Nutritional interventions for the prevention of cognitive impairment and dementia in developing economies in East-Asia: a systematic review and meta-analysis

Nutritional Interventions for the Prevention of Cognitive Decline in Patients With Mild Cognitive Impairment and Alzheimer Disease: Protocol for a Network Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Mild cognitive impairment (MCI) is the stage between cognitive decline due to physiological aging and the severity of decline seen in neurodegenerative disorders like Alzheimer disease (AD), which is among the most prevalent neurodegenerative disorders characterized by cognitive impairment. People with MCI are at increased risk of developing AD. Although MCI and AD are incurable, nutritional interventions can potentially delay or prevent their onset. Consequently, effective interventions used to decelerate or alleviate the progress of cognitive impairment in older people are a significant focus in geriatric care. Given the synergistic effects of nutrition on health, assessing the effectiveness of nutritional supplements or dietary composition in preventing MCI or AD is essential for developing interventional strategies.

OBJECTIVE

Our study aims to assess the effectiveness of various nutritional interventions, including special dietary types, dietary patterns, specific foods, nutritional intake, and nutritional supplements, in preventing cognitive decline among patients diagnosed with MCI or AD. To achieve this, we will use a comprehensive approach, including network meta-analysis, pairwise meta-analysis, and systematic review of randomized controlled trials (RCTs).

METHODS

The review will follow the Population, Intervention, Comparison, Outcome (PICO) model and the PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) guidelines. Two investigators will independently search PubMed electronically. Data extraction will follow the inclusion criteria, and data will be assessed for risk of bias using a revised tool. Additionally, evidence quality will be evaluated using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) framework. The outcomes of interest are assessing the cognitive outcomes in patients with MCI or AD. A systematic literature search will be conducted, identifying randomized controlled trials that investigate the impact of these nutritional interventions on cognitive function decline in individuals with MCI and AD. Network meta-analyses (random-effects model) and pairwise meta-analyses will then estimate the relative effectiveness of different nutritional interventions.

RESULTS

We included 51 studies, published between 1999 and 2023 (27 studies for AD and 24 studies for MCI) and involving 8420 participants. We completed data extraction for all 51 studies by December 2023. Currently, we are actively engaged in data analysis and manuscript preparation. We plan to finalize the manuscript and publish the comprehensive results by the end of 2024.

CONCLUSIONS

Our study holds significant clinical relevance given the rising prevalence of AD and the potential influence of nutritional interventions on cognitive function in individuals with MCI and AD. By investigating this relationship, our research aims to inform evidence-based decision-making in the development of prevention strategies for MCI and AD. The outcomes are expected to contribute to the establishment of reliable recommendations for MCI or AD management, providing substantial support in the field.

TRIAL REGISTRATION

PROSPERO CRD42022331173; http://tinyurl.com/3snjp7a4.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/47196.

A narrative review about cognitive impairment in metabolic Dysfunction-Associated liver disease (MASLD): Another matter to face through a holistic approach

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic hepatic disorder worldwide in both adults and children. It is well established that MASLD represents the hepatic manifestation of the metabolic syndrome whose definition includes the presence of obesity, type 2 diabetes (T2D), dyslipidemia, hypertension and hypercoagulability. All these conditions contribute to a chronic inflammatory status which may impact on blood brain barrier (BBB) integrity leading to an impaired function of central nervous system (CNS).

