Effects of breakfast and caffeine on cognitive performance, mood and cardiovascular functioning

Analysis of Eating Habits and Body Composition of Young Adult Poles

BACKGROUND

Obesity and overweight affect a large proportion of the world's population. Increasingly, this problem can be observed among young adults. The aim of the study was to identify the motivations and barriers to healthy eating habits among young Poles, the relationship between physical activity and healthy eating and the impact of healthy eating on the body composition of the young.

METHODS

The method used in the research was a diagnostic survey using direct personal interviews. The research was conducted in the years 2016-2019 on a group of 399 young Poles aged 18-26. Their body composition was analyzed by determining resistance and reactance using the biological impedance method, with a TANITA SC-330ST Body Composition Analyzer.

RESULTS AND CONCLUSION

The main reasons for healthy eating among young Poles are the intent to follow a doctor's recommendations, to lose weight and to live a healthy lifestyle and to follow a trend. On the other hand, the largest barriers to proper nutrition are: lack of time to prepare healthy meals and of financial resources, inability to prepare meals and limited knowledge of the principles of healthy eating. The eating behavior varied significantly in relation to the physical activity of the respondents. Active people's eating habits were the best, and those of sedentary people the worst. Healthy eaters also had normal body composition indicators (adipose tissue level, BMI, body type). Young adults should be educated on the principles of healthy eating and have access to healthy food in canteens and vending machines, both at work and at university.

Experimental study of pre- and postnatal caffeine exposure and its observable effects on selected neurotransmitters and behavioural attributes at puberty : Caffeine exposure and its observable effects on selected neurotranmitters and behaviour

Caffeine is globally consumed as a stimulant in beverages. It is also ingested in purified forms as power and tablets. Concerns have been raised about the potential consequences of intrauterine and early life caffeine exposure on brain health. This study modeled caffeine exposure during pregnancy and early postanal life until puberty, and the potential consequences. Caffeine powder was dissolved in distilled water. Thirty-two (n = 32) pregnant mice (Mus musculus) (dams) were divided into four groups- A, B, C and D. Group A animals served as a control, receiving placebo. Caffeine doses in mg/kg body weight were administered as follows: Group B, 10 mg/kg; Group C, 50 mg/kg; Group D, 120 mg/kg. Prenatal caffeine exposure [phase I] lasted throughout pregnancy. Half the number of offspring (pups) were sacrificed at birth; the rest were recruited into phase II and the experiment continued till day 35, marking puberty. Brain samples were processed following sacrifice. γ-aminobutyric acid (GABA), acetylcholine (ACh), and serotonin (5Ht) neurotransmitters were assayed in homogenates to evaluate functional neurochemistry. Anxiety and memory as neurobehavioural attributes were observed using the elevated plus and Barnes' mazes respectively. Continuous caffeine exposure produced positive effects on short and long-term memory parameters; the pattern interestingly was irregular and appeared more effective with the lowest experimental dose. Anxiety test results showed no attributable significant aberrations. Caffeine exposure persistently altered the neurochemistry of selected neurotransmitters including ACh and 5Ht, including when exposure lasted only during pregnancy. ACh significantly increased in group B^C+ to 0.3475μgg-¹ relative to control's 0.2508μgg-¹; pre-and continuous postnatal exposure in Group B increased 5Ht to 0.2203 μgg-¹ and 0.2213 μgg-¹ respectively relative to control's 0.1863 μgg-¹. From the current investigation, caffeine exposure in pregnancy had persistent effects on brain functional attributes including neurotransmitters activities, memory and anxiety. Caffeine in moderate doses affected memory positively but produced negative effects at the higher dosage including increased anxiety tendencies.

Drinking coffee enhances neurocognitive function by reorganizing brain functional connectivity

The purpose of this study was to identify the mechanisms underlying effects of coffee on cognition in the context of brain networks. Here we investigated functional connectivity before and after drinking coffee using graph-theoretic analysis of electroencephalography (EEG). Twenty-one healthy adults voluntarily participated in this study. The resting-state EEG data and results of neuropsychological tests were consecutively acquired before and 30 min after coffee consumption. Graph analyses were performed and compared before and after coffee consumption. Correlation analyses were conducted to assess the relationship between changes in graph measures and those in cognitive function tests. Functional connectivity (FC) was reorganized toward more efficient network properties after coffee consumption. Performance in Digit Span tests and Trail Making Test Part B improved after coffee consumption, and the improved performance in executive function was correlated with changes in graph measures, reflecting a shift toward efficient network properties. The beneficial effects of coffee on cognitive function might be attributed to the reorganization of FC toward more efficient network properties. Based on our findings, the patterns of network reorganization could be used as quantitative markers to elucidate the mechanisms underlying the beneficial effects of coffee on cognition, especially executive function.

