Identifying and Characterizing the Effects of Nutrition on Hippocampal Memory

In this review we provide evidence linking relational memory to the hippocampus, as well as examples of sensitive relational memory tasks that may help characterize the subtle effects of nutrition on learning and memory. Research into dietary effects on cognition is in its nascent stages, and many studies have cast a wide net with respect to areas of cognition to investigate. However, it may be that nutrition will have a disproportionate effect on particular cognitive domains. Thus, researchers interested in nutrition-cognition interactions may wish to apply a more targeted approach when selecting cognitive domains. We suggest that hippocampus-based relational memory may be extraordinarily sensitive to the effects of nutrition. The hippocampus shows unique plastic capabilities, making its structure and function responsive to an array of lifestyle factors and environmental conditions, including dietary intake. A major function of the hippocampus is relational memory, defined as learning and memory for the constituent elements and facts that comprise events. Here we identify several sensitive tests of relational memory that may be used to examine what may be subtle effects of nutrition on hippocampus and memory. We then turn to the literature on aerobic exercise and cognition to provide examples of translational research programs that have successfully applied this targeted approach centering on the hippocampus and sensitive relational memory tools. Finally, we discuss selected findings from animal and human research on nutrition and the hippocampus and advocate for the role of relational memory tasks in future research.     

Prenatal Folate and Choline Levels and Brain and Cognitive Development in Children: A Critical Narrative Review

Women’s nutritional status during pregnancy can have long-term effects on children’s brains and cognitive development. Folate and choline are methyl-donor nutrients and are important for closure of the neural tube during fetal development. They have also been associated with brain and cognitive development in children. Animal studies have observed that prenatal folate and choline supplementation is associated with better cognitive outcomes in offspring and that these nutrients may have interactive effects on brain development. Although some human studies have reported associations between maternal folate and choline levels and child cognitive outcomes, results are not consistent, and no human studies have investigated the potential interactive effects of folate and choline. This lack of consistency could be due to differences in the methods used to assess folate and choline levels, the gestational trimester at which they were measured, and lack of consideration of potential confounding variables. This narrative review discusses and critically reviews current research examining the associations between maternal levels of folate and choline during pregnancy and brain and cognitive development in children. Directions for future research that will increase our understanding of the effects of these nutrients on children’s neurodevelopment are discussed.     

A Comprehensive Review of Eggs,Choline, and Lutein on Cognition Across the Life-span

In 2030, one in five Americans will be older than 65 years, and with that an increase in the number of individuals who experience loss in cognitive capacity is to be expected. At the same time, nutrition within the first 1000 days postconception has been suggested to strongly influence cognitive outcomes across the life-span in humans. Eggs are a primary source of both choline and the xanthophyll carotenoid lutein in the western diet, and both have been suggested to influence cognitive function in humans. This comprehensive review critically examines the effects of eggs, choline, and lutein on cognition across the life-span. There seems to be clear scientific evidence to suggest that both choline and lutein play a vital role in brain and neurological development during the first 1000 days postconception. The extent to which higher intakes of choline have the potential to enhance or influence cognition during childhood, adulthood, and/or age-related cognitive decline needs further investigation. Emerging but consistent research suggests that lutein has the potential to influence cognition across the life-span and that sufficient intakes during mid to late adulthood may help to ward off age-related cognitive decline. Macular pigment optical density (MPOD) seems to be a reliable and consistent biomarker of brain lutein concentrations across the life-span and potentially one for clinically assessing cognitive status. This review summarizes the current peer-reviewed literature and existing gaps in research.     

Prenatal and Postnatal Choline Supplementation in Fetal Alcohol Spectrum Disorder

Fetal alcohol spectrum disorder (FASD) is common and represents a significant public health burden, yet very few interventions have been tested in FASD. Cognitive deficits are core features of FASD, ranging from broad intellectual impairment to selective problems in attention, executive functioning, memory, visual–perceptual/motor skills, social cognition, and academics. One potential intervention for the cognitive impairments associated with FASD is the essential nutrient choline, which is known to have numerous direct effects on brain and cognition in both typical and atypical development. We provide a summary of the literature supporting the use of choline as a neurodevelopmental intervention in those affected by prenatal alcohol. We first discuss how alcohol interferes with normal brain development. We then provide a comprehensive overview of the nutrient choline and discuss its role in typical brain development and its application in the optimization of brain development following early insult. Next, we review the preclinical literature that provides evidence of choline’s potential as an intervention following alcohol exposure. Then, we review a handful of existing human studies of choline supplementation in FASD. Lastly, we conclude with a review of practical considerations in choline supplementation, including dose, formulation, and feasibility in children.     

