How Managing Diet, Exercise, and Hearing Loss Can Lower Alzheimer’s Risk
- Most people with Alzheimer’s disease are 65 years and older. The risk doubles every five years after age 65.
- Age, family history, genetics, and lifestyle choices all contribute to the risk of Alzheimer’s disease.
- Studies show that exercising and eating a Mediterranean diet can reduce the risk of cognitive decline.
The concern of developing Alzheimer’s disease can make brain health products and interventions appealing. However, with a surge of these products on the market, knowing which are scientifically proven to be safe and effective is challenging.
“Be skeptical, because the FDA [Food and Drug Administration] allows all kinds of stuff on the shelf and tens of billions of dollars are spent every year on supplements that don’t have to have good evidence to be sold as long as they are safe in the doses that are being sold,” Dr. Howard Fillit, founding executive director and chief science officer of the Alzheimer’s Drug Discovery Foundation (ADDF), told Healthline.
Fillit says knowing the risk factors associated with Alzheimer’s is the first step in understanding what may or may not help in preventing and treating the disease.
Risk factors of Alzheimer’s disease
Age is the greatest known risk factor of Alzheimer’s disease. Most people with the disease are 65 years and older. The risk doubles every five years after that and increases to almost one-third after 85, according to the Alzheimer’s Association.
In addition to age, genetics is a powerful indicator of risk. Fillit breaks down genetics into two categories. The first is familial Alzheimer’s, which involves having a mutation in a gene for the protein that’s found in the brains of people with Alzheimer’s disease.
“Particularly the beta-amyloid protein, and when you have the mutation in that gene it means that you’re going to get Alzheimer’s disease, and it means that anybody in your family who has the same gene is going to get it,” Fillit said.
People who have these genes start showing symptoms of Alzheimer’s in their 30s, 40s, or 50s.
“There are other genes that have been discovered more recently that seem to be associated with Alzheimer’s disease like TREM2, but mainly it is in these beta-amyloid genes,” Fillit said.
The second category is genetic risk factors. This means if you have a certain gene type, you have an increased risk for developing Alzheimer’s disease but aren’t guaranteed to develop the disease.
“The important one here is a molecule called apolipoprotein E (APOE), [which] carries cholesterol, and it helps to traffic cholesterol in the brain and body,” Fillit said.
Fillit explains there are three kinds of APOE in humans. APOE2 is a protective gene, and those who have it have about a 5 percent chance of developing Alzheimer’s. About 70 percent of people who have APOE3 have a baseline risk of Alzheimer’s disease, he says.
“You can get any gene. One from mom and one from dad, so you could be a 2-2 or 2-3, and if you get a 2-3 you are somewhat protected from Alzheimer’s disease, and if you’re a 2-2 you’re really protected against Alzheimer’s disease,” Fillit explained.
Those with APOE4 have an increased risk as well.
“APOE 3-4 have an increased risk of about five times the general population, and they represent about 15 percent of people, and those who are 4-4 have about 15 times the risk of Alzheimer’s. Those with APOE4-4 represent about 5 percent of the population, and they get the disease about 10 years earlier than the average person, so maybe at 65 rather than 75,” Fillit said.
While the increases associated with APOE are known, he adds that with all genetic risks it’s hard to figure out exactly what the genes are doing to cause or contribute to Alzheimer’s disease.
Additional factors for Alzheimer’s disease include:
- Head injury. An impact to the head that causes brain injury has been linked to future risk of dementia.
- Heart health. Research shows a connection between brain health and heart health. The risk of developing Alzheimer’s may be increased by conditions that damage the heart and blood vessels, such as heart disease, diabetes, stroke, high blood pressure, and high cholesterol.
In addition to managing chronic conditions like diabetes and hypertension, managing hearing loss may also contribute to cognitive decline. A study of Medicare HMO patients found that adults 66 and older who got a hearing aid for newly diagnosed hearing loss had a lower risk for being diagnosed with dementia, depression, or anxiety for the first time over the next 3 years. “We have always known that untreated hearing loss can significantly limit a person’s quality of life since they will tend to withdraw from many of the familial, social, and occupational opportunities that have always meant a lot to them. But over the past decade, there has been a growing accumulation of scientific evidence that untreated hearing loss is also a factor in accelerating cognitive decline in the later years,” Donald Schum, PhD, vice president of audiology for Oticon, told Healthline. He connects hearing loss to both social isolation and cognitive decline. “One of the cornerstones of healthy aging has been the ability to maintain quality connections to family, friends, and other key contacts in an older adult’s life. It has been clearly established that these contacts have an overall positive influence on health by reducing stress, isolation, and loneliness,” Schum said. “When hearing loss goes untreated, the person may start to gradually withdraw from these interaction opportunities. And sometimes that happens without the person being consciously aware they’re doing it,” he said. While more scientific evidence is needed, he says the published work so far indicates that the use of hearing aids can slow the rate of cognitive decline to levels that are experienced by older adults without hearing loss.
“In fact, a major work published in The LancetTrusted Source from 2018 identified hearing loss as the No. 1 treatable cause of premature cognitive decline,” he said.