Plasma brain-derived neurotrophic factor and dynamic cerebral autoregulation in acute response to glycemic control following breakfast in young men

We examined the acute impact of both low- and high-glycemic index (GI) breakfasts on plasma brain-derived neurotrophic factor (BDNF) and dynamic cerebral autoregulation (dCA) compared with breakfast omission. Ten healthy men (age 24 ± 1 yr) performed three trials in a randomized crossover order; omission and Low-GI (GI = 40) and High-GI (GI = 71) breakfast conditions. Middle cerebral artery velocity (transcranial Doppler ultrasonography) and arterial pressure (finger photoplethysmography) were continuously measured for 5 min before and 120 min following breakfast consumption to determine dCA using transfer function analysis. After these measurements of dCA, venous blood samples for the assessment of plasma BDNF were obtained. Moreover, blood glucose was measured before breakfast and every 30 min thereafter. The area under the curve of 2 h postprandial blood glucose in the High-GI trial was higher than the Low-GI trial (P < 0.01). The GI of the breakfast did not affect BDNF. In addition, both very-low (VLF) and low-frequency (LF) transfer function phase or gains were not changed during the omission trial. In contrast, LF gain (High-GI P < 0.05) and normalized gain (Low-GI P < 0.05) were decreased by both GI trials, while a decrease in VLF phase was observed in only the High-GI trial (P < 0.05). These findings indicate that breakfast consumption augmented dCA in the LF range but High-GI breakfast attenuated cerebral blood flow regulation against slow change (i.e., the VLF range) in arterial pressure. Thus we propose that breakfast and glycemic control may be an important strategy to optimize cerebrovascular health.

Effects of caffeine ingestion on dynamic visual acuity: a placebo-controlled, double-blind, balanced-crossover study in low caffeine consumers

BACKGROUND

Acute caffeine ingestion has been associated with improvements in cognitive performance and visual functioning. The main objective of this study was to determine the effects of caffeine intake on dynamic visual acuity (DVA).

METHODS

Twenty-one low caffeine consumers (22.5 ± 1.6 years) took part in this placebo-controlled, double-blind, and balanced crossover study. In two different days and following a random order, participants ingested either caffeine (4 mg/kg) or placebo, and DVA was measured after 60 min of ingesting the corresponding capsule. A recently developed and validated software (moV& test, V&mp Vision Suite, Waterloo, Canada) was used to assess DVA.

RESULTS

We found a greater accuracy for both the horizontal and random motion paths of DVA after caffeine ingestion (p < 0.001 and p = 0.002, respectively). In regard to the speed of the response, our data revealed that caffeine intake was associated with a faster reaction time for horizontally (p = 0.012) but not for randomly (p = 0.846) moving targets. Also, participants reported higher levels of perceived activation after consuming caffeine in comparison to placebo (p < 0.001).

CONCLUSIONS

Our data suggest that caffeine intake (i.e., a capsule containing 4 mg/kg) has an ergogenic effect on DVA, which may be of special relevance in real-word contexts that require to accurately and rapidly detect moving targets (e.g., sports, driving, or piloting).

Effects of Various Doses of Caffeine Ingestion on Intermittent Exercise Performance and Cognition

To date, no study has examined the effects of caffeine on prolonged intermittent exercise performance that imitates certain team-sports, and the suitable concentration of caffeine for improved intermittent exercise performance remains elusive. The purpose of the present cross-over, double-blind preliminary study was to investigate effects of low, moderate, and high doses of caffeine ingestion on intermittent exercise performance and cognition. Ten males performed a familiarization session and four experimental trials. Participants ingested capsules of placebo or caffeine (3, 6, or 9 mg/kg) at 1 h before exercise, rested quietly, and then performed cycling for 2 × 30 min. The cycling protocol consisted of maximal power pedaling for 5 s (mass × 0.075 kp) every minute, separated by unloaded pedaling for 25 s and rest for 30 s. At pre-ingestion of capsules, 1 h post-ingestion, and post-exercise, participants completed the Stroop task. The mean power-output (MPO), peak power-output (PPO), and response time (RT) in the Stroop task were measured. Only 3 mg/kg of caffeine had positive effects on the mean PPO and MPO; 3 mg/kg caffeine decreased RTs significantly in the incongruent and congruent conditions. These results indicate that the ingestion of low-dose caffeine had greater positive effects on the participants' physical strength during prolonged intermittent exercise and cognition than moderate- or high-dose caffeine.

Effects of prebiotics on affect and cognition in human intervention studies

Studies conducted in rodents have highlighted that neurobiological processes underlying cognition and affect are modulated by the gut microbiota. Certain dietary fibers are able to modulate the composition of gut microbiota and are thus considered prebiotics. A review of the impact of the available prebiotic intervention studies in humans on cognition and affect, addressing the potential mediating role of the microbiota, was conducted. PubMed, Scopus, and PsycINFO were selected as sources. Fourteen articles were eligible for narrative synthesis. Data extraction and quality assessment were performed with characteristics established a priori. Some chronic prebiotic interventions (>28 d) improved affect and verbal episodic memory compared with a placebo. Acute prebiotic interventions (<24 h) were more efficient in improving cognitive variables (eg, verbal episodic memory). Future research should measure microbiota using adequate methodologies and recruit patients with dysbiosis, inflammation, or psychopathology. More research is needed to unravel the conditions required to obtain effects on affect and cognition.

Caffeine improves text reading and global perception

BACKGROUND

Reading is a unique human skill. Several brain networks involved in this complex skill mainly involve the left hemisphere language areas. Nevertheless, nonlinguistic networks found in the right hemisphere also seem to be involved in sentence and text reading. These areas do not deal with phonological information, but are involved in verbal and nonverbal pattern information processing. The right hemisphere is responsible for global processing of a scene, which is needed for developing reading skills.

AIMS

Caffeine seems to affect global pattern processing specifically. Consequently, our aim was to discover if it could enhance text reading skill.

