En español | Almost 6 million people in the United States live with Alzheimer's disease or other dementias, a number that's expected to grow rapidly over the next 30 years as the population of Americans 65-plus rises. Now, research presented on the first day of the Alzheimer's Association's International Conference 2019 suggests that healthy lifestyle choices — including eating right, exercising, not smoking and engaging in cognitively stimulating activities — may significantly reduce this risk, even among people with a genetic predisposition to the disease.
The results of these studies confirm earlier ones, most notably a 2017 Lancet study that found that roughly a third of all dementia risk factors, such as obesity, high blood pressure and depression, can be modified. “But what's encouraging about them is that the data are so strong” and come from “longitudinal studies with large sample sizes,” says Gary Small, M.D., the Parlow-Solomon professor on aging at the David Geffen School of Medicine at UCLA. “This research is also empowering, because it shows us we can truly make a positive difference with lifestyle. It's not all about our inherited genes but also has to do with the choices we make every day, like whether or not to have another serving of vegetables or save appetite for a big piece of apple pie."
The first study looked at five healthy-lifestyle factors — a nutritious diet, exercising at least 150 minutes a week, not smoking, limiting alcohol intake and engaging in cognitively stimulating activities (such as reading newspapers, playing cards or visiting libraries and museums) — and examined how these reduced Alzheimer's risk. People who adhered to at least four of these healthy habits had a 60 percent decrease in risk, and even those who had two or three of them had a 37 percent decrease in risk, compared with those who engaged in one or none. “While we were expecting to find a protective effect of lifestyle behaviors, I was surprised by their magnitude,” says study author Klodian Dhana, M.D., assistant professor in the Department of Internal Medicine at Rush University Medical Center in Chicago.
These results were bolstered by a UK study of over 150,000 people, presented today at the conference. It found that while chances of developing dementia were 60 percent higher in those at genetic risk of the condition, that number was more than halved among participants who followed a healthy diet, exercised regularly, eschewed smoking and consumed alcohol only in moderation. “This is exciting because it shows that even if you're at increased genetic risk, you can reduce your Alzheimer's risk through lifestyle, just like how people with a family history of heart disease can reduce their cardiovascular risk,” notes Maria C. Carrillo, chief science officer at the Alzheimer's Association.
Two studies also reinforced the effect early in life that negative lifestyle habits, like smoking and excessive drinking, can have on dementia risk. Researchers at the University of California, San Francisco followed more than 3,000 young adults ages 18 to 30 for 25 years and found that smoking over a pack a day for more than a decade was associated with reduced cognitive function that showed up as early as the 40s. “There have been a lot of studies looking at smoking later in life and cognitive impairment, but none that demonstrates that effects can show up this early,” says study author Amber Bahorik, a postdoctoral researcher at UCSF. Another study presented by Bahorik found that female veterans with alcohol-use disorder had three times the risk of developing dementia.
The research presented also stresses the importance of making sure to keep your brain active and engaged throughout your lifetime, observes Babak Tousi, M.D., a dementia specialist at the Cleveland Clinic Lou Ruvo Center for Brain Health. Although living in an area with high air pollution has been shown to raise dementia risk, a University of Southern California study presented today found that older women with high cognitive reserve (calculated based on cognitive tests, years of education, job status, and levels of physical activity) showed only about a 20 percent increased risk of developing the condition, compared with 113 percent among those with lower cognitive reserve. “Your brain is like any other muscle in your body — the more you strengthen it, the more resistant it will be to environmental and physical stress,” Tousi explains.
And if these recommendations altogether seem a little overwhelming, experts stress that taking even small steps toward a healthier lifestyle is worthwhile. When it comes to diet and dementia risk, the best research now points to the MIND diet, a hybrid of the Mediterranean and DASH (dietary approaches to stop hypertension) diets that's rich in whole grains; berries; green, leafy vegetables; olive oil; poultry; and fish. “I would encourage consuming more vegetables, particularly leafy greens, and to replace red meat with poultry and avoid fried foods,” Dhana says. Up to one glass of wine a day can also be beneficial, he adds, provided it's paired with a healthy diet and not smoking cigarettes. If exercise seems daunting, just make sure you incorporate brisk walking into your daily routine most days of the week. And make time each day to read the paper or books, play card games or do a crossword puzzle. “The typical processs of aging is associated with a decline in memory, processing speed and reasoning, even in the absence of dementia,” Dhana notes. “That makes it even more important for older adults to engage in stimulating cognitive activities to maintain their cognitive skills."
Moving forward, the Alzheimer's Association is leading the U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER), the first large-scale examination of combined interventions, including physical exercise, nutritional counseling, and cognitive and social stimulation, in the United States. Results are expected in 2023. “What we are starting to see, across the board, whether you inherited a genetic predisposition to dementia or live in a place that increases your risk, is that you may be able to overcome some of this with lifestyle,” Carrillo says. “Even more exciting, even a little bit counts."