AIM OF REVIEW

Since the mechanisms underlying the brain-liver-gut axis derangement are still inconclusive, the present narrative review aims to make a roundup of the most recent studies regarding the cognitive decline in MASLD also highlighting possible therapeutic strategies to reach a holistic advantage for the patients.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Due to its ever-growing prevalence, the MASLD-related mental dysfunction represents an enormous socio-economic burden since it largely impacts on the quality of life of patients as well as on their working productivity. Indeed, cognitive decline in MASLD translates in low concentration and processing speed, reduced memory, sleepiness but also anxiety and depression. Chronic systemic inflammation, hyperammonemia, genetic background and intestinal dysbiosis possibly contribute to the cognitive decline in MASLD patients. However, its diagnosis is still underestimated since the leading mechanisms are multi-faceted and unexplained and do not exist standardized diagnostic tools or cognitive test strategies. In this scenario, nutritional and lifestyle interventions as well as intestinal microbiota manipulation (probiotics, fecal transplantation) may represent new approaches to counteract mental impairment in these subjects. In sum, to face the "mental aspect" of this multifactorial disease which is almost unexplored, cognitive tools should be introduced in the management of MASLD patients.

Can Nutrition Contribute to a Reduction in Sarcopenia, Frailty, and Comorbidities in a Super-Aged Society?

Many countries are facing the advent of super-aging societies, where sarcopenia and frailty will become pertinent problems. The prevalence of comorbidities is a major problem in countries with aged populations as elderly people suffer from various diseases, such as diabetes, heart failure, chronic kidney disease and dementia. All of these diseases are associated with sarcopenia and frailty, and they frequently cause falls, fractures, and a decline in activities of daily living. Fractures in the elderly people are associated with bone fragility, which is influenced by diabetes and chronic kidney disease. Nutritional support for chronic disease patients and sarcopenic individuals with adequate energy and protein intake, vitamin D supplementation, blood glucose level management for individuals with diabetes, obesity prevention, nutritional education for healthy individuals, and the enlightenment of society could be crucial to solve the health-related problems in super-aging societies.

Serum Homocysteine, Vitamin B12, Folate, and Their Association with Mild Cognitive Impairment and Subtypes of Dementia

BACKGROUND

Although elevated levels of homocysteine (Hcy) are associated with cognitive impairment and dementia, the relevance of Hcy, vitamin B12, and folate levels to subtypes of dementia are still unknown.

OBJECTIVE

To investigate the changes of Hcy, vitamin B12, and folate levels in mild cognitive impairment (MCI) and subtypes of dementia including Alzheimer's disease (AD), vascular dementia (VaD), frontotemporal dementia (FTD), and Lewy body dementia (LBD), and their relationships with cognitive function and magnetic resonance imaging (MRI) markers.

METHODS

We measured serum levels of Hcy, vitamin B12, and folate in 257 subjects. Each subject underwent cognitive function assessment and brain MRI test. The Fazekas and temporal lobe atrophy (MTA) visual rating scales were used to assess the degree of white matter hyperintensities and MTA, respectively.

RESULTS

Serum levels of Hcy was higher and vitamin B12 was lower in AD, VaD, FTD, and LBD groups than cognitively normal controls. No significant differences of folate levels were found among 6 groups. Hcy levels were positively correlated with MTA total score in AD (r = 0.448, p < 0.001). Vitamin B12 levels were positively correlated with MoCA in VaD (r = 0.497), and negatively correlated with MTA total score in AD (r = - 0.325) (ps < 0.05). Hyperhomocysteinemia may increase the risk of AD (OR = 2.744), VaD (OR = 3.600), and FTD (OR = 3.244) in the adjusted model (ps < 0.05).

CONCLUSION

Hcy and vitamin B12 levels are associated with MTA in AD. Vitamin B12 levels are associated with general cognition in VaD. Hyperhomocysteinemia is a risk factor for not only AD and VaD but also FTD.

