Can lifestyle modifications delay or prevent Alzheimer’s disease?

Kirtan Kriya is a meditation technique that is easy to learn and practice by older adults and can improve memory in patients at risk for developing AD.³⁷ However, more rigorous RCTs conducted in larger samples of older adults are needed to better evaluate the effect of all meditation techniques for delaying or preventing AD (level IB with respect to improvement in cognitive functioning/level III for AD delay/risk reduction).³⁸

Spiritual activities, such as going to places of worship or religious meditation, have been associated with a lower prevalence of AD. Attending religious services, gatherings, or retreats involves a social component because these activities often are practiced in groups. They also confer a method of dealing with psychological distress and depression. Additionally, frequent readings of religious texts represents a mentally stimulating activity that may also contribute to delaying/preventing AD (level III).³⁹

Diet

In the past decade, a growing body of evidence has linked diet to cognition. Individuals with a higher intake of calories and fat are at higher risk for developing AD.⁴⁰ The incidence of AD rose in Japan after the country transitioned to a more Westernized diet.⁴¹ A modern Western diet rich in saturated fatty acids and simple carbohydrates may negatively impact hippocampus-mediated functions such as memory and learning, and is associated with an increased risk of AD.⁴² In contrast with high-glycemic and fatty diets, a “healthy diet” is associated with a decrease in beta-amyloid burden, inflammation, and oxidative stress.^43,44

Studies focusing on dietary patterns rather than a single nutrient for delaying or preventing AD have yielded more robust and consistent results.⁴⁵ In a recent meta-analysis, adhering to a Mediterranean diet—which is rich in fruits and vegetables, whole grains, olive oil, and fish; moderate in some dairy products and wine; and low in red meat—was associated with a decreased risk of AD; this evidence was derived mostly from epidemiologic studies.⁴⁶ Scarmeas et al⁸ found that high adherence to the Mediterranean diet was associated with 32% to 40% reduced risk of AD. Combining this diet with physical exercise was associated with an up to 67% reduced risk (level III). The Dietary Approaches to Stop Hypertension (DASH) diet, which is rich in total grains, fruits, vegetables, and dairy products, but low in sodium and sweets, correlated with neuro­cognitive improvement in patients with hypertension.⁴⁷ Both the Mediterranean and DASH diets have been associated with better cognitive function⁴⁸ and slower cognitive decline.⁴⁹ Thus, an attempt to combine the neuroprotective components from both diets led to the creation of the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) diet, which also has been associated with a lower incidence of AD.⁵⁰

Besides specific diets, some food groups have also been found to promote brain health and may help delay or prevent AD. Berries have the highest amount of antioxidants of all fruit. Among vegetables, tomatoes and green leafy vegetables have the highest amount of nutrients for the brain. Nuts, such as walnuts, which are rich in omega-3 fatty acids, are also considered “power foods” for the brain; however, they should be consumed in moderation because they are also rich in fat. Monounsaturated fatty acids, which are found in olives and olive oil, are also beneficial for the brain. Among the 3 types of omega-3 fatty acids, the most important for cognition is docosahexaenoic acid (DHA) because it constitutes 40% of all fatty acids in the brain. Mainly found in oily fish, DHA has antioxidant and anti-inflammatory properties that may delay or prevent AD. Low levels of DHA have been found in patients with AD.⁵¹

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