Diet quality and cognitive function in mid-aged and older men and women

Comparison of Eating Habits, Body Composition and Densitometric Parameters between Subjects with Normal Cognitive Function and Mild Cognitive Impairment: An Observational Study

The role of nutrition in the ageing process of the brain is pivotal. Therefore, the study aimed to compare eating habits, body composition and densitometric parameters between subjects with normal cognitive function (NCF) and mild cognitive impairment (MCI). A total of 95 subjects with NCF (74% of women) and 95 individuals with MCI (77% of women) aged 50-70 years were studied. Densitometric parameters were evaluated using dual-energy X-ray absorptiometry methods. Eating habits were assessed using the food frequency questionnaire and 3-day diary records, and advanced glycation end products (AGEs) intake was calculated. Significant differences between groups were detected for the %fat in the right arm (NCF vs. MCI: 38.4 (30.4-46.8) vs. 43.5 (35.5-49.2)%, p = 0.0407). Moreover, the MCI group had a significantly lower intake of calcium (p = 0.0010), phosphor (p = 0.0411), vitamins B2 (p = 0.0138) and B12 (p = 0.0024) compared to the NCF group, with both groups also differing in the frequency of butter (p = 0.0191) and fermented milk beverages (p = 0.0398) intake. Analysis restricted to women showed significant differences between groups in right arm %fat, VAT mass, calcium, vitamins B2, B12, butter and fermented milk products intake, while in men, differences were detected in the intake of calcium, iodine, vitamin B1, water and AGEs. In conclusion, subjects with NCF and MCI have comparable densitometric variables but differ significantly in some body composition parameters and the intake of some food groups and nutrients.

Inverse Association between Cheese Consumption and Lower Cognitive Function in Japanese Community-Dwelling Older Adults Based on a Cross-Sectional Study

Diet modification may contribute to the prevention of age-related cognitive decline. The association between dairy product consumption and cognitive function in older people remains unknown. We investigated whether cheese intake is associated with lower cognitive function (LCF) in community-dwelling older adults. This cross-sectional study included 1503 adults aged over 65 years. The analyzed data were obtained through face-to-face interviews and functional ability measurement. Cognitive function was assessed using the mini-mental state examination (MMSE), and a score ≤23 was defined as LCF. The prevalence of LCF was 4.6%, and this group had smaller calf circumference, slower usual walking speed, and a more frequent history of anemia than subjects with MMSE scores >23. After adjusting for confounding factors, logistic regression analysis revealed cheese intake (odds ratio (OR) = 0.404, 95% confidence interval (CI) = 0.198-0.824), age (OR = 1.170, 95% CI = 1.089-1.256), usual walking speed (OR = 0.171, 95% CI = 0.062-0.472) and calf circumference (OR = 0.823, 95% CI = 0.747-0.908) to be significant factors associated with LCF. Although the present study was an analysis of cross-sectional data of Japanese community-dwelling older adults, the results suggest that cheese intake is inversely associated with LCF.

Dietary sodium/potassium intake and cognitive impairment in older patients with hypertension: Data from NHANES 2011-2014

This study aimed to assess the relationship between dietary sodium/potassium intake and cognition in elderly individuals with hypertension. We designed a cross-sectional study based on the 2011-2014 National Health and Nutrition Examination Survey (NHANES) 2011-2014. A multivariable-logistic regression analysis was performed to analyze the relationship between sodium/potassium intake and cognitive impairment. Restricted cubic spline (RCS) based on regression analysis to assess the nonlinear dose-response relationship between dietary sodium intake and cognitive performance. Out of the 2276 participants included in this study, 1670 patients had hypertension. Compared with the lowest quartile of dietary sodium intake, the lowest weighted odds ratio of cognitive impairment in DSST was observed in Q4 (OR = 0.45, 0.29-0.70), and a similar trend was observed in AFT (OR = 0.34, 0.18-0.65). After adjusting the covariates, the lowest weighted multivariable-adjusted OR of cognitive impairment in DSST were also observed in Q4 (OR = 0.47, 0.26-0.84) compared with the lowest quartile of dietary sodium intake. The RCS results showed that dietary sodium intake was U-shaped and associated with the risk of cognitive impairment in the DSST (P_{non-linearity}  = 0.0067). In addition, no significant association was observed between dietary potassium intake and different dimensions of cognitive performance. In conclusion, excessively high and low low dietary sodium were associated with impairment of specific processing speed, sustained attention, and working memory for elderly patients with hypertension in the United States. However, no association was observed between dietary potassium intake and cognition.

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

BACKGROUND & AIMS

A balanced diet integrating several foods and nutrients may promote the maintenance of brain function. Previous studies have substantiated the above hypothesis in the regional population in Japan. This study aimed to investigate the potential effect of dietary diversity on the risk of disabling dementia in a nationwide large-scale cohort of the Japanese population.