The Protective and Long-Lasting Effects of Human Milk Oligosaccharides on Cognition in Mammals

Over the last few years, research indicated that Human Milk Oligosaccharides (HMOs) may serve to enhance cognition during development. HMOs hereby provide an exciting avenue in the understanding of the molecular mechanisms that contribute to cognitive development. Therefore, this review aims to summarize the reported observations regarding the effects of HMOs on memory and cognition in rats, mice and piglets. Our main findings illustrate that the administration of fucosylated (single or combined with Lacto-N-neoTetraose (LNnT) and other oligosaccharides) and sialylated HMOs results in marked improvements in spatial memory and an accelerated learning rate in operant tasks. Such beneficial effects of HMOs on cognition already become apparent during infancy, especially when the behavioural tasks are cognitively more demanding. When animals age, its effects become increasingly more apparent in simpler tasks as well. Furthermore, the combination of HMOs with other oligosaccharides yields different effects on memory performance as opposed to single HMO administration. In addition, an enhanced hippocampal long-term potentiation (LTP) response both at a young and at a mature age are reported as well. These results point towards the possibility that HMOs administered either in singular or combination forms have long-lasting, beneficial effects on memory and cognition in mammals.     

The Association of Healthful Diets and Cognitive Function: A Review

The association of diet with mild cognitive impairment has not been extensively studied. Consumption of a healthful diet may help to attenuate age-related decline in older adults. Published studies have suggested that greater adherence to a Mediterranean-style dietary pattern is associated with a lower risk of developing Alzheimer's disease and with a slower rate of cognitive decline with age. However, published findings are inconsistent. The discrepancies most likely can be explained by the variations in both dietary and cognitive methodologies. It is not clear how diet contributes to the development of neurocognitive changes with age. This review will update available knowledge on the relationship between adherence to healthful diets and cognition and document the need for researchers to adopt more coherent and uniform methodology to allow for better quantification of the association of diet with cognitive function. There appears to be a relationship between diet and cognition.     

Potential of Caffeine in Alzheimer’s Disease—A Review of Experimental Studies

Alzheimer’s disease (AD) is the most common type of dementia leading to progressive memory loss and cognitive impairment. Considering that pharmacological treatment options for AD are few and not satisfactory, increasing attention is being paid to dietary components that may affect the development of the disease. Such a dietary component may be caffeine contained in coffee, tea or energy drinks. Although epidemiological data suggest that caffeine intake may counteract the development of cognitive impairment, results of those studies are not conclusive. The aim of the present study is to review the existing experimental studies on the efficacy of caffeine against AD and AD-related cognitive impairment, focusing on the proposed protective mechanisms of action. In conclusion, the reports of studies on experimental AD models generally supported the notion that caffeine may exert some beneficial effects in AD. However, further studies are necessary to elucidate the role of caffeine in the effects of its sources on cognition and possibly AD risk.     

Prenatal Exposure to Polychlorinated Biphenyls: A Neuropsychologic Analysis

Objectives

A large body of literature documents the effects of prenatal exposure to polychlorinated biphenyls (PCBs) on cognitive development of children. Despite this fact, no integrative synthesis has been published yet to identify the cognitive functions that are particularly affected. Our aim is to review this literature in an attempt to identify the cognitive profile associated with prenatal PCB exposure.

Data sources

Studies were identified by searching the PubMed database for articles published before June 2008. We reviewed data from nine prospective longitudinal birth cohorts for different aspects of cognition.

Data extraction

Associations between indicators of prenatal PCB exposure and performance on cognitive tasks reported in the selected studies are summarized and classified as general cognitive abilities, verbal or visual–spatial skills, memory, attention, and executive functions.

Data synthesis

The most consistent effects observed across studies are impaired executive functioning related to increased prenatal PCB exposure. Negative effects on processing speed, verbal abilities, and visual recognition memory are also reported by most studies. Converging results from different cohort studies in which exposure arises from different sources make it unlikely that co-exposure with another associated contaminant is responsible for the observed effects.

Conclusion

Prenatal PCB exposure appears to be related to a relatively specific cognitive profile of impairments. Failure to assess functions that are specifically impaired may explain the absence of effects found in some studies. Our findings have implications in the selection of cognitive assessment methods in future studies.     

