A study of glycaemic effects following acute anthocyanin-rich blueberry supplementation in healthy young adults

The postprandial response to ingested carbohydrate is recognised as a marker of metabolic health. Postprandial hyperglycaemia is observed in type 2 diabetes mellitus and is a significant risk factor for cardiovascular disease. Cognitive deficits are also associated with type 2 diabetes. Therefore interventions which moderate postprandial glucose profiles are desirable. Here we investigated the impact of anthocyanin-rich wild blueberries on postprandial glucose response. Seventeen healthy young adults consumed a range of doses of freeze-dried wild blueberry powder, in smoothie form, in both sugar-matched and no-added-sugar conditions. Plasma glucose was determined by a capillary sampling method at baseline and at regular intervals up to 2.5 hours postprandially. Blueberries were observed to significantly extend the postprandial glucose response beyond the period observed for a sugar-matched control, characteristic of a beneficial glycaemic response. Furthermore, blueberries were observed to reduce peak postprandial glucose levels, although statistical significance was not achieved. The findings suggest a tempering of the postprandial glucose response in the presence of anthocyanin-rich blueberry, and are discussed with reference to likely glucoregulatory mechanisms of action and their implications for cognitive and type 2 diabetes research

Stereopsis in end-stage renal disease (ESRD)

We investigated an effect of end-stage renal disease (ESRD) on the visual system by measuring the ability of 21 patients to perceive depth in the random dot stereograms and circles of the Randot Test. To control for other factors which might influence performance on the tests of stereopsis, patients were compared with healthy controls matched for age, years of education, IQ, and general cognitive ability. Vernier acuity (thought to reflect mainly central processing) and Landolt acuity (more sensitive to retinal and optical abnormalities) were also measured, but the study did not include a formal ophthalmological examination. All controls could perceive depth in random dot stereograms, whereas 9/21 patients could not. Patients who could perceive depth had worse stereoacuity than did their matched controls. The patient group as a whole had worse Vernier and Landolt acuities than the controls. The stereoblind patient subgroup had similar Vernier acuity to the stereoscopic subgroup, but worse Landolt acuity, and were more likely to have peripheral vascular disease. We conclude that ESRD had affected structures both within the eye, and within the visual brain. However, the similarity of Vernier acuity and difference of Landolt acuity in the stereoblind and stereoscopic patient subgroups suggest that the differences in stereoscopic ability arise from abnormalities in the eyes rather than in the brain

Latent learning in end stage renal disease (ESRD)

Cognitive functions such as attention and memory are known to be impaired in End Stage Renal Disease (ESRD), but the sites of the neural changes underlying these impairments are uncertain. Patients and controls took part in a latent learning task, which had previously shown a dissociation between patients with Parkinson’s disease and those with medial temporal damage. ESRD patients (n=24) and age and education-matched controls (n=24) were randomly assigned to either an exposed or unexposed condition. In Phase 1 of the task, participants learned that a cue (word) on the back of a schematic head predicted that the subsequently seen face would be smiling. For the exposed (but not unexposed) condition, an additional (irrelevant) colour cue was shown during presentation. In Phase 2, a different association, between colour and facial expression, was learned. Instructions were the same for each phase: participants had to predict whether the subsequently viewed face was going to be happy or sad. No difference in error rate between the groups was found in Phase 1, suggesting that patients and controls learned at a similar rate. However, in Phase 2, a significant interaction was found between group and condition, with exposed controls performing significantly worse than unexposed (therefore demonstrating learned irrelevance). In contrast, exposed patients made a similar number of errors to unexposed in Phase 2. The pattern of results in ESRD was different from that previously found in Parkinson’s disease, suggesting a different neural origin

The nature of impairments of memory in patients with end-stage renal disease (ESRD)

Possible impairments of memory in end-stage renal disease (ESRD) were investigated in two experiments. In Experiment 1, in which stimulus words were presented visually, participants were tested on conceptual or perceptual memory tasks, with retrieval being either explicit or implicit. Compared with healthy controls, ESRD patients were impaired when memory required conceptual but not when it required perceptual processing, regardless of whether retrieval was explicit or implicit. An impairment of conceptual implicit memory (priming) in the ESRD group represented a previously unreported deficit compared to healthy aging. There were no significant differences between pre- and immediate post-dialysis memory performance in ESRD patients on any of the tasks. In Experiment 2, in which presentation was auditory, patients again performed worse than controls on an explicit conceptual memory task. We conclude that the type of processing required by the task (conceptual vs. perceptual) is more important than the type of retrieval (explicit vs. implicit) in memory failures in ESRD patients, perhaps because temporal brain regions are more susceptible to the effects of the illness than are posterior regions

Flavonoid-Rich Mixed Berries Maintain and Improve Cognitive Function Over a 6h Period in Young Healthy Adults

Research with young adults has previously indicated flavonoid-rich berry interventions facilitate improved executive function (EF) and positive affect 20 min–2 h post-dosing. There has been little consideration of the impact of a berry intervention over a working day and interventions have also tended to consider only a single berry type. This study investigated the temporal profile of EF and mood changes over a 6 h period following a mixed-berry intervention. We hypothesized berry-related benefits would be most evident when participants were cognitively compromised on demanding elements of the task or during periods of fatigue. The study employed a single-blind, randomized, placebo controlled, between-subjects design. Forty participants aged 20–30 years consumed a 400 mL smoothie containing equal blueberry, strawberry, raspberry, and blackberry (n = 20) or matched placebo (n = 20). Mood was assessed using the Positive and Negative Affect Schedule; EF was tested using the Modified Attention Network (MANT) and Task Switching (TST) Tasks. Testing commenced at baseline then 2, 4 and 6 h post-dosing. As expected, following placebo intervention, performance decreased across the day as participants became cognitively fatigued. However, following berry intervention, participants maintained accuracy on both cognitive tasks up to and including 6 h, and demonstrated quicker response times on the MANT at 2 and 4 h, and TST at 6 h. This study demonstrates the efficacy of flavonoid rich berries in maintaining or improving cognitive performance across the 6 h day