METHODS

A total of 38,797 participants (17,708 men and 21,089 women) aged 45-74 years were followed up for a median of 11.0 years. The daily frequencies of the consumption of each of the 133 food and beverage items listed on a food frequency questionnaire (excluding five alcoholic beverages) were measured. The dietary diversity score was calculated as the number of food items consumed per day. Multivariable adjusted Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of the dietary diversity score quintile groups.

RESULTS

We documented 4302 participants with disabling dementia (11.1%) during the follow-up period. Among women, the dietary diversity score was inversely associated with disabling dementia (highest quintile HR [with the lowest quintile as the reference]: 0.67; 95% CI: 0.56-0.78; Q1-Q5 p for trend <0.001), but this was not true among men (highest quintile HR: 1.06; 95% CI: 0.87-1.29; Q1-Q5 p for trend = 0.415). These results did not change substantially when using disabling dementia with stroke as the outcome; the association remained significant among women but was absent among men.

CONCLUSIONS

Our findings indicate that eating a variety of foods may prevent disabling dementia only among women. Thus, the habit of consuming a variety of food items has important public health implications for women.

No Effect of Calorie Restriction or Dietary Patterns on Spatial Working Memory During a 2-Year Intervention: A Secondary Analysis of the CALERIE Trial

BACKGROUND

The effect of calorie restriction (CR) on cognitive function is not well understood, and the impact of the dietary patterns consumed during CR has not been investigated.

OBJECTIVES

We analyzed the combined association of CR and dietary quality with spatial working memory (SWM) in healthy adults without obesity.

METHODS

The Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trial was a 2-y, multisite clinical trial. This trial was registered at clinicaltrials.gov as NCT00427193. Participants were randomized to a 25% reduction in EI (n = 143) or an ad libitum Control (n = 76). The Dietary Inflammatory Index (DII) and the Healthy Eating Index (HEI) captured dietary quality, with a lower DII and higher HEI score indicating a healthier diet. The Cambridge Neuropsychological Test Automated Battery battery was used to assess SWM. Longitudinal associations between each dietary pattern index and SWM for CR and Control were assessed by multivariable negative binomial models that included baseline, 12-mo, and 24-mo visits.

RESULTS

Participants were aged 38.1 ± 7.2 y with a BMI of 25.1 ± 1.7 kg/m². A total of 70% of the participants were female. Baseline mean DII and HEI scores were -0.15 (range: -3.77, 4.21) and 59.1 (24.1, 91.0) and did not differ between groups. Improvements in DII and HEI were significantly different between CR and Control over 2 y (both P-interaction = 0.001). In longitudinal analyses, there was no association of either index with SWM. Furthermore, though within-group improvements in SWM were observed at 12 mo, there was no statistically significant difference between CR (SWM errors: 9.0; 95% CI: 1.9, 41.6) and Control (11.7; 95% CI: 2.6, 53.5; P > 0.99), holding DII constant. Comparable results were observed at 24 mo and for the HEI.

CONCLUSIONS

Dietary quality during CR was not associated with measures of SWM over 2 y in healthy adults without obesity. These results suggest that, in healthy populations, dietary patterns and CR may have a limited impact on working memory. Further research is required to understand the concurrent effect of these nutritional strategies.

Apolipoprotein E gene variants shape the association between dietary fibre intake and cognitive decline risk in community-dwelling older adults

BACKGROUND

healthy dietary patterns have been associated with lower risk for age-related cognitive decline. However, little is known about the specific role of dietary fibre on cognitive decline in older adults.

OBJECTIVE

this study aimed to examine the association between dietary fibre and cognitive decline in older adults and to assess the influence of genetic, lifestyle and clinical characteristics in this association.

DESIGN AND PARTICIPANTS

the Invecchiare in Chianti, aging in the Chianti area study is a cohort study of community-dwelling older adults from Italy. Cognitive function, dietary and clinical data were collected at baseline and years 3, 6, 9 and 15. Our study comprised 848 participants aged ≥ 65 years (56% female) with 2,038 observations.

MAIN OUTCOME AND MEASURES

cognitive decline was defined as a decrease ≥3 units in the Mini-Mental State Examination score during consecutive visits. Hazard ratios for cognitive decline were estimated using time-dependent Cox regression models.

RESULTS

energy-adjusted fibre intake was not associated with cognitive decline during the 15-years follow-up (P > 0.05). However, fibre intake showed a significant interaction with Apolipoprotein E (APOE) haplotype for cognitive decline (P = 0.02). In participants with APOE-ɛ4 haplotype, an increase in 5 g/d of fibre intake was significantly associated with a 30% lower risk for cognitive decline. No association was observed in participants with APOE-ɛ2 and APOE-ɛ3 haplotypes.

CONCLUSIONS AND RELEVANCE

dietary fibre intake was not associated with cognitive decline amongst older adults for 15 years of follow-up. Nonetheless, older subjects with APOE-ɛ4 haplotype may benefit from higher fibre intakes based on the reduced risk for cognitive decline in this high-risk group.

