The incidence of cognitive decline is rising, leading to increased attention on the preventive role of healthy foods on brain function. Previous reviews including primarily observational studies suggested that dietary proteins may improve cognitive performance, but evidence from individual randomised controlled trials (RCT) is less consistent. Therefore, this systematic review examined the long-term effects of dietary proteins from RCT, considering both their amount and type, on cognitive performance (psychomotor speed and attention, executive function, memory and global cognition). Alterations in cerebral blood flow (CBF) – a validated brain vascular function marker – were also considered. A total of 4747 studies were identified through a systematic search, resulting in twenty-three included papers reporting effects on cognitive performance (n = 23) and CBF (n = 3). Improvements were observed in three out of the nine studies that evaluated psychomotor speed which compared a dietary protein intervention with a non-protein or lower-protein control. Of the six beneficial observations on working memory (n = 12), declarative memory (n = 10) and visuospatial memory (n = 10), five were nut interventions from three different trials. Limited studies focusing on global cognition suggested that specific target populations, namely subacute stroke or dementia, may benefit more than healthy individuals from increased dietary protein intake. From the three studies involving CBF, improvements in regional blood flow were associated with most cognitive performance outcomes. The comparative effects of different protein types warrant further investigation. Overall, this review encourages additional research into protein-rich foods or supplements which could potentially prevent or mitigate cognitive decline.

The idea that some abilities might be enhanced by adversity is gaining traction. Adaptation-based approaches have uncovered a few specific abilities enhanced by particular adversity exposures. Yet, for a field to grow, we must not dig too deep, too soon. In this paper, we complement confirmatory research with principled exploration. We draw on two insights from adaptation-based research: 1) enhanced performance manifests within individuals, and 2) reduced and enhanced performance can co-occur. Although commonly assumed, relative performance differences are rarely tested. To quantify them, we need a wide variety of ability measures. However, rather than using adaptive logic to predict which abilities are enhanced or reduced, we develop statistical criteria to identify three data patterns: reduced, enhanced, and intact performance. With these criteria, we analyzed data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development to investigate how adversity shapes within-person performance across 10 abilities in a cognitive and achievement battery. Our goals are to document adversity-shaped cognitive performance patterns, identify drivers of reduced performance, identify sets of “intact” abilities, and discover new enhanced abilities. We believe principled exploration with clear criteria can help break new theoretical and empirical ground, remap old territory, and advance theory development.

The role of flavonoids on cognitive performance in older adults has been intensively studied, with the subclass of anthocyanins showing promising outcomes(1). However, there is conflicting evidence in the case of individuals at high risk of developing dementia, namely those with mild cognitive impairment (MCI). A recent study has suggested that cognitive scores in people with MCI were higher in those who had higher anthocyanin intake (>10 mg)(2). Baseline data from 65 participants of an ongoing clinical trial that had an MIS (Memory Index Score) score ≤ 13 with self-reported subjective memory complaints, (mean age 69.1y ± 6.2) were used to investigate the relationship between dietary anthocyanin intake and indices of mood and cognitive performance. Repeated 24-hour dietary intake was recorded through Intake24 (a computer-based program) for three days (2Xweekday and 1Xweekend day) and anthocyanin intake was quantified using the PhenolExplorer food composition database. The primary outcome of interest was the Buschke and Grober Free and Cued Selective Reminding Test-Immediate Recall (FCSRT+IR) (assesses auditory anterograde memory functioning), while other cognitive functions assessed included: Spot the Word-2 (assessing premorbid estimate); Oral Symbol Digit Test (speed of processing); List Sorting (working memory); Trail Making Test A & B (speed of processing/executive function); and Verbal Fluency (language/semantic memory). Subjective memory complaints were assessed using the Memory Assessment Clinic-Q (MAC-Q) and mood was assessed using the Geriatric Depression Scale (GDS). Independent t-tests were used to compare differences in cognitive tasks and mood scores between high (>10 mg/d) and low consumers of anthocyanins (<10 mg/d). There was a trend for high anthocyanin consumers (n = 35, median = 44.87 (10.01, 177.83)) to score better on FCSRT-Delayed Free Recall scores (16.57 ± 3.74) compared to lower consumers (n = 30, median = 0.01 (0, 9.51)), (15.97 ± 0.18) with a mean difference (SE) of −1.06 (0.58) (p = 0.06) suggesting recall of 1.06 more words after a 20-30 minute delay. Higher consumers had a lower GDS score (1.77 ± 3.73) compared to lower consumers (3.73 ± 1.77), p = 0.01. Spot the word test scores (assesses premorbid verbal abilities using a robust lexical decision task) were higher for high anthocyanin consumers (53.06 ± 4.38) compared to lower consumers (50.40 ± 4.38), mean difference (SE) = −2.66 (1.10), p = 0.01, meaning participants with higher intake of dietary anthocyanin were able to point at 2.7 more real words than low consumers. Dietary consumption of anthocyanin in older adults with MIS is associated with beneficial effects on depressive scores and the ability to retrieve words. Further research is warranted to identify optimal dosage for recommended intake. This cross-sectional study used baseline data from a randomised controlled trial registered with the Australian New Zealand Clinical Trials Registry (ANZCTR):12622000065796.

