Diet and Cognition

It has been demonstrated that the "meal-recall effect" - which reduces snacking - occurs when one remembers a meal consumed a few hours earlier rather than the day before. In this study by Szypula, Ahern & Cheke (2020), the authors recruited and assessed participants' (n = 77, mean age = 33.30 ± 14.98, mean BMI = 23.77 ± 3.72, 74% female) intake of biscuits during a fictitious taste test in two separate sessions, before which participants remembered a recent or distant meal to reproduce this effect. Secondly, the authors investigated whether variables that might impact meal-memory quality, particularly individual variations in recall depth and memory capacity, would affect the meal-recall effect. To achieve this, only individuals with a low or high capacity for recollection were chosen for the research and placed in either the guided-recall or unguided-recall groups. Participants were asked to remember what they had eaten in the unguided condition and were then prodded for more information about their meal in the guided state. In a conversation with the researcher or by recording their memory on a computer, participants were asked to describe their meal dinner in detail. The authors discovered that, in contrast to the original theories, only the written group showed the meal-recall effect, while the verbal group did not. The participants in the written, guided group seemed to snack on 8 g more biscuits after remembering a recent (vs. remote) meal, while their peers in the written, unguided group consumed about 9 g fewer biscuits after remembering a recent (vs. remote) meal. Memory capacity had no impact on how strong the meal-recall effect was, and the verbal group did not exhibit the meal-recall effect. The authors conclude that their findings emphasize the significance of environmental elements in controlling the meal-recall effect. [NPID: Adult, Body Mass Index, diet, eating, meals, mental recall, snacks, time factors]

A third of our day is made up of sleep, which is crucial to our health and happiness. Numerous variables affect sleep, with nutrition playing a major role in how different sleep metrics are affected. Positive sleep results are produced by scheduling meals using techniques like chrono-nutrition. In addition, eating foods high in important amino acids, eating foods with a low glycemic index, and eating certain vegetables high in antioxidants can all improve the quality of your slumber. Losing weight and restricting certain dietary components like coffee, nicotine, and alcohol are other nutrition-related aspects that can have an impact on sleep quality. In this publication, Pattnaik et al. (2022) discuss how some of these variables may be extremely important for the quality of sleep. [NPID: Sleep, diet, nutrition, weight loss, dietary restriction, sleep quality]

Dietary intake and other lifestyle choices are amongst a myriad of modifiable risk factors that impact cognitive health, which in turn affects the quality of life, morbidity, and death on a global scale. Nuts are nutrient-rich and contain several substances that may serve as neuroprotectants, such as monounsaturated and polyunsaturated fatty acids, fiber, non-sodium minerals, B vitamins, and extremely bioactive polyphenols. Nuts have been suggested to be good for brain health because greater nut intake is associated with reduced cardiovascular risk and a lower load of cardiovascular risk factors that also impact neurodegenerative diseases. In this narrative overview by Nishi et al. (2023), the impact of nut intake on cognitive function is discussed in light of recent demographic, mechanistic, and clinical trial data. A potential role for nuts in the preservation of cognitive health and the avoidance of cognitive decline in people across their lifetime, especially in elderly adults and those at greater risk, is suggested by a currently available body of limited and unclear evidence. The nut variety most hopeful for maintaining brain health is walnuts, owing to their rich content of plant-based polyunsaturated omega-3 fatty acid and alpha-linolenic acid. Given the limited definitive evidence available to date, especially regarding cognitive health biomarkers and hard outcomes, the authors highlight the need for future studies to better elucidate the impact of nuts on the maintenance of cognitive health, as well as the prevention and management of cognitive decline and dementia, including Alzheimer disease. [NPID: Nuts, cognitive performance, brain health, Dementia, lifespan, aging, epidemiological studies, clinical trials]

Individuals who suffer from mild cognitive impairment (MCI) or dementia are unable to execute instrumental activities of daily living (iADLs) in an independent fashion, rendering them reliant upon others to survive. Such individuals suffer from a higher likelihood of quality of life reduction and institutionalization in assisted living facilities. The roles played by the Mediterranean diet (MedDiet, rich in whole grains, vegetables, and olive oil) in protecting against cognitive and functional decline have been a topic of growing scientific interest. In this cross-sectional study by Allcock, Mantzioris & Villani (2022), the authors investigated the impact of MedDiet fidelity on cognitive and functional outcomes in a population of 294 older adults living within the community (males n = 91, mean age = 70.4 ± 6.2 years). Participants’ functional status was evaluated using a modified Lawton's iADL scale, while MedDiet fidelity was evaluated using the Mediterranean Diet Adherence Screener (MEDAS), in addition to the AD8 dementia screening for cognitive risks. Analysis of the results revealed a significantly improved functional status and cognition with MedDiet fidelity (after controlling for potential variables, significant improvement of cognitive status in participants with existing impairments). The authors conclude that MedDiet fidelity helps improve physical health, and functional and cognitive status in older adults, however further studies are necessary to understand these relationships, especially longitudinal studies on large cohorts. [NPID: Diet, cognitive impairment, functional status, dementia, older adults, Mediterranean Diet]