Association of Dietary Quality with Cognitive Function in Chinese Adults Aged 55 Years and Above: A Longitudinal Study

OBJECTIVES

Diet is an important modifiable factor for brain health and aging. Present study aimed to explore association of dietary quality with cognitive function and poor cognition in middle-aged and older adults participating in the China Health and Nutrition Survey (CHNS).

DESIGN

A longitudinal study with a twenty-year follow-up.

SETTING AND PARTICIPANTS

Data were drawn from the CHNS 1997, 2000, 2004, 2006, 2015 and 2018. Subjects aged 55 years and more who participated in at least two waves and had completed data on socio-demographics, lifestyle, disease history, anthropometrics, dietary measure and cognitive assessment were eligible in present study.

METHODS

Baseline diet were assessed by 3-day 24-hour dietary recalls and used to evaluate diet quality via China Elderly Dietary Guidelines Index 2022 (CDGI 2022-E). Cognitive function was examined using part items of the Telephone Interview for Cognitive Status-modified. Three-level linear mixed effects models and three-level mixed effects logistic regression models were performed to estimate the association between diet quality and cognitive function and odds of poor cognition, respectively.

RESULTS

At baseline, 4173 subjects with median age of 63.7 years were recruited. Median of CDGI 2022-E total score was 44.7. Median score of global cognition was 16.0, and the proportion of people with poor cognitive function was 13.9%. Difference in global cognitive score was observed by tertiles of CDGI 2022-E (p<0.05). Significant associations of high diet quality with increment in global cognitive score [β (95%CI): 0.704 (0.394~1.015)], composite cognitive z score [0.086 (0.045~0.128)] and standardized verbal memory score [0.221 (0.122~0.320)] were observed in total subjects. Consistent associations were also found in those below 65 years at baseline. The likelihood of poor cognition in the highest tertile of CDGI 2022-E decreased by 18% (95%CI: 0.698~0.965) relative to the lowest tertile group in total population.

CONCLUSIONS

High diet quality may be beneficial for improving cognitive function and delaying cognitive decline in Chinese middle-aged and older population.

The Effect of Nighttime Snacking on Cognitive Function in Older Adults: Evidence from Observational and Experimental Studies

Evidence shows that supplementary snacking could provide older adults with nutrients that cannot be obtained through three meals a day. However, whether and how supplementary snacking, especially nighttime snacking, affects older adults' cognitive function remain unclear. The present study examined the effect of nighttime snacking on cognitive function for older adults. In study 1, we investigated the association between nighttime snacking and cognitive function based on data from 2618 community-dwelling older adults from the China health and nutrition survey (CHNS). In study 2, we conducted an experiment (n = 50) to explore how nighttime acute energy intake influences older adults' performance on cognitive tasks (immediate recall, short-term delayed recall, and long-term delayed recall). Both the observational and experimental studies suggested that nighttime snacking facilitated older adults' cognitive abilities, such as memory and mathematical ability, as indicated by subjective measures (study 1) and objective measures (studies 1 and 2). Moreover, this beneficial effect was moderated by cognitive load. These findings bridge the gap in the literature on the relationships between older adults' nighttime snacking and cognitive function, providing insight into how to improve older adults' dietary behaviors and cognitive function.

Appetitive interoception, the hippocampus and western-style diet

Obesity, Type 2 diabetes and other metabolic disorders continue to pose serious challenges to human health and well-being. An important source of these challenges is the overconsumption of saturated fats and sugar, main staples of what has been called the Western-style diet (WD). The current paper describes a theoretical model and supporting evidence that links intake of a WD to interference with a specific brain substrate that underlies processing of interoceptive signals of hunger and satiety. We review findings from rats and humans that the capacity of these signals to modulate the strength of appetitive and eating behavior depends on the functional integrity of the hippocampus and the learning memory operations it performs. Important among these operations is the use of contextual information to retrieve memories that are associated with other events. Within our framework, satiety provides an interoceptive context that informs animals that food cues and appetitive behavior will not be followed by rewarding postingestive outcomes. This serves to prevent those cues and responses from retrieving those reward memories. The findings reviewed provide evidence that consuming a WD and the high amounts of saturated fat and sugar it contains (a) is associated with the emergence of pathophysiologies to which the hippocampus appears selectively vulnerable (b) impairs hippocampal-dependent learning and memory (HDLM) and (c) weakens behavioral control by interoceptive hunger and satiety contextual stimuli. It is hypothesized that these consequences of WD intake may establish the conditions for a vicious cycle of further WD intake, obesity, and potentially cognitive decline.

