Is Alzheimer's Disease Genetic?

WEDNESDAY, June 21, 2023 (HealthDay News) -- Alzheimer's disease is a devastating diagnosis, and if a close relative has had it you may worry whether you will be next.

According to the National Institutes of Health, it is estimated that over 6 million Americans over 65 suffer from Alzheimer’s. Since this is primarily a disease that comes with age, those numbers are expected to go up as the population ages.

For those who have family members with this disease, there is the ultimate question, “Is Alzheimer’s disease hereditary?” But there are others: How does Alzheimer’s develop? Are there things I can do to lower my risk? Here, experts address these questions.

Is Alzheimer’s genetic?

Since Alzheimer’s disease is most common in those in their late 70s and 80s, age is the greatest risk factor for this disease.

However, researchers have discovered several genes that are associated either with an increased risk (risk genes: APOE-2, APOE-3 and APOE-4) of developing Alzheimer’s, or those that directly cause the disease (deterministic genes: APP, PS1, PS2).

According to the Alzheimer's Association, 40% to 65% of people diagnosed with Alzheimer's have the APOE-4 gene, which is the risk gene most likely to be associated with Alzheimer’s disease.

Deterministic genes only account for 1% of all cases and cause the inherited early-onset forms in which symptoms usually develop between the early 40s and mid-50s.

So, to answer the question, while 45% to 60% of Alzheimer’s patients inherit a risk for the disease, only 1% actually inherit the gene which essentially guarantees an Alzheimer’s diagnosis.

How does Alzheimer’s disease develop?

According to the Alzheimer’s Association, Alzheimer’s disease develops when proteins build up in the brain to form structures called "plaques" and "tangles." This causes brain cells to die and damages functions controlled by the brain.

Your brain has billions of neurons that communicate with each other through electrical charges that run down axons from one neuron to another, where chemicals jump across the synapse between them allowing them to communicate and perform all of our body’s functions. Inside the neurons there is tau, a protein that supports the microtubules that provide nutrients to the cells.

Researchers believe that with Alzheimer’s, abnormal tau builds up in the neuron, causing the microtubules to tangle. This prevents nutrients and other essential supplies from moving through the cell and it dies. In addition, plaques form around the neurons when pieces of a protein called beta-amyloid clump together.

However, researchers believe that other forces could be at work in our bodies, which lead to Alzheimer’s.

• Your vascular system fails to provide enough blood and nutrients to the brain
• The brain lacks the glucose needed to provide enough energy for the brain’s activities
• Chronic inflammation sets in as the debris is not cleared properly from around the neurons

Eventually, the neurons can’t communicate and they die, and the brain begins to shrink.

Is Alzheimer’s disease preventable?

"Not yet,” Dr. Jonathan Graff-Radford said in a recent Mayo Clinic article. “But there's strong evidence that healthy lifestyle habits — such as diet, exercise and not smoking — may play a role in reducing your risk of Alzheimer's disease and other types of dementia.”

While there is some “encouraging but inconclusive” evidence that maintaining healthy blood pressure, increasing physical activity and taking part in cognitive training may be helpful, more studies are needed to give a definitive answer. However, there are several steps you can take to promote a healthy brain. These include the following, according to Mayo Clinic:

• Stop smoking
• Control high blood pressure, high cholesterol and diabetes, as these are vascular risk factors
• Eat a diet (Mediterranean or MIND) that's rich in fruits, vegetables and lean proteins rich in omega 3 fatty acids
• Stay socially and physically active. Include some aerobic exercise, as it is believed to be the most beneficial for prevention
• Maintain a healthy weight
• Do what you can to maintain mental health
• Seek out activities that use your cognitive (thinking) skills, like reading, playing board games, crafts, puzzles, hobbies, working and volunteering
• If you need a hearing aid, get one. Being able to hear conversations will keep your mind sharper
• Limit your alcohol intake