Refined carbohydrate intake in relation to non-verbal intelligence among Tehrani schoolchildren

Nutrition and cognitive health: A life course approach

Multiple factors affect cognitive health, such as age-related changes in the brain, injuries, mood disorders, substance abuse, and diseases. While some cannot be changed, evidence exists of many potentially possibly modifiable lifestyle factors: diet, physical activity, cognitive and social engagement, smoking and alcohol consumption which may stabilize or improve declining cognitive function. In nutrition, the focus has been mainly on its role in brain development in the early years. There is a strong emerging need to identify the role of diet and nutrition factors on age-related cognitive decline, which will open up the use of new approaches for prevention, treatment or management of age-related disorders and maintaining a good quality of life among older adults. While data on effect of high protein diets is not consistent, low-fat diets are protective against cognitive decline. Several micronutrients like B group vitamins and iron, as well as many polyphenols play a crucial role in cognitive health. Mediterranean, Nordic, DASH, and MIND diets are linked to a lower risk of cognitive decline and dementia. The relationship between the gut microbiome and brain function through the gut-brain axis has led to the emergence of data on the beneficial effects of dietary fibers and probiotics through the management of gut microbes. A “whole diet” approach as well as macro- and micro-nutrient intake levels that have protective effects against cardiovascular diseases are most likely to be effective against neurodegenerative disorders too. Young adulthood and middle age are crucial periods for determining cognitive health in old age. The importance of cardio metabolic risk factors such as obesity and hypertension, smoking and physical inactivity that develop in middle age suggest that preventive approaches are required for target populations in their 40s and 50s, much before they develop dementia. The commonality of dementia risk with cardiovascular and diabetes risk suggests that dementia could be added to present non-communicable disease management programs in primary healthcare and broader public health programs.

Is the association between dietary patterns and cognition mediated by children's adiposity? A longitudinal approach in Generation XXI birth cohort

BACKGROUND/AIMS

There is a consistent body of evidence on the association between single nutrients and cognition, but the role of a healthful dietary pattern on cognition in children has been seldomly studied. This study aims to assess the association between dietary patterns at 4 years (y) and cognitive abilities at 10-13y and examine whether adiposity mediated these associations.

METHODS

This study used data from a sub-sample of the population-based birth cohort Generation XXI, with complete information on diet and cognition (n = 3575). At 4y, data on dietary intake was collected by a validated food frequency questionnaire and dietary patterns were derived by latent class analysis, namely Energy-dense food (EDF) pattern, Snacking pattern and Healthier pattern (Reference). At 10-13y, the Portuguese Version of the Wechsler Intelligence Scale for Children®-Third Edition was administered by trained psychologists and age-adjusted composite scores were computed: a Full-Scale Intelligence Quotient (IQ), plus a Verbal IQ, Performance IQ and Processing Speed IQ. Age- and sex-specific body mass index (BMI) z-scores, body fat percentage from bioimpedance, and waist-to-weight ratio and waist-to-hip ratio were used as measures of adiposity. Regression coefficients and 95% confidence intervals (CI) were computed using linear regression models (adjusted for maternal age and education, pre-pregnancy BMI, smoking and alcohol intake during pregnancy, child's sex, birthweight, exclusive breastfeeding duration and having siblings at 4y). Mediation analysis was conducted using path analysis.

RESULTS

After adjustment, children classified in the EDF or a Snacking patterns at 4y were more likely to have lower scores on total IQ (β = -0.116; 95%CI:-0.192,-0.039 and β = -0.148; 95%CI -0.252,-0.044, respectively), Verbal IQ (β = -0.104; 95%CI -0.177, -0.031 and β = -0.163; 95%CI -0.262,-0.064, respectively) and Performance IQ (β = -0.116 95%CI -0.193,-0.040 and β = -0.147; 95%CI -0.250,-0.042, respectively) at 10-13y, when compared to those classified in the Healthier pattern. None of the adiposity measures seemed to explain the associations between dietary patterns and IQ.

CONCLUSION

This study supports that early unhealthy dietary patterns were associated with lower child's cognitive ability, but this effect did not seem to be mediated by adiposity.

