About 5.2 million Americans currently suffer from Alzheimer’s disease, and the aging population will drive that number to an estimated 7.1 million by 2025, according to the Alzheimer’s Association. Researchers have identified several types of brain abnormalities in people with the disease, notably plaques made of clumps of beta-amyloid protein and tangles of a protein called tau. Both correlate with the death of brain cells, leading to progressive memory loss, dwindling social skills and, eventually, death. As Dr. Marwan Sabbagh, director of the Banner Sun Health Research Institute and co-author of "The Alzheimer’s Prevention Cookbook," puts it, Alzheimer’s memory loss goes beyond the usual “I forgot where I put my keys” to “I forgot what my keys are for.” Age, family history, having the Apolipoprotein E genotype and being female are the leading predictors of the disease. But researchers are finding other predictive correlations, especially in lifestyle.
Several biomarkers seem to correlate with Alzheimer’s, including certain proteins in spinal fluid or blood and mutations detectable by brain imaging. Michael Weiner, principal investigator for the Alzheimer’s Disease Neuroimaging Initiative and director of San Francisco’s Center for Imaging of Neurodegenerative Disease, works with PET scans of study participants’ brains. While definitive Alzheimer’s diagnoses have formerly been made postmortem, Weiner said he was surprised to discover he could detect the Alzheimer’s-correlated amyloid protein in living people. Brain changes can begin 25 years before the onset of the disease. A 2012 study led by Dr. Michelle Mielke of the Mayo Clinic found that women with the highest level of a fatty compound called serum ceramide in their blood were 10 times more likely to develop Alzheimer’s than women with lower levels of the compound. However, patients often avoid these types of tests for fear of losing medical insurance.
Heart history. Trouble with the vascular system is linked to Alzheimer’s. High blood pressure, especially in midlife, increases your risk. So can your heart history. People who have previously had a heart attack are more than twice as likely to develop dementia, whether it's Alzheimer’s or another type. Weiner emphasizes the importance of controlling your blood pressure. Decreasing stress also helps lower your risk of developing Alzheimer’s.
Diabetes and obesity. Insulin-resistant diabetes could double or even quadruple your chances of getting Alzheimer’s. An enzyme in your brain is responsible for decreasing both insulin and amyloid, so too much insulin may interfere with the enzyme’s ability to remove the amyloid. Obesity also increases your odds, especially for women, who may be three times as likely to develop Alzheimer’s as their thinner peers, according to the Fortanasce-Barton Neurology Center. Obese men increase their risk by about 30 percent. Exercise benefits both the obese and the diabetic. Dr. Joe Verghese, director of the Resnick Gerontology Center at the Albert Einstein College of Medicine, prescribes physical activity and clean living. He admits that both he and his patients might rather take a pill than exercise and eat right. “I hate exercise,” he says. “But I do it because it’s good for me. A lot of this is common sense.”
Low education. Lower levels of formal education and a general lack of mental stimulation correlate with increased risk of Alzheimer’s. Verghese led a study that identified dancing as the most helpful physical activity for avoiding Alzheimer’s, partly due to the social aspect. “You don’t usually dance alone,” he says. “Social interaction has been said to reduce stress levels, which are bad for the brain.” Sabbagh agrees, noting, “People who do volunteering, traveling, crossword puzzles — you name it, those people tend to be better off intellectually.” But the science is fuzzy, he says, because socially engaged people tend to take better care of themselves in general. He’s also uncertain about the dose and intensity. “If I do three hours of volunteering or sudoku versus one hour, am I more protected?” he asks. And does he have to do the New York Times crossword, or is the one in his local Arizona paper sufficient?