The Effects of “Diet–Smoking–Gender” Three-Way Interactions on Cognitive Impairment among Chinese Older Adults

Investigations on gender variations in the risk factors of cognitive impairment are required to promote future precision medicine among older adults, as well as to contribute to a better understanding of the “male–female health-survival paradox”. With this study, we aimed to investigate the effects of “diet–smoking–gender” three-way interactions on cognitive impairments among Chinese older adults. We conducted a 16-year prospective cohort study among 15,953, 15,555, 16,849, 9716, 7116, and 13,165 older adults from the 2002, 2005, 2008–2009, 2011–2012, 2014, and 2017–2018 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS), respectively. Cognitive impairment was measured by the Mini-Mental State Examination (MMSE). The dietary diversity score (DDS) was calculated using the CLHLS food frequency questionnaire. Generalized estimating equations (GEE) were used to assess the “diet–smoking–gender” three-way interaction effects on cognitive impairment across the six waves of CLHLS. We found that higher dietary diversity was associated with lower probability of cognitive impairment among older adults (OR = 0.92; 95%CI = 0.90, 0.98). However, smoking behavior may negatively influence the protective effect of higher dietary diversity on cognitive function among females (OR = 1.26; 95%CI = 1.07, 1.49). Our findings imply that we should take gender differences and lifestyle behaviors into consideration in implementing dietary interventions to improve cognitive function among older adults.

Are dietary patterns becoming more processed? The effects of different dietary patterns on cognition: A review

Background: Identifying dietary patterns that promote healthy aging has become increasingly important due to changes in food processing and consumption of processed foods. Recently, the effects of these foods and unhealthy dietary patterns on cognitive function have become more widely recognized. Aim: The aim of this review is to discuss the association between various dietary patterns and cognition in older age, while also highlighting growing evidence that ultra processed food (UPF) may negatively impact healthy aging. Methods: We have performed a non-systematic literature review searches in Google Scholar electronic database with pre-defined terms relating to UPF, diet, dietary patterns, cognition and ageing. Results: The most prevalent diets in the literature include the Western, Mediterranean, Dietary Approach to Stop Hypertension (DASH), Mediterranean-DASH Intervention for Neurogenerative Delay (MIND), Japanese, Nordic, and plant-based diets. Based on the findings, higher intakes of fresh fruit and vegetables, wholegrains and oily fish are common components of dietary patterns that are positively associated with better cognitive function. In contrast, the characteristics of a Western style dietary pattern, consisting of high amounts of UPF's, are increasing in many countries even where the staple dietary pattern was identified as healthy (i.e. Japan). Conclusion: The consumption of UPF, classified by the NOVA food classification system as industrially manufactured foods containing high levels of starches, vegetable oils, sugar, emulsifiers, and foods additives, has a negative impact on the overall nutritional quality of individual diets.

Three Different Types of β-Glucans Enhance Cognition: The Role of the Gut-Brain Axis

Background

Dietary fiber is fermented in the lower gastrointestinal tract, potentially impacting the microbial ecosystem and thus may improve elements of cognition and brain function via the gut-brain axis. β-glucans, soluble dietary fiber, have different macrostructures and may exhibit different effects on the gut-brain axis. This study aimed to compare the effects of β-glucans from mushroom, curdlan and oats bran, representing β-(1,3)/(1,6)-glucan, β-(1,3)-glucan or β-(1,3)/(1,4)-glucan, on cognition and the gut-brain axis.

Methods

C57BL/6J mice were fed with either control diet or diets supplemented with β-glucans from mushroom, curdlan and oats bran for 15 weeks. The cognitive functions were evaluated by using the temporal order memory and Y-maze tests. The parameters of the gut-brain axis were examined, including the synaptic proteins and ultrastructure and microglia status in the hippocampus and prefrontal cortex (PFC), as well as colonic immune response and mucus thickness and gut microbiota profiles.

Results

All three supplementations with β-glucans enhanced the temporal order recognition memory. Brain-derived neurotrophic factor (BDNF) and the post-synaptic protein 95 (PSD95) increased in the PFC. Furthermore, mushroom β-glucan significantly increased the post-synaptic thickness of synaptic ultrastructure in the PFC whilst the other two β-glucans had no significant effect. Three β-glucan supplementations decreased the microglia number in the PFC and hippocampus, and affected complement C3 and cytokines expression differentially. In the colon, every β-glucan supplementation increased the number of CD206 positive cells and promoted the expression of IL-10 and reduced IL-6 and TNF-α expression. The correlation analysis highlights that degree of cognitive behavior improved by β-glucan supplementations was significantly associated with microglia status in the hippocampus and PFC and the number of colonic M2 macrophages. In addition, only β-glucan from oat bran altered gut microbiota and enhanced intestinal mucus.

Conclusions

We firstly demonstrated long-term supplementation of β-glucans enhanced recognition memory. Comparing the effects of β-glucans on the gut-brain axis, we found that β-glucans with different molecular structures exhibit differentia actions on synapses, inflammation in the brain and gut, and gut microbiota. This study may shed light on how to select appropriate β-glucans as supplementation for the prevention of cognitive deficit or improving immune function clinically.

Association between blood metals mixtures concentrations and cognitive performance, and effect modification by diet in older US adults

Background:

Chronic exposure to heavy metals has been associated with adverse neurological outcomes in older adults. Inflammatory processes are suspected as an underlying pathway by which metals exert their neurotoxicity. In parallel, a diet rich in antioxidant and anti-inflammatory components may protect against chronic inflammation.

