General methodological considerations for the assessment of nutritional influences on human cognitive functions

Effects of a games-based physical education lesson on cognitive function in adolescents

Despite the importance of physical education (PE) lessons for physical activity in adolescents, the acute cognitive responses to PE lessons have not been explored; a gap in the literature that this study addresses. Following familiarisation, 76 (39 female) adolescents (12.2 ± 0.4 y) completed two trials (60 min games-based PE lesson and 60 min academic lesson) separated by 7-d in a counterbalanced, crossover design. Attention, executive function, working memory, and perception were assessed 30 min before, immediately post, and 45 min post-lesson in both trials. Participants were split into high-and low-fit groups based on a gender-specific median split of distance run on the multi-stage fitness test. Furthermore, participants were split into high and low MVPA groups based on a gender-specific median split of MVPA time (time spent >64% HR max) during the PE lesson. Overall, a 60 min games-based PE lesson had no effect on perception, working memory, attention, or executive function in adolescents (all p > 0.05) unless MVPA time is high. The physical activity-cognition relationship was moderated by MVPA, as working memory improved post-PE lesson in adolescents who completed more MVPA during their PE lesson (time*trial*MVPA interaction, p < 0.05, partial η2 = 0.119). Furthermore, high-fit adolescents displayed superior cognitive function than their low-fit counterparts, across all domains of cognitive function (main effect of fitness, all p < 0.05, partial η2 0.014–0.121). This study provides novel evidence that MVPA time moderates the cognitive response to a games-based PE lesson; and emphasises that higher levels of fitness are beneficial for cognitive function in adolescents.

Perspective: Advancing dietary guidance for cognitive health - focus on solutions to harmonization of test selection, implementation, and evaluation

This perspective paper is a product of a workshop of experts convened by Institute for the Advancement of Food and Nutrition Sciences (IAFNS), a non-profit organization that brings together scientists from government, academia, and industry to catalyze science relevant to food and nutrition. An expert group was convened in March 2022 to discuss the current issues surrounding cognitive task selection in nutrition research, with a focus on solutions towards informing dietary guidance for cognitive health, to address a gap identified in the 2020 US DGAC report, specifically the "considerable variation in testing methods used, [and] inconsistent validity and reliability of cognitive testing methods" (p.31). To address this issue, we firstly undertook an umbrella review of relevant reviews already undertaken; these indicate agreement on some of the issues that affect heterogeneity in task selection, and on many of the fundamental principles underlying selection of cognitive outcome measures. However, resolving the points of disagreement is critical to ensuring meaningful impact on the issue of heterogeneity in task selection; these issues hamper evaluation of existing data for informing dietary guidance. This summary of the literature is therefore followed by the expert group's perspective in the form of a discussion of potential solutions to these challenges, with the aim of building on the work of previous reviews in the area and advancing dietary guidance for cognitive health. STATEMENT OF SIGNIFICANCE: Despite several high-quality reviews in this field over the last two decades, there has been little in the way of substantive change in the methods being used to conduct studies, hampering harmonization of the evidence and thus, its utility for informing dietary guidance. The present paper comprehensively updates the field by firstly providing an umbrella review of the published reviews, followed by the IAFNS expert group's perspective on how to move the field forward by addressing the challenges and areas of disagreement in the existing reviews. REGISTERED ON PROSPERO: CRD42022348106. Data described in the manuscript, code book, and analytic code will be made publicly and freely available without restriction at doi.org/10.17605/OSF.IO/XRZCK.

An After-School Football Session Transiently Improves Cognitive Function in Children

The aim of the present study was to evaluate the effect of a real-world after-school football session on subsequent cognitive function in primary school children. Following ethical approval, 100 children (aged 8−9 year) from the same after-school football club were randomly assigned to either an intervention (60 min football activity) or control (continued to rest) group. Cognitive function (selective visual attention, short term memory and long-term memory) was assessed prior to, immediately following and 45 min following the football session (and at the respective timepoints in the control group). Data were analysed via two-way (group * time) mixed methods ANOVA. The pattern of change in all domains of cognition over time, was different between the football and control groups (group * time, all p < 0.001). Specifically, performance on all cognitive tasks was greater immediately following the football session in the intervention group compared to the control group (selective visual attention, p = 0.003; short-term memory, p = 0.004; long-term memory, p < 0.001). However, there was no difference between the group 45 min following the football session (p = 0.132−0.393). These findings suggest that an after-school football session enhances cognition immediately post-activity in primary school children.

The impact of glycaemic load on cognitive performance: A meta-analysis and guiding principles for future research

The effect of breakfast glycaemic load (GL) on cognition was systematically examined. Randomised and non-randomised controlled trials were identified using PubMed, Scopus, and Cochrane Library (up to May 2022). 15 studies involving adults (aged 20 - 80 years) were included. Studies had a low risk, or some concerns, of bias. A random-effects meta-analysis model revealed no effect of GL on cognition up to 119 min post-consumption. However, after 120 min, immediate episodic memory scores were better following a low-GL compared to a high-GL (SMD = 0.16, 95% confidence interval [CI] = -0.00 to 0.32, p = 0.05, I2 = 5%). Subgroup analyses indicated that the benefit was greater in younger adults (<35 years) and those with better GT. A qualitative synthesis of 16 studies involving children and adolescents (aged 5 - 17 years) suggested that a low-GL breakfast may also benefit episodic memory and attention after 120 min. Methodological practises were identified which could explain a failure to detect benefits in some studies. Consequently, guiding principles were developed to optimise future study design.

