When it comes to preventing Alzheimer's disease and other forms of dementia, medical science is working on it big time. But so far, all we've got are generalities about averting or minimizing the condition: Get a good education and keep learning throughout life. Don't smoke. Drink moderately. Keep your blood pressure and cholesterol numbers in the desired range. Exercise daily. Don't get fat. Have friends, a social life, a community.
All of these things are linked to a reduced risk of memory loss later in life. But none has the proven cause-and-effect that comes from the gold standard of research, the large-scale clinical trial. That isn't stopping countless makers of computer programs, video games, nutritional supplements and diet programs from trying to sell you assurance that you always will remember your spouse, who the current president is and where you left your reading glasses. So I want to go through the limitations of what we know, what is on the research horizon to treat memory loss and then to point to some lifestyle choices that -- what the heck -- can't hurt and might help.
There is no magic pill to prevent the cruel degeneration of Alzheimer's disease. Two years ago, a scientific panel convened by the National Institutes of Health to examine all the scientific evidence on preventing it ended up struggling with ways to give the bad news to a public eager for breakthroughs. Here's what they came up with:
Currently, no evidence of even moderate scientific quality exists to support the association of any modifiable factor (such as nutritional supplements, herbal preparations, dietary factors, prescription or nonprescription drugs, social or economic factors, medical conditions, toxins, or environmental exposures) with reduced risk for Alzheimer disease.
The Need for Answers
As Patti Davis so eloquently indicated by the title of her book about her father President Reagan, The Long Goodbye, Alzheimer's is the painfully slow loss of all that makes us unique human beings: memories of where we came from, who we've loved, what we've accomplished; thinking skills; and even the ability to carry out the most basic daily needs like dressing, eating and bathing.
That's the human side. On the economic side, Alzheimer's is one of the major problems taking the American healthcare system, Medicare and the country as a whole down the road to bankruptcy. Today, the cost of caring for Alzheimer's patients is $200 billion, $140 billion of it in Medicare and Medicaid costs.
At present, some 5.4 million Americans live with Alzheimer's. Projections are that, with the aging of baby boomers, by 2050 some 16 million people will have the disease, and if nothing is done, the cost will total $1.1 trillion.
On the Research Horizon
We're learning more about the biological markers associated with Alzheimer's disease. For example, we know that certain brain abnormalities such as amyloid plaques and neurofibrillary tangles probably appear 10 to 20 years before a patient shows any symptoms. Yet we have no way of positively identifying these markers short of a brain biopsy until after the patient dies and an autopsy is performed. My colleagues, are studying whether examinations of the eye may provide an earlier way to detect plaque buildups, and have shown that this is possible in animal models of Alzheimer's. Imaging of amyloid plaques in the brain using a radioactive material that binds to the amyloid protein also is being actively explored. Other researchers are looking at other biomarkers to see if there are changes that can accurately predict the onset of Alzheimer's. This is an important step in identifying people who could benefit from treatment in the future if and when better treatment becomes available. And it can help sort out which patients have Alzheimer's, the most common cause of memory loss, rather than some other form of dementia.
Recent findings on something as observable as the way a patient walks may help physicians figure out if someone is on the road to cognitive impairment, including Alzheimer's disease. One such study measured the stride and speed of more than 1,300 people as they walked and also measured their cognitive function. Fifteen months later, researchers gave the people the same walking measures and the same thinking and memory test. Those who lost speed and took smaller steps also performed more poorly on memory tests. It could be that small changes in the way a person walks could be an early indication of cognitive decline.
For now, there are a few drugs to treat Alzheimer's that may help some people retain thinking and memory skills for a short while. But so far, their effectiveness is short term, and they don't change the underlying brain damage being done by the disease.
Clues from Observational Studies
Just because we don't have definitive answers from clinical trials — those scientific studies in which groups of volunteers are randomly assigned to either take a pill or not, practice a lifestyle change or not — doesn't mean we have nothing to go on to make decisions. Other types of studies, called epidemiological or observational studies, provide considerable insight and guidance for scientists to develop hypotheses for further, more rigorous research. They suggest associations, or links, between, say, a specific nutrient and increased or decreased risks. Keep in mind that such links aren't definitive proof. Still, they can help people worried about memory loss begin to try some things, especially those that are good for them anyway.
So for the umpteenth time, let me urge you to exercise. A number of observational studies have linked increased physical activity to a reduced risk of dementia. The Nurses' Health Study of more than 18,000 nurses, for example, showed that women with higher levels of physical activity over a two-year period scored better on cognitive tests than women who exercised less. Another study found that men who walked at least two miles a day were 1.8 times less likely to suffer memory loss than more sedentary men over a period of six years.
And while there has been no big clinical trial of the exercise theory, a recent small trial put 138 people 50 and older to the test. Half the volunteers received education about memory loss. The other half of the group received similar education, and, in addition, were asked to exercise three times a week (most chose walking) and to keep a diary of their physical activity. After 18 months, those who exercised showed modest improvement in memory relative to the group that was not encouraged to exercise.
You also should eat sensibly, and perhaps count a reduced risk of memory loss among the dozens or hundreds of ways that it might well serve you. That means low intake of saturated fats, like cheese, butter and fatty meats, and high consumption of fruits, vegetables and fish.
Other lifestyle links to a reduced risk of Alzheimer's or dementia include having friends, a book club, a religious group or golf buddies. A spouse helps — people who have never been married have a higher risk of Alzheimer's disease. Current smokers have a higher risk of memory loss, but the evidence on former smokers is unclear.
It's only recently that science has discovered that our adult brains, though at a much, much slower pace than the developing brains of children, continue to grow new brain cells and create new connections between them. It's called neuroplasticity. That breakthrough understanding of the brain has implications for preventing memory loss and leads to the theory that such things as reading, engaging in conversation, or working crossword puzzles just might protect against mental decline.
Maybe more challenging activities will help even more than crossword puzzles. One federally funded research study is looking closely at older adults involved in learning digital photography or attending quilting classes. Researchers will compare their cognitive function over time with that of older adults involved in more low-key mental activities, like attending social groups or playing Scrabble.
But even the most mentally agile people can fall victim to Alzheimer's or other forms of dementia. We don't want memory impairment to go the way of lung cancer, with society blaming patients for getting this disease because they didn't read, socially interact or think enough. Until science comes up with better treatments for this too common end-of-life misery, the best we can do are the things we already know to be good for us.