Can drugs help?
There are two types of drugs on the market at this time that focus on enhancing memory and cognitive function. Fillit says cholinesterase inhibitors are modestly effective in treating the symptoms of Alzheimer’s, while memantine drugs help improve memory and cognitive function in people with moderate to severe dementia.
Rebecca Edelmayer, PhD, director of scientific engagement at the Alzheimer’s Association, says that while there are several FDA-approved prescription medications to treat the cognitive symptoms of Alzheimer’s disease, many are most beneficial in the earliest stages of the disease.
“But we know there are some individuals who are not benefiting from these medicines, and we need to improve upon the medicines that are available, so there are many clinical trials underway today… looking at ways to better treat both the cognitive and behavioral symptoms of Alzheimer’s disease and other dementia,” Edelmayer told Healthline.
Fillit agrees, noting that the ADDF supports programs working to find Alzheimer’s medications, particularly those focused on APOE.
“I think we’ve come up with what’s looking like a promising answer. We haven’t figured it out yet, probably because the APOE is so complicated. We think fixing it with gene therapy is the way to go, so we’ve been supporting a gene therapy program at Weill Cornell here in New York, and that program has progressed into clinical trial,” he said.
The idea behind the research is to take the APOE2 gene and put it inside a noninfectious virus, which is then injected into the brain.
“The virus would make the APOE2, and the APOE would offset the APOE4 risk. It’s a strategy that is FDA approved. We’re in phase I to see about the safety,” Fillit said.
He adds that there are many drugs close to development for Alzheimer’s symptoms, such as agitation and psychosis.
“What we really want are drugs that are going to treat the cause of Alzheimer’s disease or the factors that make it progress,” he said. “There are over 100 drugs right now in development that are directed in many different ways to treat the underlying pathways that cause Alzheimer’s disease.”
He says the drugs focus on a variety of contributors to the disease, including the protein beta-amyloid, the molecule tau, inflammation that occurs in the brain, genetics, and metabolic disorders.
Research shows that practicing heart-healthy lifestyle choices, such as exercising, eating a Mediterranean diet, avoiding stress, not smoking, drinking alcohol in moderation, and managing conditions like diabetes, hypertension, and atherosclerosis, can help with Alzheimer’s disease.
“We used to say that what’s good for your heart is good for your brain, so all the healthy lifestyle things that people do to prevent a heart attack or stroke… it turns out that, with new research that’s been done using what are called multi-domain lifestyle interventions to see what impact it has on Alzheimer’s disease, it’s been shown that these lifestyle interventions really work,” Fillit said.
Worldwide studies report that although Alzheimer’s can’t be completely prevented with lifestyle choices, it may be delayed.
Fillit points out that the average age of Alzheimer’s onset is 75 or 76, and the life expectancy for the U.S. population is about 78.
“The idea with the modeling is that if you can delay the onset of Alzheimer’s disease by just 5 years, you would delay the onset of serious cognitive impairment beyond the time of death, and so people would be able to live into old age without suffering dementia, and that’s looking like a very achievable goal from these prevention studies,” Fillit said.
According to the ADDF’s Cognitive Vitality Reports, which contain more than 200 reports analyzing drugs, supplements, nutraceuticals, nonpharmacologic interventions, and risk factors related to brain health, the following lifestyle factors have an impact
Fillit says that while the brain shrinks with aging, studies show that aerobic exercise can increase its size.
For instance, the Harvard Aging Brain Study followed older adults and documented their physical activity, risk for cardiovascular disease, brain volume, and levels of brain amyloid plaques, which are the toxic protein found in people with Alzheimer’s disease.
Researchers found that higher physical activity was linked to less cognitive decline and less brain volume loss, even in those with amyloid plaques.
Additionally, a systematic review from the World Health Organization (WHO)Trusted Source found that studies point to aerobic training having a greater impact on brain health than resistance training
Based on observational diets, the WHOTrusted Source recommends nutrition similar to a Mediterranean diet to reduce the risk of cognitive decline and dementia.
“Fruits and vegetables have most impact, and it’s most likely because they contain antioxidants. The plants live under the sun 24/7 and the sun is a powerful oxidant, so Mother Nature had to help the plants develop chemistry that has the best antioxidants so the plants could survive,” Fillit said.
Specific foods within this type of diet aren’t yet recommended.
Edelmayer says studies are showing more and more that physical activity as well as nutrition and cognitive stimulation across a life course can potentially change the trajectory for developing cognitive impairment and dementia.
“We don’t have a particular recipe today to suggest what the best recommendation for risk reduction strategy would be, but overall we know enough information that suggest that a heart-healthy diet and maintaining a physically active lifestyle is going to be something that will potentially reduce your risk for cognitive decline and dementia,” she said.
She adds that access to healthy lifestyle choices, such as exercise and diet, aren’t always attainable for everyone.
“We have to be truly understanding of what the scientific data are implying when talking about risk because that’s also going to inform how we develop a strategy for every individual to help decrease their risk over their life course,” Edelmayer said.
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