Week: Primary Progressive Aphasia Patients with Alzheimer’s Keep Their Memory

Welcome to Study of the Week from Patient Worthy. In this segment, we select a study we posted about from the previous week that we think is of particular interest or importance and go more in-depth. In this story we will talk about the details of the study and explain why it’s important, who will be impacted, and more.

If you read our short form research stories and find yourself wanting to learn more, you’ve come to the right place.


This week’s study is…

Memory resilience in Alzheimer’s disease with primary progressive aphasia

We previously published a story about this research in a story titled “These Alzheimer’s Patients Keep Their Memory,” which can be found here. The study was originally published in the medical journal Neurology. You can view the abstract of it here.

What Happened?

The rare neurodegenerative illness called primary progressive aphasia (PPA) is known to cause issues with language that tend to progressively worsen as time passes. Prior research has revealed that around 40 percent of patients with this disorder also have Alzheimer’s disease, the leading cause of dementia. However, little research has investigated the character of Alzheimer’s disease in primary progressive aphasia patients.

The goal of this study was to investigate the relationship between the two conditions, including determining if memory preservation was better in these patients. If this was found to be true, the researchers aimed to research the factors that could attribute to the memory preservation effect despite the presence of the neurofibrillary degeneration typical of Alzheimer’s in the mediotemporal area, which is linked to memory retention and formation. Scientists had already understood that memory was not affected as much initially in primary progressive aphasia patients, but it wasn’t clear how long this effect persisted in comparison to Alzheimer’s patients without PPA.

The researchers compared a group of 17 patients diagnosed with PPA and Alzheimer’s and a group of 14 patients with typical Alzheimer’s. The researchers tested the episodic memory of these patients using images of common, everyday objects. At the initial test, the PPA patients showed no signs of memory loss and their episodic memory continued to be preserved when tested again an average of 2.4 years later. This group had displayed symptoms of disease for an average of six years. In this same time period the patients saw a steady decline in language ability. 

In the other group (Alzheimer’s but no PPA), memory and language both declined in the same time period. Some factors that the scientists identified that could explain the difference include:

  • Asymmetric, left-sided mediotemporal atrophy in PPA patients (although bilateral hippocampo-entorhinal neurofibrillary degeneration at Braak stages V and VI was still present)
  • Reduced incidence of mediotemporal TDP-43 pathology and Apolipoprotein E4 in PPA patients.


About Alzheimer’s Disease

Alzheimer’s disease, often just called Alzheimer’s, is a neurodegenerative illness affecting the brain that is primarily characterized by memory loss and dementia, which progressively worsens over time. Alzheimer’s disease is the leading cause of dementia around the world, being linked to around 70 percent of cases. The cause of this disease isn’t clear, but a family history of the disease, particularly in the patient’s parents, appears to be the dominant risk factor. Other possible factors may include high blood pressure, depression, and head injuries. Memory decline is often the first recognized symptom; others include mood swings, disorientation, and difficulty speaking; these symptoms worsen over time to the extent that the person cannot function in daily life; paranoia, aggression, and then apathy are common. Treatment is symptomatic and supportive, and no known medications can halt disease progression. Life expectancy following diagnosis is between three to nine years. To learn more about Alzheimer’s disease, click here.

About Primary Progressive Aphasia

Primary progressive aphasia (PPA) is a rare neurological syndrome characterized by a progressive decline in language function over time. Specific symptoms can vary depending on which area of the left hemisphere is damaged. The cause of primary progressive aphasia and other forms of aphasia remain unknown. While the disease is not directly inherited, family history is probably the strongest risk factor. One study suggested that vasectomy could be a risk factor for men; the disease tends to appear in the sixties or seventies. The primary symptoms involve loss of language processing, such as speech loss, writing loss, and reading loss; memory impairment is present in some cases. Treatment options are limited; medications used for Alzheimer’s may be utilized, but benefits are unclear; behavioral interventions such as social or speech therapies may be tried. These treatments do little to slow language decline. To learn more about primary progressive aphasia, click here.

Why Does it Matter?

Where there are some limitations to this study, such as the small sample size, the findings nevertheless present an interesting picture that can help us learn more about these progressive, neurodegenerative diseases that are, at this juncture, incurable and lack effective treatment options. There is a dire need for the scientific world to enhance our understanding of PPA and Alzheimer’s so that new treatments can be successfully developed and outcomes for these patients can improve.

It is also very clear that the findings from this study are quite preliminary and that much more research will be necessary to further understand the mechanism that allows memory retention in patients with both Alzheimer’s and PPA. However, this line of research might help lead to a breakthrough that could ultimately allow for new treatments.

Check back the Monday of each week for the next installment in this series.

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