Lutein Has a Positive Impact on Brain Health in Healthy Older Adults: A Systematic Review of Randomized Controlled Trials and Cohort Studies

A previous systematic review revealed that lutein intake leads to improved cognitive function among older adults. However, the association between lutein intake and brain health remains unclear. Methods: We searched the Web of Science, PubMed, PsycInfo, and Cochrane Library for research papers. The criteria were (1) an intervention study using oral lutein intake or a cross-sectional study that examined lutein levels and the brain, (2) participants were older adults, and (3) brain activities or structures were measured using a brain imaging technique (magnetic resonance imaging (MRI) or electroencephalography (EEG)). Results: Seven studies using MRI (brain activities during rest, cognitive tasks, and brain structure) and two studies using EEG were included. We mainly focused on MRI studies. Three intervention studies using MRI indicated that 10 mg lutein intake over 12 months had a positive impact on healthy older adults’ brain activities during learning, resting-state connectivity, and gray matter volumes. Four cross-sectional studies using MRI suggested that lutein was positively associated with brain structure and neural efficiency during cognitive tasks. Conclusion: Although only nine studies that used similar datasets were reviewed, this systematic review indicates that lutein has beneficial effects on healthy older adults’ brain health

Fruit and vegetable intake: change with age across childhood and adolescence

Abstract Eating fruit and vegetables (FV) offers important health benefits for children and adolescents, but their average intake is low. To explore if negative trends with age exist as children grow, this study modelled differences in fruit and vegetable consumption from childhood to young adulthood. A pseudo-panel was constructed using Years 1-4 (combined) of the Rolling Programme of the UK National Diet and Nutrition Survey (2008/09 – 2011/12). Intake of fruits and vegetables in the NDNS was recorded using 4- day unweighted food diaries. Data consisted of 2131 observations of individuals aged 2 to 23 years. Age-year-cohort decomposition regression analyses were used to separate age effects from year and cohort effects in the data. Total energy intake was included to account for age differences in overall energy consumption. Fruit intake started to decrease from the age of 7 for boys and girls and reached its lowest level during adolescence. By 17 years boys were consuming 0.93 (p = 0.037) less fruit portions compared to the age of two. By 15 years, girls were consuming 0.8 fruit portions less (p = 0.053). Vegetable intake changed little during childhood and adolescence (p = 0.0834 and p = 0.843 for change between 7 and 12 years, boys and girls respectively). There was unclear evidence of recovery of FV intakes in early adulthood. Efforts to improve FV intake should consider these trends, and focus attention on the factors influencing intake across childhood and adolescence in order to improve the nutritional quality of diets during these periods

Cognitive tests used in chronic adult human randomised controlled trial micronutrient and phytochemical intervention studies

In recent years there has been a rapid growth of interest in exploring the relationship between nutritional therapies and the maintenance of cognitive function in adulthood. Emerging evidence reveals an increasingly complex picture with respect to the benefits of various food constituents on learning, memory and psychomotor function in adults. However, to date, there has been little consensus in human studies on the range of cognitive domains to be tested or the particular tests to be employed. To illustrate the potential difficulties that this poses, we conducted a systematic review of existing human adult randomised controlled trial (RCT) studies that have investigated the effects of 24 d to 36 months of supplementation with flavonoids and micronutrients on cognitive performance. There were thirty-nine studies employing a total of 121 different cognitive tasks that met the criteria for inclusion. Results showed that less than half of these studies reported positive effects of treatment, with some important cognitive domains either under-represented or not explored at all. Although there was some evidence of sensitivity to nutritional supplementation in a number of domains (for example, executive function, spatial working memory), interpretation is currently difficult given the prevailing 'scattergun approach' for selecting cognitive tests. Specifically, the practice means that it is often difficult to distinguish between a boundary condition for a particular nutrient and a lack of task sensitivity. We argue that for significant future progress to be made, researchers need to pay much closer attention to existing human RCT and animal data, as well as to more basic issues surrounding task sensitivity, statistical power and type I error

A potential barrier to adherence? Memory for future intentions is impaired in hemodialysis patients

Introduction: End-stage renal disease (ESRD) has been associated with a range of cognitive deficits, including impaired retrospective memory and attention. Prospective Memory (PM) is memory for future intentions, such as remembering to take medication on time. PM has not been examined in any ESRD patients, yet the implications upon diet and medication management could have potentially detrimental effects on patient welfare. This is the first study to examine PM in ESRD patients being treated with hemodialysis (HD). Methods: HD patients (n=18) were compared to age and education-matched controls (n=18) on a boardgame task that emulates a typical week of activities (i.e. grocery shopping, meetings with friends), requiring the participant to remember a series of upcoming tasks. Other measures were also examined, including general cognitive decline, measures of independent living, IQ and mood. Findings: Patients recalled significantly fewer upcoming events than the control group, suggesting an impairment of PM. No significant relationship was found between PM performance and any other measures, suggesting the difference between groups is likely due to the effects of ESRD, HD treatment or some associated comorbidity. Discussion: This is the first study to demonstrate a PM deficit in patients undergoing HD treatment. This finding contributes to the current knowledge of the cognitive profile of patients undergoing HD, whilst also highlighting the implications that a PM deficit may have on patient quality of life. The finding may go some way to explaining variances in patients’ ability to monitor and adhere to medication and dietary regimes, and ultimately, to live independently. The study also highlights the necessity of viewing treatment for ESRD as a holistic process to maximise patient wellbeing