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Eating More Berries May Reduce Cognitive Decline in the Elderly

Annals of Neurology 25 APR 2012

Blueberries, blackberries and strawberries. Blueberries and strawberries, which are high in flavonoids, appear to reduce cognitive decline in older adults according to a new study Blueberries and strawberries, which are high in flavonoids, appear to reduce cognitive decline in older adults according to a new study recently published in Annals of Neurology, a journal of the American Neurological Association and Child Neurology Society. The study results suggest that cognitive aging could be delayed by up to 2.5 years in elderly who consume greater amounts of the flavonoid-rich berries.

Flavonoids are compounds found in plants that generally have powerful antioxidant and anti-inflammatory properties. Experts believe that stress and inflammation contribute to cognitive impairment and that increasing consumption of flavonoids could mitigate the harmful effects. Previous studies of the positive effects of flavonoids, particularly anthocyanidins, are limited to animal models or very small trials in older persons, but have shown greater consumption of foods with these compounds improve cognitive function.

According to the 2010 U.S. Census, elderly Americans -- those 65 years of age and older -- increased by 15% between 2000 and 2010, faster than the total U.S. population, which saw a 9.7% increase during the same time period. "As the U.S. population ages, understanding the health issues facing this group becomes increasingly important," said Dr. Elizabeth Devore with Brigham and Women's Hospital and Harvard Medical School in Boston, Mass. "Our study examined whether greater intake of berries could slow rates of cognitive decline."

The research team used data from the Nurses' Health Study -- a cohort of 121,700 female, registered nurses between the ages of 30 and 55 who completed health and lifestyle questionnaires beginning in 1976. Since 1980 participants were surveyed every four years regarding their frequency of food consumption. Between 1995 and 2001, cognitive function was measured in 16,010 subjects over the age of 70 years, at 2-year intervals. Women included in the present study had a mean age of 74 and mean body mass index of 26. Findings show that increased consumption of blueberries and strawberries appear to slow cognitive decline in older women. A greater intake of anthocyanidins and total flavonoids was also associated with reduce cognitive degeneration. Researchers observed that women who had higher berry intake delayed cognitive aging by up to 2.5 years. The authors caution that while they did control for other health factors in the modeling, they cannot rule out the possibility that the preserved cognition in those who eat more berries may be also influenced by other lifestyle choices, such as exercising more.

"We provide the first epidemiologic evidence that berries may slow progression of cognitive decline in elderly women," notes Dr. Devore. "Our findings have significant public health implications as increasing berry intake is a fairly simple dietary modification to test cognition protection in older adults."

Berries May Slow Memory Loss: Eating More Blueberries and Strawberries Is Linked to Better Brain Function With Age Eating berries at least once a week may protect the brain from age-related memory loss; a large new study shows. The study included more than 16,000 women who are taking part in the Nurses' Health Study.

Researchers have been keeping tabs on the women's diets since 1980. Between 1995 and 2001, researchers also measured the mental function of women who were over 70 and had not had a stroke. Mental functioning was measured during three telephone interviews that were spaced about two years apart. In the interviews, researchers asked the women to recall details from a paragraph they'd just heard, for example, or to remember the order of words or numbers in a list. When researchers compared women who ate the most blueberries and strawberries to those who ate the fewest, they found that those who ate the most had a slower rate of developing memory problems. The difference was equal to about two-and-a-half years of aging. "This is pretty compelling evidence to suggest that berries do appear to have memory benefits," says researcher Elizabeth E. Devore, ScD, instructor in medicine at Brigham and Women's Hospital in Boston.

What may be even better news is that the biggest berry eaters in the study weren't eating mounds of them every day. On average, they were eating a single half-cup serving of blueberries or two half-cup servings of strawberries each week. "These are simple interventions that appear to have pretty healthful effects," Devore says. The study can't prove that berries protected the women's brains directly.

In fact, women in the study who ate berries regularly also got more exercise and had higher incomes -- two factors that are also linked to having better health. But researchers say that even after they adjusted their results to account for differences like that, having a diet high in fruits and vegetables, particularly berries, still appeared to be linked to having a sharper memory.

How Berries May Be Good for the Brain The study, which is published in the Annals of Neurology, builds on smaller studies in mice and humans that have suggested that berries may benefit the brain. Berries, particularly blueberries, are rich in a particular kind of antioxidant compound called anthocyanidins. Anthocyanidins have the ability to move from the blood into the brain. And studies in animals have shown that these compounds concentrate in brain centers responsible for memory and learning. Further studies in mice that are bred to develop brain changes similar to those seen in Alzheimer's patients show that blueberries protect these mice from memory declines. And small studies in humans with early memory loss have shown that adding 1/2 to 1 cup of blueberry juice to the diet each day for three months improved some measures of memory.

