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Will You Get Alzheimer's If Your Relative Has It?

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After finding out one of your parents, grandparents, siblings or other family member has Alzheimer’s disease, you might find yourself wondering, Does that mean I’ll get Alzheimer’s, too? It’s a natural thought, especially after you see news reports about families in which several members across multiple generations are diagnosed with the disease. But the answer to the question, “If my mom had Alzheimer’s, does that mean I’m more likely to get it?” is not a simple yes or no.

Here’s the short answer:

Is Alzheimer’s hereditary?

For those with the rare early-onset familial Alzheimer’s disease, yes, Alzheimer’s is hereditary. But for the more common late-onset form of Alzheimer’s, experts don’t know for sure. The APOE-e4 gene increases your risk, but doesn’t guarantee you’ll get it. Other risk factors like cholesterol, exercise level, age and blood pressure are more significant than family history or genetics.

And here are more facts you should consider:

1. Scientists can’t say for sure whether family history predicts Alzheimer’s or not.

There is one rare type of Alzheimer’s disease, called early-onset familial Alzheimer’s disease (FAD), that is known to be genetic and will appear throughout a family tree. However, this accounts for only 5 percent of all Alzheimer’s cases.

For the rest, Alzheimer’s research is not conclusive. Some studies indicate that people with a parent or sibling who has Alzheimer’s have a slightly higher risk of developing it themselves. But experts hesitate to say for sure whether you’re considerably more likely to develop Alzheimer’s if a family member has it.

Patrick Lyden, MD, neurology professor at Cedars-Sinai in Los Angeles, told The Mighty this idea has gotten into the public mindset likely due to news reports about the rare family-inherited dementias, but there isn’t a definite one-to-one risk for Alzheimer’s. In fact, this is one of the most common misconceptions he encounters.

“If you have one parent with Alzheimer’s and you’re worried about your own risk, that’s where we really don’t know,” Lyden said. “In some cases those are hereditary, but a lot of times when you’re talking about something that’s so common, it might just be a coincidence.”

2. There is a genetic test for an “Alzheimer’s gene,” but it doesn’t predict if you’ll get the disease.

Scientists identified one gene, called APOE, that has been shown to potentially affect your risk of developing Alzheimer’s disease. Genetic testing, for example through the at-home testing company 23andMe, offers a test that will discover if you have the version of the gene, called APOE-e4, that is associated with an 15- to 20-percent increase in the likelihood of developing Alzheimer’s. Every person has zero, one or two copies of APOE-e4, and the more you have, the greater your risk.

However, it’s important to remember that even if you do have the “bad gene,” that doesn’t necessarily mean you will get Alzheimer’s disease. Not everyone with the risky gene gets Alzheimer’s, and not everyone who has Alzheimer’s has the risky gene, so it’s not a predictive test.

3. There are other risk factors that are more significant than genetics.

While genetics and hereditary factors may or may not contribute much risk, other factors have been shown to lower your chance of developing Alzheimer’s. These include: controlled cholesterol and blood pressure, avoiding type 2 diabetes by maintaining your ideal body weight, and exercise. Socialization is another important risk factor — mouse studies have found that even for mice that are bred to get Alzheimer’s, being housed with company led to the mice developing Alzheimer’s later in their lives. Human studies have also found that loneliness increases Alzheimer’s risk.

“Anybody who has a thought or it’s crossed their mind about dementia risk, get with the exercise program, get with the Mediterranean diet, get with the weight loss,” Lyden said. “You’ll do more for yourself in that respect than all the genetic tests in the world.”

4. Finding out your genetic or hereditary risk may not ultimately affect you.

Because risk factors like blood pressure and diet are more influential than genetics (and you can actually do something to lower them as risk factors), you might ultimately decide that you don’t really need to know your genetic or hereditary risk. Anyone, whether they have a family member with Alzheimer’s disease or not, can benefit from working to lower their risk.

“A lot of my patients decide against [genetic testing]. Because what are you going to do? You’re going to do diet and exercise,” Lyden said. “So if you’re going to do diet and exercise anyway, why bother finding out that you have this gene.”

If you just found out a relative has been diagnosed with Alzheimer’s disease, try not to jump to the conclusion that you will 100% get it, too. Science does not indicate you need to assume your diagnosis is coming. For the best chance of lowering your risk of Alzheimer’s, focus on maintaining a healthy lifestyle. And if you have a loved one with Alzheimer’s and are looking for support, check out these articles written by people who have been there:

Getty photo by Wavebreakmedia

Originally published: April 4, 2019
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