Lack of fruits, vegetables and spices in diet. Diets low in vegetables may speed cognitive decline. One reason for this involves homocysteine, an amino acid in blood plasma. Higher levels seem to increase your risk of Alzheimer’s, among other deadly diseases. You need folate and other B vitamins to properly break down homocysteine. While all types of vegetables will help, Sabbagh recommends kale, squash, eggplant, collard greens and blueberries as cognitive superstars. Certain spices, notably cinnamon and turmeric, may also have a dramatic effect. “There’s clear evidence that people in India, at least from epidemiological data, have less Alzheimer’s,” says Sabbagh. “One of the environmental things people attribute it to is the presence of turmeric.” He also recommends following the Mediterranean diet.
Head traumas. Boxers’ cerebral spinal fluid contains elevated markers for Alzheimer’s disease, according to a 2006 study led by Henrik Zetterberg of the Sahlgrenska Academy at Göteborg University in Sweden as well as a larger 2012 study led by Sanna Neselius at the same institution. In Alzheimer’s earliest stages, the disease can change levels of beta-amyloid and tau — proteins associated with clumps and tangles — in spinal fluid. Boxers who have the Apolipoprotein E genotype are at even greater risk. Alzheimer’s patients who suffered significant head injuries before age 65 showed symptoms at an earlier age than those who hadn’t had head injuries. Sabbagh recommends avoiding contact sports involving your head and using protective headgear.
Gait changes. A deteriorating gait and the inability to simultaneously walk and talk may indicate the onset of Alzheimer’s. “Walking while talking is a divided attention task,” says Verghese, who has long studied gait changes in patients with non-Alzheimer’s dementia. “Now, if you are in the early stages of dementia or actually have dementia, then this becomes more challenging because you have limited attention resources.” Five different studies presented at the 2012 Alzheimer’s Association International Conference tied gait change to the disease. Alzheimer’s correlated with slower and/or erratic walking and difficulty in performing such tasks as walking while counting backward.
Poor navigation. Since Alzheimer’s starts in the hippocampus, often called the brain’s seat of memory, disorientation is a hallmark of the disease. This accounts for why people with Alzheimer’s are notorious for wandering off and getting lost. “Navigational problems might arise very early in the course of cognitive decline,” says Verghese. He’s now working on a National Institutes of Health-funded study that looks at people’s ability to navigate and whether those who are navigationally challenged will face faster cognitive decline.
Depression and social withdrawal. People who suffer from depression earlier in life are more likely to develop Alzheimer’s as they age. A study by the Multi-Institutional Research in Alzheimer’s Genetic Epidemiology group, led by Robert Green of Harvard Medical School and published in Archives of Neurology in 2003, found a significant link between Alzheimer’s diagnoses and people who had shown symptoms of depression within the past year. So while doctors have long noted that people with Alzheimer’s tend to become depressed and withdraw socially, recent studies show that the depression predates dementia.
Sleep problems. Sleep disorders such as sleep apnea have been linked to cognitive deficits. Previous studies found Alzheimer’s plaque developing in mice’s brains when their sleeping schedules were significantly disrupted. A study released in 2012 correlated sleep disruption and Alzheimer’s in humans. The Washington University study, led by David Holtzman of the college's Department of Neurology, studied 145 cognitively normal people. Those with biomarkers for Alzheimer’s, as measured in their spinal fluid, were the worst sleepers. They spent more of their time in bed awake and napped more frequently during the day than those without the Alzheimer’s biomarkers. Sleep apnea is also linked to nighttime cardiac events and high blood pressure, both of which also correlate with Alzheimer’s.
A few lifestyle tips to end on hopeful note. Despite what he describes as nihilism about the disease within much of the medical community, Sabbagh emphasizes that there’s hope. Medications to treat the disease have improved in the past 16 years, he says. “The field itself is moving forward very rapidly. Granted, there are lots of frustrations and failures, but that doesn’t mean the science has stood still.” Sabbagh recommends making lifestyle changes as a preventative strategy right away. Eat your greens. Exercise. Value your social connections, and use your brain power. “You should not wait,” Sabbagh says, “because by the time you become symptomatic, the pathology in your brain is significant.”