METHODS

In two mechanistic studies (n=24 and n=53), we tested several reading skills, global and local perception, alerting, spatial attention and executive functions, as well as rapid automatised naming and phonological memory, using a double-blind, within-subjects, repeated-measures design in typical young adult readers.

RESULTS

A single dose of 200 mg caffeine improved global processing, without any effect on local information processing, alerting, spatial attention and executive or phonological functions. This improvement in global processing was accompanied by faster text reading speed of meaningful sentences, whereas single word/pseudoword or pseudoword text reading abilities were not affected. These effects of caffeine on reading ability were enhanced by mild sleep deprivation.

CONCLUSIONS

These findings show that a small quantity of caffeine could improve global processing and text reading skills in adults.

Attentional and working memory performance following alcohol and energy drink: A randomised, double-blind, placebo-controlled, factorial design laboratory study

Alcohol mixed with energy drinks (AMED) studies have typically not shown antagonism of acute alcohol effects by energy drink (ED), particularly over relatively short time frames. This study investigated the effects of alcohol, ED, and AMED on attentional and working memory processes over a 3 h period. Twenty-four young adults took part in a randomised, double-blind, placebo-controlled, factorial, 4-arm study. They were administered 0.6g/kg alcohol and 250 ml ED (containing 80 mg caffeine), and matching placebos alone and in combination. A battery of attentional and working memory measures was completed at baseline then 45, 90 and 180 min post-treatment. Alcohol produced a characteristic shift in speed/accuracy trade-off, having little effect on reaction times while increasing errors on all attentional measures (4-choice Reaction Time, Number Pairs and Visual Search), as well as a composite Attentional error score and one working memory task (Serial Sevens). ED alone improved two working memory measures (Memory Scanning accuracy and Digit-Symbol reaction times) and improved speed of responding on a composite Working Memory score. There was no consistent pattern of AMED vs. alcohol effects; AMED produced more errors than alcohol alone on one attentional measure (Visual Search errors) at 45 min only whereas AMED resulted in fewer errors on the Serial Sevens task at 90 min and better Digit-Symbol accuracy and reaction time at 45 min. Alcohol consumption increases error rate across several attentional and working memory processes. Mutual antagonism between alcohol and ED showed no consistent pattern and likely reflects a complex interaction between caffeine and alcohol levels, phase of the blood alcohol limb, task domain and cognitive load.

Eating breakfast, fruit and vegetable intake and their relation with happiness in college students

PURPOSE

Nutrition plays a major role in physical and mental health. The aim of this study was to evaluate the relationships between happiness and fruit and vegetable intake as well as eating breakfast in students.

METHODS

In this cross-sectional web-based study, all students of Qazvin University of Medical Sciences in Iran who attended course classes were invited to participate in the study. Five hundred forty-one students filled out the web-based questionnaire which included questions related to measurement of happiness, breakfast, fruit and vegetable consumption and socio-economic and demographic information. Analysis of covariance was used to assess the relationship between happiness and breakfast, fruit and vegetable consumption by adjustments for covariates.

RESULTS

Measure of happiness was positively associated with eating breakfast, number of meals eaten daily and the amount of fruit and vegetable consumption (P values were <0.001, 0.008, 0.02, and 0.045 respectively). Students who ate breakfast every day, more than 8 servings of fruit and vegetables daily, and had 3 meals in addition to 1-2 snacks per day had the highest happiness score.

CONCLUSION

Healthier behavior pattern was associated with higher happiness scores among medical students.

The Effects of Breakfast and Breakfast Composition on Cognition in Adults

Extensive literature has addressed the acute cognitive effects of breaking a fast. Recent reviews in this line of work have synthesized available research on the cognitive consequences of fasting compared with nutrient intake and the cognitive effects of macronutrient consumption. These largely have been inconclusive, possibly in part because of selection criteria limiting the scope of studies covered. The purpose of the current review is to integrate the results of the literature examining the cognitive effects of breakfast and breakfast composition in adults with the use of a flexible definition of breakfast, specifically, any caloric intake after a fasting period of ≥8 h. This review includes 38 studies that examine the acute cognitive impact of breakfast and 16 studies that examine the effects of breakfast composition. Results suggest that healthy adults show a small but robust advantage for memory (particularly delayed recall) from consuming breakfast. Largely equivocal results emerge for attention and motor and executive function; there were no effects from breakfast on language. Regarding breakfast composition, a smaller number of studies and widely disparate methodology addressing this question preclude definitive conclusions about the effects of cognition. A subset of this literature examines these questions in the context of glucoregulation; the findings emphasize the importance of considering differences in glucoregulation in research designs, even among healthy cohorts. The limitations of this literature include methodologic differences, such as the use of different tests to measure cognitive constructs, as well as the effects of timing in test administration.

