Analysis of 2 major studies points to a diet that can preserve cognitive function

Everyone ages but the negative changes that come with getting older are not necessarily inevitable. What diet you choose to follow can mitigate forgetfulness, disrupted thought processing, and memory loss, suggests a new study.

The Mediterranean diet has an especially powerful effect on the mind, according to an evaluation of 7,758 people. This analysis adds to a growing list of studies linking the Mediterranean diet to positive outcomes.

Researchers found that people who ate a Mediterranean diet had higher cognitive function and less risk of cognitive impairment.

While eating Mediterranean had no meaningful effect on the rate of cognitive decline, the team did find a link between eating fish more than twice a week and slower cognitive decline. Fish is a hallmark of the Mediterranean diet, alongside vegetables, whole grains, and olive oil.

“You really are what you eat,” lead author Emily Chew, director of the National Eye Institute and lead author of the studies, tells Inverse.

These results were published Tuesday in the journal Alzheimer's and Dementia.

Currently, strategies that can improve the symptoms of dementia are limited. There are no treatments that prevent, delay or modify the course of the disease. It is a leading cause of disability in older people, with rates "soaring" across the United States.

"Dementia is increasing and the epidemic of it is unbelievable," Chew says.

Determining an effective preventive strategy that can alter the trajectory of cognitive decline is desperately needed and would be "particularly fruitful" for this population, Chew says.

To explore if the Mediterranean diet is a worthwhile approach, Chew and her colleagues examined data previously collected by two massive clinical trials called AREDS and AREDS2. Both trials examined nutritional supplements as a potential treatment for age-related macular degeneration, a progressive eye disease causing blurred vision and vision loss, and reported their findings in 1999 and 2012.

These studies included information about the participants' diet and assessed their cognitive function periodically over five and ten year periods, respectively. The researchers also asked participants to report how often they consumed nine components of the Mediterranean diet: fish, nuts, olive oil, legumes, fruit, vegetables, whole grains, red meat, and alcohol.

The studies also looked at cognitive function. The AREDS study tested participants' cognitive function at five years, while AREDS2 tested cognitive function in participants at baseline and again two, four, and 10 years later.

Chew's new evaluation shows that participants who stuck closest to the Mediterranean diet had the lowest risk of cognitive impairment. Eating lots of fish and vegetables appeared to have the greatest protective effect.

At 10 years, participants with the highest fish consumption had the slowest rate of cognitive decline.

Even people with the APOE gene, a genetic risk factor for dementia and Alzheimer's disease, showed higher cognitive function and lower risk of cognitive impairment on the Mediterranean diet.

Why is the Mediterranean diet good for you?

This diet's positive effects aren't just because people skipped the potato chips and candy bars. It's the abundance of nutrient-rich foods like vegetables and fish that's important, Chew explains.

Luckily, achieving some of these potential brain benefits doesn't require a total diet overhaul. Radically changing what one eats is a complicated task, shaped by economic factors and social pressures, Chew points out. Instead of a total overhaul, she suggests making small changes — like eating more leafy greens and fish — that can add up over time.

"If we can just convince people to eat a can of tuna once or twice a week, it's going be pretty good," Chew says.

The new studies, however large, are also observational, so more work is needed to definitively link this diet to cognitive preservation. Some of the studies' participants were dealing with age-related macular degeneration — a factor that may have affected the results.

Still, Chew describes this finding as "compelling" and says it jibes with other, randomized controlled studies that evaluated the diet. Controlled studies are important in order to give solid recommendations around what and how to eat to promote brain health, Chew explains.

"Meanwhile, it won't hurt you to do this," Chew says. "In fact, it may benefit you."

LONGEVITY HACKS is a regular series from Inverse on the science-backed strategies to live better, healthier, and longer without medicine.

HOW THIS AFFECTS LONGEVITY — This research shows maintaining a Mediterranean diet may keep the brain healthy as you age. In the study, people who ate Mediterranean had higher cognitive function and less risk of cognitive impairment. The study also linked eating fish more than two times per week to slower cognitive decline.

WHY IT’S A HACK — Currently, strategies to improve the symptoms of dementia are limited. Determining an effective preventive strategy that can alter the trajectory of cognitive decline is desperately needed, and the study points to the Mediterranean diet as a possibility.

SCIENCE IN ACTION —This research doesn’t mean a total diet overhaul — swapping a few servings of fish or leafy greens for processed or sugary foods is a good idea, the researchers say.

HACK SCORE OUT OF 10 — 🐟🐟🐟🐟🐟🐟🐟🐟(8/10 foods rich in omega-3s)

Abstract:

Introduction: The objective was to determine whether closer adherence to the alternative Mediterranean Diet (aMED) was associated with altered cognitive function. Methods: Observational analyses of participants (n = 7,756) enrolled in two ran- domized trials of nutritional supplements for age-related macular degeneration: Age- Related Eye Disease Study (AREDS) and AREDS2.

Results: Odds ratios for cognitive impairment, in aMED tertile 3 (vs 1), were 0.36 (P = .0001) for Modified Mini-Mental State (<80) and 0.56 (P = .001) for composite score in AREDS, and 0.56 for Telephone Interview Cognitive Status-Modified (<30) and 0.48 for composite score (each P < .0001) in AREDS2. Fish intake was associated with higher cognitive function. In AREDS2, rate of cognitive decline over 5 to 10 years was not significantly different by aMED but was significantly slower (P = .019) with higher fish intake.

Discussion: Closer Mediterranean diet adherence was associated with lower risk of cognitive impairment but not slower decline in cognitive function. Apolipoprotein E (APOE) haplotype did not influence these relationships.