The Role of Nutrition in Cognitive Function and Brain Ageing in the Elderly

The Relationship between Diet, Depression, and Alzheimer's Disease: A Narrative Review

PURPOSE OF REVIEW

This narrative review evaluates the role of diet in the relationship between depression and Alzheimer's disease (AD).

RECENT FINDINGS

AD and depression are often comorbid, and depression appears to independently increase the future risk of AD. Evidence suggests diet influences the risk of both conditions directly and indirectly. Diet impacts neurochemical and biological processes that may affect the development and progression of depression and cognitive dysfunction. The dietary components offering the greatest protection against depression and AD are yet to be determined. Current evidence highlights the importance of polyphenolic compounds, folate, B vitamins, and polyunsaturated fatty acids, along with adherence to dietary patterns like the Mediterranean diet, which includes multiple beneficial dietary factors.

SUMMARY

The investigation of dietary factors in the prevention of depression and AD is a comparatively young field of research. Comprehensive highly characterised longitudinal datasets and advanced analytical approaches are required to further examine the complex relationship between diet, depression, and AD. There is a critical need for more research in this area to develop effective preventive strategies aimed at maintaining mental and physical health with advancing age.

Underlying Mechanisms of the Protective Effects of Lifestyle Factors On Age-Related Diseases

The rise in life expectancy has significantly increased the occurrence of age-related chronic diseases, leading to escalating expenses for both society and individuals. Among the main factors influencing health and lifespan, lifestyle takes a forefront position. Specifically, nutrition, mental activity, and physical exercise influence the molecular and functional mechanisms that contribute to the prevention of major age-related diseases. Gaining deeper insights into the mechanisms that drive the positive effects of healthy lifestyles is valuable for creating interventions to prevent or postpone the development of chronic degenerative diseases. This review summarizes the main mechanisms that underlie the positive effect of lifestyle factors in counteracting the major age-related diseases involving brain health, musculoskeletal function, cancer, frailty, and cardiovascular diseases, among others. This knowledge will help to identify high-risk populations for targeted intervention trials and discover new biomarkers associated with healthy aging.

The impact of sustainable diets οn cognitive function in an ageing society: A mini-review

The increasing number of older people raises important health concerns because, in part, of the associated cognitive and functional impairment. The United Nations is taking action with its Decade of Healthy Ageing (2021-2030) campaign, by promoting Sustainable Development Goals and shifting our focus towards more sustainable diets. In this mini-review, sustainable dietary patterns are evaluated, with a focus on healthy plant-based diets, the Mediterranean diet, the Dietary Approaches to Stop Hypertension (DASH) diet, and the Mediterranean-DASH Intervention for Neurodegenerative Delay diet. The review analyzes and describes whether older people's cognitive performance can benefit from the adoption of these sustainable diets. The results of primary studies indicate that the Mediterranean diet and healthy plant-based diets can prevent cognitive impairment by improving cognitive function, language and memory. Plant-based dietary patterns with incorporated Mediterranean foods (high consumption of fruit, vegetables, and fish) are associated with delayed cognitive ageing. Additionally, adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay diet is associated with improved cognitive resilience and lower risk of dementia after 16 years of follow-up. Although consumption of red meat and elevated body mass index are both associated with cognitive dysfunction, some studies have had contradictory findings. Concerns exist regarding the development of chronic diseases, cognitive and functional impairment, as well as disability as age advances. Thus, the policies of the United Nations should ensure healthy ageing for all older individuals. Nonetheless, more research is required to evaluate older people's willingness and readiness to adopt a more sustainable way of eating.

Impact of micronutrients and nutraceuticals on cognitive function and performance in Alzheimer's disease

Alzheimer's disease (AD) is a major global health problem today and is the most common form of dementia. AD is characterized by the formation of β-amyloid (Aβ) plaques and neurofibrillary clusters, leading to decreased brain acetylcholine levels in the brain. Another mechanism underlying the pathogenesis of AD is the abnormal phosphorylation of tau protein that accumulates at the level of neurofibrillary aggregates, and the areas most affected by this pathological process are usually the cholinergic neurons in cortical, subcortical, and hippocampal areas. These effects result in decreased cognitive function, brain atrophy, and neuronal death. Malnutrition and weight loss are the most frequent manifestations of AD, and these are also associated with greater cognitive decline. Several studies have confirmed that a balanced low-calorie diet and proper nutritional intake may be considered important factors in counteracting or slowing the progression of AD, whereas a high-fat or hypercholesterolemic diet predisposes to an increased risk of developing AD. Especially, fruits, vegetables, antioxidants, vitamins, polyunsaturated fatty acids, and micronutrients supplementation exert positive effects on aging-related changes in the brain due to their antioxidant, anti-inflammatory, and radical scavenging properties. The purpose of this review is to summarize some possible nutritional factors that may contribute to the progression or prevention of AD, understand the role that nutrition plays in the formation of Aβ plaques typical of this neurodegenerative disease, to identify some potential therapeutic strategies that may involve some natural compounds, in delaying the progression of the disease.

Nutritional Status and Physical Exercise Are Associated with Cognitive Function in Chinese Community-Dwelling Older Adults: The Role of Happiness

We aim to assess the relationship between nutrition status, physical exercise, and cognitive function and particularly examine how happiness modifies and mediates the relationship, among 699 seniors aged 60 and above in Shanghai, China. Linear regression models were used to validate the effects of nutrition and exercise on cognitive function and to test their interaction effects with happiness. When the interactions were significant, stratified analyses in sub-groups were conducted. Mediation effects of happiness were examined using two-step causal mediation models. We confirmed that better nutrition (p < 0.001) and exercise (p = 0.009) were significantly associated with less cognitive decline. Furthermore, the effects of nutrition and exercise on cognitive decline were significant in the unhappy (happiness < 20) (p < 0.001) and younger (age < 74) sub-groups (p = 0.015). Happiness partially mediated 11.5% of the negative association of cognitive decline with nutrition (p = 0.015) and 23.0% of that with exercise (p = 0.017). This study suggests that happiness moderates and partially mediates the effects of exercise and nutrition on cognitive status. The beneficial effects of exercise and nutrition were stronger in less happy or younger seniors. Future intervention studies are required to confirm this path relationship.

Impact of Nutritional Interventions on Alzheimer's Disease: A Systematic Review and Meta-Analysis

The most prevalent type of dementia, especially in older persons, is Alzheimer's disease (AD), which has clinical signs of progressive cognitive decline and functional impairment. However, new research indicates that AD patients' dietary patterns and nutritional intake could hold the key to staving off some of the complications. Therefore, the primary aim of this investigation was to analyze various dietary patterns and the subsequent impact of the resulting nutritional intake on AD patients. Various online databases (PubMed, Scopus, Web of Science, and Google Scholar) were searched using appropriate keywords, reference searches, and citation searches. The databases were accessed using the search phrases "Alzheimer's disease," "dietary habits," "minerals," "nutritional profile," and "vitamins." Fifteen of the 21 investigations that we selected for our systematic review and subsequent meta-analysis revealed that micronutrient supplementation and some dietary patterns were helpful in alleviating a few of the symptoms of AD, especially with regard to the progression of dementia in the assessed patients. It was shown that dietary interventions and nutritional adjustments can considerably delay the onset of AD and the varying degrees of dementia that often accompany it. However, there were some areas of ambiguity in our findings because a few of the chosen studies did not document any noticeable improvements in the patient's conditions.