Global population patterns are gravitating towards an aging population. Recent publications demonstrate how dietary habits are potentially linked to cognition in the elderly. In this cross-sectional study by Mumme et al. (2022), the authors examined the relationship between cognitive function and dietary patterns in a population of 371 older adult participants (65 to 74 years of age, 36% males) of the REACH study (Researching Eating, Activity, and Cognitive Health) who do not require assisted living measures. Dietary patterns were deduced using a 109-item validated food frequency questionnaire, while cognition was evaluated using COMPASS (Computerized Mental Performance Assessment System) to look at six domains, namely attention and vigilance, cognition, executive function, working memory, episodic memory, and spatial memory. Analysis of the results revealed that participants adopted one of three dietary patterns which accounted for an 18% dietary variability: a 'Mediterranean style' diet (rich in leafy vegetables, salad vegetables, avocados, olives, alliums, white fish and shellfish, oily fish, nuts and seeds, berries and other vegetables), a ‘Western’ diet (rich in sauces, condiments, processed meats, biscuits, cakes, puddings, meat pies, chips, and processed fish), and a ‘Prudent’ diet (rich in soy-based foods, whole grains, dried legumes, fresh and frozen legumes, and carrots). These diets were not linked to any of the cognitive domains investigated in the study, however, cognitive function was associated with education level and age. The authors conclude that dietary patterns have no relationship to cognitive function in investigated older adults. [NPID: Apolipoprotein E, episodic memory, executive function, global cognition, healthy aging, Mediterranean diet, principal component analysis, western dietary pattern, working memory]

The MIND diet (combining the Mediterranean diet and the Dietary Approaches to Stop Hypertension diet) was found to slow cognitive decline and lower the risk of Alzheimer's disease (AD) dementia in the older adult population. In this study by Dhana et al. (2021), the authors investigated if the links between cognition and the MIND diet were free from the influence of frequently encountered brain conditions. Using data on 569 descendants from the Rush Memory and Aging Project (MAP) that met the desired criteria (cognitive testing proximal to demise, sufficient dietary data, and autopsy data). Analysis of the data revealed a substantial association between improved global cognitive function proximal to demise and elevated MIND dietary scores, an association that remained significant after accounting for AD and other observed brain pathologies, preexisting mild cognitive decline, and postmortem diagnosis of AD. Thus, the authors conclude that the MIND diet enhances cognitive function irrespective of brain pathology, which may present the MIND diet as a potential measure to enhance cognitive resilience in older adults. [NPID: Amyloid β, MIND diet, brain pathology, cognition]

Despite published evidence pointing to the health benefits of a plant-based diet, the level of evidence investigating the links between cognitive health and plant-based food remains insufficient. Recent publications postulate the impact of certain macronutrients on overall cognition, however, the mechanisms behind the interaction between plant-based foods and cognitive domains are not clear. In this cross-sectional study by Ramey et al. (2022), the authors examined the links between cognitive domains and a plant-based diet in a sample of 3039 older adult participants of the National Health and Nutrition Examination Survey between 2011 and 2014 (NHANES). Data on macronutrient intake was collected using 24-hour dietary interviews, while cognitive domains were investigated using performance tests (executive function and long-term memory, through digital symbol substitution test, delayed word recall, and animal fluency). Analysis of the results revealed that fidelity to plant-based dietary patterns was linked to improved performance on all cognitive tasks investigated, in addition to a reduction in baseline levels of inflammation. Further analysis demonstrated a relationship between plant-based diets and executive function, which explained the improvements observed in memory enhancements. The authors conclude that their results present preliminary evidence of the impact of plant-based dietary patterns on improving cognition, specifically in executive control domains, though further work is necessary to identify the causality behind these observations and involved mechanisms, for example, the observed reductions in inflammatory levels. [NPID: Diet, NHANES, executive function, memory, nutrition, older adults, plant-based diet, vegan diet]