The Influence of a Competitive Field Hockey Match on Cognitive Function

Despite the known positive effects of acute exercise on cognition, the effects of a competitive team sport match are unknown. In a randomized crossover design, 20 female and 17 male field hockey players (19.7 ± 1.2 years) completed a battery of cognitive tests (Visual Search, Stroop, Corsi Blocks, and Rapid Visual Information Processing) prior to, at half-time, and immediately following a competitive match (or control trial of seated rest); with effect sizes (ES) presented as raw ES from mixed effect models. Blood samples were collected prior to and following the match and control trial, and analyzed for adrenaline, noradrenaline, brain derived neurotrophic factor (BDNF), cathepsin B, and cortisol. The match improved response times for a simple perception task at full-time (ES = –14 ms; P < 0.01) and response times on the complex executive function task improved at half-time (ES = –44 ms; P < 0.01). Working memory declined at full-time on the match (ES = –0.6 blocks; P < 0.01). The change in working memory was negatively correlated with increases in cortisol (r = –0.314, P = 0.01; medium), as was the change in simple perception response time and the change in noradrenaline concentration (r = –0.284, P = 0.01; small to medium). This study is the first to highlight the effects a competitive hockey match can have on cognition. These findings have implications for performance optimization, as understanding the influence on specific cognitive domains across a match allows for the investigation into strategies to improve these aspects.

Ready-to-eat cereal and milk for breakfast compared with no breakfast has a positive acute effect on cognitive function and subjective state in 11-13-year-olds: a school-based, randomised, controlled, parallel groups trial

PURPOSE

We tested the acute effect of breakfast (ready-to-eat-cereal [RTEC] and milk) versus (vs.) no breakfast on cognitive function and subjective state in adolescents.

METHODS

Healthy adolescents (n = 234) aged 11-13 years were recruited to take part in this school-based, acute, randomised, controlled, parallel groups trial with two interventions; Breakfast or No Breakfast. The breakfast intervention consisted of ad libitum intake of RTEC (up to 70 g) with milk (up to 300 ml) administered in a naturalistic school breakfast programme environment. Cognitive function was assessed at baseline and + 70 and + 215 min post-intervention in a group-testing situation, similar to a school classroom context. The CANTAB test battery included: Simple Reaction Time (SRT), 5-Choice Reaction Time (5-CRT), Rapid Visual Information Processing (RVIP), and Paired Associates Learning (PAL; primary outcome). Data collection commenced January 2011 and ended May 2011. This trial was retrospectively registered at www.clinicaltrials.gov as NCT03979027 on 07/06/2019.

RESULTS

A significant effect of the intervention (CMH[1] = 7.29, p < 0.01) was found for the number of levels achieved on the PAL task. A significant difference between interventions was found when baseline performance reached level 2 (JT, z = 2.58, p < 0.01), such that 100% of participants in the breakfast intervention reached the maximum level 4 but only 41.7% of those in the no breakfast intervention reached level 4. A significant baseline*intervention interaction (F[1,202] = 6.95, p < 0.01) was found for total errors made on the PAL task, indicating that participants who made above-average errors at baseline reduced the total number of errors made at subsequent test sessions following breakfast consumption whilst those in the no breakfast intervention did not. There was a positive effect of breakfast on reaction time and visual-sustained attention. The results also demonstrated interactions of intervention with baseline cognitive performance, such that breakfast conferred a greater advantage for performance when baseline performance was poorer.

CONCLUSION

Consuming breakfast has a positive acute effect on cognition in adolescents.

Cognitive performance, mood and satiety following ingestion of beverages imparting different glycaemic responses: a randomised double-blind crossover trial

BACKGROUND/OBJECTIVE

The relationship between postprandial glycaemic responses and cognitive performance, mood and satiety are inconsistent. The objective of this study is to compare the effects of different glycaemic responses, induced by beverages with different glycaemic index (GI) (sucrose and isomaltulose), and a non-glycaemic control (sucralose), on cognition, mood and satiety.

SUBJECTS/METHODS

In this double-blinded, randomised crossover trial, healthy adults (n = 55) received sucrose (GI 65), isomaltulose (GI 32) and sucralose (non-caloric negative control) drinks on separate occasions. The Complex Figure test, the Word Recall test, Trail Making Test Part B and the Stroop test were administered 60 min after beverages ingestion. Mood and satiety were tested along with cognitive performance.

