After years of hope and hype, finding a cure for Alzheimer’s disease and other types of dementia seems as distant as ever. The true breakthroughs have come in ways to deter the disease, and some scientists view prevention as the best prospect for defeating it.
“We’ve got to take care of our brains every single day,” says neurologist David Perlmutter, MD, FACN, ABIHM, author of the New York Times bestsellers Grain Brain: The Surprising Truth About Wheat, Carbs, and Sugar — Your Brain’s Silent Killers and Brain Maker: The Power of Gut Microbes to Heal and Protect Your Brain — for Life. “We are the architects of our brain’s destiny in that we absolutely control our brain’s health via the lifestyle choices that we make each and every day.” (Visit “Overcoming Grain Brain” for more.)
Alzheimer’s disease begins 20 years or more before memory loss and other symptoms develop, according to the Alzheimer’s Association’s 2024 Alzheimer’s Disease Facts and Figures report. “Alzheimer’s disease is a type of brain disease, just as coronary artery disease is a type of heart disease. It is caused by damage to nerve cells (neurons) in the brain,” the report authors explain. “In Alzheimer’s disease, the neurons damaged first are those in parts of the brain responsible for memory, language, and thinking, which is why the first symptoms tend to be memory, language, and thinking problems.”
In a recent issue of the Lancet focused on dementia prevention, an executive summary stated that about 40 percent of worldwide dementias are potentially preventable. But other scientists disagree: They believe the number could be far larger.
“I believe that 80 to 90 percent of prospective cases can be substantially delayed or prevented,” writes neuroscientist Michael Merzenich, PhD, professor emeritus of the University of California, San Francisco, in a 2023 Medscape commentary.
The key to prevention? Living a fit and healthy lifestyle, says Perlmutter.
A New Look at Alzheimer’s Pathology
The focus on prevention comes in part due to a revised understanding of what causes Alzheimer’s. It was long believed that amyloid beta-protein plaque in the brain triggered neurodegeneration by strangling brain nerve cells: The plaque was thought to cause tangles made of another protein, called tau, within the nerves.
Battling amyloid became the nexus of research, and thus funding, into pharmaceuticals and cures for Alzheimer’s — to the detriment of other research avenues, Perlmutter says. But this explanation of Alzheimer’s pathology came under suspicion following 2022 reports of fraudulent past research, as well as other findings.
Now, many experts are shifting the focus away from amyloid plaques and toward metabolism. “What makes a good brain go bad ultimately turns out to be a metabolic change,” Perlmutter explains. “It is a bioenergetic issue: a failure of the brain’s ability to supply blood to itself and to use the fuel in that blood, which is glucose, to power itself.”
A 2017 review published in Frontiers in Aging Neuroscience details the metabolic failure and connection between Alzheimer’s Disease and insulin resistance. It highlights research that finds brain-glucose hypometabolism, or decreased brain-glucose consumption, may occur decades before clinical manifestations of Alzheimer’s.
In addition, the authors report that people with insulin resistance or type 2 diabetes have an increased risk of developing the disease.
“Now, using PET [positron emission tomography] scans and even more recently MRI [magnetic resonance imaging], we can detect and predict who’s going to have Alzheimer’s based on the loss of energy utilization — even when there’s no clinical issue like memory failure,” says Perlmutter.
With a better understanding of Alzheimer’s pathology, scientists could better focus on a preventive prescription.
The Importance of a Healthy Lifestyle
The link between lifestyle and memory decline in older adults became even clearer thanks to a 10-year cohort study published in the BMJ in 2023 that followed 29,072 people (46 percent of whom identified as female). “Our results show that a healthy lifestyle was associated with a slower rate of memory decline in cognitively normal older individuals, including in people who are genetically susceptible to memory decline,” the authors report.
“We found that diet had the strongest association with memory, followed by cognitive activity, physical exercise, and social contact. Although each lifestyle factor contributed differentially to slowing memory decline, our results showed that participants who maintained more healthy lifestyle factors had a significantly slower memory decline than those with fewer healthy lifestyle factors.”
Among those the study followed were people who carried the so-called Alzheimer’s gene, APOE4. “This means that the gene is really less important than we had thought,” Perlmutter explains. “Carrying the APOE4 allele does not condemn an individual to cognitive decline; lifestyle is so important.”
9 Strategies for Reducing the Risk of Dementia
The best preventive measures remain fundamental, says Perlmutter: Eat well, move your body, and exercise your brain. But the latest research has added some other items to this list.
1) Eat well.
What you eat does more than just fuel your body: It fuels your brain as well, and in multiple ways.