Breakfast and Energy Drink Consumption in Secondary School Children: Breakfast Omission, in Isolation or in Combination with Frequent Energy Drink Use, is Associated with Stress, Anxiety, and Depression Cross-Sectionally, but not at 6-Month Follow-Up

A considerable amount of research suggests that breakfast omission and the frequent use of caffeinated energy drinks may be associated with undesirable effects, and particularly so in children and adolescents. The current paper presents cross-sectional and longitudinal data from the Cornish Academies Project to investigate the effects of consuming energy drinks and missing breakfast on stress, anxiety, and depression in a cohort of secondary school children from the South West of England. Questionnaires were administered at two time-points (spaced 6 months apart) to collect information relating to diet and lifestyle over the previous 6 months. Demographic and school data were acquired through the School Information Management System, and single-item measures of stress, anxiety, and depression were administered at the second time-point only. Associations between breakfast and energy drink consumption and stress, anxiety, and depression were investigated, and a multivariate approach was taken so that additional variance from diet, demography, and lifestyle could be controlled for statistically. Cross-sectional analyses showed that breakfast omission was consistently associated with negative outcomes, and that this was largely observed for both those who frequently consumed energy drinks and those who did not. However, cross-lag analyses showed that neither breakfast omission or energy drink consumption, alone or in combination, was predictive of stress, anxiety, or depression at 6-month follow-up. This suggests that associations between breakfast and mental health may be bi-directional rather than breakfast being the causal factor.

Test-retest reliability and effects of repeated testing and satiety on performance of an Emotional Test Battery

The P1vital® Oxford Emotional Test Battery (ETB) comprises five computerized tasks designed to assess cognition and emotional processing in human participants. It has been used in between-subjects experimental designs; however, it is unclear whether the battery can be used in crossover designs. This is of particular importance given the increasing use of ETB tasks for repeated assessment of depressed patients in clinical trials and clinical practice. In addition, although satiety state has been reported to affect performance on some cognitive and emotional tasks, it is not known whether it can influence performance on the ETB. Two studies explored these issues. In Experiment 1, 30 healthy women were tested on the ETB on 4 separate occasions (each a week apart) in a within-subjects design. In Experiment 2, another 30 healthy women were randomized to either a satiated or a hungry condition, where they were given an ad libitum lunch of cheese sandwiches, before (satiated) or after (hungry) they were asked to complete the ETB. Experiment 1 demonstrated good test–retest reliability for the ETB. One of the tasks was free from practice effects, whilst performance on the other four tasks stabilized after the first two sessions. In Experiment 2, eating to satiety only affected performance on a single ETB task. These results suggest that the ETB can be used in crossover designs after two initial training sessions. Further, as a robust satiety manipulation had only a limited effect on a single ETB task, it is unlikely that appetitive state will confound ETB performance.

Human Motives, Happiness, and the Puzzle of Parenthood: Commentary on Kenrick et al. (2010)

It is presumed that happiness, and its associated positive emotions, signal to the individual that an adaptive problem has been solved, thus allowing her to shift attention to other concerns, perhaps those "higher" on the revised motivational hierarchy proposed by Kenrick et al (2010, this issue). In this commentary, we present a sampling of longitudinal and experimental evidence supporting two predictions: (a) that people will feel happy after realizing fundamental human motives, and (b) that in turn, the experience of happiness will galvanize people to fulfill these very motives. However, one conspicuous exception to our argument that happiness is both a consequence and a stimulus of human motives is parenthood, which paradoxically is associated with decrements in well-being. Two broad sets of explanations to account for this puzzle are discussed. The first involves evolutionary accounts: that children interfere with lower level needs, that short-term costs of having children are outweighed by long-term benefits, and that the modern-day context of raising children is at odds with our ancestors' environments. The second possibility involves measurement: namely, problems with study designs and the difficulty of capturing on paper or computer screen what is precisely so wonderful and elusive that children grant their parents.

Chewing gum: cognitive performance, mood, well-being, and associated physiology

Recent evidence has indicated that chewing gum can enhance attention, as well as promoting well-being and work performance. Four studies (two experiments and two intervention studies) examined the robustness of and mechanisms for these effects. Study 1 investigated the acute effect of gum on mood in the absence of task performance. Study 2 examined the effect of rate and force of chewing on mood and attention performance. Study 3 assessed the effects of chewing gum during one working day on well-being and performance, as well as postwork mood and cognitive performance. In Study 4, performance and well-being were reported throughout the workday and at the end of the day, and heart rate and cortisol were measured. Under experimental conditions, gum was associated with higher alertness regardless of whether performance tasks were completed and altered sustained attention. Rate of chewing and subjective force of chewing did not alter mood but had some limited effects on attention. Chewing gum during the workday was associated with higher productivity and fewer cognitive problems, raised cortisol levels in the morning, and did not affect heart rate. The results emphasise that chewing gum can attenuate reductions in alertness, suggesting that chewing gum enhances worker performance.

Effects and after-effects of chewing gum on vigilance, heart rate, EEG and mood

Research has shown that chewing gum improves attention, although the mechanism for this effect remains unclear. This study investigated the effects and after-effects of chewing gum on vigilance, mood, heart rate and EEG. Participants completed a vigilance task four times; at baseline, with or without chewing gum, and twice post-chewing. EEG alpha and beta power at left frontal and temporal lobes, subjective mood and heart rate were assessed. Chewing gum shortened reaction time and increased the rate of hits, although hits fell during the second post-chewing task. Chewing gum heightened heart rate, but only during chewing. Gum also increased beta power at F7 and T3 immediately post-chewing, but not following the post-chewing tasks. The findings show that chewing gum affects several different indicators of alertness.