Benefits of Wasabi Supplements with 6-MSITC (6-Methylsulfinyl Hexyl Isothiocyanate) on Memory Functioning in Healthy Adults Aged 60 Years and Older: Evidence from a Double-Blinded Randomized Controlled Trial

BACKGROUND

Cognitive functions decline with age. Declined cognitive functions negatively affect daily behaviors. Previous studies showed the positive effect of spices and herbs on cognition. In this study, we investigated the positive impact of wasabi, which is a traditional Japanese spice, on cognitive functions. The main bioactive compound of wasabi is 6-MSITC (6 methylsulfinyl hexyl isothiocyanate), which has anti-oxidant and anti-inflammatory functions. Anti-oxidants and anti-inflammatories have an important role in cognitive health. Therefore, 6-MSITC is expected to have positive effects on cognitive function. Previous studies showed the beneficial effects on cognitive functions in middle-aged adults. However, it is unclear that 6-MSITC has a positive effect on cognitive functions in healthy older adults aged 60 years and over. Here, we investigated whether 12 weeks' 6-MSITC intervention enhances cognitive performance in older adults using a double-blinded randomized controlled trial (RCT).

METHODS

Seventy-two older adults were randomly assigned to 6-MSITC or placebo groups. Participants were asked to take a supplement (6-MSITC or a placebo) for 12 weeks. We checked a wide range of cognitive performances (e.g., executive function, episodic memory, processing speed, working memory, and attention) at the pre- and post-intervention periods.

RESULTS

The 6-MSITC group showed a significant improvement in working and episodic memory performances compared to the placebo group. However, we did not find any significant improvements in other cognitive domains.

DISCUSSION

This study firstly demonstrates scientific evidence that 6-MSITC may enhance working memory and episodic memory in older adults. We discuss the potential mechanism for improving cognitive functions after 6-MSITC intake.

Association between nutrition and cognition in a multi-ethnic cohort from Singapore

BACKGROUND

Nutrition, a modifiable risk factor, presents a low-cost prevention strategy to reduce the burden of cognitive impairment and dementia. However, studies examining the effects of dietary patterns on cognition are lacking in multi-ethnic Asian populations. We investigate the association between diet quality, measured with the Alternative Healthy Eating Index (AHEI)-2010, and cognitive impairment in middle-aged and older adults of different ethnicities (Chinese, Malay, Indian) in Singapore.

METHODS

This cross-sectional study (n = 3138; mean age: 50.4 ± 9.8, 58.4% women) was based on data from the Singapore Multi-Ethnic Cohort. Dietary intake collected with a validated semi-quantitative Food Frequency Questionnaire was converted into AHEI-2010 scores. Cognition, assessed with the Mini-Mental State Examination (MMSE), was analysed as a continuous or binary outcome (cognitively impaired or not, using cut-offs of ≥ 24, 26 or 28 for no education, primary school education and secondary school education and above). Multivariable linear and logistic regression models were used to examine associations between AHEI-2010 and cognition, adjusting for covariates.

RESULTS

A total of 988 (31.5%) participants had cognitive impairment. Higher AHEI-2010 scores were significantly associated with higher MMSE scores [β = 0.44; 95% confidence interval (CI) 0.22-0.67 highest vs. lowest quartile; p-trend < 0.001] and lower odds of cognitive impairment [OR 0.69; 95% CI 0.54-0.88; p-trend = 0.01] after adjusting for all the covariates. No significant associations were observed for individual dietary components of the AHEI-2010 with MMSE or cognitive impairment.

CONCLUSION

Healthier dietary patterns were associated with better cognitive function in middle-aged and older Singaporeans. These findings could inform better support to promote healthier dietary patterns in Asian populations.

Association between choline supplementation and Alzheimer's disease risk: a systematic review protocol

Background and aims

There is growing evidence suggesting choline intake might have beneficial effects on cognitive function in the elderly. However, some studies report no relationship between choline intake and cognitive function or improvement in Alzheimer's disease patients. This protocol is for a systematic review of choline intake and Alzheimer's disease that aims to assess the comparative clinical effectiveness of choline supplementation on Alzheimer's disease risk.

Methods and analysis

literature search will be performed in PubMed, MEDLINE, EMBASE, CINAHL, Scopus, Cochrane, and the Web of Science electronic databases from inception until October 2023. We will follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Studies will be included if they compared two different time points of choline biomarkers measures in men or women (65+) with Alzheimer's Disease. The risk of bias in the included studies will be assessed within the Covidence data-management software.

Results

This review will summarize the clinical trial and quasi-experimental evidence of choline intake on Alzheimer's disease risk for adults aged 65+. The results from all eligible studies included in the analysis will be presented in tables, text, and figures. A descriptive synthesis will present the characteristics of included studies (e.g., age, sex of participants, type, length of intervention and comparator, and outcome measures), critical appraisal results, and descriptions of the main findings.

Discussion

This systematic review will summarize the existing evidence on the association between Choline intake and AD and to make recommendations if appropriate. The results of this review will be considered with respect to whether there is enough evidence of benefit to merit a more definitive randomized controlled trial. The results will be disseminated through peer-reviewed journals population.

Conclusion

This protocol outlines the methodology for a systematic review of choline intake and AD. The resulting systematic review from this protocol will form an evidence-based foundation to advance nutrition care for individuals with AD or poor cognitive function.

Systematic review registration

http://www.crd.york.ac.uk/PROSPERO, identifier CRD42023395004.

The effect of weight loss following 18 months of lifestyle intervention on brain age assessed with resting-state functional connectivity

Background

Obesity negatively impacts multiple bodily systems, including the central nervous system. Retrospective studies that estimated chronological age from neuroimaging have found accelerated brain aging in obesity, but it is unclear how this estimation would be affected by weight loss following a lifestyle intervention.

Methods

In a sub-study of 102 participants of the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT-PLUS) trial, we tested the effect of weight loss following 18 months of lifestyle intervention on predicted brain age based on magnetic resonance imaging (MRI)-assessed resting-state functional connectivity (RSFC). We further examined how dynamics in multiple health factors, including anthropometric measurements, blood biomarkers, and fat deposition, can account for changes in brain age.

Results

To establish our method, we first demonstrated that our model could successfully predict chronological age from RSFC in three cohorts (n=291;358;102). We then found that among the DIRECT-PLUS participants, 1% of body weight loss resulted in an 8.9 months' attenuation of brain age. Attenuation of brain age was significantly associated with improved liver biomarkers, decreased liver fat, and visceral and deep subcutaneous adipose tissues after 18 months of intervention. Finally, we showed that lower consumption of processed food, sweets and beverages were associated with attenuated brain age.

Conclusions

Successful weight loss following lifestyle intervention might have a beneficial effect on the trajectory of brain aging.

Funding

The German Research Foundation (DFG), German Research Foundation - project number 209933838 - SFB 1052; B11, Israel Ministry of Health grant 87472511 (to I Shai); Israel Ministry of Science and Technology grant 3-13604 (to I Shai); and the California Walnuts Commission 09933838 SFB 105 (to I Shai).

Characterizing Canadian long-term care home consumed foods and their inflammatory potential: a secondary analysis

BACKGROUND

Nutrient dense food that supports health is a goal of food service in long-term care (LTC). The objective of this work was to characterize the "healthfulness" of foods in Canadian LTC and inflammatory potential of the LTC diet and how this varied by key covariates. Here, we define foods to have higher "healthfulness" if the are in accordance with the evidence-based 2019 Canada's Food Guide, or with comparatively lower inflammatory potential.

METHODS

We conducted a secondary analysis of the Making the Most of Mealtimes dataset (32 LTC homes; four provinces). A novel computational algorithm categorized food items from 3-day weighed food records into 68 expert-informed categories and Canada's Food Guide (CFG) food groups. The dietary inflammatory potential of these food sources was assessed using the Dietary Inflammatory Index (DII). Comparisons were made by sex, diet texture, and nutritional status.

RESULTS

Consumption patterns using expert-informed categories indicated no single protein or vegetable source was among the top 5 most commonly consumed foods. In terms of CFG's groups, protein food sources (i.e., foods with a high protein content) represented the highest proportion of daily calorie intake (33.4%; animal-based: 31.6%, plant-based: 1.8%), followed by other foods (31.3%) including juice (9.8%), grains (25.0%; refined: 15.0%, whole: 10.0%), and vegetables/fruits (10.3%; plain: 4.9%, with additions: 5.4%). The overall DII score (mean, IQR) was positive (0.93, 0.23 to 1.75) indicating foods consumed tend towards a pro-inflammatory response. DII was significantly associated with sex (female higher; p<0.0001), and diet (minced higher; p=0.036).