To start with, people with cardiovascular risk factors — type 2 diabetes, hypertension, and metabolic obesity — also have an increased risk of Alzheimer’s. This reinforces the benefits of a plant-based diet that includes plenty of healthy fats and fiber and is low in sugar and simple and refined carbohydrates.
Keeping your microbiome healthy with quality whole foods is critical, says Perlmutter. Eating too much sugar, too many simple carbohydrates, and too little fiber or healthy fats can fuel bad gut bacteria. Fermented foods, like sauerkraut, pickles, and yogurt with probiotic bacteria, as well as prebiotic fibers, are essential because they feed good gut bacteria.
“When a woman is pregnant, we say, ‘You have to be careful because you’re eating for two.’ But actually, each and every one of us is eating for the hundred trillion bacteria in our guts,” he explains. “Everything you eat either nurtures or damages your microbiome, so you really want to focus on avoiding things that are going to damage the microbiome.”
Perlmutter recommends choosing organic and non-GMO foods whenever possible because pesticides, herbicides, and other toxins can harm that bacterial habitat.
To protect and enhance the brain’s metabolic health, we need to ensure an adequate blood supply and the efficient utilization of glucose, he adds.
“Central to this is a gas … in the brain and the body called nitric oxide. Nitric oxide does two things: It improves glucose utilization by enhancing how insulin works, and it improves blood supply via vascular perfusion,” he explains. “Nitric oxide is a powerful mechanism helping exercise do its beautiful thing in our bodies. Exercise increases our ability to use glucose and improves blood supply.”
A 2018 study in Frontiers in Physiology examined the importance of nitric oxide as it relates to Alzheimer’s. “When we look at nitric oxide availability, we see a strong correlation of reduction in blood flow with reduction in nitric oxide bioavailability in the brain as we age — but worse, as it relates to the development of end-stage Alzheimer’s,” Perlmutter says.
Our bodies make nitric oxide in two ways. The first way is that cells in the endothelium — the thin layer of muscle lining blood vessels — produce nitric oxide from the amino acid L-arginine, which we can get from nuts and meat.
The second way is by processing nitrates from food, which are converted by bacteria in our mouths or stomachs into nitrites and then into nitric oxide. Foods rich in nitrates include colorful vegetables — think beets, garlic, fennel, arugula, radishes, and leafy greens such as spinach, arugula, chard, kale, and parsley — as well as meats, dark chocolate, citrus fruits, pomegranates, watermelon, nuts and seeds, and red wine.
Perlmutter is starting a study using nitric oxide to target the brain metabolism of people with Alzheimer’s.
2) Move your body.
Exercise has been hailed as a key to keeping our bodies and brains healthy. In fact, building muscles and conditioning your heart and circulatory system are side effects — exercise is really about your brain. Physical activity builds your gray matter in myriad ways, keeping it healthy while also making you more alert, creative, motivated, and perceptive.
“Our muscles are an endocrine organ, secreting chemicals that work throughout the body,” Perlmutter explains. “We activate that endocrine organ when we exercise, and the muscles create myokines — chemicals, or cytokines, synthesized and released by muscle cells during muscular contractions that are the molecular mediators of the great things that happen to our body and our brain when we exercise.”
The concept of the “myokinome” sums up the activity of all the myokines, which regulate the brain’s metabolism. Myokines include interleukin-6 (IL-6), ketone bodies, lactate, irisin, cathepsin-B, and brain-derived neurotrophic factor (BDNF).
Among these, IL-6 increases our ability to use glucose and blood sugar, break down fats and muscle, and use fatty acids. It does all this — while helping our metabolism — by triggering AMP-activated protein kinase, a pathway that allows us to use fat as a fuel and to grow new mitochondria, the energy powerplants within our cells — including within our brain cells. (Learn more about mitochondria at “The Care and Feeding of Your Mitochondria.”)
“We’re now looking at the notion of proper muscle-to-brain signaling as an important mechanism relating to brain health,” says Perlmutter. “When we don’t utilize this process, we may set ourselves up for brain disease.”
So how much exercise do you need to help your brain? A 2022 study in JAMA Neurology followed 78,430 adults with dementia for nearly seven years. “Our findings suggest that approximately 9,800 steps per day may be optimal to lower the risk of dementia,” the authors report.
But more importantly, the study “found no minimal threshold for the beneficial association of step counts with incident dementia.” In other words, any exercise is good, and more is better.
3) Exercise your brain.
Help keep your brain sharp by learning new things and staying socially active. There are several reasons to do this, and although they are currently theoretical, studies are under way.
The cognitive-reserve hypothesis holds that the more you learn, the more neuronal connections you make in your brain. These serve as a sort of brain trust as you age and compensate for the loss of other cells, so you can afford to lose more neurons before you show clinical symptoms of Alzheimer’s.
