Preventing dementia: The promising, the disappointing and the inconclusive

What's proved to prevent the development of dementia after the age of 80?

Not brain training, not medication, not regular exercise, not a healthier diet and not a busy social calendar, according to a series of reports published Monday.

But ask the question a bit differently, and the answer is not quite as discouraging: What should you be doing anyway right now that might delay or prevent the development of dementia late in life?

Some combination of all of the above.

Most of us hope to live well into old age, and doing so with our marbles intact is typically a condition we attach to that wish. But half or more of Americans over the age of 90 will be beset with some type of dementia, and 1 in 10 people age 65 and older has Alzheimer's disease.

Scientific research, in its highest and most rigorous form, has done little to illuminate a single path to prevent or forestall dementia and cognitive decline. That grim conclusion emerged in four reports published by the Annals of Internal Medicine.

Culling the highest-quality research it could find on preventing Alzheimer's disease and other dementias, the Minnesota Evidence-based Practice Center concluded that cognitive training has not been shown definitively to work. Neither have prescription medications or over-the-counter dietary supplements. They couldn't even find a single exercise regimen that fit the bill.

These findings underpinned a recent report by the National Academy of Medicine on preventing dementia. But while the Minnesota group found an absence of decisive effects, it documented some highly suggestive evidence that some things were helpful—in particular, for the effects of exercise, and for strategies, including medications, that manage diabetes and control high blood pressure and worrisome cholesterol at midlife.

Several studies, the group noted, suggested that those who perform aerobic and/or resistance training fare better in staving off cognitive decline and dementia than do more sedentary folk.

"We believe that those findings provide a signal that physical activity offers cognitive benefit," the Minnesota group concluded. The problem, they added, was that studies did not go on for long enough, or enroll enough participants, "to show the true long-term effect of a physically active lifestyle."

Meanwhile, the Minnesota data analysts wrote, studies that follow large populations over a long period of time "mostly showed that diabetes, midlife hypertension, and midlife hyperlipidemia were associated with increased dementia risk" and that use of cholesterol-lowering statin drugs and non-steroidal anti-inflammatory medications such as ibuprofen "was associated with lower dementia risk."

Rigorous clinical trials failed to find clear benefits for such medications, the analysts noted. But the kinds of trials that would do so would have to take into account so many factors that play a role in overall health, and for so long, that that they are "not likely to be logistically or financially feasible."

"All evidence indicates that there is no magic bullet," Dr. Eric B. Larson, an internist with a focus on Alzheimer's disease, wrote in an editorial.

Despite the incomplete science, patients still want their doctors to give them concrete advice.

"When people ask me how to prevent dementia, they often want a simple answer, such as vitamins, dietary supplements, or the latest hyped idea," wrote Larson, the executive director of Kaiser Permanente's Washington Health Research Institute.

"I tell them that they can take many common-sense actions that promote health throughout life and may help to avoid or delay" Alzheimer's disease and related dementias.

Among those actions, Larson includes not smoking, engaging in regular physical activity, controlling diabetes, hypertension and cholesterol, and maintaining a healthy diet and weight.

"Engaging in cognitively stimulating activities and avoiding social isolation also are probably beneficial," Larson wrote. And as patients age, doctors "should do what we can to correct their vision and hearing loss."

"Note that none of these recommendations has harmful side effects," he added.

Knowing the many things that go into making a brain healthy and resilient, a mixed approach just makes sense, said Keith Fargo, director of scientific programs and outreach for the Alzheimer's Association.

"You can't make one good choice in your life and expect that's going to have an impact," Fargo said. "But we do believe if you make a number of choices, the totality of those things together can make an impact. After all, your doctor doesn't just say, 'Take your statin.' The medical advice is to make a broad effort to live a healthier lifestyle, and that's good advice for protecting your brain health as well."

The Alzheimer's Association has distilled many research findings into an easy guide for patients called "Ten Ways to Love Your Brain."

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