An examination of the demographic predictors of adolescent breakfast consumption, content, and context

Background

Breakfast consumption is important to health; however, adolescents often skip breakfast, and an increased understanding of the breakfast consumption patterns of adolescents is needed. The purpose of this study was to identify the predictors of breakfast eating, including the content and context, in an adolescent sample from Australia and England.

Methods

Four-hundred and eighty-one students completed an online questionnaire measuring breakfast skipping, and breakfast content (what was eaten) and context (who they ate with, involvement in preparation). Logistic regression was conducted to investigate the predictors of skipping breakfast, breakfast context, and consumption of the ten most commonly consumed foods. Chi-square analyses were used to examine differences in breakfast content according to context.

Results

Most students (88%) had consumed breakfast on the day of the survey; breakfast skipping was more common in England (18%) than in Australia (8%). Country, gender, socioeconomic status, and body mass index (BMI) were all predictors of breakfast content and context. Whether adolescents ate with others and/or were involved in breakfast preparation predicted the content of breakfast consumed.

Conclusions

This study provides a comprehensive examination of the factors underlying breakfast consumption (content and context) and has important implications for the development of evidence-based interventions to improve rates of breakfast consumption and the quality of food consumed amongst adolescents.

The influence of glycemic index on cognitive functioning: a systematic review of the evidence

The impact of the rate of carbohydrate absorption, as measured by the carbohydrate's glycemic index (GI) on cognitive performance, is not clear. The aim of this review was to systematically assess the relevant research studies. A systematic review of English-language articles using Medline, Cochrane Central Register of Controlled Trials, EMBASE, PsycINFO, and PsycARTICLES (up to July 2012) using the search terms "glyc(a)emic index" or "glycaemic load" combined with "cognitive function" or "cognition" or "memory" was carried out. Inclusion and exclusion criteria were prespecified. Eligibility of the identified studies was assessed independently by the 2 reviewers. Independent extraction of data was carried out by the 2 authors using predefined data fields. The primary outcome measure was the effect on cognitive function (CF) after the consumption of meals varying in GI. Eleven eligible studies were identified. The age range of the participants varied from 6 to 82 y old. Overall, the findings were inconsistent, with some studies showing benefits toward either the high-GI or the low-GI meal, others not finding any differences between the 2 meals, and other studies showing a positive or negative effect on performance on only some cognitive domain or domains after consumption of 1 of the 2 meals. A number of methodologic and confounding factors were identified that could explain these inconsistencies. These include the study design, the selected sample (size, age, blood glucose regulation), the timing of testing, the cognitive domain being examined, the number and type of cognitive tests used, the meals provided (composition, size), the timing of blood samples collected, as well as the possibility of bias because participants and investigators were not blinded to randomization. A low-GI meal may favor CF in adults, but the findings at present are inconclusive. On the basis of this review, it is suggested that future studies address the identified methodologic issues and some recommendations are proposed to this effect.

Impacts of the Primary School Free Breakfast Initiative on socio-economic inequalities in breakfast consumption among 9-11-year-old schoolchildren in Wales

Objectives

Universal interventions may widen or narrow inequalities if disproportionately effective among higher or lower socio-economic groups. The present paper examines impacts of the Primary School Free Breakfast Initiative in Wales on inequalities in children's dietary behaviours and cognitive functioning.

Design

Cluster-randomised controlled trial. Responses were linked to free school meal (FSM) entitlement via the Secure Anonymised Information Linkage databank. Impacts on inequalities were evaluated using weighted school-level regression models with interaction terms for intervention × whole-school percentage FSM entitlement and intervention × aggregated individual FSM entitlement. Individual-level regression models included interaction terms for intervention × individual FSM entitlement.

Setting

Fifty-five intervention and fifty-six wait-list control primary schools.

Subjects

Approximately 4500 children completed measures of dietary behaviours and cognitive tests at baseline and 12-month follow-up.

Results

School-level models indicated that children in intervention schools ate a greater number of healthy items for breakfast than children in control schools (b = 0·25; 95 % CI 0·07, 0·44), with larger increases observed in more deprived schools (interaction term b = 1·76; 95 % CI 0·36, 3·16). An interaction between intervention and household-level deprivation was not significant. Despite no main effects on breakfast skipping, a significant interaction was observed, indicating declines in breakfast skipping in more deprived schools (interaction term b = −0·07; 95 % CI −0·15, −0·00) and households (OR = 0·67; 95 % CI 0·46, 0·98). No significant influence on inequality was observed for the remaining outcomes.

Conclusions

Universal breakfast provision may reduce socio-economic inequalities in consumption of healthy breakfast items and breakfast skipping. There was no evidence of intervention-generated inequalities in any outcomes.

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.

Caffeine as an attention enhancer: reviewing existing assumptions

RATIONALE

Despite the large number of studies on the behavioural effects of caffeine, an unequivocal conclusion had not been reached. In this review, we seek to disentangle a number of questions.

OBJECTIVE

Whereas there is a general consensus that caffeine can improve performance on simple tasks, it is not clear whether complex tasks are also affected, or if caffeine affects performance of the three attention networks (alerting, orienting and executive control). Other questions being raised in this review are whether effects are more pronounced for higher levels of caffeine, are influenced by habitual caffeine use and whether there effects are due to withdrawal reversal.

METHOD

Literature review of double-blind placebo controlled studies that assessed acute effects of caffeine on attention tasks in healthy adult volunteers.

