Relationships between macronutrient intake, handicaps, and cognitive impairments in free living elderly people

Protein Intake and Cognitive Function in Older Adults: A Systematic Review and Meta-Analysis

Introduction:

The present study investigated the association between protein intake and cognitive function in older adults.

Methods:

We performed a literature search with no restriction on publication year in MEDLINE, SCOPUS, CINAHL, AgeLine from inception up to October 2020. Observational studies that investigated as a primary or secondary outcome the association of protein intake and cognitive function in older adults aged ⩾60 years were included.

Results:

Nine cross-sectional studies that investigated a total of 4929 older adults were included in the qualitative analysis. Overall cognitive function was examined in 6 studies. Four investigations reported null associations and 2 studies found that older adults with a high protein intake had higher global cognitive function than their counterparts. Results from the meta-analysis suggested that there were no significant associations between protein consumption and global cognitive function in older adults, regardless of gender. Three studies investigated other cognitive domains. Memory and protein intake were significantly and positively correlated in all studies. In addition, visuospatial, verbal fluency, processing speed, and sustained attention were positively associated with protein consumption in 1 study each.

Conclusion:

No significant associations between protein intake and global cognitive function were observed in neither qualitative nor quantitative analyses. The association between protein consumption with multiple other cognitive domains were also tested. As a whole, 3 studies reported a positive and significant association between high protein intake and memory, while 1 study observed a significant and positive association with visuospatial, verbal fluency, processing speed, and sustained attention.

Macronutrient Intake and Inadequacies of Community-Dwelling Older Adults, a Systematic Review

BACKGROUND

Anorexia of ageing may predispose older adults to under-nutrition and protein energy malnutrition. Studies, however, report a large variation in nutrient inadequacies among community-dwelling older adults.

SUMMARY

This systematic review provides a comprehensive overview of the energy and macronutrient intakes and possible inadequacies in community-dwelling older adults. PubMed and EMBASE were screened up to December 2013; data from national nutrition surveys were added. Forty-six studies were included, following the PRISMA guideline.

KEY MESSAGES

Mean daily energy intake was 8.9 MJ in men and 7.3 MJ in women. Mean daily carbohydrate and protein intakes were 46 and 15 En% in men and 47 and 16 En% in women, respectively. Mean daily total fat, saturated fatty acid (SFA), mono-unsaturated fatty acid (MUFA) and poly-unsaturated fatty acid intakes were respectively 34, 13, 13 and 5-6 En%. The carbohydrates and MUFA intakes are below the acceptable macronutrient distribution ranges (AMDR). Fat intake is relatively high, and SFA intake exceeds the upper-AMDR. Based on the estimated average requirement (EAR) cut-point method, 10-12% of older adults do not meet the EAR for protein. To interpret a possible energy imbalance additional information is needed on physical activity, energy expenditure and body weight changes. This systematic review indicates a suboptimal dietary macronutrient distribution and a large variation in nutrient intakes among community-dwelling older adults.

Carbohydrates for improving the cognitive performance of independent-living older adults with normal cognition or mild cognitive impairment

BACKGROUND

Mild cognitive impairment (MCI) is an intermediate state between normal cognition and dementia in which daily function is largely intact. This condition may present an opportunity for research into the prevention of dementia. Carbohydrate is an essential and easily accessible macronutrient which influences cognitive performance. A better understanding of carbohydrate-driven cognitive changes in normal cognition and mild cognitive impairment may suggest ways to prevent or reduce cognitive decline.

OBJECTIVES

To assess the effectiveness of carbohydrates in improving cognitive function in older adults.

SEARCH STRATEGY

We searched ALOIS, the Cochrane Dementia and Cognitive Improvement Group Specialized Register on 22 June 2010 using the terms: carbohydrates OR carbohydrate OR monosaccharides OR disaccharides OR oligosaccharides OR polysaccharides OR CARBS. ALOIS contains records from all major healthcare databases (The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS) as well as from many trial databases and grey literature sources.

SELECTION CRITERIA

All randomised controlled trials (RCT) that have examined the efficacy of any form of carbohydrates in normal cognition and MCI.

DATA COLLECTION AND ANALYSIS

One review author selected and retrieved relevant articles for further assessment. The remaining authors independently assessed whether any of the retrieved trials should be included. Disagreements were resolved by discussion. 

MAIN RESULTS

There is no suitable RCT of any form of carbohydrates involving independent-living older adults with normal cognition or mild cognitive impairment.

AUTHORS' CONCLUSIONS

There are no suitable RCTs on which to base any recommendations about the use of any form of carbohydrate for enhancing cognitive performance in older adults with normal cognition or mild cognitive impairment. More studies of many different carbohydrates are needed to tease out complex nutritional issues and further evaluate memory improvement.

