Food for Thought: Can Diet Prevent Alzheimer’s Disease?

Vegetables arranged in the shape of a brain.
Photo: BRAIN MADE OUT OF FRUITS AND VEGETABLES©GETTYIMAGES/TIJANA87

As the American population ages, the incidence of Alzheimer’s disease also continues to rise. While researchers continue to study Alzheimer’s, studies suggest diet may play a role in its prevention or delayed onset.

Alzheimer’s, which has no known cure, accounts for 60 to 80 percent of all cases of dementia and is the sixth-leading cause of death in the United States. Nearly 6 million Americans are living with Alzheimer’s, and the number is estimated to rise to almost 14 million by 2050.

While there are many signs and symptoms of Alzheimer’s disease, the initial indicator usually is difficulty remembering newly learned information. Other symptoms that may develop include confusion about events, times and places; significant mood and behavior changes; and difficulty speaking. Additionally, Alzheimer’s may have nutrition-related symptoms such as forgetting how to use cutlery, loss of appetite or forgetting about previous meals. Other symptoms may include unintentional weight loss, difficulty swallowing or swallowing without chewing, forgetting how to eat or drink and attempting to eat inedible items.

Although Alzheimer’s disease is not a normal part of the aging process, the biggest risk factor is increasing age. Most people with Alzheimer’s are older than 65. The risk of developing Alzheimer’s doubles after 65 and nearly one-third of people over 85 will develop the disease. “Early onset” Alzheimer’s occurs in people younger than 65 — about 5 percent of all diagnosed cases; however, the number of people who suffer from early onset could be higher since it is not commonly recognized and therefore more difficult to diagnose.

Anyone with a parent or sibling with Alzheimer’s disease has a greater risk of developing the condition; risk increases if multiple family members have Alzheimer’s. Genetics and other factors, such as head injury, also can increase risk; in addition, Hispanics and African-Americans are at greater risk. Poor heart health or poor overall vascular health, as well as lifestyle factors such as tobacco use and excessive alcohol consumption, can increase chances of developing Alzheimer’s. On the other hand, staying socially active, exercising and following a healthy diet may decrease risk.

Based on the latest research, the Alzheimer’s Association recommends the Mediterranean diet and the Dietary Approaches to Stop Hypertension, or DASH, diet, both of which may decrease risks of developing heart disease and dementia.

Mediterranean Diet
This diet is highly focused on plant foods such as fruits, vegetables and whole grains; foods containing heart-healthy fats including olive oil; spices and occasional fish, poultry and dairy. Red meat and salt are limited.

Studies have shown the Mediterranean diet may help prevent or delay the onset of Alzheimer’s disease by 1½ to 3½ years. Participants in a 2018 study were 30 to 60 years old with no dementia; they received brain imaging scans at the start and end of a two-year period. About half the group reported practicing a high adherence to the diet, while the other half reported following a Western diet. Follow-up scans revealed the Western diet group had higher betaamyloid protein deposits and lower energy use, both signs of early dementia.

Meta-analyses and systematic reviews have found a large body of research that suggests the Mediterranean diet may help decrease risks for several brain-related diseases including depression, stroke, Alzheimer’s disease and mild cognitive impairment, which can progress to Alzheimer’s.

It’s not exactly known how the Mediterranean diet may help delay or prevent dementia. Some theories suggest high amounts of antioxidants from foods in the diet may play a role, while others speculate the high amount of beneficial fats may contribute to vascular health, which can contribute to better brain health.

Most studies are observational and many use dietary recalls, which can be unreliable. To further strengthen the recommendation of the Mediterranean diet for Alzheimer’s disease, more randomized controlled studies with longer follow-up periods are needed.

DASH Diet
Although there is less research on the DASH diet as it relates specifically to the delay, prevention or treatment of Alzheimer’s disease, this eating pattern is recommended by the Alzheimer’s Association. The DASH diet involve consuming lots of fruits, vegetables and whole grains, limiting saturated fats, salt and added sugars, and aiming to be high in potassium. DASH is very similar to the Mediterranean diet, but puts less emphasis on olive oil as the primary fat source and does not promote regular alcohol consumption.

In the limited pool of research, there is a correlation between adherence to the DASH diet and lower incidence of cognitive decline. A greater amount of research suggests following the DASH diet can help prevent other conditions, including hypertension and cardiovascular disease. Several studies have found the DASH diet improves cardiovascular and vascular health by reducing blood lipid levels and blood pressure. Cardiovascular and vascular health have been directly correlated with brain health and Alzheimer’s risk, which may explain the association’s endorsement of the diet, but more research is needed on the DASH diet and its impact on Alzheimer’s disease.

MIND Diet
The Mediterranean-DASH Intervention for Neurodegenerative Delay, or MIND, diet was created by researchers as an eating pattern specifically targeted to brain health. The diet is a combination of aspects from the Mediterranean and DASH diets, with more specific recommendations: 10 foods to incorporate and five foods to avoid.