RESULTS

Caffeine improves performance on simple and complex attention tasks, and affects the alerting, and executive control networks. Furthermore, there is inconclusive evidence on dose-related performance effects of caffeine, or the influence of habitual caffeine consumption on the performance effects of caffeine. Finally, caffeine's effects cannot be attributed to withdrawal reversal.

CONCLUSIONS

Evidence shows that caffeine has clear beneficial effects on attention, and that the effects are even more widespread than previously assumed.

Acute effects of caffeine on attention: a comparison of non-consumers and withdrawn consumers

Despite the large number of studies on caffeine and attention, interpretation is often difficult because of methodological weaknesses. In the present study, use of a small battery of tests with four key outcome measures, combined with an appropriate sample size, addresses many of these problems. This methodology was used to examine whether effects of caffeine (a dose of 2 mg/kg) could be explained in terms of reversal of the effects of caffeine withdrawal. This was achieved by examining effects in non-consumers (N = 35), who could not be withdrawn, and also in a group of consumers (N = 35) who had undergone withdrawal for a week and no longer reported symptoms of withdrawal. The results showed no effect of short-term withdrawal on the performance measures, even though subjective reports showed an increase in symptoms after withdrawal. In contrast, the caffeine challenge carried out on Day 8 showed that ingestion of caffeine was associated with faster simple reaction time, fewer long responses, greater detection of targets in the cognitive vigilance task, and faster encoding of new information. These results suggest that it is important to continue to investigate mechanisms underlying these effects of caffeine and to further evaluate the practical implications of such effects.

Effects of caffeine on alcohol-related changes in behavioural control and perceived intoxication in light caffeine consumers

RATIONALE

Caffeinated alcoholic beverages have been associated with increased risk of alcohol-related harms. However, few studies have examined these combined effects on behavioural control, which is believed to underlie many of the negative effects of alcohol consumption. In addition, studies have often omitted subjective measures, and none have directly assessed the role of caffeine consumer history.

OBJECTIVES

To examine the combined effects of alcohol and caffeine on measures of behavioural control and perceived intoxication in abstinent, light caffeine consumers.

METHODS

Participants (n = 28; 50% male) attended four sessions at which they consumed one of the following beverages in a randomised order: placebo, alcohol alone (0.6 g/kg), caffeine alone (2.0 mg/kg), and alcohol/caffeine. They completed measures of mood, intoxication, anxiety and alcohol craving before and after a task battery comprising measures of behavioural control and reaction time performance.

RESULTS

Caffeine attenuated alcohol-related performance deficits on stop-signal accuracy, had no effect on go-no-go performance deficits, and worsened accuracy on the Stroop task. Caffeine did not influence absolute changes in perceived intoxication but there was suggestion that caffeine may have changed the nature of intoxication with increases in stimulation.

CONCLUSIONS

Caffeine appears to have mixed effects on alcohol intoxication that are task-dependent. We found increased stimulation in the alcohol/caffeine condition, supporting the contention that caffeinated alcoholic beverages enable an individual to drink for longer. Future research should model real world drinking behaviour by examining how these effects change across multiple drink administrations.

Demand characteristics, pre-test attitudes and time-on-task trends in the effects of chewing gum on attention and reported mood in healthy volunteers

Previous research has indicated that chewing gum enhances reported alertness, but has variable effects on attention. Demand characteristics may explain these effects. The current study investigated the effects of gum and demand characteristics on attention and reported mood over time. Participants completed measures of mood and attention, with and without chewing gum. To manipulate demand characteristics, they were told that the hypothesised effect of gum was either positive or negative, or no hypothesis was mentioned. Attitudes towards gum were assessed pre- and post-manipulation. Gum increased reported alertness; this effect was only significant for positive and neutral demand characteristics. Vigilance accuracy was reduced for chewing gum, but only in the fourth minute of the task, and gum reduced focussed attention accuracy, but only for the first 64 trials. Demand characteristics did not moderate time-on-task effects. Gum improved selective attention. A positive effect on response organisation was observed; this was significant when demand characteristics and pre-test attitudes to gum were both negative. The results suggest that demand characteristics moderate effects on self-reported alertness and response organisation, but cannot explain time-on-task effects or variable main effects on other aspects of attention.

Eating breakfast enhances the efficiency of neural networks engaged during mental arithmetic in school-aged children

To determine the influence of a morning meal on complex mental functions in children (8-11 y), time-frequency analyses were applied to electroencephalographic (EEG) activity recorded while children solved simple addition problems after an overnight fast and again after having either eaten or skipped breakfast. Power of low frequency EEG activity [2 Hertz (Hz) bands in the 2-12 Hz range] was determined from recordings over frontal and parietal brain regions associated with mathematical thinking during mental calculation of correctly answered problems. Analyses were adjusted for background variables known to influence or reflect the development of mathematical skills, i.e., age and measures of math competence and math fluency. Relative to fed children, those who continued to fast showed greater power increases in upper theta (6-8 Hz) and both alpha bands (8-10 Hz; 10-12 Hz) across sites. Increased theta suggests greater demands on working memory. Increased alpha may facilitate task-essential activity by suppressing non-task-essential activity. Fasting children also had greater delta (2-4 Hz) and greater lower-theta (4-6 Hz) power in left frontal recordings-indicating a region-specific emphasis on both working memory for mental calculation (theta) and activation of processes that suppress interfering activity (delta). Fed children also showed a significant increase in correct responses while children who continued to fast did not. Taken together the findings suggest that neural network activity involved in processing numerical information is functionally enhanced and performance is improved in children who have eaten breakfast, whereas greater mental effort is required for this mathematical thinking in children who skip breakfast.