RESULTS

Comparing between isomaltulose and sucrose, there were no significant differences in the mean (95% CI) for the following: Complex Figure: immediate recall -0.6 (-1.7, 0.5), delayed recall -0.8 (-1.9, 0.3); Word recall: immediate recall 0.2 (-0.7, 1.1), delayed recall 0.5 (-0.4, 1.4); Trail Making: completing time -2.4 (-7.5, 2.7) s; Stroop: time used for correct congruent responses -9 (-31, 14) ms and correct incongruent responses -18 (-42, 6) ms. No differences among beverages were found in the mood and satiety scores with exception that participants felt more energetic 60 min after isomaltulose ingestion (p = 0.028 for difference with sucrose) and hungrier 30 min after isomaltulose ingestion (p = 0.036 for difference with sucrose; p = 0.022 for difference with sucralose).

CONCLUSION

Under these study conditions there is no convincing evidence for an effect of glycaemic response on cognitive performance, mood or satiety.

Predictors of low perceptual-motor skills in children at 4-5 years of age

Abstract Objectives: the purpose of this study was to evaluate the predictors of low perceptual-motor skills in children at preschool age. Methods: this is a cross-sectional study nested in a birth cohort involving mother-child pairs. The children’s perceptual-motor skills were assessed individually in their homes when they were 4-5 years old using the Pre-Literacy Skills and Knowledge Test (THCP®), a vali-dated Brazilian instrument. Logistic regression analysis was used to estimate the association between cognitive perceptual-motor skills and potential maternal and child risk factors. Results: of the 199 children included in the study, 53.8% were boys, 90.8% attended school, and 91.1% were enrolled in a public school. Among the children, 114 (57.3%), 41 (20.6%) and 44 (22.1%) had low, moderate and high perceptual-motor skills, respectively. Multivariate logistic regression analysis revealed greater odds of children at preschool age having low perceptual motor skills for boys (OR=2.10; CI95%= 1.14-3.88), children who did not attend school (OR=4.61; CI95%= 1.21-17.49), and those with a household income <5 minimum wages (MW) (OR=4.28; CI95%= 1.49-12.26). Conclusions: our study showed that male gender, not attending school and a monthly household income <5 MW were predictors of low perceptual-motor skills in children at 4-5 years of age.

Effects of carbohydrate and protein co-ingestion during short-term moderate-intensity exercise on cognitive function

BACKGROUND

This study aimed to investigate the effects of isocaloric carbohydrate-electrolyte solution (CES) and carbohydrates-electrolyte-protein solution (CEPS) consumed during moderate-intensity exercise on cognitive function.

METHODS

Twenty-three healthy participants (age: 21.7±1.5 years, Body Mass Index: 21.8±2.0 kg/m2, and peak oxygen consumption (VO2peak): 42.4±6.9 mL/kg/min) were recruited in the study. Participants completed two main experiment trials using a cross-over study design. In each trial, they completed 30 minutes of 70% VO2peak cycling, and one of two solutions (CES or CEPS) was consumed. A battery of cognitive function tests (imPACT Package) was administrated at rest and immediately post-exercise.

RESULTS

Blood glucose concentrations decreased in both trials. Heart rate and blood lactate concentrations increased in both trials. However, no significant main effects of the exercise on all cognitive function variables (verbal and visual memory, visual-motor speed, reaction time, impulse control, and cognitive efficiency index) were observed (all P>0.05). Also, there was no difference in any of the cognitive function variables between the CES and CEPS trials (all P>0.05).

CONCLUSIONS

There was no difference in the cognitive performance when CES or CES-PRO solutions was consumed during 30 minutes moderate-intensity cycling.

Does antenatal micronutrient supplementation improve children's cognitive function? Evidence from the follow-up of a double-blind randomised controlled trial in Nepal

Introduction

Multiple Micronutrient (MMN) supplementation during pregnancy can decrease the proportion of infants born low birth weight and small for gestational age. Supplementation could also enhance children's cognitive function by improving access to key nutrients during fetal brain development and increasing birth weight, especially in areas where undernutrition is common. We tested the hypothesis that children whose mothers received MMN supplementation during pregnancy would have higher intelligence in early adolescence compared with those receiving Iron and Folic Acid (IFA) only.

Methods

We followed up children in Nepal, whose mothers took part in a double-blind Randomised Controlled Trial (RCT) that compared the effects on birth weight and gestational duration of antenatal MMN versus IFA supplementation. We assessed children's Full Scale Intelligence Quotient (FSIQ) using the Universal Non-verbal Intelligence Test (UNIT), and their executive function using the counting Stroop test. The parent trial was registered as ISRCTN88625934.

Results

We identified 813 (76%) of the 1069 children whose mothers took part in the parent trial. We found no differences in FSIQ at 12 years between MMN and IFA groups (absolute difference in means (diff): 1.25, 95% CI -0.57 to 3.06). Similarly, there were no differences in mean UNIT memory (diff: 1.41, 95% CI -0.48 to 3.30), reasoning (diff: 1.17, 95% CI -0.72 to 3.06), symbolic (diff: 0.97, 95% CI -0.67 to 2.60) or non-symbolic quotients (diff: 1.39, 95% CI -0.60 to 3.38).