“Studies have shown that progression to AD or other dementias is driven primarily by the progressive deterioration of organic brain health, expressed by the loss of what psychologists have termed ‘cognitive reserve,’” Merzenich explains in his 2023 Medscape commentary. “Cognitive reserve is resilience arising from active brain usage, akin to physical resilience attributable to a physically active life. Scientific studies have shown us that an individual’s cognitive resilience (reserve) is a greater predictor of risk for dementia than are amyloid plaques — indeed, greater than any combination of pathologic markers in dementia patients.”
Brain games like Sudoku and bridge, intellectual conversations, and learning a musical instrument or foreign language can all help build those vital neurons.
(See “Live and Learn: The Benefits of Lifelong Learning” and “13 Creative Ways to Learn Something New” to discover how lifelong learning can improve your health and happiness.)
4) Get your z’s.
Along with its myriad benefits to physical and mental health, sleep provides your brain a chance to clean itself out and rejuvenate. Experts advise getting seven to eight hours of sleep religiously, especially if you’re over 40. (Good sleep is essential to our health, vitality, and well-being. Unfortunately, it’s also the first thing to go when we’re stressed. Explore our “Why Sleep Matters to Your Health” collection to find dozens of strategies and tips to sleep well and reclaim your health.)
5) Protect your vision.
A study of 16,690 adults aged 50 and older, published in JAMA Neurology in 2022, suggests that eyesight impairment could be a key, modifiable factor. Regular eye exams are more important as you age, helping to protect your vision by catching eye diseases and conditions early.
Wear sunglasses outdoors even on cloudy days to block UVA and UVB radiation. And give your eyes a rest every 20 minutes or so when looking at a computer or tablet (see “5 Ways to Ease Digital Eyestrain” for additional tips). An estimated 1.8 percent (more than 100,000 people) of all U.S. dementia cases “could potentially have been prevented through healthy vision,” study authors write.
And a 2021 University of Washington study published in JAMA Internal Medicine found that participants who underwent cataract surgery lowered their risk of dementia by 29 percent compared with those who avoided the procedure. (See “The Cognitive Benefits of Cataract Surgery” for more.)
6) Maintain your hearing.
In its 2020 report, the Lancet Commission on Dementia Prevention, Intervention, and Care ranks hearing impairment, which is defined by the National Institutes of Health as a hearing loss of more than 40 decibels, as a top concern. A 2019 study in JAMA Otolaryngology reviewed the cognitive effects of hearing loss on 6,451 older adults and concluded that every 10-decibel reduction in hearing resulted in reduced cognition.
The Lancet’s report encourages the use of hearing aids as a preventive measure to reduce the risk of associated dementia. As of October 2022, hearing aids are available over the counter in the United States. (For more, enjoy this podcast from Life Time Talks, “Listen Up: Why Taking Care of Your Hearing Health Matters.”)
7) Prevent head injuries.
The 2020 Lancet report warns that concussions and traumatic brain injuries increase dementia risk. Wear a helmet when bicycling, motorcycling, or horseback riding. And if you’re in an accident where you may have hit or even jostled your head, get checked out by a medical professional.
And remember, you don’t actually have to hit your head to get a concussion: one can result from whiplash, or even from the shock waves of an explosion.
Research uncovering the brain’s neuroplasticity — the ability of the brain to grow and adapt throughout our lives — has led to progressive therapies for treatment. (For more on treating head injuries, see “How to Treat Postconcussion Syndrome.”)
8) Limit alcohol use.
It’s long been known that heavy drinking is associated with cognitive impairment and dementia. The Centers for Disease Control and Prevention defines “moderate drinking” as no more than two drinks a day for men and one per day for women.
But some new research is challenging the notion that alcohol offers any benefits for health. The Lancet report states, “Decreasing harmful alcohol drinking could potentially reduce young-onset and later-life dementia.”
9) Breathe well.
Exposure to air pollution — including from first- or second-hand tobacco smoke — can contribute to the onset of dementia, the Lancet report states. “Stopping smoking, even in later life, ameliorates this risk,” the authors advise. (For more, see “Can Air Pollution Affect Your IQ?”)
Alzheimer’s is a disease that develops gradually over many years, Perlmutter explains, and this underscores the importance of prevention long before the first symptoms show up.
“Now that we are secure in the science underpinning the central role of metabolic abnormalities in terms of Alzheimer’s causation, and understand that these changes presage the noticeable changes in cognition by decades, it is mandatory that we do everything to maintain our best metabolism through our lifestyle choices early in our lives,” Perlmutter says before quoting John F. Kennedy’s maxim: “The time to repair the roof is when the sun is shining.”