CONCLUSIONS

"Healthfulness" of Canadian LTC menus may be enhanced by lowering inflammatory potential to support chronic disease management through further shifts from refined to whole grains, incorporating more plant-based proteins, and moving towards serving plain vegetables and fruits. However, there are multiple layers of complexities to consider when optimising foods aligned with the CFG, and shifting to foods with anti-inflammatory potential for enhanced health benefits, while balancing nutrition and ensuring sufficient food and fluid intake to prevent or treat malnutrition.

Impact of the MIND Diet on Cognition in Individuals with Dementia

BACKGROUND

Alzheimer's disease (AD) plagues 6.5 million Americans 65+, yet treatments are lacking. The Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet has been developed to address the expansive impact of dementias on the general public. This systematic review evaluated the impact of the MIND diet on cognition in those with pathologies across the dementia spectrum.

OBJECTIVE

To evaluate the application of the MIND diet for prevention and/or treatment of dementia.

METHODS

PubMed was used to conduct a search using the MIND diet and terms related to cognition. Articles were excluded if they were published prior to 2018, studied a population without dementia or significant risk factors, or did not include those 65 + . The overall quality of each source was analyzed based on the cognitive test(s) used, the selection of subjects, and the sample size.

RESULTS

The search generated 33 papers, which yielded 11 articles after screening. Of these studies, one was conducted on those with mild cognitive impairment, one with AD, two with general dementia, and seven with at-risk individuals. All the studies found a positive correlation between adherence and some form of cognitive functioning, but results were mixed for specific cognitive domains.

CONCLUSIONS

These findings suggest that the MIND diet may be a useful long-term treatment option for those with various dementia pathologies. However, more research is needed on subjects with onset dementias. Additionally, there is a need for more research into the mechanisms behind the common comorbidities.

Multi-Domain Interventions for Dementia Prevention - A Systematic Review

OBJECTIVES

There is a growing incidence of cognitive decline and dementia associated with the ageing population. Lifestyle factors such as diet, physical activity, and cognitive activities may individually or collectively be undertaken to increase one's odds of preventing cognitive decline and future dementia. This study will examine whether clinical trials using multidomain lifestyle intervention can significantly decrease the risk of cognitive decline and therefore dementia.

DESIGN, SETTING AND PARTICIPANTS

This systematic literature review of multidomain lifestyle interventions for the prevention of cognitive decline and dementia followed the PRISMA guidelines. Clinical trials involving multidomain intervention (i.e., diet and physical activity, or without cognitive training) in older adults (≥ 49 years old) at higher risk of dementia were identified through 5 electronic databases (EMBASE, MEDLINE, CINAHL, Cochrane, and Scopus). A comprehensive search was performed to identify and retrieve publications until 15 November 2022. Trials were published in English.

RESULTS

The included studies (n=15) assessed change in cognition in response to a multidomain lifestyle intervention. However, the cognitive outcome measures used in these studies were heterogeneous. Despite this heterogeneity, two thirds of the studies showed improvement in cognition following a multidomain intervention (n=10 with a total of 9,439 participants). However, five studies reported no improvement in cognition following the multidomain intervention. The most common form of dietary intervention included higher amount of fruit and vegetable intake; whole-grain cereal products instead of refined; low fat options in milk and meat products; and limiting sucrose intake to less than 50 g/day. Most clinical trial studies were powered to examining the effects of multidomain interventions in cognition but were not designed to test the contribution of individual domains (i.e., dietary changes, increased physical activity, or increased cognitive stimulation alone).

CONCLUSION

This systematic review aimed to determine the effect of multimodal lifestyle interventions on cognitive outcomes in older adults at risk of dementia. We found that participants with conditions that may increase the risk of dementia, (e.g., hypertension, cardiovascular fragility) do benefit from multi-modal lifestyle changes including diet, physical activity, and cognitive training. Two thirds of studies using multidomain lifestyle interventions showed improvements in cognitive function. Trials with a focus on cognitive training, dietary improvement, and physical activity may prevent or delay cognitive decline in older adults including those at risk of developing dementia. Future studies should consider longer follow-up periods and adequate power to be able to examine the effects of each lifestyle component in the context of multimodal interventions.

Nutrition Patterns of Polish Esports Players

The aim of this study was to quantify the dietary patterns (DPs) of Polish esports players aged 18-26 years. Data were obtained via questionnaires that assessed dietary habits and frequency of food consumption. Dietary patterns were derived using Principal Component Analysis (PCA) and Factor Analysis (FA). In total, nine distinct DPs were identified. Eight DPs were considered unhealthy; 'fast food', 'High-processed food, meat and confectionery', 'Sweet', 'Fat-diary products', 'Vegetable-fruit', 'Spices and additives', 'Fats' and 'Cereal'; and only one was deemed healthy. E-athletes presented mostly poor dietary habits, which included: irregular eating of meals, frequent snacking, at least three meals a day and composition of snacks, frying of meat dishes and sweetening of hot drinks. Healthy dietary habits included proper hydration during the day and consumption of mainly non-sparkling water. The unbalanced and largely unhealthy dietary habits of esports players raise health concerns for these e-athletes, particularly when combined with a sedentary lifestyle. Future research could assess the nutritional knowledge of this group as it relates to national guidelines, investigate interventions designed to introduce healthier eating options into their lifestyle and examine the relationship between DPs and health or cognitive performance.

Worldwide impact of lifestyle predictors of dementia prevalence: An eXplainable Artificial Intelligence analysis

Introduction

Dementia is an umbrella term indicating a group of diseases that affect the cognitive sphere. Dementia is not a mere individual health issue, since its interference with the ability to carry out daily activities entails a series of collateral problems, comprising exclusion of patients from civil rights and welfare, unpaid caregiving work, mostly performed by women, and an additional burden on the public healthcare systems. Thus, gender and wealth inequalities (both among individuals and among countries) tend to amplify the social impact of such a disease. Since at present there is no cure for dementia but only drug treatments to slow down its progress and mitigate the symptoms, it is essential to work on prevention and early diagnosis, identifying the risk factors that increase the probability of its onset. The complex and multifactorial etiology of dementia, resulting from an interplay between genetics and environmental factors, can benefit from a multidisciplinary approach that follows the "One Health" guidelines of the World Health Organization.

Methods

In this work, we apply methods of Artificial Intelligence and complex systems physics to investigate the possibility to predict dementia prevalence throughout world countries from a set of variables concerning individual health, food consumption, substance use and abuse, healthcare system efficiency. The analysis uses publicly available indicator values at a country level, referred to a time window of 26 years.

Results

Employing methods based on eXplainable Artificial Intelligence (XAI) and complex networks, we identify a group of lifestyle factors, mostly concerning nutrition, that contribute the most to dementia incidence prediction.

Discussion

The proposed approach provides a methodological basis to develop quantitative tools for action patterns against such a disease, which involves issues deeply related with sustainable, such as good health and resposible food consumption.

Enhancing children's cognitive function and achievement through carotenoid consumption: The Integrated Childhood Ocular Nutrition Study (iCONS) protocol

Lutein and zeaxanthin (L + Z) are carotenoids that accumulate in neural tissue and potentially confer benefits to cognition. Whereas cross-sectional studies have revealed positive associations between macular carotenoids (MC) and cognition, no studies have investigated whether L + Z supplementation impacts MC and cognition in childhood. Accordingly, the Integrated Childhood Ocular Nutrition Study aims to investigate the impact of L + Z supplementation over 9-months on academic abilities, attentional control, memory, and MC among preadolescent children. Children 8-10 years (N = 288) will enroll in a 9-month double-blind, placebo-controlled, randomized trial. The study is registered and approved as a clinical trial on the U.S. National Library of Medicine http://ClinicalTrials.gov registry (NCT05177679). Participants will be randomized into an active (10 mg lutein+2 mg zeaxanthin) or waitlist placebo-controlled group. Primary outcomes include hippocampal-dependent memory, attentional inhibition, and academic achievement using a spatial reconstruction task, an Eriksen flanker task, and the Kaufman Test of Academic and Educational Achievement 3rd edition, respectively. Secondary outcomes include event-related brain potentials of attentional resource allocation and information processing speed (i.e., P3/P300 amplitude and latency) recorded during the flanker task. Macular pigment optical density (MPOD) will be assessed using heterochromatic flicker photometry. Cognitive assessments will be completed prior to and after completion of the supplementation period. MPOD will be quantified prior to, at the mid-point of (4-5 months), and after (9 months) the supplementation period. It is hypothesized that L + Z supplementation will improve cognition and academic achievement. Further, benefits for cognition and achievement are anticipated to be mediated by increases in MC among treatment group participants.