Dietary fatty acids in dementia and predementia syndromes: epidemiological evidence and possible underlying mechanisms

Drugs currently used in the treatment of cognitive impairment and dementia have a very limited therapeutic value, suggesting the necessity to potentially individualize new strategies able to prevent and to slow down the progression of predementia and dementia syndromes. An increasing body of epidemiological evidence suggested that elevated saturated fatty acids (SFA) could have negative effects on age-related cognitive decline (ARCD) and mild cognitive impairment (MCI). Furthermore, a clear reduction of risk for cognitive decline has been found in population samples with elevated fish consumption, high intake of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), particularly n-3 PUFA. Epidemiological findings demonstrated that high PUFA intake appeared to have borderline non-significant trend for a protective effect against the development of MCI. Several hypotheses could explain the association between dietary unsaturated fatty acids and cognitive functioning, including mechanisms through the co-presence of antioxidant compounds in food groups rich in fatty acids, via atherosclerosis and thrombosis, inflammation, accumulation of b-amyloid, or via an effect in maintaining the structural integrity of neuronal membranes, determining the fluidity of synaptosomal membranes that thereby regulate neuronal transmission. However, recent findings from clinical trials with n-3 PUFA supplementation showed efficacy on depressive symptoms only in non-apolipoprotein E (APOE) epsilon4 carriers, and on cognitive symptoms only in very mild Alzheimer's disease (AD) subgroups, MCI patients, and cognitively unimpaired subjects non-APOE epsilon4 carriers. These data together with epidemiological evidence support a possible role of fatty acid intake in maintaining adequate cognitive functioning and possibly for the prevention and management of cognitive decline and dementia, but not when the AD process has already taken over.

Lifestyle-related factors in predementia and dementia syndromes

Cognitive decline and dementia have a deep impact on the health and quality of life of older subjects and their caregivers. Since the therapeutic options currently available have demonstrated limited efficacy, the search for preventive strategies for cognitive decline and dementia are mandatory. A possible role of lifestyle-related factors was recently proposed for age-related changes of cognitive function, predementia syndromes and the cognitive decline of degenerative (Alzheimer's disease [AD]) or vascular origin. At present, cumulative evidence suggests that vascular risk factors may be important in the development of mild cognitive impairment (MCI), dementia and AD. Moderate alcohol drinking has been proposed as a protective factor against MCI and dementia in several longitudinal studies, but contrasting findings also exist. The Mediterranean diet could therefore be an interesting model with which to further study the association between dietary patterns and cognitive functioning, given the suggested role of many components of this diet (monounsaturated fatty acids, polyunsaturated fatty acids, cereals and red wine) in contrasting cognitive impairment and dementia. The association between low education and predementia and dementia syndromes is supported by the majority of studies, but very few studies have investigated whether this association may be attributed with lifestyle factors that covary with education. Studies in the literature seem to identify in physical exercise one promising strategy in decreasing cognitive decline, but some of the limitations of these studies do not allow us to draw definite conclusions. At present, in older subjects, healthy diets, antioxidant supplements, the prevention of nutritional deficiencies, and moderate physical activity could be considered the first line of defense against the development and progression of predementia and dementia syndromes. However, in most cases, these were only observational studies, and results are awaited from large multicenter randomized clinical trials in older persons that may clarify the possible synergy, for example, between moderate exercise, physical activity and healthy Mediterranean diet on cognition in the elderly.

Dairy, fruit, and vegetable intakes and functional limitations and disability in a biracial cohort: the Atherosclerosis Risk in Communities Study

BACKGROUND

Dairy, fruit, and vegetable intakes may be associated with functional limitations and disability through their role in muscle function, osteoporosis, and prevention of the oxidative damage associated with aging and chronic disease.

OBJECTIVE

The associations between dairy, fruit, and vegetable intakes and functional limitations and disability were examined in African Americans and whites (baseline age: 45-64 y; n=9404) in the Atherosclerosis Risk in Communities (ARIC) Study.

DESIGN

Logistic regression analyses were used to ascertain the associations between usual dairy, fruit, and vegetable intakes obtained at baseline by using a food-frequency questionnaire and lower-extremity function, activities of daily living (ADLs), and instrumental ADLs (IADLs) self-reported approximately 9 y later in models stratified by race and sex.

RESULTS

Baseline dairy, fruit, and vegetable intakes tended to be inversely associated with impaired lower-extremity function, ADLs, and IADLs approximately 9 y later, particularly in African American women. For example, in African American women, baseline dairy intakes were inversely associated with impaired ADLs and IADLs [odds ratio (95% CI): 0.60 (0.40, 0.90) and 0.69 (0.48, 0.98), respectively [corrected] in the 3rd versus the [corrected] 1st tertile of intake (P [corrected] for trend<0.05]. Combined baseline intakes of fruit and vegetables were also inversely associated with impaired lower-extremity function, ADLs, and IADLs [odds ratio (95% CI): 0.67 (0.47, 0.95), 0.52 (0.36, 0.76), and 0.64 (0.45, 0.90), respectively; P for trend<0.05].

CONCLUSIONS

Dairy, fruit, and vegetable intakes may be inversely associated with functional limitations and disability. Further research is needed to ascertain the effect of diet on subsequent functional limitations and disability.

