An epidemiological research study made headlines last year with findings that suggested that as much as half of all risk for Alzheimer’s disease (AD) and all-cause dementia in the U. S. can be attributed to just seven potentially modifiable risk factors. The extensive review of available AD research and careful mathematical model suggests that a 10- to 25-percent reduction in these seven risk factors—diabetes mellitus, midlife hypertension, obesity, present smoking, depression, physical inactivity, and cognitive inactivity—might theoretically have prevented up to 492,000 Americans from developing AD. Over the next 40 years, these risk reductions might cut AD numbers by nearly 3 million cases, the researchers said.
Since the publication of that widely respected review in the September 2011 issue of The Lancet Neurology, new research has continued to bolster the authors’ conclusions, and underscored the importance of convincing the public that changing unhealthy behaviors now may well help them avoid AD or dementia later on.
“We need to educate people about how these risk factors may make them more susceptible to AD, and inform them about strategies they can adopt to increase their chances of staying cognitively healthy as they age,” says Deborah Blacker, MD, Director of the Gerontology Research Unit at Massachusetts General Hospital (MGH). “For many individuals, it may be possible to help prevent AD by decreasing behaviors that make them vulnerable to dementia and substituting healthier behaviors.
“It should be noted that many of the studies reviewed by the researchers focused on risk factors observed in mid-life, raising the possibility that the earlier people adopt healthy behaviors and manage medical conditions such as hypertension and obesity, the greater the likelihood that they can avoid dementia. But behavioral changes made in older age are nevertheless desirable because of their impact on overall health.”
Updating the data
New research that supports the Lancet Neurology findings are summarized below, along with ways to lower risk:
Physical inactivity: A study of 546 older adults, published in the Aug. 14, 2012 online edition of Molecular Psychiatry, found that levels of beta-amyloid, an important biomarker associated with AD, were lowest in the brains and blood of participants who engaged in the most physical activity. Another study published in the April 18, 2012 online issue of Neurology suggests that all forms of physical activity, including activities such as cooking and cleaning as well as formal exercise, can help protect older adults from cognitive decline. Of 716 older participants, those in the bottom 10 percent of daily physical activity were 2.3 times as likely to develop AD as those in the top 10 percent. Suggestion: Strive for at least 30 minutes of exercise five days a week, and try to integrate physical activity into your daily life as much as possible.
Depression: A 50-year study that followed 13,535 people from mid-life into older age revealed that participants who suffered depressive symptoms in middle age had a 20 percent increased risk for dementia in older age, and those who suffered depressive symptoms in late life had a 70 percent increased risk for dementia. According to the study, which was published in the May 2012 Archives of General Psychiatry, people who displayed depressive symptoms in both middle and late life had an 80 percent increased risk for dementia. Suggestion: Know the symptoms of depression—such as loss of interest in once-pleasurable activities, feelings of sadness, worthlessness and/or hopelessness, fatigue, difficulty concentrating, irritability, and changes in sleep and appetite—and see a medical care provider or counselor if symptoms persist for two weeks or longer. Some research suggests that treatment for depression, even in older age, may improve cognitive function, although this is not yet conclusively proven.
Smoking: A 25-year study that looked at smoking behaviors and cognitive performance from mid-life to older age in 5,099 men found that men who smoked experienced a significantly faster cognitive decline than men who did not smoke, with the deterioration equivalent to about 10 years of aging. However, smokers who quit and resisted cigarettes for at least 10 years showed no faster rate of decline than men who had never smoked, according to a report published Feb. 6, 2012 in the online issue of the Archives of General Psychiatry. Suggestion: If you smoke, quit. If you are seriously addicted to tobacco, see your health care provider for help in giving up the habit.
Mid-life hypertension: High blood pressure in mid-life is associated with future development of dementia, but the association is less clear in older age. In fact, new research published Sept. 20, 2012 in the journal Neurology Today suggests that hypotension, or low blood pressure, may increase dementia risk in late life in some people, possibly by causing inadequate blood flow in the brain. The study found that people with low blood pressure were more likely to have brain atrophy and memory impairment—but only if they had had hypertension during mid-life. Suggestion: Maintain healthy blood pressure levels to prevent damage to brain vasculature and tissues. Be sure your blood pressure is checked regularly and that you have a doctor’s help in maintaining blood pressure control.
Obesity: A study of 1,233 adults presented at the April 2012 annual meeting of the American Academy of Neurology found that those who consumed the highest-calorie diet were more than twice as likely to develop mild cognitive impairment as those who consumed the diet lowest in calories. Suggestion: If you eat a high-calorie diet, cut down on your calorie intake and eat foods that make up a healthy diet, such as fruits, vegetables, lean meat, fish, whole grains and low-fat dairy products. Excercise regularly.
Mental inactivity: Research published in the May 2012 issue of the Archives of Neurology compared the brain images of 65 healthy older adults with those of 10 AD patients of comparable age, and 11 younger adults. Results showed that subjects who reported the greatest lifelong cognitive activity, through mental activities such as reading, writing, and playing games had brain levels of beta-amyloid comparable to those of the younger adults, while those who reported the least cognitive activity had amyloid levels comparable to those of the AD patients. Suggestion: Stay mentally active with pastimes you enjoy that keep your brain stimulated, such as working puzzles, making music, or socializing.
Diabetes: An examination of the brains of diabetic mice may help explain why people with diabetes are at higher risk for AD. The mice had greater accumulations of beta-amyloid and tau proteins—both hallmarks of AD—within the cells that surround cerebral blood vessels. These cells, in turn, release inflammatory molecules that injure or kill neurons and lead to AD-like changes in the brain, according to a report in the October 2012 issue of Aging Cell. Suggestion: Watch your weight and eat a healthy low-fat diet (see Obesity, above). If you have diabetes, follow your doctor’s advice to maintain good blood sugar control.