Diet, nutrition, and cognitive function: A narrative review of Japanese longitudinal studies

In aging societies, the number of older people with cognitive decline and dementia is increasing. Proper nutrition is a key factor that can help in the prevention of these age-related impairments. This narrative review of longitudinal studies in Japan outlines the relationship between nutrition and the brain and focuses on Japanese nutritional epidemiologic studies. The results of Japanese cohort studies suggest that rather than a single food or nutrient, a nutritionally balanced diet that integrates a variety of foods and nutrients can contribute to the maintenance of brain function and be effective in preventing dementia. In addition, this review considers a nutritional approach to reducing the severity of cognitive decline in individuals with mild cognitive impairment and dementia, and suggests lifelong strategies for the prevention of cognitive decline. It is important that we consider the practice of eating not only as a way to obtain nutrients, but also as an important lifestyle habit to maintain our physical and mental health. Geriatr Gerontol Int 2022; 22: 825-831.

MedDiet adherence score for the association between inflammatory markers and cognitive performance in the elderly: a study of the NHANES 2011-2014

Background

To explore the optimal Mediterranean diet (MedDiet) adherence score threshold for the association between inflammatory markers and cognitive performance among older adults.

Methods

In this cross-sectional study, we selected data of the elderly (≥ 60 years old) from the National Health and Nutrition Examination Survey (NHANES) 2011–2014 (n = 2830). Participants completed at least one cognitive measurement and two 24-h food recalls. By analyzing the relation between inflammatory markers and cognitive performance using the subdivided MedDiet adherence score, we got the optimal MedDiet adherence score threshold. Then the optimal threshold was used to divide participants into high and low MedDiet adherence groups and multivariate logistic regression models were developed to examine the association between inflammatory markers and cognitive performance in each group. Subgroup analysis was conducted based on gender, race, BMI, physical activity level, and chronic diseases.

Results

We chose 4 as the optimal MedDiet adherence score threshold and included these participants whose MedDiet adherence score was 4 or above into the high MedDiet adherence group, while the MedDiet adherence score of the low adherence group was less than 4. We found that the increased white blood cell (WBC) count (OR = 1.44, 95% CI: 1.09–1.90, P = 0.008), neutrophil count (OR = 1.30, 95% CI: 1.03–1.65, P = 0.023), and neutrophil-albumin ratio (NAR) (OR = 1.34, 95% CI: 1.06–1.70, P = 0.012) were all related to a higher risk of low cognitive performance in the low MedDiet adherence group. A higher PLR was linked to a reduced risk of low cognitive performance (OR = 0.86, 95% CI: 0.74–1.00, P = 0.036) in the high MedDiet adherence group. Significant differences were found in the associations of WBC count, neutrophil count and NAR with low cognitive performance between the low and high MedDiet adherence groups (all P < 0.001). The weakened negative association between inflammatory markers and cognitive performance in the high MedDiet adherence group also existed among male, non-Hispanic white, normal-weight, overweight, moderate work activity, moderate recreational activity, non-depression, hypertension, non-hypertension, non-diabetes, non-stroke, non-heart failure, non-coronary heart disease, or non-heart attack subpopulations of older adults.

Conclusions

The optimal threshold for the MedDiet adherence score was 4, and the negative association between inflammation and cognitive performance could be weakened in older adults whose MedDiet adherence score was ≥ 4.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03140-1.

The combined effect of physical activity and fruit and vegetable intake on decreasing cognitive decline in older Taiwanese adults

The factors associated with cognitive decline among older adults include physical activity and fruit and vegetable intake. However, the long-term effects of concomitant physical activity and fruit and vegetable intake are unknown. This 16-year longitudinal study explored the joint effect of mitigating cognitive decline in a cohort of older Taiwanese individuals. Five population-based surveys (Taiwan Longitudinal Survey on Aging [1999–2015]) involving 4440 respondents over 53 years old in 1999 were conducted. Cognitive function was assessed using the Short Portable Mental Status Questionnaire (SPMSQ). The demographic, socioeconomic, health-related, behavioral, and disease status covariates were adjusted in the regression analysis. Trends in cognitive decline were observed over 16 years. The risk of cognitive decline decreased by 63% when high physical activity and high fruit and vegetable intake were combined (odds ratio 0.37; 95% confidence interval 0.23–0.59), indicating a potential combined effect of physical activity and fruit and vegetable intake on mitigating cognitive decline. These personal actions are safe, effective, and economical approaches to health promotion and disease prevention.

Comparison of the Impact of the Mediterranean Diet, Anti-Inflammatory Diet, Seventh-Day Adventist Diet, and Ketogenic Diet Relative to Cognition and Cognitive Decline

PURPOSE OF REVIEW

Increasing evidence points toward the importance of diet and its impact on cognitive decline. This review seeks to clarify the impact of four diets on cognition: the Mediterranean diet, the anti-inflammatory diet, the Seventh Day Adventist diet, and the Ketogenic diet.

RECENT FINDINGS

Of the diets reviewed, the Mediterranean diet provides the strongest evidence for efficacy. Studies regarding the anti-inflammatory diet and Seventh Day Adventist diet are sparse, heterogeneous in quality and outcome measurements, providing limited reliable data. There is also minimal research confirming the cognitive benefits of the Ketogenic diet. Increasing evidence supports the use of the Mediterranean diet to reduce cognitive decline. The MIND-diet, a combination of the Mediterranean and DASH diets, seems especially promising, likely due to its anti-inflammatory properties. The Ketogenic diet may also have potential efficacy; however, adherence in older populations may be difficult given frequent adverse effects. Future research should focus on long-term, well-controlled studies confirming the impact of various diets, as well as the combination of diets and lifestyle modification.

Effects of Lifestyle Factors on Cognition in Minority Population of Older Adults: A Review

The onset of dementia and Alzheimer's disease (AD) is projected to expand over the next several decades in the United States as the population ages. However, the cognitive health burden is not equally distributed among the population, as Hispanics and African Americans are at higher risk of AD when compared with Non-Hispanic Whites. There is some evidence to indicate that cognitive decline may be associated with lifestyle factors and that interventions in these domains may prevent or delay this decline. These lifestyle factors include social engagement, physical activity, both aerobic and strength training, dietary intake, sleep and stress. This review summarizes, in general, what is known about the relationship between risk factors and cognition and, in particular what is known about this relationship in minority populations. The results show that the relationship between these risk factors and cognitive decline is stronger for some of the factors such as physical activity and dietary intake and weaker for the other factors depending on what is measured and in what populations. It does appear, however, that the studies in minority populations is limited and warrants more targeted research and interventions.

Mediterranean-Type Diet and Brain Structural Change from 73 to 79 Years in the Lothian Birth Cohort 1936

OBJECTIVES

To test whether Mediterranean-type Diet (MeDi) at age 70 years is associated with longitudinal trajectories of total brain MRI volume over a six-year period from age 73 to 79.

DESIGN

Cohort study which uses a correlational design.

SETTING

Participants residing in the Lothian region of Scotland and living independently in the community.

PARTICIPANTS

A relatively healthy Scottish sample drawn from the Lothian Birth Cohort 1936.