On the MIND diet, people should eat six or more servings of green, leafy vegetables each week and one additional serving of vegetables daily. The only fruits mentioned in this eating pattern are berries, which are recommended twice a week because of their high antioxidant content. The MIND diet recommends five or more servings of nuts per week and using only olive oil as an added fat. Three servings of whole grains should be eaten daily; fish at least once a week; beans at least four times a week; poultry twice a week; and no more than one glass of wine per day. Foods to avoid or limit include butter and margarine, cheese, red meat, fried foods, pastries and sweets.

Created in 2015, the MIND diet is relatively new and more research is needed to support it. The most notable research study comes from Rush University Medical Center, which followed more than 900 participants for an average of 4½ years. Researchers found the MIND diet may reduce the risk of developing Alzheimer’s by as much as 53 percent.

More Research Needed
Alzheimer’s disease is an increasing problem and current research hints that diet may be able to help. However, more research is needed on the role of nutrition, including these three diets, on the ability to prevent or delay Alzheimer’s and dementia. Because research shows overall positive health outcomes from both the Mediterranean and DASH diets, registered dietitian nutritionists may feel most comfortable recommending them to patients and clients who are concerned about brain and overall health.

TREATING ALZHEIMER’S WITH FOOD

Research on diet for treating Alzheimer’s disease is limited and there is no specific nutrition prescription. However, good nutrition is imperative and there are several recommendations and modifications that can help people who have Alzheimer’s:

  • Follow an overall healthy diet.
  • Limit distractions that can interfere with food intake, such as television.
  • Avoid having too many items on the table to prevent confusion.
  • Only serve one or two food items at a time.
  • Avoid patterned plates.
  • Modify food textures as needed.
  • Allow plenty of time to complete a meal.
  • Consider liberalizing diets to incorporate favorite foods.
  • If weight loss is a concern, consider fortified foods and supplements.

References

Adopt a Healthy Diet. Alzheimer’s Association website. Published 2018. Accessed October 6, 2018.
Alzheimer’s. Published 2018. Accessed October 6, 2018.
Alzheimer’s: Nutrition Prescription. Nutrition Care Manual website. Published 2018. Accessed October 7, 2018.
Berti V, Walters M, Sterling J et al. Mediterranean diet and 3-year Alzheimer brain biomarker changes in middle-aged adults. Neurology. 2018;90(20):e1789-e1798.
DASH Eating Plan. National Heart, Lung, and Blood Institute website. Published 2018. Accessed October 7, 2018.
Diet May Help Prevent Alzheimer’s. Rush University Medical Center website. Published 2018. Accessed October 7, 2018.
Early Onset Dementia: A National Challenge, A Future Crisis. Alzheimer’s Association website. Published 2018. Accessed October 6, 2018.
Facts and Figures. Alzheimer’s Association website. alz.org/alzheimers-dementia/facts-figures. Published 2018. Accessed October 6, 2018.
Food and Eating. Alzheimer’s Association website. Published 2018. Accessed October 7, 2018.
Graff-Radford J. Alzheimer’s: Can a Mediterranean diet lower my risk? Mayo Clinic website. Published 2018. Accessed October 6, 2018.
Meal Times. Alzheimer Society of Canada website. Published September 2012. Accessed October 6, 2018.
Mediterranean diet and dementia. Alzheimer’s Society website. Accessed October 7, 2018.
Morris MC, Tangney CC, Wang Y, Sacks FM, Bennett DA, Aggarwal NT. MIND Diet Associated with Reduced Incidence of Alzheimer’s Disease. Alzheimers Dement. 2015;11(9):1007-1014.
Pearson K. The MIND Diet: A Detailed Guide for Beginners. Healthline website. Published 2018. Accessed October 6, 2018.
Psaltopoulou T, Sergentanis T, Panagiotakos D, Sergentanis I, Kosti R, Scarmeas N. Mediterranean diet, stroke, cognitive impairment, and depression: A meta-analysis. Ann Neurol. 2013;74(4):580-591.
Reynolds S. Mediterranean diet may slow development of Alzheimer’s disease. National Institutes of Health website. Published May 15, 2018. Accessed October 6, 2018.
Risk Factors. Alzheimer’s Association website. Published 2018. Accessed October 6, 2018.
Singh B, Parsaik AK, Mielke MM, et al. Association of Mediterranean diet with Mild Cognitive Impairment and Alzheimer’s disease: A Systematic Review and Meta-Analysis. J Alz Dis. 2014;39(2):271-282.
Tangney CC. DASH and Mediterranean-type Dietary Patterns to Maintain Cognitive Health. Curr Nutr Rep. 2014;3(1):51-61.
The MIND Diet — Fighting Dementia With Food. Today’s Geriatric Medicine website. Published 2018. Accessed October 7, 2018.
What Is Alzheimer’s? Alzheimer’s Association website. Published 2018. Accessed October 6, 2018.

Esther Ellis
Esther Ellis, MS, RD, LDN, is a retail dietitian and freelance writer based in New Orleans.