Dietary diversity and risk of late-life disabling dementia in middle-aged and older adults

Dietary diversity and cognitive performance in older adults: a systematic review

BACKGROUND AND OBJECTIVE

Promoting dietary diversity (DD), which refers to the variety or the number of different food groups that people eat over the time given, is important for brain health maintenance and may be beneficial for inhibiting neurodegenerative diseases. This research aimed to review the literature and summarize research evidence for achieving an inclusive estimate concerning the relationship between DD and cognitive function in adults.

METHODS

We systematically queried the databases of PubMed, Web of Science, and Google Scholar, without imposing any date restrictions, up to June 2024 to identify original literature that sheds light on the intricate relationship between DD and cognitive function. Employing rigorous criteria, we meticulously screened studies, eliminating duplicates or those unrelated to our focus. Subsequently, we critically evaluated the findings from the selected studies, descriptively summarizing them. Additionally, we engaged in an in-depth exploration of potential mechanistic pathways linking DD to cognitive performance.

RESULTS

Of the 388 citations obtained, 23 articles were included in the final review. All the studies reported a positive association between DD score and cognitive functioning and indicated that higher DD was accompanied by good memory (n = 3) and lower risk of cognitive decline (n = 19), dementia (n = 3), and Alzheimer's disease (n = 1).

CONCLUSION

The results indicate that sustaining a diverse diet among older people may help maintain cognitive functioning. Dietary diversity represents a promising clinical avenue for mitigating cognitive decline associated with diverse brain disorders, potentially preventing or attenuating deterioration.

Association of dietary diversity, genetic susceptibility, and the risk of incident dementia: A prospective cohort study

BACKGROUND

Previous studies have revealed how single foods or nutrients affect dementia, but the evidence for a potential link between dietary diversity and dementia is inconsistent.

OBJECTIVES

This study aimed to evaluate the association between dietary diversity and the risk of incident dementia.

DESIGN, SETTING AND PARTICIPANTS

This prospective study included 104,572 white participants without dementia at baseline recruited between 2006 and 2010 from the UK Biobank.

MEASUREMENTS

Dietary Diversity Score (DDS) was acquired through the Oxford WebQ's 24-hour dietary recall survey spanning from 2009 to 2012. Cox proportional hazards models were used to estimate the associations between DDS, diversity scores of food groups and the risk of incident dementia. Stratified analyses were subsequently conducted to assess the potential variations across different demographic, socioeconomic, and genetic risk groups.

RESULTS

Over a median follow-up period of 10.44 years, 725 participants developed incident dementia. A higher DDS was associated with a lower risk of incident dementia (HR: 0.95; 95 % CI: 0.93-0.97). Stratified analyses revealed statistical significance in this association for individuals under 65 years old (HR: 0.95; 95 % CI: 0.92-0.98), and those with higher polygenic risk scores (PRS; HR: 0.92; 95 % CI: 0.89-0.95). Among five food groups, a higher diversity score for meat and protein alternatives was associated with a lower risk of dementia (HR: 0.92; 95 % CI: 0.86-0.99).

CONCLUSION

Enhancing dietary diversity reduces dementia risk, and is potentially influenced by genetic predisposition. Consuming a diverse range of foods may be an effective strategy against dementia.

Longitudinal associations between dietary diversity and serum lipid markers in Japanese workers

OBJECTIVE

The aim of this study was to determine the longitudinal associations between dietary diversity score and serum lipid markers in a five-year follow-up period in Japanese workers.

METHODS

This study included 745 participants aged 20-60 years in 2012-2013 without dyslipidemia at baseline who participated at least once from 2013 to 2017. Dietary intake was assessed using a food frequency questionnaire, and dietary diversity score was determined using the Quantitative Index for Dietary Diversity. Principal component analysis was used to determine three dietary patterns: healthy, western, and sweetener. Lipid markers including total cholesterol, triglycerides, LDL-cholesterol, HDL-cholesterol, and non-HDL-cholesterol were measured. Generalized estimating equations were used for calculating the cumulative mean of lipid profiles in the follow-up period according to the dietary diversity score at baseline with control of confounding factors.