In this paper by Parent et al. (2021), the authors amass evidence that explores the links between memory and eating, in both humans and rodents. Humans who suffer from amnesia demonstrate a hindrance in their memory of meals consumed, hunger, and satiety processing, and they tend to overeat and become obese. Healthy individuals have intact memories of their meals, which curtails overeating in the next meals. Research on rodents points to the dorsal hippocampal neural activity playing a role in controlling food consumption in the next meals through the use of meal-related memory, while the ventral hippocampus was found to interact with neuropeptide and endocrine systems to monitor energy status and modulate eating behaviors, in addition to the finding that the administration of hypercaloric diets and subsequent obesity affected rodents’ ventral and dorsal hippocampal processes. In humans, hippocampal derangements and memory impairments were also implicated in developing obesity. The authors comment that these findings demonstrate a potential mechanism that is implicated in the onset and/or course of diet-induced obesity, through hippocampal derangements induced by excess dietary intake, which in turn would lead to overconsumption. Finally, the authors bring forth this point of view to serve as a new perspective on cerebral control over feeding behaviors, the neural pathogenesis of eating-related disorders, and to enhance diet-induced obesity interventions. [NPID: Amnesia, appetite, cognition, diet, episodic memory, food intake, hippocampus, interoception]

Current research points to the relationship between consuming ultra-processed foods (UPF) and health derangements such as cardiovascular disease, depression, and all-cause mortality. The evidence on the links between UPF and dementia, on the other hand, remains insufficient. Li et al. (2022) examined the links between dementia incidence and UPF consumption using a sample from the UK Biobank study (n = 72083, ≥ 55 years old, dementia-free at baseline). The participants were followed up through March 2021, and had their all-cause dementia (from Alzheimer’s disease or vascular dementia) verified through electronic hospital and mortality records. UPF definitions were set according to the NOVA classifications. The authors report an incidence of dementia in 518 of the participants (119 vascular dementia and 287 Alzheimer’s disease cases) throughout the follow-up period (10.0 years, n = 717333 participants). UPF consumption was linked to an increased risk of developing dementia, Alzheimer’s disease, and vascular dementia. Furthermore, substituting the contribution of UPF to overall dietary intake by 10% and replacing it with minimally processed or unprocessed food led to a reduction in the risk of developing dementia by 19%. The authors conclude that their prospective cohort study demonstrates the relationship between increased UPF consumption and higher risks of developing dementia, in addition to the impact of minimally processed or unprocessed food substitution on the reduction in dementia risk. [NPID: Ultra-processed food, dementia, Alzheimer’s disease, vascular dementia]

In their study, Lowe, Kolev, and Hall (2016) sought out to investigate the impact of aerobic exercise on executive function, particularly on inhibitory control, and how this might transfer to self-control in terms of one’s dietary intake. 51 participants, enlisted in a cross-over study, completed sessions involving moderate treadmill exercise (experimental condition) and minimal effort walking (control condition) with a 7-day interval between sessions. Ahead of the exercise sessions, participants performed a set of Stroop tasks (designed to measure a person’s selective attention capacity and skills, processing speed, and to evaluate overall executive processing abilities), as well as a bogus taste test including three, calorie dense snack foods, and two control foods, with the measurement parameter being the extent of food eaten during the taste test. Results demonstrated that moderate exercise positively impacted participants’ performance on Stroop tasks, in addition to decreasing the amount of snack foods consumed during the taste test, with no impact on control of foods consumed. Thus, the authors conclude that these results demonstrate that moderate exercise sessions can help strengthen inhibitory control, and this can transfer to self-control over food consumed. [NPID: Brain, cognition, diet, executive function, exercise, self-control]

Current evidence has linked nutrition and social cognition, with several dietary formats and a few probiotics reported as influencers. Nonetheless, there have been no studies that investigate the influence of particular nutrients on social cognition. Ugartemendia et al. (2020) aimed to investigate the potential links between dietary macronutrients and the social and affective information handling in a population of university students aged 21.3 ± 2.9 years, with a BMI of 22.8 ± 3.9. Participant social cognition and dietary patterns were collected and evaluated using questionnaires and dietary records. The participants completed the WHO-5 Well Being Index, Beck's Anxiety Inventory, Beck's Depression Inventory, Ruminative Response Scale (RSS), Leiden Index of Depression Sensitivity (LEIDS-r), Empathy Quotient (EQ), and the Interpersonal Reactivity Index (IRI). When the authors investigated social cognition and macronutrients, the students, whose diet was found to include a high consumption of proteins and saturated fatty acids, were observed to have a positive association between lipids, particularly cholesterol, and the Perspective-Taking Scale (a part of IRI). Carbohydrates were observed to impact the RSS, alluding that eating complex carbohydrates may increase the chances of developing depression. Furthermore, the brooding factor (part of RRS) was impacted negatively by dietary consumption of carbohydrates and proteins, in particular, fiber and aspartate. The authors conclude that diet may play a role in affecting several elements of social cognition and mood. Specifically, a diet low in cholesterol and rich in fiber, complex carbohydrates, and aspartate, affects the handling of social and affective information and psychic well-being more favorably. [NPID: Nutrition, social cognition, university students, RSS, IRI, fiber]