Conclusion

Our follow-up of a double-blind RCT in Nepal found no evidence of benefit from antenatal MMN compared with IFA for children's overall intelligence and executive function at 12 years.

Spearmint Extract Improves Working Memory in Men and Women with Age-Associated Memory Impairment

OBJECTIVE

The purpose of this study was to investigate the effects of supplementation with a spearmint (Mentha spicata L.) extract, high in polyphenols including rosmarinic acid, on cognitive performance, sleep, and mood in individuals with age-associated memory impairment (AAMI).

DESIGN

Subjects with AAMI (N = 90; 67% female; age = 59.4 ± 0.6 years) were randomly assigned (n = 30/group) to consume 900, 600, or 0 mg/day (two capsules, once daily) spearmint extract for 90 days, in this double-blind, placebo-controlled trial. Assessments were completed for cognition (days 0, 45, and 90), sleep (days 0 and 90), and mood (days 0 and 90) by using the Cognitive Drug Research (CDR) System™, Leeds Sleep Evaluation Questionnaire (LSEQ), and Profile of Mood States (POMS™), respectively.

RESULTS

Quality of working memory and spatial working memory accuracy improved after supplementation with 900 mg/day spearmint extract by 15% (p = 0.0469) and 9% (p = 0.0456), respectively, versus placebo. Subjects consuming 900 mg/day spearmint extract reported improvement in their ability to fall asleep, relative to subjects consuming placebo (p = 0.0046). Overall treatment effects were evident for vigor-activity (p = 0.0399), total mood disturbance (p = 0.0374), and alertness and behavior following wakefulness (p = 0.0415), with trends observed for improvements after spearmint supplementation relative to placebo.

CONCLUSIONS

These results suggest that the distinct spearmint extract may be a beneficial nutritional intervention for cognitive health in older subjects with AAMI.

Fatty fish intake and attention performance in 14-15 year old adolescents: FINS-TEENS - a randomized controlled trial

Background

Fatty fish is the dominant dietary source of n-3 LCPUFAs but it also contains other micronutrients considered important for brain development and function. To our knowledge, the effect of fatty fish intake on cognitive function in adolescents has not been investigated in randomized controlled trials (RCTs) previously. The aim of the present trial was to investigate whether consumption of fatty fish meals three times per week for 12 weeks could alter attention performance in adolescents compared to similar meals with meat or n-3 LCPUFA supplements.

Methods

In the Fish Intervention Studies-TEENS (FINS-TEENS), adolescents from eight secondary schools (n = 426; age: 14-15y) were individually randomized. Attention performance was assessed with the d2 test of attention. Differences between groups from pre to post intervention were assessed with linear mixed effect models and general estimates equation. The fish group was set as reference. Dietary compliance was recorded for each meal throughout the trial and controlled for in the adjusted analyses.

Results

The improvement in processing speed was significantly lower in the meat (−11.8; 95% CI: -23.3, −0.4) and supplement (−13.4; 95% CI: -24.9, −1.8) group compared to the fish group (reference). The supplement group also showed inferior improvement in total performance (−10.4; 95% CI: -20.0, −0.7) compared to the fish group (reference). The results were slightly affected when controlling for dietary compliance. Omission errors decreased in the meat group compared to the fish group (Incidence rate ratio = 0.85; 95% CI: 0.74, 0.98), but the difference disappeared when controlling for dietary compliance.

Conclusions

We observed a small beneficial effect of fatty fish, compared to meat meals and supplements on processing speed. However, these results are difficult to interpret due to low dietary compliance. This study shows that different taste preferences among participants is challenging in intervention trials with food. A prospective cohort design may be a better alternative when studying diet in the future.

Trial registration number

ClinicalTrials.gov registration number: NCT02350322.

Electronic supplementary material

The online version of this article (10.1186/s12937-017-0287-9) contains supplementary material, which is available to authorized users.

Iodine Deficiency and the Brain: Effects and Mechanisms

Iodine is an essential micronutrient needed in human diets. As iodine is an integral component of thyroid hormone, it mediates the effects of thyroid hormone on brain development. Iodine deficiency is the most prevalent and preventable cause of mental impairment in the world. The exact mechanism through which iodine influences the brain is unclear, but is generally thought to begin with genetic expression. Many brain structures and systems appear to be affected with iodine deficiency, including areas such as the hippocampus, microstructures such as myelin, and neurotransmitters. The clearest evidence comes from the studies examining cognition in the cases of iodine deprivation or interventions involving iodine supplementation. Nevertheless, there are many inconsistencies and gaps in the literature of iodine deficiency, especially over the lifespan. This paper summarizes the literature on this topic, suggests a causal mechanism for iodine's effect on the brain, and indicates areas for the future research (e.g., using magnetic resonance imaging (MRI) and functional MRI to examine how iodine supplementation facilitates cognitive functioning).

