Personalized nutrition for dementia prevention

Effects of APOE4 on omega-3 brain metabolism across the lifespan

Omega-3 (n-3) polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA), have important roles in human nutrition and brain health by promoting neuronal functions, maintaining inflammatory homeostasis, and providing structural integrity. As Alzheimer's disease (AD) pathology progresses, DHA metabolism in the brain becomes dysregulated, the timing and extent of which may be influenced by the apolipoprotein E ε4 (APOE4) allele. Here, we discuss how maintaining adequate DHA intake early in life may slow the progression to AD dementia in cognitively normal individuals with APOE4, how recent advances in DHA brain imaging could offer insights leading to more personalized preventive strategies, and how alternative strategies targeting PUFA metabolism pathways may be more effective in mitigating disease progression in patients with existing AD dementia.

Perspective: Promoting Healthy Aging through Nutrition: A Research Centers Collaborative Network Workshop Report

Within 20 y, the number of adults in the United States over the age of 65 y is expected to more than double and the number over age 85 y is expected to more than triple. The risk for most chronic diseases and disabilities increases with age, so this demographic shift carries significant implications for the individual, health care providers, and population health. Strategies that delay or prevent the onset of age-related diseases are becoming increasingly important. Although considerable progress has been made in understanding the contribution of nutrition to healthy aging, it has become increasingly apparent that much remains to be learned, especially because the aging process is highly variable. Most federal nutrition programs and nutrition research studies define all adults over age 65 y as "older" and do not account for physiological and metabolic changes that occur throughout older adulthood that influence nutritional needs. Moreover, the older adult population is becoming more racially and ethnically diverse, so cultural preferences and other social determinants of health need to be considered. The Research Centers Collaborative Network sponsored a 1.5-d multidisciplinary workshop that included sessions on dietary patterns in health and disease, timing and targeting interventions, and health disparities and the social context of diet and food choice. The agenda and presentations can be found at https://www.rccn-aging.org/nutrition-2023-rccn-workshop. Here we summarize the workshop's themes and discussions and highlight research gaps that if filled will considerably advance our understanding of the role of nutrition in healthy aging.

Can the gut microbiome inform the effects of omega-3 fatty acid supplementation trials on cognition?

PURPOSE OF REVIEW

Most omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation clinical trials report inconsistent or null findings on measures of cognition or Alzheimer's disease (AD) with a relatively large variability in the response to n-3 PUFA supplementation. The purpose of this review is to identify whether the gut microbiome together with the metabolome can provide critical insights to understand this heterogeneity in the response to n-3 PUFA supplementation.

RECENT FINDINGS

A Western diet with high saturated fat and omega-6 fatty acid content, obesity, and lack of exercise puts strain on the gut microbiome resulting in imbalance, dysbiosis, reduced bacterial diversity, and increased abundance of the pro-inflammatory taxa. A plant-based diet has beneficial effects on the gut microbiota even when deficient in n-3 PUFAs. Human and animal studies show that increased intake of the n-3 PUFAs correlates with increased beneficial intestinal bacteria when compared to a Western diet.

SUMMARY

The composition of the gut microbiota can help define the effects of n-3 PUFA supplementation on the brain and lead to more personalized nutritional interventions.

Role of Artificial Intelligence in Multinomial Decisions and Preventative Nutrition in Alzheimer's Disease

Alzheimer's disease (AD) affects 50 million people worldwide, an increase of 35 million since 2015, and it is known for memory loss and cognitive decline. Considering the morbidity associated with AD, it is important to explore lifestyle elements influencing the chances of developing AD, with special emphasis on nutritional aspects. This review will first discuss how dietary factors have an impact in AD development and the possible role of Artificial Intelligence (AI) and Machine Learning (ML) in preventative care of AD patients through nutrition. The Mediterranean-DASH diets provide individuals with many nutrient benefits which assists the prevention of neurodegeneration by having neuroprotective roles. Lack of micronutrients, protein-energy, and polyunsaturated fatty acids increase the chance of cognitive decline, loss of memory, and synaptic dysfunction among others. ML software has the ability to design models of algorithms from data introduced to present practical solutions that are accessible and easy to use. It can give predictions for a precise medicine approach to evaluate individuals as a whole. There is no doubt the future of nutritional science lies on customizing diets for individuals to reduce dementia risk factors, maintain overall health and brain function.

The gut-derived metabolites as mediators of the effect of healthy nutrition on the brain

Nutrition is now well recognized to be an environmental factor which positively or negatively influences the risk to develop neurological and psychiatric disorders. The gut microbiota has recently been shown to be an important actor mediating the relationship between environmental factors, including nutrition, and brain function. While its composition has been widely studied and associated with the risk of brain diseases, the mechanisms underlying the relationship between the gut and brain diseases remain to be explored. The wide range of bioactive molecules produced by the gut microbiota, called gut-derived metabolites (GDM), represent new players in the gut to brain interactions and become interesting target to promote brain health. The aim of this narrative review is to highlight some GDMs of interest that are produced in response to healthy food consumption and to summarize what is known about their potential effects on brain function. Overall, GDMs represent future useful biomarkers for the development of personalized nutrition. Indeed, their quantification after nutritional interventions is a useful tool to determine individuals' ability to produce microbiota-derived bioactive compounds upon consumption of specific food or nutrients. Moreover, GDMs represent also a new therapeutic approach to counteract the lack of response to conventional nutritional interventions.

