Meta AnalysisID 419

基于可可的干预措施对人类脑血流和认知功能的影响：系统评价和Meta分析

CRD42022323404

The aim is evaluate the effects of cocoa-based products on cerebral blood flow and cognitive function (global and domain specific e.g., memory, executive function and speed) in humans. We will therefore undertake a syste

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Meta Analysis Id: 419
Evidence Id: 8977
Core Evidence Id: 8977
Source Meta Analysis Id: 397
Herb2 Meta Analysis Id: HBMA000397
Crd Id: CRD42022323404
Title: Effects of cocoa-based interventions on cerebral blood flow and cognitive function in humans: A systematic review and meta-analysis
Review Question: The aim is evaluate the effects of cocoa-based products on cerebral blood flow and cognitive function (global and domain specific e.g., memory, executive function and speed) in humans. We will therefore undertake a systematic review of observational studies and randomised clinical trials (RCTs) and meta-analysis of the available evidence. The specific research questions are: • Does the ingestion of cocoa-based products (i.e., cocoa, cocoa-extracts, chocolate) improve cerebral blood flow and global and domain-specific cognitive function and what is the magnitude of the effect size? • Does the form of cocoa-based products (food vs extracts; cocoa vs cocoa-derived products, cocoa-derived flavanols) differentially influence the effect on cerebral blood flow and global and domain-specific cognitive function? • Do age, BMI, health status, type of study and study duration modify the effects/associations of cocoa-based products on cerebral blood flow and global and domain-specific cognitive function?
Study Type Included: Inclusion Criteria • Study Design: observational studies and randomised clinical trials conducted in human adult subjects. No distinction will be made on the specific design of the studies (parallel, cross-over, cross-sectional, case-control or cohort) and trials (duration, placebo controlled, cross-over, blindness) Exclusion Criteria • Study Design: we will exclude ecological observational studies and non-randomised clinical interventions. • Interventions: studies will be excluded if the cocoa-based supplementation was implemented alongside another intervention and no appropriate control group could be identified.
Condition Being Studied: The review is investigating the link between chocolate (including cocoa and cocoa flavanols) intake and cerebral blood flow and cognitive ability (i.e., performance on cognitive test including for example test of global cognitive function, memory, executive function and speed). There will be no restriction on the tests used. Chocolate has a variety of substances that have the potential to affect neurocognitive function, such as cocoa. Flavanols, a subgroup of polyphenols, which are usually found in cocoa and cocoa-derived products, are intensively researched as possibly psychoactive components of chocolate. Cocoa and cocoa-derived products are considered to have the ability to prevent cognitive decline and maintain cognitive capacities. Previous investigations have shown that cocoa flavanols (CFs) have antioxidant and anti-inflammatory characteristics, as well as neuroprotective and neuromodulator effects, which might also enhance vascular function. It appears that the cognitive enhancements of acute CF supplementation are linked to its vasodilatory effects. Important evidence is starting to emerge in this research area and this systematic review will be key to identifying the main discoveries as well as research gaps to inform the development of new studies.
Participant: Inclusion Criteria • Study Design: observational studies and randomised clinical trials conducted in human adult subjects. No distinction will be made on the specific design of the studies (parallel, cross-over, cross-sectional, case-control or cohort) and trials (duration, placebo controlled, cross-over, blindness). • Subjects: adult participants (age≥18 years). We will include subjects with and without health comorbidities. • Interventions: studies based on cocoa-based products supplementation will be included if they provide information on the type cocoa-product or extract, dose, formulation, frequency and route of administration. • Observational studies: studies will be included if they provide information on the intake of cocoa-derived products evaluated by the administration of validated dietary assessment tools. • Outcomes: 1) global and domain-specific cognitive function; 2) cerebral blood flow measured by different techniques including MRI, ultrasound or NIRS for both trials and observational studies. Exclusion Criteria • Study Design: we will exclude ecological observational studies and non-randomised clinical interventions. • Interventions: studies will be excluded if the cocoa-based supplementation was implemented alongside another intervention and no appropriate control group could be identified. • Outcomes: randomised studies will be excluded if cognition was only measured at baseline.
Animal
Human Disease Modelled