MEASUREMENTS

Total brain volume measurements were available at ages 73, 76 and 79 (N ranged 332 to 563). Adherence to the MeDi was based on food frequency questionnaire data collected three years before the baseline imaging scans, and was used in growth curve models to predict the trajectory of total brain volume change.

RESULTS

No association was found (p>.05) between adherence to the MeDi at age 70 and total brain volume change from 73 to 79 years in minimally-adjusted (sex) or fully adjusted models controlling for additional health confounders.

CONCLUSIONS

Variation in adherence to the MeDi was not predictive of total brain atrophy over a six-year period. This suggests that previous findings of dietary associations with brain volume are not long lasting or become less important as ageing-related conditions account for greater variation in brain volume change. More frequent collection of dietary intake data is needed to clarify these findings.

Effect of food insecurity on the cognitive problems among elderly in India

BACKGROUND

Food Insecurity (FI) is a crucial social determinant of health, independent of other socioeconomic factors, as inadequate food resources create a threat to physical and mental health especially among older person. The present study explores the associations between FI and cognitive ability among the aged population in India.

METHODS

To measure the cognitive functioning we have used two proxies, word recall and computational problem. Descriptive analysis and multivariable logistic regression was used to understand the prevalence of word recall and computational problem by food security and some selected sociodemographic parameters. All the results were reported at 95% confidence interval.

RESULTS

We have used the data from the first wave of longitudinal ageing study of India (LASI), with a sample of 31,464 older persons 60 years and above. The study identified that 17 and 5% of the older population in India experiencing computational and word recall problem, respectively. It was found that respondents from food secure households were 14% less likely to have word recall problems [AOR:0.86, 95% CI:0.31-0.98], and 55% likely to have computational problems [AOR:0.45, 95% CI:0.29-0.70]. We also found poor cognitive functioning among those experiencing disability, severe ADL, and IADL. Further, factors such as age, education, marital status, working status, health related factors were the major contributors to the cognitive functioning in older adults.

CONCLUSION

This study suggest that food insecurity is associated with a lower level of cognition among the elderly in India, which highlight the need of food policy and interventional strategies to address food insecurity, especially among the individuals belonging to lower wealth quintiles. Furthermore, increasing the coverage of food distribution may also help to decrease the burden of disease for the at most risk population. Also, there is a need for specific programs and policies that improve the availability of nutritious food among elderly.

Development of the First WHO Guidelines for Risk Reduction of Cognitive Decline and Dementia: Lessons Learned and Future Directions

The first WHO guidelines for risk reduction of cognitive decline and dementia marked an important milestone in the field of dementia prevention. In this paper, we discuss the evidence reviewed as part of the guidelines development and present the main themes emerged from its synthesis, to inform future research and policies on dementia risk reduction. The role of intervention effect-size; the mismatch between observational and intervention-based evidence; the heterogeneity of evidence among intervention trials; the importance of intervention duration; the role of timing of exposure to a certain risk factor and interventions; the relationship between intervention intensity and response; the link between individual risk factors and specific dementia pathologies; and the need for tailored interventions emerged as the main themes. The interaction and clustering of individual risk factors, including genetics, was identified as the overarching theme. The evidence collected indicates that multidomain approaches targeting simultaneously multiple risk factors and tailored at both individual and population level, are likely to be most effective and feasible in dementia risk reduction. The current status of multidomain intervention trials aimed to cognitive impairment/dementia prevention was also briefly reviewed. Primary results were presented focusing on methodological differences and the potential of design harmonization for improving evidence quality. Since multidomain intervention trials address a condition with slow clinical manifestation—like dementia—in a relatively short time frame, the need for surrogate outcomes was also discussed, with a specific focus on the potential utility of dementia risk scores. Finally, we considered how multidomain intervention could be most effectively implemented in a public health context and the implications world-wide for other non-communicable diseases targeting common risk factors, taking into account the limited evidence in low-middle income countries. In conclusion, the evidence from the first WHO guidelines for risk reduction of cognitive decline and dementia indicated that “one size does not fit all,” and multidomain approaches adaptable to different populations and individuals are likely to be the most effective. Harmonization in trial design, the use of appropriate outcome measures, and sustainability in large at-risk populations in the context of other chronic disorders also emerged as key elements.

Food and Microbiota Metabolites Associate with Cognitive Decline in Older Subjects: A 12-Year Prospective Study

SCOPE

Diet is considered an important modulator of cognitive decline and dementia, but the available evidence is, however, still fragmented and often inconsistent.

METHODS AND RESULTS

The article studies the long-term prospective Three-City Cohort, which consists of two separate nested case-control sample sets from different geographic regions (Bordeaux, n = 418; Dijon, n = 424). Cognitive decline is evaluated through five neuropsychological tests (Mini-Mental State Examination, Benton Visual Retention Test, Isaac's Set Test, Trail-Making Test part A, and Trail-Making Test part B). The food-related and microbiota-derived circulating metabolome is studied in participants free of dementia at baseline, by subjecting serum samples to large-scale quantitative metabolomics analysis. A protective association is found between metabolites derived from cocoa, coffee, mushrooms, red wine, the microbial metabolism of polyphenol-rich foods, and cognitive decline, as well as a negative association with metabolites related to unhealthy dietary components, such as artificial sweeteners and alcohol.

CONCLUSION

These results provide insight into the early metabolic events that are associated with the later risk to develop cognitive decline within the crosstalk between diet, gut microbiota and the endogenous metabolism, which can help identify potential targets for preventive and therapeutic strategies to preserve cognitive health.

The Effects of Intermittent Fasting on Brain and Cognitive Function

The importance of diet and the gut-brain axis for brain health and cognitive function is increasingly acknowledged. Dietary interventions are tested for their potential to prevent and/or treat brain disorders. Intermittent fasting (IF), the abstinence or strong limitation of calories for 12 to 48 h, alternated with periods of regular food intake, has shown promising results on neurobiological health in animal models. In this review article, we discuss the potential benefits of IF on cognitive function and the possible effects on the prevention and progress of brain-related disorders in animals and humans. We do so by summarizing the effects of IF which through metabolic, cellular, and circadian mechanisms lead to anatomical and functional changes in the brain. Our review shows that there is no clear evidence of a positive short-term effect of IF on cognition in healthy subjects. Clinical studies show benefits of IF for epilepsy, Alzheimer’s disease, and multiple sclerosis on disease symptoms and progress. Findings from animal studies show mechanisms by which Parkinson’s disease, ischemic stroke, autism spectrum disorder, and mood and anxiety disorders could benefit from IF. Future research should disentangle whether positive effects of IF hold true regardless of age or the presence of obesity. Moreover, variations in fasting patterns, total caloric intake, and intake of specific nutrients may be relevant components of IF success. Longitudinal studies and randomized clinical trials (RCTs) will provide a window into the long-term effects of IF on the development and progress of brain-related diseases.

The Influence of Nutrition in Alzheimer's Disease: Neuroinflammation and the Microbiome vs. Transmissible Prion

Alzheimer's disease (AD) is a primary, progressive, neurodegenerative disorder. Many risk factors for the development of AD have been investigated, including nutrition. Although it has been proven that nutrition plays a role in AD, the precise mechanisms through which nutrition exerts its influence remain undefined. The object of this study is to address this issue by elucidating some of the mechanisms through which nutrition interacts with AD. This work is a qualitative systematic bibliographic review of the current literature searchable on various available databases, including PubMed, Web of Science, and Google Scholar. Our evidence comprises 31 articles selected after a systematic search process. Patients suffering with AD present a characteristic microbiome that promotes changes in microglia generating a proinflammatory state. Many similarities exist between AD and prion diseases, both in terms of symptoms and in the molecular mechanisms of pathogenesis. Changes in the composition of the gut microbiome due to dietary habits could be one of the environmental factors affecting the development of AD; however, this is probably not the only factor. Similarly, the mechanism for self-propagation of beta-amyloid seen in AD is similar to that seen in prions.