The aim of this study was to investigate the effects of guarana supplementation on cognitive performance before and after a bout of maximal intensity cycling and to compare this to an equivalent caffeine dose. Twenty-five participants completed the randomised double-blind crossover trial by performing cognitive tests with one of three supplements, on three different days: guarana (125 mg/kg), caffeine (5 mg/kg) or placebo (65 mg/kg protein powder). After 30 min of rest, participants performed simple (SRT) and choice reaction time (CRT) tests, an immediate word recall test and Bond–Lader mood scale. This was followed by a cycling V̇O2max test, and cognitive tests were then immediately repeated. Guarana supplementation decreased CRT before exercise (407 (sd 45) ms) in comparison with placebo (421 (sd 46) ms, P = 0·030) but not caffeine (417 (sd 42) ms). SRT after exercise decreased following guarana supplementation (306 (sd 28) ms) in comparison with placebo (323 (sd 32) ms, P = 0·003) but not caffeine (315 (sd 32) ms). Intra-individual variability on CRT significantly improved from before (111·4 (sd 60·5) ms) to after exercise (81·85 (sd 43·1) ms) following guarana supplementation, and no differences were observed for caffeine and placebo (P > 0·05). Alertness scores significantly improved following guarana supplementation (63·3 (sd 13·8)) in comparison with placebo (57·4 (sd 13·4), P = 0·014) but not caffeine (61·2 (sd 12·8)). There were no changes to V̇O2max, immediate word recall or any other Bond–Lader mood scales. Guarana supplementation appears to impact several parameters of cognition. These results support the use of guarana supplementation to possibly maintain speed of attention immediately following a maximal intensity exercise test (V̇O2max).

A computerized version of the object alternation test (OAT) was employed in unmedicated obsessive–compulsive disorder (OCD) patients and matched healthy controls. OCD patients performed normally on the OAT but scored below controls on a task assessing visuo-spatial working memory. The results challenge the concept of the OAT as a sensitive instrument for orbitofrontal dysfunction in OCD.

Specific language impairment (SLI) is a very common childhood disorder that is characterized by impairments in expressive and/or receptive language regarding different modalities. Part V of the German version of the Token Test was evaluated as a potential screening tool for the early detection of SLI. Forty-five male and 16 female monolingual native German-speaking preschoolers with SLI (4–6 years) and 61 age- and gender-matched typically developing controls were examined with a German version of the Token Test and an established intelligence measure. Token Test performance was significantly worse in preschoolers with SLI including greater group differences at age 4 than at ages 5 and 6. Analyses showed a detection rate of 77% for Part V of the Token Test in the whole sample as well as 85.1% at age 4, 80.6% at age 5, and a nonsignificant detection at age 6. Correctly detected preschoolers with SLI showed significantly worse performance than typically developing controls regarding nonverbal and verbal intelligence, numeracy, problem solving, working memory, visual attention, and memory. Children with SLI show worse Token Test performance, whereas at ages 4 and 5, Part V of the Token Test could potentially serve as a screening tool for the detection of SLI.