Objectives:

We examined the associations of blood concentrations of lead, cadmium, and manganese as a mixture with cognitive performance in older US adults and potential modification of these associations by diet as measured by the Healthy Eating Index 2015 (HEI-2015) and the Adapted Dietary Inflammatory Index (ADII).

Methods:

We used data on 1,777 adults ≥60 years old from the US National Health and Nutrition Examination Survey (NHANES; 2011–2014). We derived the ADII and the HEI-2015 from two nonconsecutive 24-hour diet recalls. Cognitive performance was measured by the Consortium to Establish a Registry for Alzheimer’s Disease (CERAD) Word Learning subtest, the animal fluency test, and the Digit Symbol Substitution Test (DSST). We also constructed a composite z-score reflecting overall cognitive performance. We used quantile g-computation to evaluate the joint associations of a mixture of metals with cognitive performance test scores. We also evaluated effect modification by sex and diet quality indices using Cochran Q tests.

Results:

The median (interquartile range) of blood metals were 0.38 μg/L (0.35), 14.70 μg/L (11.70), and 8.74 μg/L (4.06) for cadmium, lead, and manganese, respectively. Increasing blood concentrations of all metals by one quartile was associated with a decrease in overall cognitive performance (–0.04; 95% confidence interval [CI] = –0.09, 0.02), CERAD (–0.04; 95% CI = –0.12, 0.03), animal fluency (–0.02; 95% CI, –0.11, 0.06), and DSST (–0.05; 95% CI = –0.11, 0.02) test scores. These associations were more pronounced in adults with high pro-inflammatory or low-diet quality and null or positive though imprecise associations in participants with a high anti-inflammatory. These associations also varied by sex with inverse associations in men and positive associations in women.

Conclusions:

Our findings suggest that adherence to an antioxidant and anti-inflammatory diet may prevent blood metals adverse cognitive effects among older adults. If confirmed, strategies based on diet could provide a potential complementary and efficient approach to counteract effects of environmental pollutants.

Higher fruit and vegetable variety associated with lower risk of cognitive impairment in Chinese community-dwelling older men: a 4-year cohort study

PURPOSE

Few studies have examined the variety in fruit and vegetable (FV) intake with cognitive impairment in older adults. This study examined the associations of variety in fruit, vegetable and combined FV with 4-year incident cognitive impairment in Chinese community-dwelling older adults.

METHODS

Data was derived from a cohort study among Chinese community-dwelling older adults aged ≥ 65 years in Hong Kong. At baseline, a validated food frequency questionnaire was used to assess variety in fruit, vegetable and combined FV. Cognitive impairment was defined as a Community Screening Instrument of Dementia score of < 29.5 points and/or Mini-Mental State Examination score of < 27 points. Adjusted multiple logistic regression was performed to examine the associations. Results are presented as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

Of the 1518 participants [median age: 70 years (IQR 68-74), 32.7% women] included at baseline, 300 men and 111 women were newly identified as cognitively impaired at the 4-year follow-up. In men, higher variety in vegetable (adjusted OR: 0.97, 95% CI 0.95-0.99, p = 0.029) and combined FV (adjusted OR: 0.98, 95% CI 0.96-0.98, p = 0.039) were significantly associated with a lower risk of cognitive impairment. Fruit variety was not associated with cognitive impairment. In women, there were no associations between variety in fruit, vegetable and combined FV with cognitive impairment in the adjusted model.

CONCLUSION

Independent of FV quantity, higher variety in vegetable and combined FV were associated with lower risk of cognitive impairment in Chinese community-dwelling older adults, and these associations were only observed in men.

Impact of vitamin D on cognitive functions in healthy individuals: A systematic review in randomized controlled clinical trials

Various functions in the central nervous system, such as growth, development, and cognition can be influenced by vitamins and minerals, which are capable of helping to maintain brain health and function throughout life. Cognition is understood as the aspects related to knowledge, learning, and understanding, as well as the ability to develop these functions. A possible association between low levels of vit D and deficit in the performance of cognitive functions in healthy humans or with some pathological condition is discussed. Because of this, the present systematic review analyzed only randomized clinical trials carried out in healthy non-athlete adults about intellectual and/or mental processes involving cognitive functions to identify whether these individuals with different levels of vit D are capable of interfering with the performance of the cognitive function. To do so, we adopted the PRISMA method criteria and registered it in the PROSPERO database. The search was performed in PubMed (MEDLINE), PsycINFO, Science Direct, Scopus, and Web of Science databases, 2,167 records were identified. The 5 most frequent cognitive domains in the selected studies were: processing speed, attention, verbal learning/memory, executive function, and general cognitive functions. We found that there are positive changes in the following domains: verbal memory and verbal working memory, learning memory, attention, executive function, and also cognitive function in general. We highlight the following suggestions for improvements that vitamin D supplementation may promote in the cognitive domains of healthy adults: a) low doses between 400 and 600 IU/d seem to be more effective when compared to doses between 2,400 and 5,000 IU/d and b) food fortification and enrichment with vit D, need further studies, as they seem to be more or as effective as synthetic supplementation. We evident that there is a need for trials that evaluate the control of vit D levels for healthy adult individuals is important, as they have the potential to minimize health problems, especially those involved in the reduction of cognitive abilities. Thus, the development of more clinical trials to obtain satisfactory answers on this topic needs to be encouraged.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, identifier: CRD42021262413.