Feasibility and Acceptability of a Dietary Intervention to Reduce Salt Intake and Increase High-Nitrate Vegetable Consumption in Malaysian Middle-Aged and Older Adults with Elevated Blood Pressure: Findings from the DePEC-Nutrition Trial

The DePEC-Nutrition trial is a complex dietary and behavioural intervention of salt intake reduction combined with increased high-nitrate vegetable consumption among Malaysian middle-aged and older adults with elevated blood pressure. This study aimed to assess the feasibility and acceptability of the trial. Participants were recruited from the South East Asia Community Observatory (SEACO) database and randomised into one of four groups: (1) low salt; (2) high-nitrate vegetable; (3) combined high-nitrate vegetable and low salt; and (4) control. The intervention included a combination of group counselling sessions, information booklets, reinforcement videos and text messages to modify dietary behaviour. The primary outcomes evaluated were the measures of feasibility and acceptability of (1) recruitment, follow-up attendance and retention; (2) data collection procedures and clinical outcome measures; and (3) individual and combined multi-modal dietary interventions. A total of 74 participants were recruited, and the 10-month retention rate was 73%. Data collection procedures were acceptable with minimal missing data. All intervention strategies were feasible and acceptable, with group counselling being the most acceptable strategy. This study provides important insights into improving the screening process of participants, facilitating their access to the research facilities and refining the measurement protocols and dietary recommendations, which are instrumental in formulating the design of a full-scale definitive DePEC-Nutrition trial.

Influence of Dietary Nutrient Intake on Episodic Memory Across the Adult Life Span

The aim of the study was to identify nutrients that have the ability to impact brain functioning and, as a consequence, influence episodic memory. In particular, we examined recollection, the ability to recall details of previous experiences, which is the episodic memory process most affected as age advances. A sample of 1,550 healthy participants between 21 and 80 years old participated in the study. Nutritional intake was examined through a food frequency questionnaire and software developed to determine the daily consumption of 64 nutrients based on food intake during the last year. Recollection was measured through a computerized source memory paradigm. First, we identified which nutrients influence recollection across the entire adult life span. Then, moderator analyses were conducted by dividing the sample into young (21–40 years old), middle-aged (41–60 years old) and older (61–80 years old) adults to establish in which life stage nutrients influence episodic memory. Across the adult life span, recollection accuracy was shown to benefit from the intake of sodium, heme, vitamin E, niacin, vitamin B6, cholesterol, alcohol, fat, protein, and palmitic, stearic, palmitoleic, oleic, gadoleic, alpha-linoleic and linoleic acid. The effects of energy, maltose, lactose, calcium and several saturated fatty acids on recollection were modulated by age; in older adults, the consumption of these nutrients negatively influenced episodic memory performance, and in middle-aged adults, only lactose had negative effects. Several brain mechanisms that support episodic memory were influenced by specific nutrients, demonstrating the ability of food to enhance or deteriorate episodic memory.

Decreasing trend in the incidence and prevalence of dementia: a systematic review

INTRODUCTION

The progressive ageing of the population is one of the main socio-demographic phenomena, taking place at a global level. Several recent population-based studies conducted worldwide suggest that the age-specific risk of dementia may be changing in some countries and areas.

EVIDENCE ACQUISITION

This systematic review was performed using the methodology proposed by the Cochrane handbook for systematic reviews and reported following the PRISMA statement. A structured bibliographic search was performed on the databases PubMed, ISI Web of Science and the Cochrane Database of Systematic Reviews. All included studies were qualitatively assessed using the Methodological Evaluation of Observational REsearch (MORE).

EVIDENCE SYNTHESIS

The bibliographic search yielded 2394 records. Three more articles were retrieved from other sources. A total of ten studies were included, five reported data on a possible reduction in the prevalence of dementia, and five reported data on a possible reduction in its incidence.

CONCLUSIONS

The present systematic review focused on the recent observations of a possible decrease in the frequency of dementia and cognitive impairment in some Western countries (USA, UK, Sweden, the Netherlands, France, Iceland) between 1977 and 2014. The included studies have a high heterogeneity in terms of the clinical criteria used to diagnose dementia, and of the criteria used to define the clinical condition preceding dementia, such as isolated cognitive impairment. Moreover, the methodological quality with which they were conducted was also heterogeneous, with scores ranging from 1 to 7 using the MORE tool.