Breakfast glycaemic index and cognitive function in adolescent school children

It has been suggested that a low-glycaemic index (GI) breakfast may be beneficial for some elements of cognitive function (e.g. memory and attention), but the effects are not clear, especially in adolescents. Thus, the aim of the present study was to examine the effects of a low-GI breakfast, a high-GI breakfast and breakfast omission on cognitive function in adolescents. A total of fifty-two adolescents aged 12–14 years were recruited to participate in the study. Participants consumed a low-GI breakfast, a high-GI breakfast or omitted breakfast. A battery of cognitive function tests was completed 30 and 120 min following breakfast consumption and capillary blood samples were taken during the 120 min postprandial period. The findings show that there was a greater improvement in response times following a low-GI breakfast, compared with breakfast omission on the Stroop (P = 0·009) and Flanker (P = 0·041) tasks, and compared with a high-GI breakfast on the Sternberg paradigm (P = 0·013). Furthermore, accuracy on all three tests was better maintained on the low-GI trial compared with the high-GI (Stroop:P = 0·039; Sternberg:P = 0·018; Flanker:P = 0·014) and breakfast omission (Stroop:P < 0·001; Sternberg:P = 0·050; Flanker:P = 0·014) trials. Following the low-GI breakfast, participants displayed a lower glycaemic response (P < 0·001) than following the high-GI breakfast, but there was no difference in the insulinaemic response (P = 0·063) between the high- and low-GI breakfasts. Therefore, we conclude that a low-GI breakfast is most beneficial for adolescents' cognitive function, compared with a high-GI breakfast or breakfast omission.

Behavioral and perceived stressor effects on urinary catecholamine excretion in adult Samoans

OBJECTIVES

The effects of perceptions and behaviors related to culturally patterned socioeconomic obligations on catecholamine excretion rates were studied in a cross-sectional sample of Samoan adults.

METHODS

A total of 378 participants, ages 29-62 years, from 9 villages throughout Samoa, provided timed overnight urine specimens, and self-reported perceptions and behaviors associated with contributions to one's family, aiga, and chief, matai, and communal gift exchanges, fa'alavelave. Urinary norepinephrine and epinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection. Age (≤40 vs. >40 years) and gender-specific regression models were estimated to detect associations with catecholamine excretion.

RESULTS

Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who view their contribution to their matai to be "just right," had significantly higher residence-adjusted norepinephrine excretion. Young women who contribute more to their matai, who consider fa'alavelave to be a financial strain, and who consider their contribution to their aiga not to be a burden, had higher epinephrine excretion. Older men who contribute more to their aiga and who perceive their contribution to their aiga to be "just right" had increased residence-adjusted epinephrine excretion.

CONCLUSIONS

Individual-level perceptions and behaviors related to traditional socioeconomic obligations are a significant correlate of increased overnight catecholamine excretion rates. Higher excretion rates may be attributed to psychosocial stress arousal associated with a discordance between personal desires for upward social mobility, and family and community-based socioeconomic obligations. Changes in patterns of individual-level psychosocial stress arousal may contribute to cardiovascular disease risk in modernizing Samoans.

Breakfast and snacks: associations with cognitive failures, minor injuries, accidents and stress

One strategy for examining effects of nutrients on cognitive function is to initially investigate foods that contain many different nutrients. If effects are demonstrated with these foods then further studies can address the role of specific nutrients. Breakfast foods (e.g., cereals, dairy products and fruit) provide many important nutrients and consumption of breakfast has been shown to be associated with beneficial effects on cognitive function. Isolating effects of specific constituents of breakfast has proved more difficult and it is still unclear what impact breakfast has on real-life performance. The present study provided initial information on associations between breakfast consumption and cognitive failures and accidents. A second aim was to examine associations between consumption of snacks which are often perceived as being unhealthy (chocolate, crisps and biscuits). A sample of over 800 nurses took part in the study. The results showed that frequency of breakfast consumption (varied breakfasts: 62% cereal) was associated with lower stress, fewer cognitive failures, injuries and accidents at work. In contrast, snacking on crisps, chocolate and biscuits was associated with higher stress, more cognitive failures and more injuries outside of work. Further research requires intervention studies to provide a clearer profile of causality and underlying mechanisms.

Ecological and sociodemographic effects on urinary catecholamine excretion in adult Samoans

BACKGROUND

Ecological and sociodemographic correlates of stress may contribute to cardiovascular disease risk in modernizing Samoans.

AIM

The effects of peri-urban vs rural residence, education, occupation, caffeine intake and cigarette consumption on urinary catecholamine excretion were studied in Samoan adults.

SUBJECTS AND METHODS

Five hundred and seven participants, aged 29-69 years, were randomly selected from nine villages throughout Samoa. Sociodemographic and lifestyle factors were assessed by questionnaire. Epinephrine and norepinephrine excretion rates were measured by high performance liquid chromatography with electrochemical detection in overnight urine samples. Age ( ≤ 40 vs >40 years) and gender-specific regression models were estimated to detect associations with BMI-adjusted catecholamine excretion.