Diet quality in an ethnically diverse population of older men in Australia

BACKGROUND/OBJECTIVES

To compare the Australian Dietary Guideline Index (DGI-2013) and the Pyramid-based Mediterranean Diet Score (pyrMDS) as measures of diet quality in an ethnically diverse group of older men.

SUBJECTS/METHODS

Seven hundred and ninety-four older men aged ≥75 participated in wave 3 (2012-2013) of the Concord Health and Ageing in Men Project. Dietary intake was assessed using a validated diet history questionnaire. Ethnicity was based on self-reported country of birth and categorised as Australian-born (418 men), Italian or Greek migrants (188), and other migrants (188). Incident cardiovascular outcomes until March 2018 were measured using the composite of major adverse cardiovascular events (MACE), which comprises all-cause mortality, acute myocardial infarction, congestive cardiac failure, coronary revascularisation and/or ischaemic stroke. Ability to predict incident cardiovascular outcomes and all-cause mortality were compared between standardised DGI-2013 pyrMDS scores by comparison of hazard ratios, discrimination (Harrell's C-statistic) and calibration (calibration plots).

RESULTS

Italian and Greek migrant men had significantly lower DGI-2013 scores (91.7 vs. 93.9; p = 0.01) but significantly higher pyrMDS scores (8.8 vs. 8.2; p < 0.0001) than Australian-born men. In the whole sample (794 men), the pyrMDS was a better predictor of both MACE (age-adjusted HR = 0.84; 95% CI = 0.75-0.94 vs. HR = 0.92; 95% CI = 0.82-1.03 for DGI-2013) and all-cause mortality (age-adjusted HR = 0.69; 95% CI = 0.60-0.80 vs. HR = 0.86; 95% CI = 0.74-0.99). The pyrMDS also demonstrated superior discrimination for predicting all-cause mortality and superior calibration for MACE and all-cause mortality.

CONCLUSIONS

The DGI-2013 appears to underestimate diet quality in older Italian and Greek migrant men. The pyrMDS appears superior to the DGI-2013 for prediction of incident cardiovascular disease and mortality regardless of ethnic background.

Association of adherence to the Australian Dietary Guidelines with cognitive performance and cognitive decline in the Sydney Memory and Ageing Study: a longitudinal analysis

This study investigated associations of adherence to the Australian Dietary Guidelines (ADG) with cognitive performance and cognitive decline over 6 years. We used longitudinal data from the Sydney Memory and Aging Study comprising 1037 community-dwelling non-demented participants aged 70–90 years. Dietary intake was assessed at baseline using the Dietary Questionnaire for Epidemiological Studies Version 2. Adherence to the ADG was scored using the Dietary Guideline Index 2013 (DGI-2013). Cognition was assessed using neuropsychological tests in six cognitive domains and global cognition at baseline and 2, 4 and 6 years later. Linear mixed models analysed the association between adherence to the ADG and cognitive function and cognitive decline over 6 years. Results indicated that overall adherence to the ADG was suboptimal (DGI-2013 mean score 43⋅8 with a standard deviation of 10⋅1; median score 44, range 12–73 with an interquartile range of 7). The percent of participants attaining recommended serves for the five food groups were 30⋅2 % for fruits, 11⋅2 % for vegetables, 54⋅6 % for cereals, 28⋅9 % for meat and alternatives and 2⋅1 % for dairy consumption. Adherence to the ADG was not associated with overall global cognition over 6 years (β = 0⋅000; 95 % CI: −0⋅007, 0⋅007; P = 0⋅95). Neither were DGI-2013 scores associated with change in global cognitive performance over 6 years (β = 0⋅002; 95 % CI: −0⋅002, 0⋅005; P = 0⋅41) nor in any individual cognitive domains. In conclusion, adherence to the ADG was not associated with cognitive health over time in this longitudinal analysis of older Australians. Future research is needed to provide evidence to support specific dietary guidelines for neurocognitive health among Australian older adults.

Dietary patterns in middle age: effects on concurrent neurocognition and risk of age-related cognitive decline

Context

Diet plays a critical role in cognitive integrity and decline in older adults. However, little is known about the relationship between diet and cognitive integrity in middle age.

Objective

To investigate the relationship between dietary patterns in healthy middle-aged adults and neurocognition both in middle age and later in life.

Data Sources

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, the following electronic databases were searched: Web of Science, Scopus, PubMed, and PsychInfo.

Data Extraction

Data from eligible articles was extracted by 2 reviewers.

Data Analysis

Articles included in the systematic review were synthesized (based on the synthesis without meta-analysis reporting guidelines) and assessed for quality (using the Joanna Briggs Institute checklist for randomized controlled trials, cohort studies, and cross-sectional studies) by 2 reviewers.

