When you read articles like this in Alzheimer’s disease journals, about how “Eating more berries may reduce cognitive decline in the elderly,” they’re talking about observational studies like this, where “berry intake appears to delay cognitive aging by up to 2.5 years” in the Harvard Nurses’ Health Study, or the “intake of nuts” appearing to delay brain aging by two years. They’re just talking about associations. Berry-eaters and nut-eaters tend to have better brain function as they age after trying to control for a bunch of other lifestyle factors, but you don’t know if it’s cause and effect…until you put it to the test. Thankfully, we now have a growing number of interventional studies that have done just that. Randomized, controlled trials where people eat berries or nuts and you can prove it—actually show improvements in cognitive performance, raising the berry nutty idea that we may be able to forestall or reverse the effects of neurodegeneration in aging with food.
For example, this study on the “effects of walnut consumption on cognitive performance.” College students split up into groups doing two months of walnuts, followed by two months of placebo or vice versa, and then they switch. How do you make a placebo nut? They baked it in. They gave people banana bread with or without nuts; same ingredients, just one with walnuts, and those on the nuts showed a significant improvement in “inference capacity,” the ability to accurately draw conclusions from a set of facts—in other words, critical thinking. And so, on a practical level, “maybe students or young professionals in…fields that involve a great deal of critical thinking or decision-making could possibly benefit and gain a slight advantage through regular consumption of walnuts.”
Or this berry study, where they randomized folks to some crazy berry smoothie with blueberries, black currants, elderberries, lingonberries, strawberries, and…a tomato. And not only did their bad cholesterol drop about 10 points, they “performed better” on short-term memory tests. So, good for heart, good for the brain. And not just better on like pencil-and-paper tests, but real-world applications. Give people Concord grape juice versus some
vegetables. “This reduction in blood flow to the brain [may be] a major risk factor for the impairment of cognitive function and development of neurodegenerative diseases, such as dementia.”