Prefrontal Cortex and Hippocampus Inflammation in Mice Fed High-Carbohydrate or High-Fat Diets

We previously reported that a high-carbohydrate diet (HCD) induced systemic inflammation and higher gene expression of proinflammatory mediators in the liver, skeletal muscle, and brain than a high-fat diet (HFD). However, the differences between the groups were less pronounced in the brain. In this study, we extended the evaluation of inflammation to specific areas of the brain. In this study, we evaluated the gene expression of caspase 2, caspase 3, caspase 9, cyclooxygenase-2 (Cox 2), inducible nitric oxide synthase (iNOS), interleukin (IL), IL-6, IL-1β, IL-10, IL-4, tumor necrosis factor-alpha (TNF-α), integrin subunit alpha m (Itgam), S100 protein (S100), allograft inflammatory factor 1 (Aif1), and glial fibrillary acidic protein (Gfap) in the prefrontal cortex and hippocampus of male Swiss mice that were fed with HCD or HFD for 8 weeks. The HCD group exhibited higher IL-1β expression, whereas the HFD group showed higher TNF-α expression in the prefrontal cortex. In the hippocampus, TNF-α expression was higher in the HFD group. IL-1β and TNF-α are proinflammatory cytokines that have been associated with impaired brain function and numerous brain disorders. Our results indicate that both HCD and HFD promote prefrontal cortex inflammation; however, the hippocampus seems more sensitive to a HFD than HCD.

Cerebral Fructose Metabolism as a Potential Mechanism Driving Alzheimer's Disease

The loss of cognitive function in Alzheimer's disease is pathologically linked with neurofibrillary tangles, amyloid deposition, and loss of neuronal communication. Cerebral insulin resistance and mitochondrial dysfunction have emerged as important contributors to pathogenesis supporting our hypothesis that cerebral fructose metabolism is a key initiating pathway for Alzheimer's disease. Fructose is unique among nutrients because it activates a survival pathway to protect animals from starvation by lowering energy in cells in association with adenosine monophosphate degradation to uric acid. The fall in energy from fructose metabolism stimulates foraging and food intake while reducing energy and oxygen needs by decreasing mitochondrial function, stimulating glycolysis, and inducing insulin resistance. When fructose metabolism is overactivated systemically, such as from excessive fructose intake, this can lead to obesity and diabetes. Herein, we present evidence that Alzheimer's disease may be driven by overactivation of cerebral fructose metabolism, in which the source of fructose is largely from endogenous production in the brain. Thus, the reduction in mitochondrial energy production is hampered by neuronal glycolysis that is inadequate, resulting in progressive loss of cerebral energy levels required for neurons to remain functional and viable. In essence, we propose that Alzheimer's disease is a modern disease driven by changes in dietary lifestyle in which fructose can disrupt cerebral metabolism and neuronal function. Inhibition of intracerebral fructose metabolism could provide a novel way to prevent and treat this disease.

The effect of short-term exposure to energy-matched diets enriched in fat or sugar on memory, gut microbiota and markers of brain inflammation and plasticity

Short-term exposure to high-energy diets impairs memory but there is little data on the relative contributions of fat and sugar to these deficits or the mechanisms responsible. Here, we investigated how these different macronutrients affect memory, neuroinflammation and neuroplasticity markers and the gut microbiota. Rats were fed matched purified diets for 2weeks; Control, Sugar, Saturated Fatty Acid (SFA) or Polyunsaturated Fatty Acid (PUFA), which varied only in the percentage of energy available from sugar and the amount and type of fat. Rats consuming SFA and Sugar were impaired on hippocampal-dependent place recognition memory compared to Controls and PUFA rats, despite all rats consuming similar amounts of energy. All rats performed comparably on the object recognition task. Hippocampal and hypothalamic inflammatory markers were not substantially affected by the diets and there was no change in the neuroplasticity marker, brain-derived neurotrophic factor. Each of the diets significantly altered the microbial composition in distinct ways. Specifically, the relative abundance of 89 taxa differed significantly between groups with the majority of these changes accounted for by the Clostridiales order and within that, Lachnospiraceae and Ruminococcaceae. These taxa showed a range of macronutrient specific correlations with place memory. In addition, Distance based Linear Models found relationships between memory, inflammation-related hippocampal genes and the gut microbiota. In conclusion, our study shows that the macronutrient profile of the diet is crucial for diet-induced memory deficits and suggests a possible link between diet, the gut microbiota and hippocampal inflammatory genes.

Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation

Chronic high-energy diets are known to induce obesity and impair memory; these changes have been associated with inflammation in brain areas crucial for memory. In this study, we investigated whether inflammation could also be related to diet-induced memory deficits, prior to obesity. We exposed rats to chow, chow supplemented with a 10% sucrose solution (Sugar) or a diet high in fat and sugar (Caf+Sugar) and assessed hippocampal-dependent and perirhinal-dependent memory at 1 week. Both high-energy diet groups displayed similar, selective hippocampal-dependent memory deficits despite the Caf+Sugar rats consuming 4-5 times more energy, and weighing significantly more than the other groups. Extreme weight gain and excessive energy intake are therefore not necessary for deficits in memory. Weight gain across the diet period however, was correlated with the memory deficits, even in the Chow rats. The Sugar rats had elevated expression of a number of inflammatory genes in the hippocampus and WAT compared to Chow and Caf+Sugar rats but not in the perirhinal cortex or hypothalamus. Blood glucose concentrations were also elevated in the Sugar rats, and were correlated with the hippocampal inflammatory markers. Together, these results indicate that liquid sugar can rapidly elevate markers of central and peripheral inflammation, in association with hyperglycemia, and this may be related to the memory deficits in the Sugar rats.

Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions

It is of vital importance to understand how the foods which are making us fat also act to impair cognition. In this review, we compare the effects of acute and chronic exposure to high-energy diets on cognition and examine the relative contributions of fat (saturated and polyunsaturated) and sugar to these deficits. Hippocampal-dependent memory appears to be particularly vulnerable to the effects of high-energy diets and these deficits can occur rapidly and prior to weight gain. More chronic diet exposure seems necessary however to impair other sorts of memory. Many potential mechanisms have been proposed to underlie diet-induced cognitive decline and we will focus on inflammation and the neurotrophic factor, brain-derived neurotrophic factor (BDNF). Finally, given supplementation of diets with omega-3 and curcumin has been shown to have positive effects on cognitive function in healthy ageing humans and in disease states, we will discuss how these nutritional interventions may attenuate diet-induced cognitive decline. We hope this approach will provide important insights into the causes of diet-induced cognitive deficits, and inform the development of novel therapeutics to prevent or ameliorate such memory impairments.

Dietary intake of schoolchildren and adolescents in developing countries

School age and adolescence is a dynamic period of growth and development forming a strong foundation for good health and productive adult life. Appropriate dietary intake is critical for forming good eating habits and provides the much needed nutrients for growth, long-term health, cognition and educational achievements. A large proportion of the population globally is in the school age or adolescence, with more than three quarters of these groups living in developing countries. An up-to-date review and discussion of the dietary intake of schoolchildren and adolescents in developing countries is suitable to provide recent data on patterns of dietary intake, adequacy of nutrient intake and their implications for public health and nutrition issues of concern. This review is based on literature published from 2000 to 2014 on dietary intake of schoolchildren and adolescents aged 6-19 years. A total of 50 studies from 42 countries reporting on dietary intake of schoolchildren and adolescents were included. The dietary intake of schoolchildren and adolescents in developing countries is limited in diversity, mainly comprising plant-based food sources, but with limited intake of fruits and vegetables. There is a low energy intake and insufficient micronutrient intake. At the same time, the available data indicate an emerging trend of consumption of high-energy snacks and beverages, particularly in urban areas. The existence of a negative and positive energy balance in the same population points to the dual burden of malnutrition and highlights the emerging nutrition transition in developing countries. This observation is important for planning public health nutrition approaches that address the concerns of the two ends of the nutrition divide.

Cognitive performance of Göttingen minipigs is affected by diet in a spatial hole-board discrimination test

Consumption of a high energy diet, containing high amounts of saturated fat and refined sugar has been associated with impairment of cognitive function in rodents and humans. We sought to contrast the effect of a high fat/cholesterol, low carbohydrate diet and a low fat, high carbohydrate/sucrose diet, relative to a standard low fat, high carbohydrate minipig diet on spatial cognition with regards to working memory and reference memory in 24 male Göttingen minipigs performing in a spatial hole-board discrimination test. We found that both working memory and reference memory were impaired by both diets relative to a standard minipig diet high in carbohydrate, low in fat and sugar. The different diets did not impact levels of brain-derived neurotrophic factor in brain tissue and neither did they affect circulatory inflammation measured by concentrations of C-reactive protein and haptoglobin in serum. However, higher levels of triglycerides were observed for minipigs fed the diets with high fat/cholesterol, low carbohydrate and low fat, high carbohydrate/sucrose compared to minipigs fed a standard minipig diet. This might explain the observed impairments in spatial cognition. These findings suggest that high dietary intake of both fat and sugar may impair spatial cognition which could be relevant for mental functioning in humans.