Summary: Greater adherence to a Mediterranean-style diet was associated with the lowest risk of cognitive impairment in two large eye-disease cohorts. Higher consumption of fish and vegetables showed the strongest protective association with cognitive decline.
Source: NIH/NEI
Researchers at the National Eye Institute (NEI), part of the National Institutes of Health, analyzed data from two major clinical studies—AREDS and AREDS2—and found that closer adherence to a Mediterranean dietary pattern correlates with better cognitive performance. The Mediterranean-style eating pattern evaluated emphasizes vegetables, whole fruits, whole grains, nuts, legumes, fish, and olive oil, while minimizing red meat and alcohol. The full study appears in the journal Alzheimer’s and Dementia.
“We often overlook how everyday diet influences both brain and eye health,” said Emily Chew, M.D., director of the NEI Division of Epidemiology and Clinical Applications and lead author. “These findings strengthen the case for considering nutrition as a factor in maintaining cognitive function with age.”
The analysis examined nine components of the Mediterranean diet, scoring participants on how closely their typical intake aligned with that pattern. Diet was assessed once at study baseline using a food-frequency questionnaire asking about average consumption during the previous year. Cognitive function was measured with standardized tools, including tests based on the Modified Mini-Mental State Examination and other validated assessments.
AREDS and AREDS2 were originally designed to study the effects of nutritional supplements on age-related macular degeneration (AMD). AREDS enrolled roughly 4,000 participants both with and without AMD, while AREDS2 enrolled about 4,000 participants who had AMD. Cognitive testing occurred at different times across the two studies: AREDS administered cognitive tests at year five, and AREDS2 assessed cognition at baseline and again at two, four, and 10 years. Together, the cohorts provided longitudinal data on diet and cognitive trajectories in a combined sample of 7,756 participants.
Overall, participants in the highest adherence group to the Mediterranean diet had the lowest odds of cognitive impairment compared with those in the lowest adherence group. Among the diet components, higher intake of fish and vegetables showed the most consistent associations with better cognitive performance. In AREDS2, participants reporting the highest fish consumption experienced the slowest rate of cognitive decline over the 10-year follow-up period.
Although the measured differences in test scores between the extreme diet-adherence groups were modest and unlikely to translate into noticeable changes in everyday function for any single individual, the authors emphasize that these small effects become meaningful across large populations. The pattern of results supports the conclusion that diet is one modifiable factor contributing to neural health and cognitive aging.
The team also evaluated the influence of genetic risk for Alzheimer’s disease. Participants carrying the apolipoprotein E (ApoE) risk haplotype tended to have lower cognitive scores and greater decline compared with noncarriers. Importantly, the cognitive benefits associated with close adherence to a Mediterranean diet were observed in both ApoE carriers and noncarriers, indicating that dietary effects on cognition operate independently of this genetic risk factor.
Funding: The AREDS and AREDS2 trials were supported by the NEI Intramural Research Program and by contracts NOI-EY-0-2127 (AREDS), HHS-N-260-2005-00007-C (AREDS2), and N01-EY-5-0007 (AREDS2). Additional support came from the NIH Office of Dietary Supplements, the National Center for Complementary and Integrative Health, the National Institute on Aging, the National Heart, Lung, and Blood Institute, and the National Institute of Neurological Disorders and Stroke. AREDS is registered under identifier NCT00594672 and AREDS2 under NCT00345176. The clinical work was conducted at the NIH Clinical Center.
About this neuroscience research article
Source:
NIH/NEI
Media contacts:
Lesley Earl – NIH/NEI
Image source:
The image is in the public domain.
Original research:
“Adherence to a Mediterranean diet and cognitive function in the Age-Related Eye Disease Studies 1 & 2” by Keenan TD, Agron E, Mares J, Clemons TE, van Asten F, Swaroop A, and Chew E, for the AREDS and AREDS2 research groups. Published in Alzheimer’s and Dementia. DOI: 10.1016/j.diabres.2020.108125. This open-access report presents the observational analysis and primary findings described above.
Abstract
Adherence to a Mediterranean diet and cognitive function in the Age-Related Eye Disease Studies 1 & 2
Introduction
The study investigated whether closer adherence to an alternative Mediterranean diet (aMED) is associated with differences in cognitive function among older adults enrolled in nutritional trials for age-related macular degeneration.
Methods
Observational analyses included 7,756 participants drawn from two randomized trials of nutritional supplements for AMD: AREDS and AREDS2.
Results
Higher aMED adherence was associated with lower odds of cognitive impairment. In AREDS, the odds ratio for cognitive impairment comparing highest versus lowest aMED tertile was 0.36 (P = .0001) on the Modified Mini-Mental State measure and 0.56 (P = .001) for a composite score. In AREDS2, odds ratios were 0.56 for the Telephone Interview for Cognitive Status–Modified and 0.48 for the composite score (each P < .0001). Fish intake correlated with higher cognitive scores, and in AREDS2 higher fish consumption was associated with a significantly slower rate of decline over the 5–10 year period (P = .019). Overall, closer Mediterranean diet adherence related to lower risk of impairment, though not consistently to slower decline across all measures. ApoE genotype did not alter these relationships.
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