Methodological Challenges in Studies Examining the Effects of Breakfast on Cognitive Performance and Appetite in Children and Adolescents

Breakfast is purported to confer a number of benefits on diet quality, health, appetite regulation, and cognitive performance. However, new evidence has challenged the long-held belief that breakfast is the most important meal of the day. This review aims to provide a comprehensive discussion of the key methodological challenges and considerations in studies assessing the effect of breakfast on cognitive performance and appetite control, along with recommendations for future research. This review focuses on the myriad challenges involved in studying children and adolescents specifically. Key methodological challenges and considerations include study design and location, sampling and sample section, choice of objective cognitive tests, choice of objective and subjective appetite measures, merits of providing a fixed breakfast compared with ad libitum, assessment and definition of habitual breakfast consumption, transparency of treatment condition, difficulty of isolating the direct effects of breakfast consumption, untangling acute and chronic effects, and influence of confounding variables. These methodological challenges have hampered a clear substantiation of the potential positive effects of breakfast on cognition and appetite control and contributed to the debate questioning the notion that breakfast is the most important meal of the day.

Importance of mental performance in parental choice of food for children aged 4-10 years: a study in four European countries

OBJECTIVE

Typically, attention focuses on how nutrition affects physical health. The present study investigated the importance that parents attach to the impact of diet on mental performance when choosing food for their child.

DESIGN

Questionnaire.

SETTING

Four European countries.

SUBJECTS

Parents of children aged 4-10 years (n 1574): England (n 397), Germany (n 389), Hungary (n 398) and Spain (n 390).

RESULTS

Most parents (80-85 %) considered the effect of food on four elements of mental performance (child's ability to learn, attention, behaviour, mood) to be moderately, very, extremely (v. slightly, not at all) important in food choices; over 90 % considered healthiness of food and making food appealing to their child important; 79·8 % cost; 76·8 % convenience. Belief that food affects mental performance was 57·4 % (ability to learn), 60·5 % (attention); less than 40 % of parents agreed they were aware which foods had an effect. Parents with lower general interest in healthy eating were less likely to consider the effect of food on mental performance elements as important. Respondents from Germany were more likely to rate mental performance as important (except behaviour); those in Hungary less likely. The most important influence on parents' decisions about feeding their child was their own experience, except Spain, where family/friends/health professionals were more important.

CONCLUSIONS

Nutrition affects brain development and cognitive functioning. Low prioritisation of the effect of food on mental performance indicates potential for educating parents.

Mental performance in 8-year-old children fed reduced protein content formula during the 1st year of life: safety analysis of a randomised clinical trial

In humans, maximum brain development occurs between the third trimester of gestation and 2 years of life. Nutrition during these critical windows of rapid brain development might be essential for later cognitive functioning and behaviour. In the last few years, trends on protein recommendations during infancy and childhood have tended to be lower than that in the past. It remains to be demonstrated that lower protein intakes among healthy infants, a part of being able to reduce obesity risk, is safe in terms of mental performance achievement. Secondary analyses of the EU CHOP, a clinical trial in which infants from five European countries were randomised to be fed a higher or a lower protein content formula during the 1st year of life. Children were assessed at the age of 8 years with a neuropsychological battery of tests that included assessments of memory (visual and verbal), attention (visual, selective, focused and sustained), visual-perceptual integration, processing speed, visual-motor coordination, verbal fluency and comprehension, impulsivity/inhibition, flexibility/shifting, working memory, reasoning, visual-spatial skills and decision making. Internalising, externalising and total behaviour problems were assessed using the Child Behaviour Checklist 4-18. Adjusted analyses considering factors that could influence neurodevelopment, such as parental education level, maternal smoking, child's gestational age at birth and head circumference, showed no differences between feeding groups in any of the assessed neuropsychological domains and behaviour. In summary, herewith we report on the safety of lower protein content in infant formulae (closer to the content of human milk) according to long-term mental performance.

The effect of diet on the physical and mental development of children: views of parents and teachers in four European countries

Although the impact of diet on physical health is an important public health issue, less attention has been devoted to the relationship between nutrition and children's mental development. The views of parents and teachers about the extent to which diet affects physical and mental development of children were compared in four European countries. An online questionnaire (developed in English and translated) was circulated through a market research agency. Participants were parents or teachers of children aged 4-10 years without learning or behavioural issues. Questionnaires were returned by 1606 parents (401 in England, Germany and Hungary; 403 in Spain) and 403 teachers (100 in each country, except for 103 in Hungary). Teachers were older than parents (35·3 % v. 18·3 % over 45 years; P<0·001) and less likely to smoke (15·9 % v. 26·3 %, P<0·001). There was no difference between the proportions of parents and teachers who felt that a child's physical development depended very much/extremely (v. moderately/slightly/not at all) on diet (overall 79·8 %). Lower proportions of both groups thought that mental development was very much/extremely influenced by diet (67·4 %). In the regression modelling, believing that physical and mental performance was greatly influenced by diet was significantly and positively associated with living in Hungary, scoring higher on a measure of General Health Interest and (parents only) level of education attained. Differences existed among countries in most views. Lower levels of awareness of the importance of diet for brain development and cognition (compared with physical health outcomes) indicate the potential for educating consumers, especially parents with lower educational attainment.