Objectives: Subjective memory complaints (SMCs) are among the key concerns in the elderly, but their role in detecting objective cognitive problems is unclear. The aim of this study was to clarify the association between SMCs (both prospective and retrospective memory complaints) and neuropsychological test performance in older adults at risk of cognitive decline. Methods: This investigation is part of the FINGER project, a multicenter randomized controlled trial aiming at preventing cognitive decline in high-risk individuals. The cognitive assessment of participants was conducted at baseline using a modified neuropsychological test battery (NTB). SMCs were evaluated with the Prospective and Retrospective Memory Questionnaire (PRMQ) in a sub-sample of 560 participants (mean age, 69.9 years). Results: Having more prospective SMCs was associated with slower processing speed, but not with other NTB domains. Retrospective SMCs were linked to poorer function on NTB total score, processing speed, and memory. Executive function domain was not associated with any PRMQ ratings. Depressive symptoms and poor quality of life diluted the observed associations for NTB total score and memory. However, the association between PRMQ and processing speed remained even after full adjustments. Conclusions: Our results indicate that self-reported memory problems, measured with PRMQ, are associated with objectively measured cognitive performance. Such complaints in healthy elderly people also seem to reflect reduced mental tempo, rather than memory deficits. Slowing of processing speed may thus be negatively related to memory self-efficacy. It is also important to consider affective factors among those who report memory problems. (JINS, 2018, 24, 1099–1109)

The relationship between obesity and cognitive impairment is important given the globally ageing population in whom cognitive decline and neurodegenerative disorders will carry grave individual, societal and financial burdens. This review examines the evidence for the link between obesity and cognitive function in terms of both the immediate effects on cognitive performance, and effects on the trajectory of cognitive ageing and likelihood of dementia. In mid-life, there is a strong association between obesity and impaired cognitive function. Anthropometric measures of obesity are also associated with reduced neural integrity (e.g. grey and white matter atrophy). Increasing age coupled with the negative metabolic consequences of obesity (e.g. type 2 diabetes mellitus) are likely to significantly contribute to cognitive decline and incidence of dementia. Stress is identified as a potential risk factor promoting abdominal obesity and contributing to impaired cognitive function. However, the potentially protective effects of obesity against cognitive decline in older age require further examination. Finally, surgical and whole diet interventions, which address obesity may improve cognitive capacity and confer some protection against later cognitive decline. In conclusion, obesity and its comorbidities are associated with impaired cognitive performance, accelerated cognitive decline and neurodegenerative pathologies such as dementia in later life. Interventions targeting mid-life obesity may prove beneficial in reducing the cognitive risks associated with obesity.

Adolescence represents an important period for the development of executive functions, which are a set of important cognitive processes including attentional control. However, very little is known regarding the associations of nutrition with components of executive functions in adolescence. Thus, the aim of this study was to investigate associations of dietary patterns and macronutrient composition with attention capacity in European adolescents. This cross-sectional study included 384 (165 boys and 219 girls) adolescents, aged 12·5–17·5 years, from five European countries in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. Attention capacity was examined using the d2 Test of Attention. Dietary intake was assessed through two non-consecutive 24 h recalls using a computer-based self-administered tool. Three dietary patterns (diet quality index, ideal diet score and Mediterranean diet score) and macronutrient/fibre intakes were calculated. Linear regression analysis was conducted adjusting for age, sex, BMI, maternal education, family affluence scale, study centre and energy intake (only for Mediterranean diet score). In these adjusted regression analyses, higher diet quality index for adolescents and ideal diet score were associated with a higher attention capacity (standardised β=0·16, P=0·002 and β=0·15, P=0·005, respectively). Conversely, Mediterranean diet score or macronutrient/fibre intake were not associated with attention capacity (P>0·05). Our results suggest that healthier dietary patterns, as indicated by higher diet quality index and ideal diet score, were associated with attention capacity in adolescence. Intervention studies investigating a causal relationship between diet quality and attention are warranted.