This 2021 firstly points out the lack of pharmaceutical treatments that are effective at curing dementia. The available drugs only delay the worsening cognition among patients with impairments. This review therefore summarized the effects of nutrients and phytonutrients (substances derived from plants believed to provide health benefits) on cognitive function. Among the ninety-six articles included in this narrative review, there were a total of 21 categories of nutrients and phytonutrients studied. These included α-lipoic acid, Bacopa monnieri, B vitamins, cholinergic precursors, vitamin D, vitamin E, Ginkgo biloba, ginseng, lion's mane mushroom, N-acetyl cysteine, omega-3 fatty acids, aloe polysaccharides, Rhodiola rosea, rosemary, saffron, tart cherries, turmeric, wild yam, Withania somnifera, xanthines, and zinc. These nutrients and phytonutrients appeared to show considerable influence over cognitive aspects such as memory, recollection, attention, intelligence, vocabulary, recognition, response inhibition, arousal, performance enhancement, planning, creative thinking, reaction time, vigilance, task switching, orientation to time, place, and person, reading, writing, comprehension, accuracy, learning, information processing speed, executive function, mental flexibility, daily functioning, decrease in mental fatigue, and freedom from distractibility. In addition, some of these nutrients/phytonutrients improved mood and contentedness, and reduced anxiety and necessity for caregiving. The listed effects were not completely consistent or common across all patient populations or health statuses. Moreover, there were minimal to no adverse effects reported. This review highlights that there are many promising nutrients and phytonutrients for treating some aspects of cognitive impairment, especially for people afflicted with Alzheimer’s Disease. These nutrients and phytonutrients should be considered by healthy adults and patients with health challenges such as Alzheimer’s, mild cognitive impairment, multiple sclerosis, and Parkinson's disease (who want to improve their cognitive function). [NPID: cognition, cognitive, brain, review, nutrients, phytonutrients, nutrition, vitamins, Alzheimer’s, dementia, fatty acids, aloe, rosemary, saffron, turmeric, yam, xanthines, zinc, Withania somnifera, Rhodiola rosea, Ginkgo biloba, ginseng, lion's mane mushroom, N-acetyl cysteine]

Hoping to better understand the cognitive–emotional processes associated with overconsumption of food, this 2017 article looks at recent research linking dietary fat intake and omega-3 polyunsaturated fatty acid imbalance with inflammation in developing, adult, and aged brains. Diet and stress exposure during early life can affect cognitive function throughout life, which indicates the high potential of early nutritional interventions in preventing cognitive impairment. Even eating fat-rich diets for a short period of time can stimulate the hippocampus to produce a greater neuroinflammatory response to mild immune problems, resulting in poorer memory. In addition, low intake levels of omega-3 polyunsaturated fatty acids can contribute to memory loss and play a part in the development of depression. Increasing our consumption of fruits and vegetables high in polyphenols can prevent and even reverse age-related cognitive deficits by lowering oxidative stress and inflammation. While more than one-third of American adults are obese (and these statistics are similar for many other countries worldwide), we have identified that it is necessary to expand our knowledge on the relationships between diet, cognition, and emotion to develop effective strategies for preventing and reducing comorbid neurological conditions in the obese. [NPID: diet, unhealthy food, nutrition, healthy food, fats, fatty acids, PUFAs, polyunsaturated fatty acids, stress, cognition, emotion, omega, stress, young, polyphenol, fruits, vegetables]

This 2017 study aimed to analyze the relationship between executive function and the consumption of saturated fat, fruits, and vegetables among an overweight/obese sample since this data had been lacking although other studies have proven the link between poorer diet and lower executive functioning among normal-weight individuals. The researchers of this present study examined the 190 participants on their intelligence, planning ability, and inhibitory control, and then looked at their diet within a month of starting a behavioral weight loss treatment program. Considering the neurological assessments on inhibitory control and planning (2 out of 3 indices), the subjects who ate more fruits and vegetables were more likely to be able to plan well and show better inhibition. There was no link found between intake of saturated fat and executive function. Not only do these results enhance our understanding on how executive functioning influences the dietary behaviors of overweight and obese individuals, the data suggests that dietary interventions aiming to assist people with obesity should consider including training components addressing executive functioning. [NPID: cognition, executive function, saturated fat, FV intake, planning ability, inhibitory control]

