The Truth About Alzheimer's Disease and Genes

Marisa Cohen

March 14, 2025 at 5:21 PM

It's heartbreaking to watch a parent with Alzheimer's, a type of dementia, lose their memory, speech, and ability to take care of themselves. The degenerative brain disease has no cure, and it's only natural to ask yourself: Is Alzheimer's hereditary?

Meet the experts: James Noble, M.D., an associate professor of neurology at Columbia University Irving Medical Center; Zaldy S. Tan, M.D., M.P.H., director of the Memory & Healthy Aging Program at Cedars-Sinai; Agenor Limon, Ph.D., an associate professor at the Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch

The answer depends on many factors, including genetics: "There are around five dozen different genes that, alone or in combination, pose a slightly higher, or slightly lower, risk in terms of people developing Alzheimer's," says James Noble, M.D., an associate professor of neurology at Columbia University Irving Medical Center. But even if you have a gene that raises your risk a bit, it doesn't mean you're destined to develop the disease, he adds.

With late-onset Alzheimer's, which generally appears at age 65 or older and is by far the most common type, the biggest risk factor is age. In fact, your risk of developing Alzheimer's increases exponentially with each decade: By 85, the average person has around a one in three chance of developing it. When symptoms appear before 65, it's known as early-onset Alzheimer's disease, which accounts for less than 10% of cases. Early-onset Alzheimer's can happen to those with no family history, but in very rare cases it can be due to an inherited genetic mutation. Inheriting this "deterministic gene" means an individual almost certainly will get Alzheimer's. Such circumstances account for 1% or less of all cases and are known to affect just a few hundred families across the world.

Which genes increase risk?

The most well-known gene that can affect the risk of Alzheimer's is the APOE gene. There are three versions (e2, e3, and e4), but it's estimated that 40% to 65% of people with Alzheimer's have APOE-e4. If you inherit one copy of APOE-e4, you have a threefold increased risk for developing Alzheimer's -- inherit two (one from each parent), and the risk is multiplied eight to 10 times.

But don't freak out: Only 2% of Americans have this genetic double whammy. And remember, even if you have e4, your risk increases proportionally. For example, it's estimated that 5% of Americans ages 65 to 74 have Alzheimer's disease. So if your risk increases threefold, you still have only a 15% chance of developing it at that age.

Should you get tested?

Detecting Alzheimer's disease early is important. And you can get tested, but it may not be that useful. Genetic testing can detect whether someone has APOE-e4, but having one or two copies of e4 cannot predict the development of Alzheimer's, and plenty of people who don't have e4 get the disease. It's important to consider testing carefully. "What are you going to do with the information?" asks Dr. Noble. "What are the possible positive and negative implications? How will this affect other people in your family?" Your genes are only a part of your story, he adds. "Only in rare circumstances do they wind up being the answer for why any particular individual gets Alzheimer's," he says.

How to boost memory

Some advice for brain strength, like eating a healthy diet, is pretty straightforward. Other recommendations, however, have become so broad -- Do crossword puzzles! Get more sleep! -- that you may feel stuck as to how to reap the brain benefits. Here, experts share what to focus on.

Cross-train your brain.

If you're on your 500th Wordle, you may want to put the phone down -- at least for a bit. When it comes to the benefits of puzzles for brain function, Zaldy S. Tan, M.D., M.P.H., director of the Memory & Healthy Aging Program at Cedars-Sinai, recommends doing other brain-boosting activities, not just repeating the same types of exercises. "Brain games, crossword puzzles, and Sudoku are meant to challenge specific areas of the brain, but our minds are complex, and different areas serve different functions," he says.

What to do: Try puzzles one day, read a book the next; take a Spanish class, go to lunch with friends. In fact, socializing may be particularly beneficial. "Social interaction is quite demanding in that you have different types of stimulation, including planning the outing as well as interacting with others, which fulfills the reward pathways of the brain," Agenor Limon, Ph.D., an associate professor at the Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch, says. Whatever you choose, engaging in a mix of activities may strengthen brain circuits and stimulate new brain connections, which can help you function if typical brain networks are disrupted due to disease. "Think of it like cross-training for the brain, because different activities give you a better chance of having the totality of your mind stimulated and engaged," says Dr. Tan.