Mediterranean diet and cognitive decline

OBJECTIVE

To investigate the possible role of diet in age-related cognitive decline (ARCD) and cognitive impairment of both degenerative (Alzheimer's disease, AD) and vascular (vascular dementia, VaD) origin.

DESIGN

Literature review.

RESULTS

In an elderly population of southern Italy with a typical Mediterranean diet, high energy intake of monounsaturated fatty acids (MUFA) appeared to be associated with a high level of protection against ARCD. In addition, dietary fat and energy in the elderly seem to be risk factors, while fish consumption and cereals are found to reduce the prevalence of AD in European and North American countries. Finally, the relative risk of dementia (AD and VaD) was lower in the subjects of a French cohort who drank three or four glasses of red wine each day compared with total abstainers.

CONCLUSION

Essential components of the Mediterranean diet--MUFA, cereals and wine--seem to be protective against cognitive decline. As such, dietary antioxidants and supplements, specific macronutrients of the Mediterranean diet, oestrogens and anti-inflammatory drugs may act synergistically with other protective factors, opening up new therapeutic interventions for cognitive decline.

The relationship between cognitive and physical performance: MacArthur Studies of Successful Aging

BACKGROUND

The relationship between change in cognitive and physical performance has yet to be fully understood. Because aging decreases the ability to learn new information while preserving more established knowledge, this article examines whether the association between change in cognitive and physical performance depends on the nature of the physical task.

METHODS

Data from the MacArthur Research Network on Successful Aging Community Study--a longitudinal three-site, cohort study of high-functioning, disability-free Americans aged 70 to 79 in 1988 (reinterviewed in 1991 and 1995)--are used for this investigation. We examine the association between change in cognitive performance and two categories of physical performance: novel/attentional demanding physical tasks (e.g., standing on a single leg) or routine physical tasks (e.g., walking at a normal pace). Change in physical performance (over 7 years) is regressed on change in cognitive performance (over the same period) controlling for baseline cognitive ability, demographic factors, health status, and behavioral characteristics.

RESULTS

The findings suggest that declines in cognitive performance are associated with declines in both novel/attentional demanding and routine physical tasks. In addition to decline in cognition, gender, prevalent health conditions (e.g., cancer, high blood pressure, and the fracture of a hip), and smoking behavior are associated with decline in performance on some physical tasks.

CONCLUSIONS

The findings suggest that the successful execution of physical tasks demands cognitive processes regardless of the nature of the task. Researchers using performance-based measures of physical functioning should pay particular attention to the cognitive capacities of their subjects and how these might influence their assessment.

High monounsaturated fatty acids intake protects against age-related cognitive decline

OBJECTIVE

To study the relationships between dietary macronutrient intakes and age-related changes in cognitive functions.

METHODS

We investigated these associations in the prevalence survey (1992 through 1993) of the Italian Longitudinal Study on Aging (ILSA). The population-based sample of 5,632 subjects of the ILSA, age 65 to 84 years, was identified from the electoral rolls of eight Italian municipalities. In this study, standardized test batteries assessing global cognitive functions (Mini-Mental State Examination [MMSE]), selective attention (Digit Cancellation Test [DCT]), and episodic memory (Babcock Story Recall Test), and a semi-quantitative food frequency questionnaire evaluating macronutrient energy intakes, were performed on 278 nondemented elderly subjects from the randomized cohort of Casamassima, Bari (n = 704).

RESULTS

There was an inverse relationship between monounsaturated fatty acids (MUFAs) energy intake and cognitive decline (MMSE < 24). The effect of education on the odds of having a MMSE score <24 decreased exponentially with the increase of MUFA intakes (over 2,400 kJ; odds ratio, 0.69). Moreover, a significant inverse association was observed between MUFA intakes and DCT score (odds ratio, 0.99). No association was found between nutritional variables and episodic memory.

CONCLUSIONS

In an elderly population of Southern Italy with a typical Mediterranean diet, high MUFA intakes appeared to be protective against age-related cognitive decline. Prospective clinical trials are needed to evaluate the impact of specific dietary macronutrient intakes on the age-related changes of cognitive functions.

Disability and cognitive impairment in the elderly

Disability and cognitive impairment show similar patterns of increasing frequency with ageing. A review of the published literature shows that there is a cross-sectional relationship between cognitive impairment and disability, independent of demographic, medical, and lifestyle factors. Some instrumental activities of daily living (IADL) items appear more specifically related to cognitive impairment, but cognition and functional impairment are distinct concepts requiring separate assessments. Subjects with low cognitive performances are at higher risk of functional impairment in the following years. Cognitive impairment as well as disability increase the risk of death and institutionalization. Preventive strategies could be directed against the risk factors of cognitive impairment and disability, and would aim to delay the onset of dementia. Prevention of disability associated with cognitive impairment needs further assessment in elderly community-dwellers. Further research is needed to better identify the specific areas cognition involved in the disablement process.