RESULTS

Norepinephrine was significantly higher in peri-urban young men and older women. Epinephrine was significantly higher in peri-urban older men. Adjustment for caffeine attenuated the relationship between residence and norepinephrine in young women.

CONCLUSION

General residential exposure to modernization in urban villages is a significant correlate of increased overnight catecholamine excretion rates and is consistent with past studies. Caffeine consumption in younger women plays a complex role in stress-related catecholamine excretion. Further studies of individual level attitudinal and behavioural factors in Samoans are needed to understand psychosocial stress, physiologic arousal and health.

Mood and the macro-nutrient composition of breakfast and the mid-day meal

Six hundred and eighty-six individuals were approached at mid-day after they had chosen a meal in a cafeteria. They were asked to rate their mood during the morning and list what they had eaten that morning. Both males and females who had eaten breakfast rather than fasting reported that they had been happier and more relaxed during the morning. The macro-nutrient compositions of breakfast and lunch were calculated and related to mood during the morning. In males, but not females, the consumption of more carbohydrate in the morning was associated with feeling happy rather than sad and relaxed rather than stressed. Further examination demonstrated that in males the amount of fat, protein and total energy consumed was not associated with mood; that is there was a selective relationship between carbohydrate intake and mood. It was not possible to establish whether the nature of breakfast influenced mood or the pre-existing mood influenced the choice of breakfast although both explanations are plausible. In females, however, there was no relationship between carbohydrate intake and mood, possibly a reflection of the smaller amounts consumed. The suggestion that mood during the morning might influence food choice at mid-day was considered but no association was found.

Effects of cereal bars for breakfast and mid-morning snacks on mood and memory

The aim of the present study was to examine the effects of consuming cereal bars, given either for breakfast or a mid-morning snack, on mood and memory. Thirty-two volunteers (16 males, 16 females; mean age, 20 years 9 months) were randomly assigned to one of four groups formed by combining breakfast (cereal bar versus no breakfast) and snack (cereal bar versus no snack) conditions. A baseline session was completed at 08:30 h followed by breakfast at 9:00 h, another test at 10:00 h, followed by a mid-morning snack and then a final test at 12:00 h. In each session, volunteers rated their mood and carried out four memory tasks: free recall; recognition memory; a verbal reasoning task; and a semantic processing task. The results showed that volunteers who consumed a cereal bar for breakfast felt more alert, happy and sociable and less anxious. In addition, they also recalled more words in a free recall task. When the cereal bar was consumed as a mid-morning snack, alertness and hedonic tone increased, especially in the group who received no breakfast. The group who had no breakfast reported reduced anxiety after consumption of the snack. Recall was also improved after the snack. These findings show that consuming cereal bars in the early and mid-morning leads to beneficial behavioural effects. The results confirm earlier research on effects of breakfast and extend our knowledge of effects of snacks. Consumption of cereal bars may have important practical applications especially in situations where preparation of breakfast is difficult.

Effects of waking time and breakfast intake prior to evaluation of psychomotor performance in the early morning

Many studies conducted in the field of chronobiology report diurnal fluctuation in cognitive and physical performance that occurs in phase with the body temperature circadian rhythm. Waking time and whether or not breakfast is consumed are currently considered to influence the diurnal fluctuation in data collected in the morning at 06:00 h and evening at 18:00 h. Nineteen male subjects participated in four test sessions to examine if wake-up time (04:00 h or 05:00 h) and eating or not eating breakfast influence psychomotor performance capacity at 06:00 h. All four sessions were separated by >/=36 h and were completed in a counterbalanced order. Each test session comprised sign cancellation, Epworth Sleepiness Scale, simple reaction time, and manual dexterity tests. Most of the results indicate that psychomotor performance when evaluated at 06:00 h under each of the four different study situations (two waking times and two breakfast conditions) is not statistically significantly different. Consequently, previous results that documented diurnal fluctuations in morning and evening performance capacities, with test sessions at 06:00 h, are confirmed. Being less efficient in the early morning than in the afternoon potentially exposes people to elevated risk of accident and injury at this time of the day. Prior waking time and/or consumption of a light meal, plus other countermeasures mentioned in the literature, are insufficient to prevent this risk.

Influence of having breakfast on cognitive performance and mood in 13- to 20-year-old high school students: results of a crossover trial

OBJECTIVE

The goal was to determine whether breakfast had effects on the cognitive performance and mood of high school students.

METHODS

A crossover trial was performed in boarding schools, involving 104 students between 13 and 20 years of age. The participants were randomly assigned to 2 equal-size groups on the morning of the first testing day. One half of the total sample received a standardized breakfast, whereas the other half received no breakfast. Seven days later, the treatment order was reversed. Measurements of cognitive function included standardized tests of attention and concentration, as well as tests of verbal and spatial memory. In addition, mood was rated with a self-administered questionnaire covering the dimensions of positive and negative affect, information uptake, arousal, and alertness. Statistical analysis consisted of repeated-measures analysis of variance.

RESULTS

Breakfast had no effect on sustained attention among high school students. Visuospatial memory was improved in male students. Self-reported alertness improved significantly in the entire study population. Male students reported feeling more positive after consuming breakfast, compared with the fasting condition.

CONCLUSIONS

This crossover trial demonstrated positive short-term effects of breakfast on cognitive functioning and self-reported alertness in high school students.