Move your body.

"Exercise undoubtedly reduces the risk for heart disease, stroke, and other vascular phenomena," says Dr. Tan. This may be a boon for your brain: Preventing vascular disease (which can cause small strokes and lesions on the brain) through exercise may help stave off a type of cognitive decline known as vascular dementia as well as Alzheimer's disease. Researchers don't know exactly why, but exercise increases blood supply to the brain and stimulates the production of chemicals that promote neuron growth.

What to do: You know the drill. Aim for at least 150 weekly minutes of moderate-intensity exercise. You want an exercise routine that includes cardio and strength training along with balance and flexibility exercises.

Skip the "brain health" supplements.

Do you really need to pop OTC pills to support your memory? "The short answer is no, unless you have a vitamin deficiency," says Dr. Tan. "Most of the over-the-counter supplements do not have sufficient research that would support their effectiveness," explains Douglas Scharre, M.D., director of Ohio State's Center for Cognitive and Memory Disorders.

What to do: If you've noticed increased forgetfulness or other memory stumbles, ask your doctor to check you for vitamin deficiencies and follow their recommendations. "If your vitamin B12 is low, it needs to be supplemented, because brain cells need B12 to function," says Dr. Tan. "And there is a link between lack of vitamin D and dementia, so it can be good to take a supplement."

Find stress relief.

While a little stress can help motivate you to achieve your goals, chronic stress tells the brain there's ongoing danger, and that can impair memory, increase risk of mental health disorders, and impact physical health.

What to do: Try to keep stress under control with an array of strategies such as deep breathing or mindfulness techniques, meditation, and spending time outdoors in nature, says Limon.

Address sleep apnea.

Established research on sleep has shown that getting deep, restorative sleep supports cognition in a variety of ways, from consolidating memories to "actively removing toxins from the brain," Dr. Scharre says. But one sleep disruptor people often miss, says Dr. Tan, is sleep apnea, which affects roughly 39 million American adults. Sleep apnea occurs when your airway gets temporarily obstructed while you're asleep, resulting in reduced airflow. This means not enough oxygen is getting to your brain, causing you to gasp for air. "We know that sleep apnea interrupts deep REM sleep and wakes you up, which can lead to sleep deprivation," says Dr. Scharre.

What to do: Talk to your doctor if you show signs of sleep apnea. One study found that older adults who received treatment were less likely to develop dementia and Alzheimer's. If you have a partner, they'll be able to spot signs like loud snoring and stop-start breathing, gasping, or choking in the middle of the night. If you sleep alone, take note of increased daytime sleepiness, frequent night wakings, and morning headaches, and consider wearing a sleep tracker; a new Apple Watch feature, for example, can detect signs of apnea. The sooner the condition is diagnosed, the better off you'll be.

The bottom line

While we are learning more and more every day about how the genes we inherit from our parents affect our risk for Alzheimer's disease, your genes are only one part of your story, says Dr. Noble. "Genetics can provide us with a deeper understanding of the pathobiology of disease and give us guidance as we research new treatments, but only in rare circumstances do they wind up being the answer for why any particular individual gets Alzheimer's," he says.

The one thing you can do -- no matter what your genetic profile -- is follow the guidelines for lowering your risk for all dementias, which includes getting regular physical exercise, eating a Mediterranean or DASH diet, keeping your brain stimulated by learning new things and staying socially engaged, managing your blood pressure, and taking care of your overall cardiovascular health. That's what Dr. Noble recommends to his patients who seem to have a higher genetic risk for Alzheimer's. "But then again, that's what we would advise anyone, no matter their genetic profile," he says.

You Might Also Like

Can Apple Cider Vinegar Lead to Weight Loss?

Bobbi Brown Shares Her Top Face-Transforming Makeup Tips for Women Over 50