Efficacy and Safety of Sesame Oil Cake Extract on Memory Function Improvement: A 12-Week, Randomized, Double-Blind, Placebo-Controlled Pilot Study

The goal of treatment for mild cognitive impairment (MCI) is to reduce the existing clinical symptoms, delay the progression of cognitive impairment and prevent the progression to Alzheimer’s disease (AD). At present, there is no effective drug therapy for AD treatment. However, early intake of dietary supplements may be effective in alleviating and delaying the MCI. This study aims to evaluate the effects of sesame oil cake extract (SOCE) supplementation on cognitive function in aged 60 years or older adults with memory impairment. A total of 70 subjects received either SOCE (n = 35) or placebo (n = 35) for 12 weeks based on random 1:1 assignment to these two groups. Cognitive function was evaluated by a computerized neurocognitive function test (CNT), and changes in the concentrations of plasma amyloid β (Aβ) proteins and urine 8-OHdG (8-hydroxy-2′-deoxyguanosine) were investigated before and after the experiment. Verbal learning test index items of the CNT improved markedly in the SOCE group compared to the placebo group (p < 0.05). Furthermore, plasma amyloid-β (1–40) and amyloid-β (1–42) levels in the SOCE group decreased significantly compared to that in the placebo group (p < 0.05). There was no statistically significant difference in urine 8-OHdG between the two groups (p > 0.05). Collectively, intake of SOCE for 12 weeks appears to have a beneficial effect on the verbal memory abilities and plasma β-amyloid levels of older adults with memory impairment.

Going with the grain: Fiber, cognition, and the microbiota-gut-brain-axis

Healthy dietary intake has been acknowledged for decades as one of the main contributors to health. More recently, the field of nutritional psychiatry has progressed our understanding regarding the importance of nutrition in supporting mental health and cognitive function. Thereby, individual nutrients, including omega-3 fatty acids and polyphenols, have been recognized to be key drivers in this relationship. With the progress in appreciating the influence of dietary fiber on health, increasingly research is focusing on deciphering its role in brain processes. However, while the importance of dietary fiber in gastrointestinal and metabolic health is well established, leading to the development of associated health claims, the evidence is not conclusive enough to support similar claims regarding cognitive function. Albeit the increasing knowledge of the impact of dietary fiber on mental health, only a few human studies have begun to shed light onto the underexplored connection between dietary fiber and cognition. Moreover, the microbiota-gut-brain axis has emerged as a key conduit for the effects of nutrition on the brain, especially fibers, that are acted on by specific bacteria to produce a variety of health-promoting metabolites. These metabolites (including short chain fatty acids) as well as the vagus nerve, the immune system, gut hormones, or the kynurenine pathway have been proposed as underlying mechanisms of the microbiota-brain crosstalk. In this minireview, we summarize the evidence available from human studies on the association between dietary fiber intake and cognitive function. We provide an overview of potential underlying mechanisms and discuss remaining questions that need to be answered in future studies. While this field is moving at a fast pace and holds promise for future important discoveries, especially data from human cohorts are required to further our understanding and drive the development of public health recommendations regarding dietary fiber in brain health.

Dietary patterns are related to cognitive functioning in elderly enriched with individuals at increased risk for Alzheimer's disease

PURPOSE

To investigate cross-sectional associations between dietary patterns and cognitive functioning in elderly free of dementia.

METHODS

Data of 389 participants from the German DELCODE study (52% female, 69 ± 6 years, mean Mini Mental State Score 29 ± 1) were included. The sample was enriched with elderly at increased risk for Alzheimer's disease (AD) by including participants with subjective cognitive decline, mild cognitive impairment (MCI) and siblings of AD patients. Mediterranean and MIND diets were derived from 148 Food Frequency Questionnaire items, and data-driven patterns by principal component analysis (PCA) of 39 food groups. Associations between dietary patterns and five cognitive domain scores were analyzed with linear regression analyses adjusted for demographics (model 1), and additionally for energy intake, BMI, other lifestyle variables and APOe4-status (model 2). For PCA-derived dietary components, final model 3 included all other dietary components.

RESULTS

In fully adjusted models, adherence to Mediterranean and MIND diet was associated with better memory. The 'alcoholic beverages' PCA component was positively associated with most cognitive domains. Exclusion of MCI subjects (n = 60) revealed that Mediterranean and MIND diet were also related to language functions; associations with the alcoholic beverages component were attenuated, but most remained significant.

CONCLUSION

In line with data from elderly population samples, Mediterranean and MIND diet and some data-derived dietary patterns were related to memory and language function. Longitudinal data are needed to draw conclusions on the putative effect of nutrition on the rate of cognitive decline, and on the potential of dietary interventions in groups at increased risk for AD.

Resveratrol Supplementation Attenuates Cognitive and Molecular Alterations under Maternal High-Fat Diet Intake: Epigenetic Inheritance over Generations

Environmental factors such as maternal high-fat diet (HFD) intake can increase the risk of age-related cognitive decline in adult offspring. Epigenetic mechanisms are a possible link between diet effect and neurodegeneration across generations. Here, we found a significant decrease in triglyceride levels in a high-fat diet with resveratrol (RSV) HFD + RSV group and the offspring. Firstly, we obtained better cognitive performance in HFD+RSV groups and their offspring. Molecularly, a significant increase in DNA methylation (5-mC) levels, as well as increased gene expression of DNA methyltransferase 1 (Dnmt1) and Dnmt3a in HFD + RSV F1 group, were found. Furthermore, a significant increase of N6-Methyladenosine methylation (m6A) levels in HFD+RSV F1, as well as changes in gene expression of its enzymes Methyltransferase like 3 (Mettl3) and FTO alpha-ketoglutarate dependent dioxygenase (Fto) were found. Moreover, we found a decrease in gene expression levels of pro-inflammatory markers such as Interleukin 1β (Il1-β), Interleukin 6 (Il-6), Tumor necrosis factor-α (Tnf-α), C-X-C motif chemokine ligand 10 (Cxcl-10), the pro-inflammatory factors monocyte chemoattractant protein 1 (Mcp-1) and Tumor growth factor-β1 (Tgf-β1) in HFD+RSV and HFD+RSV F1 groups. Moreover, there was increased gene expression of neurotrophins such as Neural growth factor (Ngf), Neurotrophin-3 (Nt3), and its receptors Tropomyosin receptor kinase TrkA and TrkB. Likewise, an increase in protein levels of brain-derived neurotrophic factor (BDNF) and phospho-protein kinase B (p-Akt) in HFD+RSV F1 was found. These results suggest that maternal RSV supplementation under HFD intake prevents cognitive decline in senescence-accelerated mice prone 8 (SAMP8) adult offspring, promoting a reduction in triglycerides and leptin plasma levels, changes in the pro-inflammatory profile, and restoring the epigenetic landscape as well as synaptic plasticity.

A Randomized Controlled Trial of High-Intensity Exercise and Executive Functioning in Cognitively Normal Older Adults

BACKGROUND

There is a paucity of interventional research that systematically assesses the role of exercise intensity and cardiorespiratory fitness, and their relationship with executive function in older adults. To address this limitation, we have examined the effect of a systematically manipulated exercise intervention on executive function.

METHODS

Ninety-nine cognitively normal participants (age = 69.10 ± 5.2 years; n = 54 female) were randomized into either a high-intensity cycle-based exercise, moderate-intensity cycle-based exercise, or no-intervention control group. All participants underwent neuropsychological testing and fitness assessment at baseline (preintervention), 6-month follow-up (postintervention), and 12-month postintervention. Executive function was measured comprehensively, including measures of each subdomain: Shifting, Updating/ Working Memory, Inhibition, Verbal Generativity, and Nonverbal Reasoning. Cardiorespiratory fitness was measured by analysis of peak aerobic capacity; VO₂peak.