Does consumption of LC omega-3 PUFA enhance cognitive performance in healthy school-aged children and throughout adulthood? Evidence from clinical trials

Long-chain (LC) omega-3 PUFA derived from marine sources may play an important role in cognitive performance throughout all life stages. Docosahexaenoic acid (DHA), the dominant omega-3 in the brain, is a major component of neuronal cell membranes and affects various neurological pathways and processess. Despite its critical role in brain function, human’s capacity to synthesize DHA de novo is limited and its consumption through the diet is important. However, many individuals do not or rarely consume seafood. The aim of this review is to critically evaluate the current evidence from randomised controlled trials (RCT) in healthy school-aged children, younger and older adults to determine whether consumption of LC omega-3 PUFA improves cognitive performance and to make recommendations for future research. Current evidence suggests that consumption of LC omega-3 PUFA, particularly DHA, may enhance cognitive performance relating to learning, cognitive development, memory and speed of performing cognitive tasks. Those who habitually consume diets low in DHA, children with low literacy ability and malnourished and older adults with age-related cognitive decline and mild cognitive impairment seem to benefit most. However, study design limitations in many RCTs hamper firm conclusions. The measurement of a uniform biomarker, e.g., % DHA in red blood cells, is essential to establish baseline DHA-status, to determine targets for cognitive performance and to facilitate dosage recommendations. It is recommended that future studies be at least 16 weeks in duration, account for potential interaction effects of gender, age and apolipoprotein E genotype, include vegan/vegetarian populations, include measures of speed of cognitive performance and include brain imaging technologies as supportive information on working mechanisms of LC omega-3 PUFA.

The effect of breakfast cereal consumption on adolescents' cognitive performance and mood

The aim of the current study was to investigate the effect of breakfast consumption on cognitive performance and mood in adolescents, and any interaction that breakfast consumption might have with cognitive load. The rationale for this approach was that the beneficial effects of any intervention with regard to cognitive function may be more readily apparent when more demands are placed on the system. Furthermore, as skipping breakfast is particularly prevalent within this age group, thus, we focused on adolescents who habitually skip breakfast. Cognitive load was modulated by varying the level of difficulty of a series of cognitive tasks tapping memory, attention, and executive functions. Mood measured with Bond–Lader scales (1974) as well as measures of thirst, hunger, and satiety were recorded at each test session both at baseline and after the completion of each test battery. Forty adolescents (mean age = 14:2) participated in this within-subjects design study. According to treatment, all participants were tested before and after the intake of a low Glycaemic index breakfast (i.e., a 35 g portion of AllBran and 125 ml semi-skimmed milk) and before and after no breakfast consumption. Assessment time had two levels: 8.00 am (baseline) and 10.45 am. The orders of cognitive load tasks were counterbalanced. Overall it appeared that following breakfast participants felt more alert, satiated, and content. Following breakfast consumption, there was evidence for improved cognitive performance across the school morning compared to breakfast omission in some tasks (e.g., Hard Word Recall, Serial 3's and Serial 7's). However, whilst participants performance on the hard version of each cognitive task was significantly poorer compared to the corresponding easy version, there was limited evidence to support the hypothesis that the effect of breakfast was greater in the more demanding versions of the tasks.

The Hydration Equation: Update on Water Balance and Cognitive Performance

To become aware of the most practical measures of hydration status.To describe sources of water input and output and the basics of water balance.To understand how hydration status may impact daily cognitive performance.

CONDENSED VERSION AND BOTTOM LINE

Water is a crucial nutrient and euhydration is necessary for optimal daily functioning. Water balance is precisely regulated within the body and many methods exist for assessing hydration status. Cognitive performance measures an individual's attentiveness, critical thinking skills, and memory. Traditionally a 2% or more body water deficit was thought to produce cognitive performance decrements; however, recent literature suggests that even mild dehydration - a body water loss of 1-2% - can impair cognitive performance. Counseling clients about their health and wellbeing should include conveying the importance of water for normal body functioning, as well as its effects on physical and cognitive performance.

Nutrition and neurodevelopment in children: focus on NUTRIMENTHE project

There is growing evidence that early nutrition affects later cognitive performance. The idea that the diet of mothers, infants, and children could affect later mental performance has major implications for public health practice and policy development and for our understanding of human biology as well as for food product development, economic progress, and future wealth creation. To date, however, much of the evidence is from animal, retrospective studies and short-term nutritional intervention studies in humans. The positive effect of micronutrients on health, especially of pregnant women eating well to maximise their child's cognitive and behavioural outcomes, is commonly acknowledged. The current evidence of an association between gestational nutrition and brain development in healthy children is more credible for folate, n-3 fatty acids, and iron. Recent findings highlight the fact that single-nutrient supplementation is less adequate than supplementation with more complex formulae. However, the optimal content of micronutrient supplementation and whether there is a long-term impact on child's neurodevelopment needs to be investigated further. Moreover, it is also evident that future studies should take into account genetic heterogeneity when evaluating nutritional effects and also nutritional recommendations. The objective of the present review is to provide a background and update on the current knowledge linking nutrition to cognition and behaviour in children, and to show how the large collaborative European Project NUTRIMENTHE is working towards this aim.

