Genetics and Alzheimer's Disease

Given that my sister has some form of early on-set dementia, I have concerns about the heredity of conditions that cause dementia.

Apparently, early-onset dementia can be caused by mutations to four genes which are passed from parent to child.  These mutations are autosomal dominant and only require one parent to pass them to the child.  Even late-onset dementia has a genetic component.  Individuals with Down Syndrome have a dramatically increased risk for dementia, specifically Alzheimer's.  Despite the genetic component, it appears that not everyone who has the mutated genes ends up with any form of Alzheimer's.  As a result, more research is needed.
Knowing the genes that are associated with any of the forms of Alzheimer's, scientists are able to provide tests to help identify those individuals at risk of developing the disease.  The question now becomes one of deciding we should be tested or not to see if we have the genetic markers.

Is it worth getting tested?  What is the impact of having a set of results which indicates a higher risk factor for something that may or may not happen?

Additional Information:
NIH's Alzheimer's Disease Genetics Fact Sheet
Memory in Adults Impacted by Versions of Four Genes
The Nanney/Felts Family: Late-Onset Alzheimer's Genetics


  1. I think the most obvious benefit is preparation. Many Americans, in particular, do not have any arrangements for long-term elder care, and are scrambling to figure out what to do if a parent or other elder relative develops these conditions. It may not be convenient or even possible to relocate a family member into one's own home, and then it becomes a question of what the family's financial responsibility might be. This question arises even without conditions such as Alzheimer's.

    Some conditions are also helped by early identification, so if symptoms begin to present, diagnosis may be faster and/or more precise.

    I think knowledge of any genetic condition - whether it be Alzheimer's or something else - is important to all of us as we make choices for ourselves and our children. It is always better to have prepared for something that may not happen than to be caught unprepared for something that definitely happens.

  2. You have a very good point which I will consider over the next few weeks. (Sometimes, I'm slow to make a decision.) The alternate side is the impact positive test results would have on the ability to secure life insurance, long term care coverage or even medical insurance.


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