RESULTS

First, the exercise intervention was found to increase cardiorespiratory fitness (VO₂peak) in the intervention groups, in comparison to the control group (F =10.40, p≤0.01). However, the authors failed to find mean differences in executive function scores between the high-intensity, moderate intensity, or inactive control group. On the basis of change scores, cardiorespiratory fitness was found to associate positively with the executive function (EF) subdomains of Updating/Working Memory (β = 0.37, p = 0.01, r = 0.34) and Verbal Generativity (β = 0.30, p = 0.03, r = 0.28) for intervention, but not control participants.

CONCLUSION

At the aggregate level, the authors failed to find evidence that 6-months of high-intensity aerobic exercise improves EF in older adults. However, it remains possible that individual differences in experimentally induced changes in cardiorespiratory fitness may be associated with changes in Updating/ Working Memory and Verbal Generativity.

Dietary patterns and trajectories of global- and domain-specific cognitive decline in the Lothian Birth Cohort 1936

Healthy dietary patterns may protect against age-related cognitive decline, but results of studies have been inconsistent and few have had extensive longitudinal follow-up with comprehensive cognitive testing. The aim of the present study was to determine associations of dietary patterns with trajectories of global- and domain-specific cognitive change over a 12-year period. Data from 863 community-dwelling, dementia-free participants from the Lothian Birth Cohort 1936 study of ageing completed a FFQ at baseline (aged 70 years) and underwent cognitive testing at baseline, and at the ages of 73, 76, 79 and 82 years. Composite cognitive scores were constructed for four cognitive domains (visuospatial ability, processing speed, memory and verbal ability) and global cognitive function. A Mediterranean-style pattern and a traditional pattern were derived using principal component analysis of self-reported dietary intakes. In fully adjusted latent growth curve models, higher baseline adherence to the Mediterranean-style dietary pattern (β = 0·056, P = 0·009) and lower baseline adherence to the traditional dietary pattern (β  =  −0·087, P < 0·001) were cross-sectionally associated with better verbal ability. A slightly steeper decline in verbal ability over 12 years was observed in those with higher Mediterranean-style diet scores at baseline (β = −0·003, P = 0·008). All other associations were non-significant. Our findings in this well-characterised Scottish cohort indicate that adherence to a healthy Mediterranean-style diet is associated cross-sectionally with better verbal (crystallised) ability, with the converse being true for the traditional diet. A healthier baseline diet did not predict a reduced risk of global- or domain-specific cognitive decline.

Dietary patterns and depression risk in older adults: systematic review and meta-analysis

CONTEXT

Diet may be one of the modifiable environmental factors that could reduce depressive symptoms or abate the development of depression without side effects. However, previous reviews mainly focused on general adult populations.

OBJECTIVE

The aim of this systematic review and meta-analysis was to explore the association between healthy dietary patterns and depression risk in older adults.

DATA SOURCES

Eight databases were searched up to September 2019. The inclusion criteria were older adults aged ≥ 65 years, healthy dietary patterns, depression assessed by a physician or by validated screening tools, and quantitative study design.

DATA EXTRACTION

Data were extracted independently by 2 researchers, and the Preferred Reporting Items for Systematic Reviews and Meta-analyses guideline was followed.

DATA ANALYSIS

Meta-analysis was conducted by calculating the pooled odds ratio (OR) and 95% CIs. A total of 18 eligible studies were meta-analyzed. Results showed that a healthy dietary pattern is associated with a reduced risk of depression in older adults (OR, 0.85; 95%CI, 0.78-0.92; P < 0.001). There was high heterogeneity (I2 = 64.9%; P < 0.001) among the studies. Subgroup analyses indicated that sample size and depression screening tools were the main sources of study heterogeneity.

CONCLUSIONS

An inverse association between healthy dietary patterns and depression risk in older adults was found. However, the high heterogeneity among the studies should be considered.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD 42020169195.

Self-Selection Bias: An Essential Design Consideration for Nutrition Trials in Healthy Populations

Many researchers have identified the issue of self-selection bias hindering the ability to detect nutrient effects in healthy populations. However, it appears that no effort has been made to mitigate this potential design flaw. By recruiting individuals on the basis of pre-trial dietary intake, the Memory and Attention Supplementation Trial aimed to capture a cohort of participants with a wide variety of dietary intake, thus increasing the likelihood of a diverse range of nutrient status. This perspective specifically examines the profile of these trial volunteers and in doing so, we present the first empirical evidence of self-selection bias when recruiting healthy volunteers for a randomized controlled trial of a nutrient-based supplement. These findings support the anecdotal proposal that traditional recruitment methods inherently attract trial volunteers who are vastly unrepresentative of the population and threatens the generalizability of this field of research. Alternative approaches to recruitment, including a-priori screening for baseline diet quality and nutrient status, are discussed as essential design recommendations to ensure accurate interpretation of nutrient effects within the context of baseline participant characteristics.

Self-Reported Diet Quality Differentiates Nutrient Intake, Blood Nutrient Status, Mood, and Cognition: Implications for Identifying Nutritional Neurocognitive Risk Factors in Middle Age

Evidence for diet quality representing a modifiable risk factor for age-related cognitive decline and mood disturbances has typically come from retrospective, cross-sectional analyses. Here a diet screening tool (DST) was used to categorize healthy middle-aged volunteers (n = 141, 40–65 years) into “optimal” or “sub-optimal” diet groups to investigate cross-sectional associations between diet quality, cognitive function, and mood. The DST distinguished levels of nutrient intake as assessed by Automated Self-Administered 24-h dietary recall and nutrient status, as assessed by blood biomarker measures. Compared with the “sub-optimal” group, the “optimal” diet group showed significantly higher intake of vitamin E (p = 0.007), magnesium (p = 0.001), zinc (p = 0.043) and fiber (p = 0.015), higher circulating levels of vitamin B6 (p = 0.030) and red blood cell folate (p = 0.026) and lower saturated fatty acids (p = 0.012). Regarding psychological outcomes, the “optimal” diet group had significantly better Stroop processing than those with a “sub-optimal” diet (p = 0.013). Regression analysis revealed that higher DST scores were associated with fewer mood disturbances (p = 0.002) and lower perceived stress (p = 0.031), although these differences were not significant when comparing “optimal” versus “sub-optimal” as discrete groups. This study demonstrates the potential of a 20-item diet screen to identify both nutritional and psychological status in an Australian setting.

Adherence to the MIND diet is associated with 12-year all-cause mortality in older adults

Objective:

To prospectively evaluate the association of three dietary patterns: the MIND (Mediterranean-DASH diet intervention for Neurodegenerative Delay) diet; a Mediterranean-type diet and a traditional diet, with all-cause mortality over a 12-year period in an older sample.

Design:

A longitudinal birth cohort study. We ascertained dietary patterns using FFQ data at baseline (2004–2007) and mortality using linkage data. Cox regression was used to estimate mortality hazard ratios (HR) with adjustment for confounders.

Setting:

The Lothian Birth Cohort 1936 (LBC1936) study in Edinburgh, Scotland.

Participants:

Dietary patterns were ascertained in 882 participants, mean age 69·5 (±0·8) years, at baseline. During the 12-year follow-up (to October 2019), 206 deaths occurred.

Results:

In the basic-adjusted model, all three dietary patterns were significantly associated with mortality, the MIND diet and Mediterranean-type diet with a lower risk and the traditional diet with a higher risk. In fully adjusted models, MIND diet score was inversely related to all-cause mortality (HR 0·88; 95 % CI 0·79, 0·97) such that the risk of death was reduced by 12 % per unit increase in MIND diet score. Participants in the top compared with the bottom third of MIND diet score had a 37 % lower risk of death (HR 0·63; 95 % CI 0·41, 0·96). No significant associations with the Mediterranean-type or traditional dietary patterns were observed in the final multivariate model.

Conclusions:

Our findings suggest that closer adherence to the MIND diet is associated with a significantly lower risk of all-cause mortality, over 12 years of follow-up, and may constitute a valid public health recommendation for prolonged survival.

