Dietary Patterns and Alzheimer's Disease: An Updated Review Linking Nutrition to Neuroscience

Abstract

Alzheimer's disease (AD) is a growing concern for the aging population worldwide. With no current cure or reliable treatments available for AD, prevention is an important and growing area of research. A range of lifestyle and dietary patterns have been studied to identify the most effective preventive lifestyle changes against AD and related dementia (ADRD) pathology. Of these, the most studied dietary patterns are the Mediterranean, DASH, MIND, ketogenic, and modified Mediterranean-ketogenic diets. However, there are discrepancies in the reported benefits among studies examining these dietary patterns. We herein compile a narrative/literature review of existing clinical evidence on the association of these patterns with ADRD symptomology and contemplate their preventive/ameliorative effects on ADRD neuropathology in various clinical milieus. By and large, plant-based dietary patterns have been found to be relatively consistently and positively correlated with preventing and reducing the odds of ADRD. These impacts stem not only from the direct impact of specific dietary components within these patterns on the brain but also from indirect effects through decreasing the deleterious effects of ADRD risk factors, such as diabetes, obesity, and cardiovascular diseases. Importantly, other psychosocial factors influence dietary intake, such as the social connection, which may directly influence diet and lifestyle, thereby also impacting ADRD risk. To this end, prospective research on ADRD should include a holistic approach, including psychosocial considerations.

Keywords: Alzheimer’s disease; Mediterranean diet; aging; brain health; cognitive impairment; dementia; diet; neurodegenerative disorders; neuroscience.

Figure 2

Hypothesized direct and indirect impacts of dietary patterns on ADRD [12,46,47,48,49,50,51,52,53,54,55,56,85,86,93,99,100,101,102,103]. BDNF: Brain-Derived Neurotrophic Factor; NMDR: N-methyl-D-aspartate receptor; CNS: central neural system; SCFAs: short-chain fatty acids; HPA: hypothalamic–pituitary–adrenal; ↑ higher; ↓ lower.

Figure 1

Preventive and ameliorative effects of dietary patterns against ADRD. Long-term adherence to prudent dietary patterns (left-side panel), in conjunction with a healthy lifestyle, may prevent ADRD via antioxidant/anti-inflammatory mechanisms and positive microbiome modulation, which are associated with lower predisposition to aging-associated neuroinflammation and insulin resistance, leading to improved lifestyle, cognitive abilities, and overall quality of life. Specific dietary patterns (right-side panel) may also ameliorate ADRD via different mechanisms, such as antioxidant/anti-inflammatory/microbiome-modulatory, attributed to specific macro- and micronutrients in these dietary patterns. ADRD: Alzheimer’s disease and related dementias; DASH: Dietary Approaches to Stop Hypertension dietary pattern; MIND: Mediterranean-DASH Intervention for Neurodegenerative Delay dietary patterns; ↑ higher; ↓ lower.