Results

Of 1558 studies identified, 34 met the eligibility criteria for inclusion. These comprised 9 cross-sectional studies, 23 longitudinal or prospective cohort studies, and 2 randomized controlled trials. Findings were mixed, with some studies reporting a significant positive relationship between adherence to various “healthy” dietary patterns and neurocognition, but others reporting no such relationship.

Conclusion

This systematic review demonstrated that adherence to the Mediterranean diet and other healthy dietary patterns in middle age can protect neurocognition later in life.

Systematic Review Registration

PROSPERO registration no. CRD42020153179.

Link Between Dietary Sodium Intake, Cognitive Function, and Dementia Risk in Middle-Aged and Older Adults: A Systematic Review

Background:

A key focus for dementia risk-reduction is the prevention of socio-demographic, lifestyle, and nutritional risk factors. High sodium intake is associated with hypertension and cardiovascular disease (both are linked to dementia), generating numerous recommendations for salt reduction to improve cardiovascular health.

Objective:

This systematic review aimed to assess, in middle- and older-aged people, the relationship between dietary sodium intake and cognitive outcomes including cognitive function, risk of cognitive decline, or dementia.

Methods:

Six databases (PubMed, EMBASE, CINAHL, Psych info, Web of Science, and Cochrane Library) were searched from inception to 1 March 2020. Data extraction included information on study design, population characteristics, sodium reduction strategy (trials) or assessment of dietary sodium intake (observational studies), measurement of cognitive function or dementia, and summary of main results. Risk-of-bias assessments were performed using the National Heart, Lung, and Blood Institute (NHLBI) assessment tool.

Results:

Fifteen studies met the inclusion criteria including one clinical trial, six cohorts, and eight cross-sectional studies. Studies reported mixed associations between sodium levels and cognition. Results from the only clinical trial showed that a lower sodium intake was associated with improved cognition over six months. In analysis restricted to only high-quality studies, three out of four studies found that higher sodium intake was associated with impaired cognitive function.

Conclusion:

There is some evidence that high salt intake is associated with poor cognition. However, findings are mixed, likely due to poor methodological quality, and heterogeneous dietary, analytical, and cognitive assessment methods and design of the studies. Reduced sodium intake may be a potential target for intervention. High quality prospective studies and clinical trials are needed.

The role of dietary diversity in preventing metabolic-related outcomes: Findings from a systematic review

Dietary diversity has been linked to insulin resistance; however, studies are inconsistent on whether dietary diversity protects against metabolic-related outcomes. We aimed to comprehensively assess metabolic-related outcomes of greater diversity across the diet and within major food groups. A systematic search of peer-reviewed literature was done in bibliographic databases (Medline, Scopus, and Web of Science) for longitudinal studies that reported on original research. Data extraction and quality appraisal used predefined criteria; reported findings were synthesized through a narrative approach. Fourteen studies were identified as eligible. Greater dietary diversity across major food groups, and diversity within fruits and/or vegetables, was associated with reduced risk of type 2 diabetes (T2D). Effects varied based on exposure definition and adjustment for known confounders. While diversity of less healthy foods was associated with greater adiposity, diversity of all foods and healthy foods was associated with reduced incidence of depression and cognitive decline. Evidence supports the protective effect of dietary diversity against cognitive decline and T2D. The association between dietary diversity and adiposity may be dependent on the healthiness of foods. Public health efforts to prevent metabolic-related diseases should include an emphasis on a varied diet as a healthy eating strategy.

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.

Association between dietary diversity and cognitive impairment among the oldest-old: Findings from a nationwide cohort study

BACKGROUND & AIMS

Dietary diversity is widely recommended in national and international guidelines; however, whether the beneficial effects on cognitive function still apply in the oldest-old (80+) has rarely been studied. This study aimed to evaluate the associations of dietary diversity with cognitive function among the oldest-old in a large prospective cohort in China.

METHODS

We conducted a long-term prospective analysis on 11,970 participants aged 80+ (6581 octogenarians, 3730 nonagenarians, and 1659 centenarians). We constructed the baseline dietary diversity score (DDS) based on eight food items of a food frequency questionnaire. Mini-mental state examination (MMSE) was used to classify the participants as having cognitive impairment or not and was also used as a continuous metric. Non-linear associations of DDS with cognitive impairment was evaluated by cox models with penalized splines. We used mixed-effect models for longitudinal data with repeated measurements of MMSE (for up to seven time during the follow-up between 1998 and 2014).

RESULTS

We documented 4778 cognitive impairment during 46,738 person-years of follow-up. Each one unit increase in DDS was associated with a 4% lower risk of cognitive impairment (adjusted hazard ratio (HR): 0.96; 95% confidential interval (CI): 0.94-0.98). Compared to participants with DDS of 0 score, those with a DDS of 1-2, 3-4, and higher than 5 scores had a lower cognitive impairment risk, the HRs were 0.86 (0.79-0.95), 0.82 (0.74-0.91), and 0.72 (0.64-0.82) respectively, and a significant trend emerged (p < 0.001). Compared with DDS of zero score, a DDS of 1-2,3-4, ≥5 was related to slower MMSE decline (β = 0.128, 0.162, 0.301, respectively, p < 0.01).

