April 20, 2015 6:32 p.m. ET
Researchers successfully tested a special diet they designed that appears to reduce the risk for developing Alzheimer’s disease.
The study compared the so-called MIND diet with the popular, heart-healthy Mediterranean diet and the DASH diet, which is intended to help control high blood pressure. The MIND diet borrows significantly from the other two, and all are largely plant-based and low in high-fat foods. But the MIND diet places particular emphasis on eating “brain-healthy” foods such as green leafy vegetables and berries, among other recommendations.
The study, conducted by researchers at Rush University Medical Center in Chicago, found strict adherence to any of the three diets lessened the chances of getting Alzheimer’s. But only the MIND diet seemed to help counter the disease even when people followed only some of the diet’s recommendations. The research was observational, not randomized or controlled, and therefore isn’t evidence the MIND diet caused a reduced risk for Alzheimer’s. Instead, the research shows there is an association between the two.
The study is part of a small body of research investigating how nutrition can improve brain health and stave off the cognitive decline and memory impairment that comes with Alzheimer’s disease and other forms of dementia. Experts say there is growing awareness that lifestyle factors—not just genetics—play a prominent role in the development of Alzheimer’s, and researchers hope to come up with an optimal diet that will lessen the chances of developing the disease. An estimated 5.1 million people in the U.S. have Alzheimer’s, a number expected to grow to 7.1 million by 2025, according to the Alzheimer’s Association.
“It’s a relatively new field compared with heart disease and diabetes and nutrition,” said Martha Clare Morris, a professor of neurological epidemiology at Rush. “As we learn more and more I think we would definitely modify or update the [MIND] diet based on the latest research,” said Dr. Morris, who was first author of the study, published recently in the journal Alzheimer’s Dementia.
The MIND diet, which took two years to develop, stands for Mediterranean-DASH Intervention for Neurodegenerative Delay. Researchers modified the Mediterranean and DASH diets based on evidence from animal and human studies looking at nutrition and the brain. DASH stands for Dietary Approaches to Stop Hypertension.
For example, fruits, a common recommendation in heart-healthy diets, haven’t been shown to slow cognitive decline or prevent dementia, but berries, and especially blueberries, have, Dr. Morris said. The MIND diet calls for eating berries at least two times a week and doesn’t include recommendations for other types of fruit. Research also has shown that green leafy vegetables protect the brain more than other vegetables. The MIND diet includes one serving of greens in addition to eating one or more other vegetables a day. The MIND diet is heavy on nuts and beans, whole grains and olive oil and recommends a glass of wine a day, all of which also are recommended by one or both of the other diets.
The study involved 923 participants who didn’t have dementia at the start of the research. Their ages ranged from 58 to 98, with a median age of 81. Participants, who were followed on average for 4.5 years, were questioned annually on how often they ate from among 144 different food items. Subjects whose diet choices adhered closely to the MIND diet had a 53% reduced risk for developing Alzheimer’s. Risk was reduced by 54% with the Mediterranean diet and 39% with the DASH diet.
Significantly, even moderate adherence to the MIND diet helped lessen the risk for Alzheimer’s, by 35%. By comparison, moderate adherence to the Mediterranean or DASH diets didn’t affect the chances of getting the disease. That finding was particularly encouraging, because many people find it easier to follow just some of a diet’s recommendations. “I think that will motivate people,” Dr. Morris said.
The study controlled for genetic predisposition, physical activity, cognitive activity and education. A further analysis controlled for various chronic medical conditions. It was the first study published on the MIND diet, and researchers expect additional small changes to be made. Cocoa and caffeine, for example, could possibly be added to the diet with more research, Dr. Morris said.
The researchers also analyzed green leafy vegetables in relation to cognitive decline. Participants who ate one to two servings of green vegetables a day had a “dramatic decrease in the rate of cognitive decline” compared with people who ate fewer greens, said Dr. Morris. “It was about the equivalent of being 11 years younger in age,” she said.
“The MIND diet may be a triple bonus. It reduces the risk for dementia, strokes and heart disease,” said Murali Doraiswamy, a professor of psychiatry at Duke University Medical Center in Durham, N.C., and an Alzheimer’s expert. Dr. Doraiswamy, who wasn’t involved in the MIND diet study, said a randomized controlled study is needed to determine if the diet really reduces dementia risk, and whether combining it with lifestyle interventions like exercise and meditation could provide additional benefits.
A Swedish study is investigating lifestyle’s effect on developing dementia. Finger, for Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, is a randomized controlled study with 1,260 at-risk participants ages 60 to 77. Subjects assigned to an intervention group were given a diet similar to the Mediterranean diet, an exercise program, cognitive training and management of metabolic and vascular risk factors such as diabetes and hypertension, said Miia Kivipelto, senior geriatrician at the Karolinska Institute in Stockholm. A control group was given general health advice.
“Our hypothesis was that maybe we need to target all these different risk factors simultaneously to get the optimal effect of the intervention,” Dr. Kivipelto said.
Initial results, based on the study’s first two years, were published recently in the Lancet. The researchers found the intervention had clear benefits in areas including memory function and processing speed. The control group had a 30% higher risk for cognitive impairment, said Dr. Kivipelto, senior author of the study.
The next step is to separate out the effects of different lifestyle interventions and see how interventions may affect people depending on genetic makeup, she said. For example, there is evidence that people with a certain variation of the apoe4 gene—a risk factor for developing dementia—are more vulnerable to unhealthy diets. Data from the Finger study could indicate whether such people might especially benefit from a healthy diet.
Suzanne Craft, a professor at Wake Forest School of Medicine in Winston-Salem, N.C., also studies the effects of diet on Alzheimer’s disease symptoms. In a 2011 randomized controlled study published in the Archives of Neurology, Dr. Craft and colleagues assigned about half of 50 older people to a Western diet relatively high in saturated fat and sugar for a month. The other half followed a more heart-healthy diet with the same number of calories. Meals were delivered to the participants.
An analysis of the participants’ spinal fluids found that the Western diet increased inflammation and levels of beta-amyloid proteins, which play a role in the development of Alzheimer’s. “If you think of the impact of eating with these kinds of patterns over years and years, it’s not hard to see how diet can have a profound effect on your risk for Alzheimer’s,” said Dr. Craft.
A follow-up study currently under way, involving 80 people age 45 to 65 years old, is comparing the diets’ effects on blood flow in the brain. The researchers are checking for biomarkers that might indicate early changes that raise a person’s risk for Alzheimer’s. “If we can identify these really early markers they may turn out to be therapeutic targets or good markers of vulnerability,” she said.