DHA supplementation improved both memory and reaction time in healthy young adults: a randomized controlled trial

BACKGROUND

Docosahexaenoic acid (DHA) is important for brain function, and its status is dependent on dietary intakes. Therefore, individuals who consume diets low in omega-3 (n-3) polyunsaturated fatty acids may cognitively benefit from DHA supplementation. Sex and apolipoprotein E genotype (APOE) affect cognition and may modulate the response to DHA supplementation.

OBJECTIVES

We investigated whether a DHA supplement improves cognitive performance in healthy young adults and whether sex and APOE modulate the response.

DESIGN

Healthy adults (n = 176; age range: 18-45 y; nonsmoking and with a low intake of DHA) completed a 6-mo randomized, placebo-controlled, double-blind intervention in which they consumed 1.16 g DHA/d or a placebo. Cognitive performance was assessed by using a computerized cognitive test battery. For all tests, z scores were calculated and clustered into cognitive domains as follows: episodic and working memory, attention, reaction time (RT) of episodic and working memory, and attention and processing speed. ANCOVA was conducted with sex and APOE as independent variables.

RESULTS

RTs of episodic and working memory improved with DHA compared with placebo [mean difference (95% CI): -0.18 SD (-0.33, -0.03 SD) (P = 0.02) and -0.36 SD (-0.58, -0.14 SD) (P = 0.002), respectively]. Sex × treatment interactions occurred for episodic memory (P = 0.006) and the RT of working memory (P = 0.03). Compared with the placebo, DHA improved episodic memory in women [0.28 SD (0.08, 0.48 SD); P = 0.006] and RTs of working memory in men [-0.60 SD (-0.95, -0.25 SD); P = 0.001]. APOE did not affect cognitive function, but there were some indications of APOE × sex × treatment interactions.

CONCLUSIONS

DHA supplementation improved memory and the RT of memory in healthy, young adults whose habitual diets were low in DHA. The response was modulated by sex. This trial was registered at the New Zealand Clinical Trials Registry (http://www.anzctr.org.au/default.aspx) as ACTRN12610000212055.

Neuropsychological testing in a rural African school-age population: evaluating contributions to variability in test performance

This study investigated the psychometric properties of a number of neuropsychological tests adapted for use in sub-Saharan Africa. A total of 308 school-age children in a predominantly rural community completed the tests. These tests were developed to assess skills similar to those measured by assessments of cognitive development published for use in Western contexts. Culturally appropriate adaptations were made to enhance within-population variability. Internal consistency ranged from .70 to .84. Scores on individual tests were related to various background factors at the level of the child, household, and neighborhood. School experience was the most consistent predictor of outcome, accounting for up to 22.9% of the variance observed. Significant associations were identified to determine salient background characteristics that should be taken into account when measuring the discrete effects of disease exposure in similar sociocultural and economic settings.

Omega 3 fatty acids on child growth, visual acuity and neurodevelopment

The aim of this review is to evaluate the effects of omega-3 long chain polyunsaturated fatty acids (n-3 LCPUFA) supplementation in pregnant and lactating women and infants during postnatal life, on the visual acuity, psychomotor development, mental performance and growth of infants and children. Eighteen publications (11 sets of randomized control clinical trial [RCTs]) assessed the effects of the n-3 LCPUFA supplementation duringpregnancyon neurodevelopment and growth, in the same subjects at different time points; 4 publications (2 data sets from RCTs) addressed physiological responses to n-3 LCPUFA supplementation duringpregnancy & lactationand 5 publications (3 data sets from RCTs) exclusively duringlactation. Some of these studies showed beneficial effects of docosahexaenoic acid (DHA) supplementation during pregnancy and/or lactation especially on visual acuity outcomes and some on long-term neurodevelopment; a few, showed positive effects on growth. There were also 15 RCTs involving term infants who received infant formula supplemented with DHA, which met our selection criteria. Many of these studies claimed a beneficial effect of such supplementation on visual, neural, or developmental outcomes and no effects on growth. Although new well designed and conducted studies are being published, evidence from RCTs does not demonstrate still a clear and consistent benefit of n-3 LCPUFA supplementation during pregnancy and/or lactation on term infants growth, neurodevelopment and visual acuity. These results should be interpreted with caution due to methodological limitations of the included studies.

Do specific dietary constituents and supplements affect mental energy? Review of the evidence

The numbers of marketing claims and food, beverage, and drug products claiming to increase mental energy have risen rapidly, thus increasing the need for scientific specificity in marketing and food label claims. Mental energy is a three-dimensional construct consisting of mood (transient feelings about the presence of fatigue or energy), motivation (determination and enthusiasm), and cognition (sustained attention and vigilance). The present review focuses on four dietary constituents/supplements (Ginkgo biloba, ginseng, glucose, and omega-3 polyunsaturated fatty acids) to illustrate the current state of the literature on dietary constituents and mental energy. The strongest evidence suggests effects of Ginkgo biloba on certain aspects of mood and on attention in healthy subjects, as well as associations between omega-3 polyunsaturated fatty acids and reduced risk of age-related cognitive decline. Limitations of the current data and challenges for future research are discussed.