Intervention: Randomised Clinical Trials Interventions testing the effects of cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products will be evaluated for inclusion. Studies will not be excluded based on route of administration, duration of intervention, number of doses (single and repeated doses) and blinding of interventions. Studies will be excluded if they fail to report the precise nature of the interventions and if there is uncertainty around the source of cocoa or cocoa-derived products. Observational Studies Studies will be included if they have used validated dietary instruments to evaluate intake of cocoa and cocoa-derived products. Biomarkers of cocoa intake will not be used due to the uncertainty around their sensitivity to assess exposure to cocoa-derived products. Studies will be excluded if they fail to report the precise source of the dietary exposure to cocoa-derived products.
Comparator Control: Randomised Clinical Trials The control group of the eligible studies will allow a clear and distinct evaluation of the effects of cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products. Combined interventions will be included only if the effects of cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products can be isolated (i.e., exercise + cocoa vs exercise alone). This will allow a precise estimate of the effect size. Observational Studies For observational studies we will have two possible scenarios based on the type of analyses conducted in the studies. Scenario 1: variables linked to cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products will be continuous and association with cognitive outcomes will be evaluated using linear regression. Statistical measures will include beta coefficients, standard error of mean, and 95%CIs. Scenario 2: variables linked to cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products will be stratified into categories and a reference group will be identified to quantify the association with cognitive outcomes. Statistical measures will include odds ratio, relative risk, and 95%CIs.
Main Outcome: Randomised clinical trials 1) Global and domain-specific cognitive function are the primary outcomes and therefore we aim to include only studies reporting information on cognitive changes after cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products. 2) Cerebral blood flow measured by different techniques including MRI, ultrasound or NIRS. Observational studies 1) Global and domain-specific cognitive function are the primary outcomes and therefore we aim to include only studies reporting information on associations of cognitive scores with intake of cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products. 2) Association of cerebral blood flow measured by different techniques including MRI, ultrasound or NIRS with intake of cocoa or cocoa-derived products or active nutritional compounds extracted from cocoa products. Measures of effect As for the continuous data of cognitive test outcomes, the mean difference (MD), standard deviation and standardized mean difference (SMD) will be applied. Besides, odds ratios (risk of being impaired on the neuropsychological test) and regression coefficients (with 95% confidence intervals) will be used for dichotomous data. In addition to this, the relative risks (RR) and its 95% confidence intervals will be used in cohort studies to evaluate the association between intake of chocolate and cognitive function and vascular health. Measurement of cerebral blood flow will be expressed as continuous data and similar to the cognitive test outcomes, the mean difference (MD), standard deviation and standardized mean difference (SMD) will be applied.
Outcome Measure
Additional Outcome: Additional outcomes are: - The compliance of the participants in the experiments. - The safety of the experiments. - Adverse events (e.g., allergy, headache). - Declaration of conflicts of interest and funding sources. Measures of effect These are descriptive measures which will be extracted and summarised in the summary data extraction table. These data will not be included in the meta-analysis
Study Method: Epidemiologic, Intervention, Meta-analysis, Systematic review
Keyword: Cerebrovascular Circulation; Cognition; Humans
Contact: Shijia Wang [email protected]
Organisational Affiliation: University of Nottingham www.nottingham.ac.uk
Funding Source: None Grant number(s) <span style=font-size: 14px>State the funder, grant or award number and the date of award</span> Not applicable
Other Selection Criteria
Final Publication
Same Topic Review: Not applicable
Published Protocol
Review Type
Language: English
Country: England
Review Stage: Review Ongoing
First Submission Date: 2022-06-15
Registration Date: 2022-06-20
Anticipated Start Date: 2022-06-19
Anticipated Completion Date: 2023-05-31
Title Cn: 基于可可的干预措施对人类脑血流和认知功能的影响：系统评价和Meta分析
Title En: Effects of cocoa-based interventions on cerebral blood flow and cognitive function in humans: A systematic review and meta-analysis
Bilingual Status: complete