Cognitive performance can continue to improve into middle age, but it generally begins to decline after age 65. In addition, age-related cognitive decline can lead to serious diseases such as dementia. Identifying the factors that help maintain brain health is key to preventing or delaying these problems, and a new study has found that eating a high-quality diet in youth and middle age could help maintain good brain function in old age.
The research was presented at NUTRITION 2024, the major annual meeting of the American Society for Nutrition, and adds to a growing body of evidence suggesting that a healthy diet could help prevent Alzheimer’s disease and age-related cognitive decline. While most previous research has focused on the eating habits of people in their 60s and 70s, this new study is the first to assess diet and cognitive ability across the lifespan, from age 4 to 70, and suggests that the links may begin much earlier than previously thought.
“These initial findings generally support current public health guidance that it is important to establish healthy dietary patterns early in life to support and maintain health throughout life,” said Kelly Cara, a recent graduate of the Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University. “Our results also provide new evidence suggesting that improvements in dietary patterns through midlife may influence cognitive performance and help mitigate or reduce cognitive decline in later years.”
Researchers have suggested that eating a healthy diet, particularly one that is rich in plant-based foods that contain high levels of antioxidants and monounsaturated and polyunsaturated fats, may support brain health by reducing oxidative stress and improving blood flow to the brain.
Foods that improve cognitive performance in old age
The scientists used data from 3,059 UK adults who participated as children in a study called the National Survey of Health and Development. Members of this cohort, called the 1946 British Birth Cohort, have provided data on dietary intakes, cognitive outcomes and other factors through questionnaires and tests for more than 75 years.
By analyzing participants’ dietary intakes at five time points in relation to their cognitive ability at seven time points, the researchers found that diet quality was closely related to trends in overall or “global” cognitive ability. For example, only about 8% of people with low-quality diets maintained high cognitive ability and only about 7% of people with high-quality diets maintained low cognitive ability compared to their peers.
Cognitive ability can have important impacts on quality of life and independence as we age. For example, at ages 68–70, participants in the highest cognitive group showed greater working memory retention, processing speed, and overall cognitive performance compared to those in the lowest cognitive group. Furthermore, nearly a quarter of participants in the lowest cognitive group showed signs of dementia at this point in their life, while none of those in the highest cognitive group showed signs of dementia.
Although most participants’ diet quality improved throughout adulthood, the researchers noted that small differences in diet quality in childhood seemed to set the tone for dietary patterns in later life, for better or worse. “This suggests that dietary intakes early in life may influence our dietary choices later in life, and the cumulative effects of diet over time are linked to the progression of our overall cognitive abilities,” Cara said.
“Dietary patterns rich in whole or less processed plant food groups, including green leafy vegetables, beans, fruits, and whole grains, may be the most protective.”
To assess diet quality, researchers used the 2020 Healthy Eating Index, which measures how closely a person’s diet matches the recommendations in the 2020–2025 Dietary Guidelines for Americans. Study participants who maintained higher cognitive skills over time compared to their peers tended to eat more of the recommended foods, such as vegetables, fruits, legumes, and whole grains, and less sodium, added sugars, and refined grains.
“Dietary patterns rich in whole or less processed plant food groups, including green leafy vegetables, beans, whole fruits, and whole grains, may be the most protective,” Cara said. “Adjusting dietary intake at any age to incorporate more of these foods and more closely align with current dietary recommendations is likely to improve our health in many ways, including our cognitive health.”
Since the study participants were predominantly Caucasian individuals from across the United Kingdom, the researchers said further research would be needed to determine whether the results can be transferred to populations with greater racial, ethnic and dietary diversity. They also noted that changes in study focus and protocols over the course of the long-running study created some gaps and inconsistencies in data collection. Despite these limitations, the researchers were able to create global cognitive ability percentile scores using data from multiple cognitive domains to assess how participants compared to their peers at each age and over time.
“Our results suggest that dietary patterns in midlife, before age 50, may be the most predictive of cognitive trends up to age 69. Future research should follow younger cohorts and plan earlier dietary interventions,” the authors conclude.
