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Study: Study uses mice and brains from deceased Alzheimer’s patients to assess BRCA1 involvement

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Contents

At a glance In-depth
Findings     limitations            
Questions for your doctor Resources


STUDY AT A GLANCE

This study is about: 

A potential role for normal protein in Alzheimer’s disease.

Why is this study important?

This study is basic research on Alzheimer’s disease.

Study findings: 

  1. Mice that do not have protein in their neurons had more damage, smaller neurons, and deficiencies in learning and memory.
  2. Brains from deceased patients with  Alzheimer’s disease had less normal protein than brains of people without Alzheimer’s.

What does this mean for me?

Currently, no association has been found between mutations and Alzheimer’s disease. While this study provided an interesting laboratory finding—reduced levels of protein in the brains of deceased Alzheimer’s patients—the results are not clinically relevant to people with mutations. Alzheimer’s disease is complex, and many things go wrong with the brain of people with the disease. This study did not show that reduced protein levels cause Alzheimer’s disease, but it did raise the question of whether reduced levels is one of the changes that occur in someone who has Alzheimer’s disease.

This study does NOT show that you have an increased risk of Alzheimer’s if you have a mutation.

Posted 12/22/15

References

Lambert J, Ibrahim-Verbass CA, Harold D, et al. “ of 74,046 individuals identifies 11 new susceptibility loci for Alzheimer's disease.” Nature Genetics. 45:1452-1458 (2013). 

Suberbielle E, Djukic B, Evans M, et al. “ repair factor depletion occurs in Alzheimer brains and impairs function in mice.” Nature Communications. Published online first on November 30, 2015.  

National Institute on Aging, “Alzheimer’s Disease Fact Sheet,” (2015) 

This article is relevant for:

This research is not relevant to people

This article is also relevant for:

BRCA mutation carriers

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Questions to Ask Questions to Ask Your Doctor

  • What are known risk factors for Alzheimer’s? 
  • I am noticing changes in my memory, can you refer me to an expert? 

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FORCE offers many peer support programs for people with inherited mutations. 

Updated: 03/12/2022

Who covered this study?

The Telegraph

'Jolie gene' linked to Alzheimer’s disease This article rates 3.0 out of 5 stars

Forbes

Breast cancer gene BRCA1 may play a role In Alzheimer's disease This article rates 2.5 out of 5 stars

TIME

How a breast cancer gene may affect Alzheimer’s This article rates 2.5 out of 5 stars

Medical News Today

Breast cancer gene BRCA1 may be involved in Alzheimer's disease This article rates 2.5 out of 5 stars

How we rated the media

IN DEPTH REVIEW OF RESEARCH

Study background:

and are involved in repairing errors in . Researchers have seen lots of damage in brains cells of patients with Alzheimer’s disease. Lennart Mucke, M.D and colleagues at the Gladstone Institute of Neurological Disease and the University of California, San Francisco want to understand what repair mechanisms might be involved in that damage. Although damage is not known to cause Alzheimer’s disease, it is seen in Alzheimer’s patients and may be an effect of the disease.

Researchers of this study wanted to know:

Whether the damage seen in the neurons of patients with Alzheimer’s could be explained by lower levels of protein.

Population(s) looked at in the study:

For the experiments looking at the levels in brains from deceased patients, researchers examined the brains of 8 patients without Alzheimer’s disease and 8 patients with Alzheimer’s disease.

Mice studies were also made:

  • mice that were genetically engineered to have some Alzheimer’s disease symptoms.
  • mice that were engineered to have less protein.

Each treatment group included 3 to 20 mice for the various experiments. 

Study findings: 

  1. Mice that do not have protein in their neurons have more damage, smaller neurons and have deficiencies in learning and memory.
  2. Brains from deceased Alzheimer’s disease patients have lower protein levels.

Limitations:

The number of patient samples used was small: 8 samples for each group. Most of the experiments were performed in mice, however, test results from mice do not conclusively indicate what will occur in humans. Importantly, the study only reviewed normal genes and not mutations associated with increased cancer risk. 

Conclusions:

While the studies looking at mice without protein appear convincing regarding a potential role for in neuronal function, no published study has associated with Alzheimer’s disease.  For many years, researchers have been looking for genetic factors that increase the risk of Alzheimer’s disease— is not a gene that is associated with the disease. More importantly, no clinical data show that people with mutations have an increased risk for developing Alzheimer’s.

Some media headlines claim that mutations may affect Alzheimer’s disease, but this cannot be concluded from the study. Everybody is born with 2 copies of the gene. People with mutations have one "bad copy" (the one with the mutation) and one "normal copy.” This Alzheimer’s disease study looked at how normal copies of work in people with Alzheimer's disease, not how mutations affect Alzheimer’s disease.   

According to the National Institute on Aging, Alzheimer’s disease is the most common form of age-related dementia in the United States.  Given how common Alzheimer’s disease is—over 5 million Americans currently live with the disease—it is likely that some families will be affected by both mutations and Alzheimer’s disease, but that does not mean that the two are associated. 

For now, the reduced levels of in Alzheimer’s patients observed by researchers is only an observation that does not conclude anything about the effects of mutations on the disease.  More research needs to be done to understand the role of normal proteins in Alzheimer’s disease, but based on current research there is no reason to believe that mutations carriers are at increased risk of Alzheimer’s disease. 

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