Nutrition and cognition: meeting the challenge to obtain credible and evidence-based facts

Nutrition provides a practical and appealing approach to cognitive enhancement, including the modulation of long-term cognitive processes such as neurodevelopment and neurodegeneration. An abundance of promising nutritional influences on cognition have been identified, but many long-term effects remain to be confirmed by data from randomized controlled trials (RCTs). The current article provides a general outline of various factors that hamper the demonstration of causal long-term nutritional effects on cognition by RCTs and advocates the development of methodological solutions to enable substantiation in future RCTs.

Validation of reaction time as a measure of cognitive function and quality of life in healthy subjects and patients

OBJECTIVE

Malnutrition is a common problem in hospitalized patients and is related to decreased cognitive function and impaired quality of life (QoL). We investigated the validity of reaction time as a simple bedside tool for measuring cognitive function in healthy subjects and patients, and additionally the relationships with QoL and malnutrition in patients.

METHODS

Healthy subjects (N = 130) were assessed for simple and complex reaction time and cognitive function (Addenbrooke cognitive examination, ACE). Patients (N = 70) were assessed for simple and complex reaction time, cognitive function (ACE), and QoL (short-form health survey) (N = 40).

RESULTS

Reaction time was related to cognitive function in both healthy subjects and patients. Reaction time was inversely related to the physical component summary of QoL in patients (r = -0.42, P < 0.001). Five of eight QoL scales and the mental component summary of QoL were significantly lower in malnourished patients. Reaction time and ACE were impaired in patients compared to healthy subjects, but not further impaired in malnourished patients.

CONCLUSION

Simple reaction time test is related to cognitive function in healthy subjects and patients and to QoL in patients. Complex reaction time test is related to more components of cognitive function. Thus, simple and complex reaction time tests could serve as bedside measurements reflecting, respectively, QoL or cognitive function.

Iodine supplementation improves cognition in mildly iodine-deficient children

BACKGROUND

The effects of severe iodine deficiency during critical periods of brain development are well documented. There is little known about the consequences of milder forms of iodine deficiency on neurodevelopment.

OBJECTIVE

The objective was to determine whether supplementing mildly iodine-deficient children with iodine improves cognition.

DESIGN

A randomized, placebo-controlled, double-blind trial was conducted in 184 children aged 10-13 y in Dunedin, New Zealand. Children were randomly assigned to receive a daily tablet containing either 150 microg I or placebo for 28 wk. Biochemical, anthropometric, and dietary data were collected from each child at baseline and after 28 wk. Cognitive performance was assessed through 4 subtests from the Wechsler Intelligence Scale for Children.

RESULTS

At baseline, children were mildly iodine deficient [median urinary iodine concentration (UIC): 63 microg/L; thyroglobulin concentration: 16.4 microg/L]. After 28 wk, iodine status improved in the supplemented group (UIC: 145 microg/L; thyroglobulin: 8.5 microg/L), whereas the placebo group remained iodine deficient (UIC: 81 microg/L; thyroglobulin: 11.6 microg/L). Iodine supplementation significantly improved scores for 2 of the 4 cognitive subtests [picture concepts (P = 0.023) and matrix reasoning (P = 0.040)] but not for letter-number sequencing (P = 0.480) or symbol search (P = 0.608). The overall cognitive score of the iodine-supplemented group was 0.19 SDs higher than that of the placebo group (P = 0.011).

CONCLUSIONS

Iodine supplementation improved perceptual reasoning in mildly iodine-deficient children and suggests that mild iodine deficiency could prevent children from attaining their full intellectual potential. The trial was registered with the Australia New Zealand Clinical Trials Register as ACTRN12608000222347.

The influence of carbohydrate on cognitive performance: a critical evaluation from the perspective of glycaemic load

Links between nutrition and cognition are widely acknowledged. Within the context of short-term cognitive performance, carbohydrate has been the dietary component most commonly investigated. The majority of studies investigating the influence of carbohydrate on cognitive performance have employed oral glucose drink interventions followed by measures of performance on cognitive tests. More recently, studies have investigated the effect of different carbohydrates on cognitive performance rather than just pure glucose drinks. To date, studies have not been evaluated based on a standardised measure of glycaemic response, such as glycaemic load. The present review provides a critical evaluation of eight studies that have explored the relationships between food carbohydrate and cognitive performance and allow glycaemic load to be used as a basis for comparison. The key finding is that these provide insufficient evidence to support a consistent effect of glycaemic load on short-term cognitive performance. Future studies should employ consistent test methodologies and describe food interventions in more detail to facilitate meaningful comparisons and interpretations of results.