RESULTS

Higher dietary diversity score was inversely associated with serum concentrations of LDL cholesterol (p for trend = 0.028), triglycerides (p for trend = 0.029), and non-HDL cholesterol (p for trend = 0.026) in women. The associations except for the association with serum triglycerides were robust after additional adjustment for three dietary patterns (healthy, western, and sweetener). The association with serum triglycerides disappeared after additional adjustment for a healthy pattern. There was no significant association between dietary diversity and dyslipidemia in men in the follow-up period.

CONCLUSIONS

This study suggests that dietary diversity is beneficial for lipid profiles in Japanese female workers.

The Dementia SomaSignal Test (dSST): A plasma proteomic predictor of 20-year dementia risk

INTRODUCTION

There is an unmet need for tools to quantify dementia risk during its multi-decade preclinical/prodromal phase, given that current biomarkers predict risk over shorter follow-up periods and are specific to Alzheimer's disease.

METHODS

Using high-throughput proteomic assays and machine learning techniques in the Atherosclerosis Risk in Communities study (n = 11,277), we developed the Dementia SomaSignal Test (dSST).

RESULTS

In addition to outperforming existing plasma biomarkers, the dSST predicted mid-life dementia risk over a 20-year follow-up across two independent cohorts with different ethnic backgrounds (areas under the curve [AUCs]: dSST 0.68-0.70, dSST+age 0.75-0.81). In a separate cohort, the dSST was associated with longitudinal declines across multiple cognitive domains, accelerated brain atrophy, and elevated measures of neuropathology (as evidenced by positron emission tomography and plasma biomarkers).

DISCUSSION

The dSST is a cost-effective, scalable, and minimally invasive protein-based prognostic aid that can quantify risk up to two decades before dementia onset.

HIGHLIGHTS

The Dementia SomaSignal Test (dSST) predicts 20-year dementia risk across two independent cohorts. dSST outperforms existing plasma biomarkers in predicting multi-decade dementia risk. dSST predicts cognitive decline and accelerated brain atrophy in a third cohort. dSST is a prognostic aid that can predict dementia risk over two decades.

Relationship between leisure activity and depression in Chinese older adults: chain mediating effect of diet and cognition

BACKGROUND

Leisure activity was associated with depression in older adults. However, the specific processes by which diet and cognition mediate the role of leisure activities and depression remain uncertain. The study aims to investigate the relationship between leisure activity and depression in older people and the underlying mechanisms involved, while constructing a comprehensive model that links these variables.

METHODS

Data came from the 2018 Chinese Longitudinal Healthy Longevity Survey. Mini-Mental State Examination and CES-D-10 were used to assess cognition and depression, respectively. PROCESS macro was employed to assess the mediation effects of diet and cognition on the relationship between leisure activity and depression.

RESULTS

Leisure activity was negatively associated with depression, with 35.90% of the total effect mediated through dietary diversity and cognitive function, of which 1.28% was from the chain-mediated effect of dietary diversity and cognition. In addition, 20.94% of the total effect mediated through a plant-based diet and cognitive function, of which 0.43% was from the chain-mediated effect of plant-based diet and cognition.

CONCLUSIONS

Leisure activities are linked to depression, with diet and cognition acting as chain-mediating factors. Public health experts recommend that older adults engage in leisure activities, ensure a broad spectrum of dietary intake, and prioritize the augmentation of plant-based diets as preventative strategies against depression.

Association between social isolation and diversity in food intake by gender in community-dwelling older adults: A cross-sectional study

AIM

Few studies have investigated the relationship between low dietary variety and clearly defined social isolation by gender. This study explored the association between dietary variety and social isolation, classified by operational definition, separately by gender in community-dwelling older adults.

METHODS

This cross-sectional study recruited respondents via mail. A total of 4798 participants aged ≥65 years participated in the on-site assessment. Social isolation was assessed by "lack of conversation," "lack of passive support," "lack of offering support," and "lack of social participation." Dietary variety was evaluated using the Dietary Variety Score (DVS).

RESULTS

The participants' median age was 73 (interquartile range 25-75: 69-77) years, and 2147 (44.7%) were male. After adjusting for covariates, with regard to male participants, a lack of offering support (β = -0.051, P = 0.019) and a lack of social participation (β = -0.089, P < 0.001) were associated with a low DVS. For female participants, only a lack of social participation was related to a low DVS (β = -0.067, P < 0.001). A lack of conversation and passive support were not associated with a low DVS for both genders (P >0.05).

CONCLUSION

The results indicate that encouraging social participation, regardless of gender, as well as preventing a lack of offering support for others among men, may contribute to improving individuals' DVS. Geriatr Gerontol Int 2024; 24: 930-938.