Habitual Choline Intakes across the Childbearing Years: A Review

Choline is an important nutrient during the first 1000 days post conception due to its roles in brain function. An increasing number of studies have measured choline intakes at the population level. We collated the evidence focusing on habitual choline intakes in the preconceptual, pregnancy, and lactation life stages. We conducted a review including studies published from 2004 to 2021. Twenty-six relevant publications were identified. After excluding studies with a high choline intake (>400 mg/day; two studies) or low choline intake (<200 mg/day; one study), average choline intake in the remaining 23 studies ranged from 233 mg/day to 383 mg/day, even with the inclusion of choline from supplements. Intakes were not higher in studies among pregnant and lactating women compared with studies in nonpregnant women. To conclude, during the childbearing years and across the globe, habitual intakes of choline from foods alone and foods and supplements combined appear to be consistently lower than the estimated adequate intakes for this target group. Urgent measures are needed to (1) improve the quality of choline data in global food composition databases, (2) encourage the reporting of choline intakes in dietary surveys, (3) raise awareness about the role(s) of choline in foetal–maternal health, and (4) consider formally advocating the use of choline supplements in women planning a pregnancy, pregnant, or lactating.     

Simultaneous EEG-fMRI for working memory of the human brain

Memory plays an important role in human life. Memory can be divided into two categories, i.e., long term memory and short term memory (STM). STM or working memory (WM) stores information for a short span of time and it is used for information manipulations and fast response activities. WM is generally involved in the higher cognitive functions of the brain. Different studies have been carried out by researchers to understand the WM process. Most of these studies were based on neuroimaging modalities like fMRI, EEG, MEG etc., which use standalone processes. Each neuroimaging modality has some pros and cons. For example, EEG gives high temporal resolution but poor spatial resolution. On the other hand, the fMRI results have a high spatial resolution but poor temporal resolution. For a more in depth understanding and insight of what is happening inside the human brain during the WM process or during cognitive tasks, high spatial as well as high temporal resolution is desirable. Over the past decade, researchers have been working to combine different modalities to achieve a high spatial and temporal resolution at the same time. Developments of MRI compatible EEG equipment in recent times have enabled researchers to combine EEG-fMRI successfully. The research publications in simultaneous EEG-fMRI have been increasing tremendously. This review is focused on the WM research involving simultaneous EEG-fMRI data acquisition and analysis. We have covered the simultaneous EEG-fMRI application in WM and data processing. Also, it adds to potential fusion methods which can be used for simultaneous EEG-fMRI for WM and cognitive tasks.     

Dairy constituents and neurocognitive health in ageing

Age-related cognitive decline (ARCD) and dementia are of increasing concern to an ageing population. In recent years, there has been considerable research focused on effective dietary interventions that may prevent or ameliorate ARCD and dementia. While a number of studies have considered the impact that dairy products may have on physiological health, particularly with regard to the metabolic syndrome and cardiovascular health, further research is currently needed in order to establish the impact that dairy products have in the promotion of healthy brain function during ageing. The present review considers the available evidence for the positive effects of dairy products on the metabolic syndrome and glucose regulation, with consideration of the implications for neurocognitive health. A literature search of current (September 2010) meta-analyses/reviews and original research regarding dairy products and cognition was conducted through SCOPUS using the following search terms for dairy consituents: dairy, milk, cheese, yoghurt, probiotics, whey protein, alpha lactalbumin, calcium, B-12, bioactive peptides and colostrinin (CLN). These search terms for dairy products were combined with the following search terms related to cognition and health: cognition, cognitive decline, dementia, Alzheimer's disease, metabolic syndrome, diabetes, insulin resistance and glucose regulation. Concerns regarding SFA and other fatty acids found in dairy products are also reviewed in relation to different forms of dairy products. The review also considers recent evidence for positive neurocognitive effects associated with bioactive peptides, CLN and proline-rich polypeptides, α-lactalbumin, vitamin B12, calcium and probiotics. Future directions for the extraction and purification of beneficial constituents are also discussed. It is concluded that low-fat dairy products, when consumed regularly as part of a balanced diet, may have a number of beneficial outcomes for neurocognitive health during ageing.     