The Effects of Methylfolate on Cognitive Decline and Dementia: A Protocol for Systematic Review and Meta-Analysis

INTRODUCTION

Dementia and cognitive decline are highly prevalent in later life and are growing public health concerns worldwide due to the increasing aging population. Individuals diagnosed with dementia have reduced mental function, resulting in social and cognitive skill deficits, increased dependence, and reduced autonomy-all of which are conditions associated with higher mortality rates. This systematic review aims to assess the effectiveness of treating dementia and cognitive decline with methylfolate. The main outcomes analyzed will be dementia and changes in cognitive function measured by different instruments in older adults treated with methylfolate. Secondary outcomes, such as inflammatory markers, plasma folic-acid levels, and total homocysteine, will also be assessed.

METHODS AND ANALYSIS

This study will be carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This protocol is registered in the International Prospective Registry of Systematic Reviews, under the code CRD42021275755. We will include clinical trials conducted with older adults diagnosed with dementia or cognitive decline and treated with folic acid. The searches will be conducted on the PubMed, Scopus, and Embase databases, and the articles will be selected by reading their titles and abstracts first, followed by the full text. The quality of the selected studies will be assessed using GRADE and the risk of bias will be assessed using the Downs-and-Black method.

ETHICS AND DISSEMINATION

The results will be presented at scientific conferences and disseminated by publishing a scientific article in an international English-language journal. We hope to find robust and significant evidence regarding the effectiveness of methylfolate supplementation in improving dementia symptoms and cognitive decline among older adults. By systematizing this evidence and possibly performing a meta-analysis study, we expect to significantly contribute to the treatment of this health problem, reduce mortality, and improve the quality of life and health of this population, boosting the development of medical protocols capable of reducing the financial effects of public health.

Metagenomic association analysis of cognitive impairment in community-dwelling older adults

The gut microbiota is reportedly involved in neurodegenerative disorders, and exploration of differences in the gut microbiota in different cognitive status could provide clues for early detection and intervention in cognitive impairment. Here, we used data from the Taizhou Imaging Study (N = 516), a community-based cohort, to compare the overall structure of the gut microbiota at the species level through metagenomic sequencing, and to explore associations with cognition. Interestingly, bacteria capable of producing short-chain fatty acids (SCFAs), such as Bacteroides massiliensis, Bifidobacterium pseudocatenulatum, Fusicatenibacter saccharivorans and Eggerthella lenta, that can biotransform polyphenols, were positively associated with better cognitive performance (p < 0.05). Although Diallister invisus and Streptococcus gordonii were not obviously related to cognition, the former was dominant in individuals with mild cognitive impairment (MCI), while the later was more abundant in cognitively normal (CN) than MCI groups, and positively associated with cognitive performance (p < 0.05). Functional analysis further supported a potential role of SCFAs and lactic acid in the association between the gut microbiota and cognition. The significant associations persisted after accounting for dietary patterns. Collectively, our results demonstrate an association between the gut microbiota and cognition in the general population, indicating a potential role in cognitive impairment. The findings provide clues for microbiome biomarkers of dementia, and insight for the prevention and treatment of dementia.

Nutritional metabolism and cerebral bioenergetics in Alzheimer's disease and related dementias

Disturbances in the brain's capacity to meet its energy demand increase the risk of synaptic loss, neurodegeneration, and cognitive decline. Nutritional and metabolic interventions that target metabolic pathways combined with diagnostics to identify deficits in cerebral bioenergetics may therefore offer novel therapeutic potential for Alzheimer's disease (AD) prevention and management. Many diet-derived natural bioactive components can govern cellular energy metabolism but their effects on brain aging are not clear. This review examines how nutritional metabolism can regulate brain bioenergetics and mitigate AD risk. We focus on leading mechanisms of cerebral bioenergetic breakdown in the aging brain at the cellular level, as well as the putative causes and consequences of disturbed bioenergetics, particularly at the blood-brain barrier with implications for nutrient brain delivery and nutritional interventions. Novel therapeutic nutrition approaches including diet patterns are provided, integrating studies of the gut microbiome, neuroimaging, and other biomarkers to guide future personalized nutritional interventions.