Cerebral blood volume and metabolism of oxygen decline as part of human ageing, and this has been previously shown to be related to cognitive decline. There is some evidence to suggest that polyphenol-rich foods can play an important role in delaying the onset or halting the progression of age-related health disorders such as CVD and Alzheimer’s disease and to improve cognitive function. In the present study, an acute, placebo-controlled, double-blinded, cross-over, randomised Latin-square design study with a washout period of at least 14 d was conducted on twenty-seven, middle-aged (defined as 45–60 years) volunteers. Participants received either a 60 ml dose of Montmorency tart cherry concentrate (MC), which contained 68·0 (sd 0·26) mg cyanidin-3-glucoside/l, 160·75 (sd 0·55) mean gallic acid equivalent/l and 0·59 (sd 0·02) mean Trolox equivalent/l, respectively, or a placebo. Cerebrovascular responses, cognitive performance and blood pressure were assessed at baseline and 1, 2, 3 and 5 h following consumption. There were significant differences in concentrations of total Hb and oxygenated Hb during the task period 1 h after MC consumption (P≤0·05). Furthermore, MC consumption significantly lowered systolic blood pressure (P≤0·05) over a period of 3 h, with peak reductions of 6±2 mmHg at 1 h after MC consumption relative to the placebo. Cognitive function and mood were not affected. These results show that a single dose of MC concentrate can modulate certain variables of vascular function; however, this does not translate to improvements in cognition or mood.

This study compared the longer-term effects of a very low-carbohydrate, high-fat diet with a high-carbohydrate, low-fat diet on cognitive performance in individuals with type 2 diabetes (T2D). In total, 115 obese adults with T2D (sixty-six males, BMI: 34·6 (sd 4·3) kg/m2, age: 58 (sd 7) years, HbA1c: 7·3 (sd 1·1) %, diabetes duration: 8 (sd 6) years) were randomised to consume either an energy-restricted, very low-carbohydrate, low-saturated-fat (LC) diet or an energy-matched high unrefined carbohydrate, low-fat (HC) diet with supervised aerobic/resistance exercise (60 min, 3 d/week) for 52 weeks. Body weight, HbA1c and cognitive performance assessing perceptual speed, reasoning speed, reasoning ability, working memory, verbal fluency, processing speed, short-term memory, inhibition and memory scanning speed were assessed before and after intervention. No differences in the changes in cognitive test performance scores between the diet groups were observed for any of the cognitive function outcomes assessed (P≥0·24 time×diet). Percentage reduction in body weight correlated with improvements with perceptual speed performance. In obese adults with T2D, both LC and HC weight-loss diets combined with exercise training had similar effects on cognitive performance. This suggests that an LC diet integrated within a lifestyle modification programme can be used as a strategy for weight and diabetes management without the concern of negatively affecting cognitive function.

Fe and n-3 long-chain PUFA (n-3 LCPUFA) have both been associated with cognition, but evidence remains inconclusive in well-nourished school-aged children. In the Optimal Well-Being, Development and Health for Danish Children through a Healthy New Nordic Diet (OPUS) School Meal Study, the 3-month intervention increased reading performance, inattention, impulsivity and dietary intake of fish and Fe. This study investigated whether the intervention influenced n-3 LCPUFA and Fe status and, if so, explored how these changes correlated with the changes in cognitive performance. The study was a cluster-randomised cross-over trial comparing school meals with packed lunch (control). At baseline and after each treatment, we measured serum ferritin, whole-blood n-3 LCPUFA and Hb, and performance in reading, mathematics and d2-test of attention. Data were analysed using mixed models (n 726) and principal component analysis of test performances (n 644), which showed two main patterns: ‘school performance’ and ‘reading comprehension’. The latter indicated that children with good reading comprehension were also more inattentive and impulsive (i.e. higher d2-test error%). The intervention improved ‘school performance’ (P=0·015), ‘reading comprehension’ (P=0·043) and EPA+DHA status 0·21 (95 % CI 0·15, 0·27) w/w % (P<0·001), but it did not affect serum ferritin or Hb. At baseline, having small Fe stores was associated with poorer ‘school performance’ in girls, but with better ‘reading comprehension’ in both boys and girls. Both baseline EPA+DHA status and the intervention-induced increase in EPA+DHA status was positively associated with ‘school performance’, suggesting that n-3 LCPUFA could potentially explain approximately 20 % of the intervention effect. These exploratory associations indicate that increased fish intake might explain some of the increase in reading performance and inattention in the study.