Lifestyle, glucose regulation and the cognitive effects of glucose load in middle-aged adults

Interventions aimed at improving glucose regulatory mechanisms have been suggested as a possible source of cognitive enhancement in the elderly. In particular, previous research has identified episodic memory as a target for facilitation after either moderate increases in glycaemia (after a glucose drink) or after improvements in glucose regulation. The present study aimed to extend this research by examining the joint effects of glucose ingestion and glucose regulation on cognition. In addition, risk factors associated with the development of poor glucose regulation in middle-aged adults were considered. In a repeated measures design, thirty-three middle-aged adults (aged 35-55 years) performed a battery of memory and non-memory tasks after either 25 g or 50 g glucose or a sweetness matched placebo drink. To assess the impact of individual differences in glucose regulation, blood glucose measurements were taken on four occasions during testing. A lifestyle and diet questionnaire was also administered. Consistent with previous research, episodic memory ability benefited from glucose ingestion when task demands were high. Blood glucose concentration was also found to predict performance across a number of cognitive domains. Interestingly, the risk factors associated with poor glucose regulation were linked to dietary impacts traditionally associated with poor health, e.g. the consumption of high-sugar sweets and drinks. The research replicates earlier work suggesting that task demands are critical to the glucose facilitation effect. Importantly, the data demonstrate clear associations between elevated glycaemia and relatively poor cognitive performance, which may be partly due to the effect of dietary and lifestyle factors.     

Acute Inositol-Stabilized Arginine Silicate Improves Cognitive Outcomes in Healthy Adults

Inositol-stabilized arginine silicate (ASI) is an ergogenic aid that upregulates nitric oxide. Acute ASI supplementation improves working memory and processing speed in young adults but there is a lack of data examining other cognitive tasks. Therefore, the purpose of this study was to examine acute ASI effects on young healthy adults by assessing multiple cognitive domains. Nineteen young adults (20.9 ± 3.2 years) completed this randomized, double-blind, crossover study consuming ASI (1.5 g ASI + 12 g dextrose) and placebo (12 g dextrose). The participants completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and two digital cognitive assessments before consuming the supplement and then completed the same battery of tests 60 min post-supplementation. Repeated measures ANOVA demonstrated that ASI consumption significantly improved total RBANS and immediate memory scores compared to the placebo (p < 0.05). However, no significant differences were displayed between trials for other cognitive domains (p > 0.05). Acute ASI ingestion increased overall RBANS scores and immediate memory scores in young adults. More research is needed to examine the acute effects of ASI on other domains of cognition, in older populations, and its long-term effects on cognition.     

Role of Dietary Protein and Thiamine Intakes on Cognitive Function in Healthy Older People: A Systematic Review

The effectiveness of nutritional interventions to prevent and maintain cognitive functioning in older adults has been gaining interest due to global population ageing. A systematic literature review was conducted to obtain and appraise relevant studies on the effects of dietary protein or thiamine on cognitive function in healthy older adults. Studies that reported on the use of nutritional supplementations and/or populations with significant cognitive impairment were excluded. Seventeen eligible studies were included. Evidence supporting an association between higher protein and/or thiamine intakes and better cognitive function is weak. There was no evidence to support the role of specific protein food sources, such as types of meat, on cognitive function. Some cross-sectional and case-control studies reported better cognition in those with higher dietary thiamine intakes, but the data remains inconclusive. Adequate protein and thiamine intake is more likely associated with achieving a good overall nutritional status which affects cognitive function rather than single nutrients. A lack of experimental studies in this area prevents the translation of these dietary messages for optimal cognitive functioning and delaying the decline in cognition with advancing age.     

Omega-3 polyunsaturated fatty acids and cognition throughout the lifespan: A review

Abstract

With increasing awareness of the effects of nutrition on physical and mental health, researchers have begun to further investigate the benefits of omega-3 polyunsaturated fatty acids (n-3 PUFA) on health and the brain; however, these benefits remain unclear across different age groups.

Objectives

The purpose of this article is to summarize the current evidence on the cognitive effects of n-3 PUFA throughout the lifespan.

Methods

An exhaustive review of the literature on the effects of n-3 PUFA on various aspects of cognition, across the lifespan, was conducted.

Results

The research suggests that n-3 PUFA positively affect pre-natal neurodevelopment; however, this cognitive-enhancing effect might diminish post-natally with maturation, as no research on child populations has clearly tied dietary n-3 PUFA to improved cognitive skills. Overall, few studies have examined the cognitive effects of n-3 PUFA through childhood, young adulthood, and middle age. At later ages, multiple studies found evidence suggesting that n-3 PUFA can protect against neurodegeneration and possibly reduce the chance of developing cognitive impairment.