Uncovering mechanisms of brain inflammation in Alzheimer's disease with APOE4: Application of single cell-type lipidomics

A chronic state of unresolved inflammation in Alzheimer's disease (AD) is intrinsically involved with the remodeling of brain lipids. This review highlights the effect of carrying the apolipoprotein E ε4 allele (APOE4) on various brain cell types in promoting an unresolved inflammatory state. Among its pleotropic effects on brain lipids, we focus on APOE4's activation of Ca²⁺ -dependent phospholipase A2 (cPLA2) and its effects on arachidonic acid, eicosapentaenoic acid, and docosahexaenoic acid signaling cascades in the brain. During the process of neurodegeneration, various brain cell types, such as astrocytes, microglia, and neurons, together with the neurovascular unit, develop distinct inflammatory phenotypes that impact their functions and have characteristic lipidomic fingerprints. We propose that lipidomic phenotyping of single cell-types harvested from brains differing by age, sex, disease severity stage, and dietary and genetic backgrounds can be employed to probe mechanisms of neurodegeneration. A better understanding of the brain cellular inflammatory/lipidomic response promises to guide the development of nutritional and drug interventions for AD dementia.

Capacity Strengthening Undertaking-Farm Organized Response of Workers against Risk for Diabetes: (C.S.U.-F.O.R.W.A.R.D. with Cal Poly)-A Concept Approach to Tackling Diabetes in Vulnerable and Underserved Farmworkers in California

In our project herein, we use the case of farmworkers, an underserved and understudied population at high risk for Type-2 Diabetes Mellitus (T2DM), as a paradigm of an integrated action-oriented research, education and extension approach involving the development of long-term equitable strategies providing empowerment and tailored-made solutions that support practical decision-making aiming to reduce risk of T2DM and ensuing cardiovascular disease (CVD). A Technology-based Empowerment Didactic module (TEDm) and an Informed Decision-Making enhancer (IDMe) coupled in a smart application (app) for farmworkers aiming to teach, set goals, monitor, and support in terms of nutrition, hydration, physical activity, sleep, and circadian rhythm towards lowering T2DM risk, is to be developed and implemented considering the particular characteristics of the population and setting. In parallel, anthropometric, biochemical, and clinical assessments will be utilized to monitor risk parameters for T2DM and compliance to dietary and wellness plans. The app incorporating anthropometric/clinical/biochemical parameters, dietary/lifestyle behavior, and extent of goal achievement can be continuously refined and improved through machine learning and re-programming. The app can function as a programmable tool constantly learning, adapting, and tailoring its services to user needs helping optimization of practical informed decision-making towards mitigating disease symptoms and associated risk factors. This work can benefit apart from the direct beneficiaries being farmworkers, the stakeholders who will be gaining a healthier, more vibrant workforce, and in turn the local communities.

Structured Long-Chain Omega-3 Fatty Acids for Improvement of Cognitive Function during Aging

Although the human lifespan has increased in the past century owing to advances in medicine and lifestyle, the human healthspan has not kept up the same pace, especially in brain aging. Consequently, the role of preventive health interventions has become a crucial strategy, in particular, the identification of nutritional compounds that could alleviate the deleterious effects of aging. Among nutrients to cope with aging in special cognitive decline, the long-chain omega-3 polyunsaturated fatty acids (ω-3 LCPUFAs) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have emerged as very promising ones. Due to their neuroinflammatory resolving effects, an increased status of DHA and EPA in the elderly has been linked to better cognitive function and a lower risk of dementia. However, the results from clinical studies do not show consistent evidence and intake recommendations for old adults are lacking. Recently, supplementation with structured forms of EPA and DHA, which can be derived natural forms or targeted structures, have proven enhanced bioavailability and powerful benefits. This review summarizes present and future perspectives of new structures of ω-3 LCPUFAs and the role of "omic" technologies combined with the use of high-throughput in vivo models to shed light on the relationships and underlying mechanisms between ω-3 LCPUFAs and healthy aging.

Dietary factors and brain health

PURPOSE OF REVIEW

Nutrition is a complex exposure (i.e., the food exposome) that influences brain function and health through multiple pathways. We review recent epidemiological studies that have improved the characterization of the food exposome and brain health in humans and have revealed promising nutrition-based strategies to prevent cognitive aging.

RECENT FINDINGS

A selection of epidemiological research from the past 18 months of both observational and clinical studies is presented, with a focus on novel findings, including novel nutrient and diet patterns, diet-related approaches to rescue brain energetics defects in aging, and biomarker-based studies to decipher specific neurobiological pathways of nutrition and brain health.

SUMMARY

Although healthy diets such as the Mediterranean diet promote brain health throughout life, specific diets, such as the Mediterranean-Dietary Approaches to Stop Hypertension Intervention for Neurodegenerative Delay diet, or specific nutrients (LC n-3 polyunsaturated fatty acids, carotenoids, vitamin D, B vitamins, polyphenols) alone or in combination, may prevent cognitive aging. Diet management approaches to rescue brain energetics defects such as the Modified Mediterranean-ketogenic diet may be promising to prevent neurodegenerative diseases. Expanding research also suggests that promotion of a healthy gut microbiome through prebiotic foods may preserve the diet-gut-brain axis with aging. Future studies should explore more individualized preventive approaches through a 'precision nutrition' framework.