The performance of bilingual children and adults in Wales on Welsh and English vocabulary and grammar and on cognitive measures is re-analysed in relation to SES indicators of parental education and parental professions. Results are reported for 732 participants ranging across seven age groups from age 3 to over 60 and from four home language types, monolingual English, and bilinguals with only English at home, Welsh and English at home, or only Welsh at home. Results reveal extensive evidence of SES influence on performance, and of a complex relation of exposure in the home and SES level on performance, modulated by the age of the participant and whether one is considering the majority or minority language.

Social cognition, referring to one’s ability to perceive and process social cues, is an important domain in schizophrenia. Numerous studies have demonstrated that patients with schizophrenia have poorer performance on tests assessing social cognition relative to healthy comparison participants. However, whether variables such as motivation are related to performance on these tests in patients with schizophrenia is unclear. One thousand three-hundred and seventy-eight patients with schizophrenia completed the Facial Emotion Discrimination Task as a measure of emotional processing, a key facet of social cognition. Level of motivation was also evaluated in these patients using a derived measure from the Quality of Life Scale. The relationship between motivation and task performance was examined using bivariate correlations and logistic regression modeling, controlling for the impact of age and overall severity of psychopathology, the latter evaluated using the Positive and Negative Syndrome Scale. Motivation was positively related to performance on the social cognition test, and this relationship remained significant after controlling for potential confounding variables such as age and illness severity. Social cognition was also related to functioning, and the relationship was mediated by level of motivation. The present study found a significant relationship between motivation and performance on a test of social cognition in a large sample of patients with schizophrenia. These findings suggest that amotivation undermines task performance, or alternatively that poor social cognitive ability impedes motivation. Future studies evaluating social cognition in patients with schizophrenia should concurrently assess for variables such as effort and motivation. (JINS, 2015, 21, 436–443)

Nutrition plays a fundamental role in supporting the structural and functional development of the human brain from conception, throughout early infancy and extending into later life. A growing body of evidence suggests that folate and the metabolically related B-vitamins are essential for brain health across all age groups, owing to their specific roles in C1 metabolism and particularly in the production of S-adenosylmethionine, a universal methyl donor essential for the production of neurotransmitters. Emerging, though not entirely consistent, evidence suggests that maternal folate status throughout pregnancy may influence neurodevelopment and behaviour of the offspring. Furthermore optimal B-vitamin status is associated with better cognitive health in ageing. Of note, a recent clinical trial provided evidence that supplementation with folic acid and related B-vitamins over a 2-year-period reduced global and regional brain atrophy, as measured by MRI scan in older adults. In terms of potential mechanisms, the effects of these B-vitamins on cognitive health may be independent or may be mediated by nutrient–nutrient and/or relevant gene–nutrient interactions. Furthermore, a new area of research suggests that the in utero environment influences health in later life. Folate, an important cofactor in C1 metabolism, is indirectly involved in DNA methylation, which in turn is considered to be one of the epigenetic mechanisms that may underlie fetal programming and brain development. The present review will explore the evidence that supports a role for folate and the related B-vitamins in brain health across the lifecycle, and potential mechanisms to explain such effects.