Increasingly needing to write yourself reminder notes or repeatedly bumping into furniture after rearranging your living room (spatial memory) is frustrating, to say the least. It also may signal future cognitive decline, including dementia, a catch-all term for memory loss and difficulty with thinking, problem-solving or language, the most common of which is Alzheimer’s disease.
“Aging is the strongest risk factor for the development and progression of cognitive decline and dementia, although genetics are certainly important, too,” says Tammy Scott, PhD, a scientist in Tufts’ HNRCA Neuroscience and Aging Laboratory. “However, environmental factors, such as inflammation and oxidative stress also play a large role.” There’s a complex interaction between what you eat and such risk factors, which scientists are exploring.
Brain-Protective Eating Patterns:
According to the Scientific Report of the 2015 Dietary Guidelines Advisory Committee, in addition to other recent research, dietary patterns higher in non-starchy vegetables, fruits, whole grains, nuts, legumes and seafood while limited in red and/or processed meats, sugar-sweetened foods and drinks, refined grains and added salt are generally associated with lower risk of age-related cognitive decline and dementia.
“Dietary patterns consistent with this recommendation include anything from a Mediterranean-style diet to a vegetarian diet,” Scott says. “Such patterns typically include nutrient-rich, plant-based foods, like leafy green vegetables, berries and extra-virgin olive oil. On the other hand, a diet that is lacking in key nutrients and that is high in unhealthy fats (trans fat and saturated fat) may contribute to age-related cognitive decline.”
Healthy eating patterns also may promote better blood sugar (blood glucose), which could help protect brain function, too. “Cognitive deficits have been observed in older people who have impaired glucose tolerance,” Scott says. “Insulin insensitivity and diabetes are risk factors for cognitive decline and dementia. Diets that are heavy in sugar and refined grains could increase cognitive risks by impairing glucose and insulin metabolism.”
The brain benefits of healthy fats were recently shown in a review of 21 observational studies that assessed intake of fish and their polyunsaturated fats along with cognitive changes in middle-age and older adults for up to two decades. As reported in the American Journal of Clinical Nutrition, the scientists found that eating one serving per week of fish was associated with a 7% lower risk of Alzheimer’s disease, compared to not eating fish.
Tree nuts and peanuts, which are rich in monounsaturated and polyunsaturated fats also may support brain health. “In animal studies, we’ve seen benefits of the equivalent of one ounce a day of walnuts for spatial memory,” says Barbara Shukitt-Hale, PhD, a research psychologist at Tufts’ HNRCA Neuroscience and Aging Laboratory. “Walnuts are high in both a plant-form of omega-3 fat and polyphenols (particularly in their papery skins). So, we’re not sure which nutrient is producing the cognitive benefit.”
Other scientists have researched nuts in humans, such as in a sub-study of the PREDIMED clinical trial, which found improvements in the memory of older adults who were given about one ounce of mixed nuts daily to eat as part of a Mediterranean diet for 4 years, compared to a control diet.
Berries may cost a bit more than some fruit, but they may give you a bigger cognitive payback. In a recent study, Scott, Shukitt-Hale and colleagues gave 40 healthy men and women (ages 60 to 75) the equivalent of 2 cups of strawberries as a freeze-dried powder or a seemingly identical placebo for 90 days. “Those who ate the powdered strawberries had improved scores on word recognition and spatial memory tests over the course of the study,” Shukitt-Hale says. No benefits on mobility, previously found in animal research, were observed.
In similar research, Shukitt-Hale reports that older adults who ate the equivalent of 1 cup of blueberries (powdered) for 90 days improved at remembering what they had already said (important to avoid repeating yourself), compared to a placebo. They also had improved accuracy when switching between tasks.
What gives berries their brain benefits? “We aren’t entirely certain,” Shukitt-Hale says. “But, the anthocyanins (colorful phytochemicals) in berries have antioxidant and anti-inflammatory properties that may help control oxidative damage and inflammation in the brain. We also think anthocyanins may have direct effects in the brain. In animal studies, we’ve observed that powdered blueberries and strawberries supported ability to make new brain neurons.”
Don’t rush out to buy a supplement of anthocyanins, however. “It’s likely the combination of everything in the berries, rather than a single compound, that’s producing the beneficial effects,” Shukitt-Hale says. “For that same reason, don’t limit yourself to blueberries or strawberries. Eat a variety of berries – and other nutrient-rich foods – because they may have different brain benefits.”
To Learn More: American Journal of Clinical Nutrition, February 2016 –
To Learn More: The FASEB Journal, April 2016 –