CONCLUSIONS

Even after the age of 80, dietary diversity may offer a simple and straightforward mean of identifying and screening individuals at high risk for cognitive impairment. Recommendation of dietary diversity may be advocated to attenuate cognitive decline and decrease the risk of cognitive impairment in the oldest-old, especially in a low income or middle-income countries.

Dietary intake of university students during COVID-19 social distancing in the Northeast of Brazil and associated factors

This study aimed to analyze the influence of COVID-19 social distancing on the dietary pattern of university students in the Northeast of Brazil and associated factors. This is a cross-sectional study of 955 students from four universities carried out via a web survey containing social, economic, demographic, and health information. A food frequency questionnaire was used to evaluate diet. Weight and dietary alterations were reported. Exploratory factor analysis and multivariate logistic regression were used as statistical analyses. The mean age was 26 and 53.7% of the students observed an increase in their weight. Four dietary patterns were identified: (1) a predominantly in natura pattern, (2) a pattern of processed and ultra-processed foods, (3) a protein-based pattern, and (4) an infusion-based pattern. It was observed that students having a darker skin colour (OR 1.8; CI 95% 1.3-2.6) and 19-29 years old and not being a health course student (OR 1.5; CI 95% 1.1-2.1) were associated with greater adhesion to the in natura pattern. Not engaging in physical activity was statistically associated with not adhering (OR 0.5; CI 95% 0.4-0.7) to that pattern. The university students who saw an alteration in their weight during the social distancing period studied presented a greater probability of consuming the processed and ultra-processed foods pattern (OR 1.8; CI 95% 1.2-2.6), while the men (OR 0.7; CI 95% 0.4-0.9) and those not engaging in physical activity (OR 0.7; CI 95% 0.5-0.9) presented less adhesion to that pattern. These findings indicate that social isolation affected the dietary intake of university students, with adhesion to mixed dietary patterns in terms of health. The adhesion to the pattern of processed and ultra-processed foods identified may affect the students' health, especially the occurrence of excess weight and obesity.

The Association between Dietary Variety and Physical Frailty in Community-Dwelling Older Adults

The aim of this cross-sectional study was to examine the association between diet variety and physical frailty in community-dwelling older adults. Data of 577 older adults (mean age: 74.0 ± 6.3 years, women: 62.5%) were analyzed. Diet variety was assessed using the Food Frequency Score (FFS) (maximum, 30 points). The FFS assessed the one-week consumption frequency of ten foods (meat, fish/shellfish, eggs, milk & dairy products, soybean products, green & yellow vegetables, potatoes, fruits, seafood, and fats & oil). Physical frailty was assessed using Fried's component (slowness, weakness, exhaustion, low physical activity, and weight loss). The participants were classified into frail, pre-frail, and non-frail groups. The prevalence of physical frailty was 6.6%. This study found significant associations between physical frailty and low FFS after adjusting for covariates (odds ratio (OR) 0.90, 95% confidence interval (CI) 0.84-0.97, p < 0.01). The optimal cutoff point of the FFS for physical frailty was ≤16 points. FFS lower than the cutoff point were significantly associated with physical frailty after adjusting for covariates (OR 3.46, 95% CI 1.60-7.50, p < 0.01). Diet variety assessed using the FFS cutoff value of ≤16 points was related to the physical frailty status in community-dwelling older adults.

The Effect of Healthy Diet on Cognitive Performance Among Healthy Seniors - A Mini Review

At present, a healthy diet appears to be one of the suitable strategies in slowing down cognitive decline in the process of aging. A number of evidence-based studies confirm its efficacy, safety, and cost-effectiveness. The aim of this mini review is to evaluate and describe recent randomized clinical and cohort studies exploring the effect of healthy diet on cognitive performance among healthy seniors, as well as to update the existing information on this research issue. For these reasons, the authors reviewed full-text, peer-reviewed journal articles written in English and available in Web of Science and PubMed between September 2017 and February 2020. Altogether nine original studies were detected. The results indicate that healthy diet and healthy diet components generally have a positive impact on the enhancement of cognitive functions. Furthermore, the findings reveal that dietary patterns, as well as single nutrients might have a significant effect on specific cognitive domains, such as memory in general, episodic memory, or processing speed. It also seems that a strict adherence to the dietary patterns and a higher diet variety have a more significant effect on the improvement of cognitive functions. Nevertheless, there seem to be gender differences in dietary behavior. More recently, personalized dietary interventions started to be used in delaying cognitive decline among healthy seniors. Therefore, more randomized control trials or N-of-1 trials should be performed in this research area in order to detect the most suitable dietary pattern or nutrients, which would, together with other modifiable lifestyle factors, contribute to the improvement of quality of life of the aging population.