Discussion

Age groups central to the lifespan require further investigation into the effects that n-3 PUFA might have on their cognitive skills. The research examining the extremities of the lifespan provides evidence that n-3 PUFA are essential for neurodevelopment and cognitive maintenance in older adulthood. Future research must develop more consistent methodologies, as variable dosages, supplementation periods, and cognitive measures across different studies have led to disparate results, making the evidence less comparable and difficult to synthesize.     

The effect of hormone therapy on cognitive function in patients with breast cancer

Preclinical and clinical studies suggest that oestrogens have an important role in brain functioning and cognitive ability. Given that hormone therapies for breast cancer reduce oestrogen levels or block oestrogen receptors, it is conceivable that these agents also influence cognitive function. Several small studies have been conducted to address this issue, but many of them are methodologically insufficient. The negative effects of oophorectomy and luteinising hormone-releasing hormone (LHRH) analogues on verbal memory and working memory have been demonstrated the most consistently, albeit only in small studies. Anastrozole and tamoxifen also appear to exert some negative effect on cognition, but well-designed studies are lacking. No data are available on the influence of the aromatase inhibitors exemestane and letrozole on cognitive function. Raloxifene, a drug that has no obvious advantages over tamoxifen and will likely not be developed further for breast cancer treatment, has no negative influence on cognitive functioning. It remains unclear whether the observed effects are transient or permanent, and to what extent age, menopausal status and duration of therapy influence the severity of cognitive effects.     

Dehydration Influences Mood and Cognition: A Plausible Hypothesis?

The hypothesis was considered that a low fluid intake disrupts cognition and mood. Most research has been carried out on young fit adults, who typically have exercised, often in heat. The results of these studies are inconsistent, preventing any conclusion. Even if the findings had been consistent, confounding variables such as fatigue and increased temperature make it unwise to extrapolate these findings. Thus in young adults there is little evidence that under normal living conditions dehydration disrupts cognition, although this may simply reflect a lack of relevant evidence. There remains the possibility that particular populations are at high risk of dehydration. It is known that renal function declines in many older individuals and thirst mechanisms become less effective. Although there are a few reports that more dehydrated older adults perform cognitive tasks less well, the body of information is limited and there have been little attempt to improve functioning by increasing hydration status. Although children are another potentially vulnerable group that have also been subject to little study, they are the group that has produced the only consistent findings in this area. Four intervention studies have found improved performance in children aged 7 to 9 years. In these studies children, eating and drinking as normal, have been tested on occasions when they have and not have consumed a drink. After a drink both memory and attention have been found to be improved.     

Role of Dietary Pattern Analysis in Determining Cognitive Status in Elderly Australian Adults

Principal Component Analysis (PCA) was used to determine the association between dietary patterns and cognitive function and to examine how classification systems based on food groups and food items affect levels of association between diet and cognitive function. The present study focuses on the older segment of the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) sample (age 60+) that completed the food frequency questionnaire at Wave 1 (1999/2000) and the mini-mental state examination and tests of memory, verbal ability and processing speed at Wave 3 (2012). Three methods were used in order to classify these foods before applying PCA. In the first instance, the 101 individual food items asked about in the questionnaire were used (no categorisation). In the second and third instances, foods were combined and reduced to 32 and 20 food groups, respectively, based on nutrient content and culinary usage—a method employed in several other published studies for PCA. Logistic regression analysis and generalized linear modelling was used to analyse the relationship between PCA-derived dietary patterns and cognitive outcome. Broader food group classifications resulted in a greater proportion of food use variance in the sample being explained (use of 101 individual foods explained 23.22% of total food use, while use of 32 and 20 food groups explained 29.74% and 30.74% of total variance in food use in the sample, respectively). Three dietary patterns were found to be associated with decreased odds of cognitive impairment (CI). Dietary patterns derived from 101 individual food items showed that for every one unit increase in ((Fruit and Vegetable Pattern: p = 0.030, OR 1.061, confidence interval: 1.006–1.118); (Fish, Legumes and Vegetable Pattern: p = 0.040, OR 1.032, confidence interval: 1.001–1.064); (Dairy, Cereal and Eggs Pattern: p = 0.003, OR 1.020, confidence interval: 1.007–1.033)), the odds of cognitive impairment decreased. Different results were observed when the effect of dietary patterns on memory, processing speed and vocabulary were examined. Complex patterns of associations between dietary factors and cognition were evident, with the most consistent finding being the protective effects of high vegetable and plant-based food item consumption and negative effects of ‘Western’ patterns on cognition. Further long-term studies and investigation of the best methods for dietary measurement are needed to better understand diet-disease relationships in this age group.