"I think it's very exciting," says Brent Small, PhD, professor of aging studies at the University of South Florida in Tampa. "Because there's not a lot that's been reported in the human literature that's focused on these types of compounds." Small is testing a blueberry-based supplement on memory in humans, but he was not involved in the new study. "The fact that they were able to see an effect for people who are generally healthy and who aren't experiencing significant drops in performance is interesting," Small says.

Brain Food: Berries Can Slow Cognitive Decline Researchers report in the journal Annals of Neurology that women who ate berries more frequently over a period of years showed slower decline in brain functions such as memory and attention when they got older than women who ate them less often. The findings don’t confirm that eating berries can prevent dementia associated with aging, or slow down Alzheimer’s, but they suggest that the fruits may play a part in keeping brains healthy. The protective effect of blueberries and strawberries isn’t an entirely new finding. But previous studies have involved animals and only a small number of people, which left open the possibility that it wasn’t the berries, but something else that might be influencing how quickly the brain lost its executive functions.

In the current analysis, Elizabeth Devore, an instructor in medicine at Brigham and Women’s Hospital, and her colleagues addressed the gap in the research by reviewing the eating habits of a single cohort of 16,000 women participating in the Nurses Health Study. During their 50s and 60s, every four years the women answered questions by phone about what they ate. And in their 70s, they came into the lab for six different cognitive function tests. Devore and her team also had information on the women’s education, income and other socioeconomic factors that can affect cognitive function. Their findings confirmed that women who ate berries at least once a week were able to slow down their cognitive decline by about 1.5 to 2.5 years. For blueberries, the effect started with about a half cup of berries each week; for strawberries, it took about a cup of the fruit per week. This effect persisted even after the scientists accounted for the fact that berry-eaters might also have other brain-healthy habits or characteristics, such as having more education and engaging in intellectually satisfying pursuits such as learning new languages or maintaining a rich network of social connections. “In the end, we did not see a lot of confounding from these factors,” says Devore.

She and her colleagues focused their attention on berries because rodent studies showed that the key compound in berries, a flavonoid called anthocyanidin, could seep through the blood and into brain tissues — specifically concentrating in the hippocampus, which is responsible for learning and memory. As an antioxidant, flavonoids also fight inflammation and oxidation, both processes that affect aging brain cells. The study is only the first to track berry consumption long term until cognitive decline set in, and the findings will need to be repeated and confirmed. But in the meantime, says Devore, it makes sense to add blueberries and strawberries to your diet, frozen or fresh. “I don’t think there are many downsides to that. The availability of berries and access to this kind of intervention is great as a public health message.” And a tasty one too.

Dietary intakes of berries and flavonoids in relation to cognitive decline

Annals of Neurology 25 APR 2012 DOI: 10.1002/ana.23594 Elizabeth E. Devore ScD1,*, Jae Hee Kang ScD1, Monique M. B. Breteler MD, PhD2,Francine Grodstein ScD1

Abstract

Objective: Berries are high in flavonoids, especially anthocyanidins, and improve cognition in experimental studies. We prospectively evaluated whether greater long-term intakes of berries and flavonoids are associated with slower rates of cognitive decline in older women.

Methods: Beginning in 1980, a semiquantitative food frequency questionnaire was administered every 4 years to Nurses' Health Study participants. In 1995–2001, we began measuring cognitive function in 16,010 participants, aged ≥70 years; follow-up assessments were conducted twice, at 2-year intervals. To ascertain long-term diet, we averaged dietary variables from 1980 through the initial cognitive interview. Using multivariate-adjusted, mixed linear regression, we estimated mean differences in slopes of cognitive decline by long-term berry and flavonoid intakes.

Results: Greater intakes of blueberries and strawberries were associated with slower rates of cognitive decline (eg, for a global score averaging all 6 cognitive tests, for blueberries: p-trend = 0.014 and mean difference = 0.04, 95% confidence interval [CI] = 0.01–0.07, comparing extreme categories of intake; for strawberries: p-trend = 0.022 and mean difference = 0.03, 95% CI = 0.00–0.06, comparing extreme categories of intake), after adjusting for multiple potential confounders. These effect estimates were equivalent to those we found for approximately 1.5 to 2.5 years of age in our cohort, indicating that berry intake appears to delay cognitive aging by up to 2.5 years. Additionally, in further supporting evidence, greater intakes of anthocyanidins and total flavonoids were associated with slower rates of cognitive decline (p-trends = 0.015 and 0.053, respectively, for the global score).

Interpretation: Higher intake of flavonoids, particularly from berries, appears to reduce rates of cognitive decline in older adults.