Plant-Based Dietary Patterns, Plant Foods, and Age-Related Cognitive Decline

The aging population is expanding, as is the prevalence of age-related cognitive decline (ARCD). Of the several risk factors that predict the onset and progression of ARCD, 2 important modifiable risk factors are diet and physical activity. Dietary patterns that emphasize plant foods can exert neuroprotective effects. In this comprehensive review, we examine studies in humans of plant-based dietary patterns and polyphenol-rich plant foods and their role in either preventing ARCD and/or improving cognitive function. As yet, there is no direct evidence to support the benefits of a vegetarian diet in preventing cognitive decline. However, there is emerging evidence for brain-health-promoting effects of several plant foods rich in polyphenols, anti-inflammatory dietary patterns, and plant-based dietary patterns such as the Mediterranean diet that include a variety of fruits, vegetables, legumes, nuts, and whole grains. The bioactive compounds present in these dietary patterns include antioxidant vitamins, polyphenols, other phytochemicals, and unsaturated fatty acids. In animal models these nutrients and non-nutrients have been shown to enhance neurogenesis, synaptic plasticity, and neuronal survival by reducing oxidative stress and neuroinflammation. In this review, we summarize the mounting evidence in favor of plant-centered dietary patterns, inclusive of polyphenol-rich foods for cognitive well-being. Randomized clinical trials support the role of plant foods (citrus fruits, grapes, berries, cocoa, nuts, green tea, and coffee) in improving specific domains of cognition, most notably frontal executive function. We also identify knowledge gaps and recommend future studies to identify whether plant-exclusive diets have an added cognitive advantage compared with plant-centered diets with fish and/or small amounts of animal foods.

The Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) Diets Are Associated with Less Cognitive Decline and a Lower Risk of Alzheimer's Disease-A Review

As there is currently no cure for dementia, there is an urgent need for preventive strategies. The current review provides an overview of the existing evidence examining the associations of the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets and their dietary components with cognitive decline, dementia, and Alzheimer's disease (AD). A systematic search was conducted within Ovid Medline for studies published up to 27 March 2019 and reference lists from existing reviews and select articles were examined to supplement the electronic search results. In total, 56 articles were included. Higher adherence to the Mediterranean diet was associated with better cognitive scores in 9 of 12 cross-sectional studies, 17 of 25 longitudinal studies, and 1 of 3 trials. Higher adherence to the DASH diet was associated with better cognitive function in 1 cross-sectional study, 2 of 5 longitudinal studies, and 1 trial. Higher adherence to the MIND diet was associated with better cognitive scores in 1 cross-sectional study and 2 of 3 longitudinal studies. Evidence on the association of these dietary patterns with dementia in general was limited. However, higher adherence to the Mediterranean diet was associated with a lower risk of AD in 1 case-control study and 6 of 8 longitudinal studies. Moreover, higher adherence to the DASH or MIND diets was associated with a lower AD risk in 1 longitudinal study. With respect to the components of these dietary patterns, olive oil may be associated with less cognitive decline. In conclusion, current scientific evidence suggests that higher adherence to the Mediterranean, DASH, or MIND diets is associated with less cognitive decline and a lower risk of AD, where the strongest associations are observed for the MIND diet.

Food Insecurity Is Associated with Lower Cognitive Functioning in a National Sample of Older Adults

BACKGROUND

Food insecurity, a social and economic condition of inadequate food resources, is known to affect cognitive development in children. However, research is sparse among adult populations, particularly older adults who may be more susceptible to accelerated cognitive decline.

OBJECTIVE

The aim of this study was to examine the associations between food insecurity and cognitive functioning among older adults.

METHODS

Data came from 1823 older adults (≥60 y) with incomes ≤300% of the federal poverty level (FPL) from the 2011-2014 NHANES. Food security was measured using the 10-item Adult Food Security Survey Module. Cognitive function was measured using the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) word learning subtest and delayed word recall, the Animal Fluency Test (AFT), and the Digit Symbol Substitution Test (DSST). The cognitive assessments were then standardized and an overall cognitive function z score was created by averaging across all cognitive assessments. Associations with food insecurity were examined using multivariate linear regression models, adjusting for sociodemographic and health characteristics.

RESULTS

In the analytic population, the prevalence of food insecurity was 23.7%. Across all cognitive assessments, the mean scores among food-insecure adults was significantly lower than the mean scores among food-secure adults. After adjusting for sociodemographic and health characteristics, food insecurity was associated with lower scores on the CERAD word learning subtest (β = -0.14, 95% CI: -0.26, -0.01), the AFT (β = -0.13, 95% CI: -0.25, -0.002), and the DSST (β = -0.24, 95% CI: -0.33, -0.15). Food insecurity was also associated with a lower score on the overall cognitive function z score (β = -0.15, 95% CI: -0.26, -0.05).

CONCLUSIONS

In this national sample of 1823 adults aged ≥60 y, food insecurity was inversely associated with cognitive function, which may translate into higher risk of cognitive impairment over time.

Role of Functional Fortified Dairy Products in Cardiometabolic Health: A Systematic Review and Meta-analyses of Randomized Clinical Trials

There is insufficient evidence on the role of functional fortified dairy products in improving health and in preventing risk factors associated with noncommunicable chronic diseases. This systematic review was conducted to summarize effects of the consumption of fortified dairy products on biomarkers of cardiometabolic risk. MEDLINE and SCOPUS databases were used to perform searches to include studies published up to 30 April 2018. Randomized clinical trials with human subjects consuming dairy products fortified with phytosterols, FAs, vitamins or minerals and relating this consumption with cardiometabolic health were included in this review. Risk of bias assessment according to Cochrane guidelines was performed to determine the quality of the trials. Forty-one studies were finally selected for this synthesis; the selected studies tested dairy products fortified with the following nutrients and bioactive components: phytosterols (n = 31), FAs (n = 8), and vitamin D (n = 2). We found that the consumption of phytosterol-fortified dairy, led to an overall LDL cholesterol reduction of -0.36 (-0.41, -0.31) mmol/L, P < 0.001; this decrease was mainly related to the dosage. Likewise, consumption of ω-3 FA-fortified dairy products resulted in a plasma LDL cholesterol reduction of -0.18 (-0.27, -0.09) mmol/L as well as a decrease of -0.18 (-0.32, -0.05) mmol/L in triacylglycerols (TG). Performing meta-analyses of the consumption of dairy products fortified with vitamin D or FAs other than ω-3 FAs and biomarkers of cardiometabolic risk was not possible because of the few available publications. Our results indicate that consumption of dairy products fortified with phytosterols and ω-3 FAs can lead to a reduction of LDL cholesterol and consumption of fortified dairy products fortified with ω-3 FAs can reduce TG concentration. However, more studies with homogeneous designs are needed to determine the advantages of using dairy products as fortification vehicles to prevent cardiometabolic risk.

Changes in Brain Volume Associated With Vegetable Intake in a General Population

Objective: Although brain atrophy is a natural process of healthy aging, diet may play a role in delaying the process across age. We sought to investigate how food groups associate brain region-specific volume changes over 4 years in a general population. Methods: We obtained data from the Korean Genome and Epidemiology Study on 848 community-dwelling individuals. The participants completed a dietary examination using a food frequency questionnaire between 2005 and 2006 to determine habitual usual intakes of food consumption and two brain magnetic resonance imaging (MRI) scans between 2011 and 2014 and between 2015 and 2017, respectively. The 106 food items in the questionnaire were regrouped into 18 food groups. A multivariable generalized linear model was used with the adjustment of potential confounding variables. Results: The average age at baseline was 53.5 years. The average follow-up year of brain MRI was 4.13 ± 0.33 years. With considering a corrected p value due to multiple comparisons, vegetable intake indicated a statistically significant inverse association with gray matter volume change (β = -2.28, p = 0.006), after adjusting for potential confounding variables. Particularly, the temporal region showed a significant inverse association with vegetable intake (β= -0.63, p = 0.002). Conclusions: In a longitudinal study among 848 cognitively healthy participants from a general population, we found significant inverse associations between vegetable intake and brain gray matter volume change, particularly the change of temporal region.