Health Information Source Patterns and Dietary Variety among Older Adults Living in Rural Japan

Dietary variety is associated with some health outcomes among older adults. Rural areas, however, often have difficulty accessing health information that influences dietary variety. This study aimed to identify patterns of health information sources by using latent class analysis and assess their association with dietary variety among older adults aged ≥ 75 in rural Japan (n = 411). Three patterns of health information sources were identified: multi-sources (29.7%), television-only (53.5%), and non-sources (16.8%). In the multi-sources pattern, more people used television, radio, and newspapers. The television-only pattern had mostly television users, with fewer other sources. The non-sources pattern had many reporting "none." Logistic regression analysis revealed that the multi-sources pattern has a significant positive effect on dietary variety compared with the non-sources pattern (odds ratio: 5.434, 95% confidence interval: 1.792-16.472), even after adjusting for socioeconomic factors and physical health status. These findings underscore the positive impact of broad access to health information on the dietary habits of older individuals. The study highlights the importance of promoting access to diverse health information sources to enhance dietary variety and overall well-being among rural older adults.

Effect of Dietary Habits on Alzheimer's Disease Progression

PURPOSE

Research on the relationship between diet and dementia among Koreans are lacking. This study investigated the association between dietary habits and dementia progression over 3 years in patients with Alzheimer's disease dementia (ADD).

MATERIALS AND METHODS

This study included 705 patients with mild-to-moderate ADD. Dietary habits were assessed using the Mini Dietary Assessment Index, comprising 10 questions. Outcome measures included the Clinical Dementia Rating scale-Sum of Boxes (CDR-SB), Seoul-Instrumental Activities of Daily Living, Caregiver-Administered Neuropsychiatric Inventory (CGA-NPI), and neuropsychological test battery (NTB) z-scores, which were evaluated annually over 3 years.

RESULTS

In Q10 (eat all food evenly without being picky), the 3-year mean differences in CDR-SB (increases in scores represent worsening) compared to the "rarely" group were -1.86 [95% confidence interval (CI)=-3.64 - -0.09, p=0.039] for the "usually" group and -2.23 (95% CI=-4.40 - -0.06, p=0.044) for the "always" group. In Q7 (add salt or soy sauce to food when eating), the 3-year mean differences in CDR-SB compared to the "always" group were -2.47 (95% CI=-4.70 - -0.24, p=0.030) for the "usually" group and -3.16 (95% CI=-5.36 - -0.96, p=0.005) for the "rarely" group. The "rarely" and "usually" groups in Q7 showed significantly less decline in NTB z-score and CGA-NPI compared to the "always" group.

CONCLUSION

Eating a balanced diet and reducing salt intake were associated with a slower decline in dementia severity, cognition, and behavioral alterations in patients with ADD.

Nutrition and Healthy Ageing in Asia: A Systematic Review

BACKGROUND

Nutrition plays a key role in modulating the likelihood of healthy ageing. In the present study, we aimed to conduct a systematic review to assess the impact of nutrition on healthy ageing in Asia.

METHODS

The systematic review was registered in the International Prospective Register of Systematic Reviews database (CRD42023408936) and conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PubMed, Web of Science, and Embase databases were searched up to February 2023 without language restrictions. We included prospective cohort studies that evaluated the associations of intake of a single food or consumption of a single nutrient at midlife; adherence to various dietary patterns at midlife; and improved adherence to dietary patterns from mid- to late life with the likelihood of healthy ageing and its components.

RESULTS

Out of 16,373 records, we included 71 papers comprising 24 cohorts from Singapore, China, Japan, and Thailand. The healthy ageing components included cognitive function, physical function, and depression. The majority of studies supported the observation that the likelihood of healthy ageing and its components in late life was positively increased by a higher consumption of healthy foods, such as vegetables, fruits, fish, nuts, legumes, tea, milk, and dairy, at midlife, and also by greater adherence to dietary patterns with high diversity scores or high total antioxidant capacities. Furthermore, improved adherence to healthy dietary patterns from mid- to late life also increased the likelihood of healthy ageing in late life.

CONCLUSION

Consuming healthy foods and adhering to healthy dietary patterns at midlife can promote the likelihood of healthy ageing. Moreover, improving diet quality from mid- to late life can still be beneficial.