In this 2020 study, 24 female patients with eating disorders (EDs) were assigned to perform an emotion processing task while being scanned using functional magnetic resonance imaging (to inspect their activity of the fronto-limbic and fronto-striatal brain areas). The aim was to compare the level of activity in these two brain regions since dysfunctions in emotional processing are thought to play a role in the development and maintenance of eating disorders like anorexia nervosa (AN) and bulimia nervosa (BN). When viewing the pleasure-stimulating images, activity in the Dorsolateral Prefrontal Cortex (DLPFC) was significantly greater in the patients with anorexia nervosa (AN) compared with the participants with bulimia nervosa (BN) and eating disorders (ED) referred to as the EDc group. Moreover, this region was triggered more in the healthy controls than the EDc group and those with BN. The left putamen of the EDc group was also found to be less activated during the pleasant condition, compared to those with anorexia and the control subjects. But during the unpleasant image session, the Orbito-frontal Cortex (OFC) was hyperactivated in the participants with anorexia relative to EDc. Although these findings should be considered as preliminary, this study gets this area of research one step closer to understanding the neural mechanisms involved in eating disorders. [NPID: cognition, eating disorders, emotion processing, eating disorders, anorexia, bulimia]

The purpose of this 2015 study was to examine the relationship between people’s executive functions, fruit and vegetable consumption, and the intake of foods rich in saturated fat. Limbers & Young found that research was lacking on the association between healthy dietary behaviors and executive functions (using behavioral rating scales), even though executive functions are important in the control of eating behaviors and are linked with overeating. Therefore, the 240 university students recruited by this study completed the Behavioral Rating Inventory of Executive Functioning-Adult Version, the 26-Item Eating Attitudes Test, and the Diet subscale of the Summary of Diabetes Self-Care Activities Questionnaire. The researchers controlled for demographic variables, body mass index, and eating styles in the analysis models. The data showed several associations, including a positive link between initiation skills and fruit and vegetable consumption in the past 7 days. Moreover, greater inhibitory control correlated with lower intake of foods high in fat. But the executive functions that predict fruit and vegetable intake was determined to be different to those that can forecast fatty food avoidance. The writers suggest future research to consider checking if the improvement of initiation and inhibition skills through behavioral interventions can lead to benefits with regards to long-term weight control. [NPID: cognition, executive function, FV intake, inhibitory control, high fat, weight control]

In this 2017 study, Korean children and adolescents were tested on their cognitive function [assessing symbol digit modalities (SDMT), verbal memory, visual memory, shift attention, reasoning, and digit span], while their diets were also examined to discover how dietary consumption may affect cognitive ability. Considering standard deviation value, the girls’ reaction times were significantly shorter than that of the boys. Overall, the standard deviations in reaction times were positively associated with the consumption of snacks, rice, and chocolate, while increases in reaction times in general correlated with higher caffeine and snack intakes. Moreover, girls performed significantly better in terms of verbal memory and symbol digit modalities tests. Higher vitamin C, B1, and potassium intake was related with greater SDMT scores, while the eating of noodles was negatively associated with verbal memory, SDMT, shift attention, and reasoning test results. Furthermore, those participants who ate more fast food were more likely to perform worse in SDMT and reasoning tests. Drinking coca-cola was linked with poorer verbal performance also. However, mushroom intake showed positive correlation with visual memory and reasoning test results, while eating more nuts was connected with better SDMT results. While these results indicated a generally better relationship between dietary intake and cognitive function among the girls compared to the boys, the findings provide evidence that diet is strongly connected to cognitive function in healthy Korean children and adolescents. [NPID: cognition, Korea, verbal memory, visual memory, attention, reaction times, caffeine, snacks, vitamin C, vitamin B1, potassium, reasoning]

This 2017 study evaluated the link between dietary patterns and macronutrient composition with attention capacity in European adolescents. The Healthy Lifestyle in Europe by Nutrition in Adolescence study recruited 384 adolescents aged between 12.5-17.5 from 5 European countries. With the help of a computer-based tool, the dietary consumption of these participants could be assessed. Three dietary patterns (diet quality index, ideal diet score and Mediterranean diet score) and macronutrient/fiber intakes were calculated to be included in the analysis models. After adjusting for age, sex, BMI, maternal education, family affluence scale, study center and energy intake (only for Mediterranean diet score), positive associations were identified between higher diet quality index for adolescents and ideal diet score, with their attention capacity. However, the subjects’ calculated Mediterranean diet score and macronutrient/fiber intake levels did not correlate with attention capacity. Since the data suggest that healthier dietary patterns were related with attention capacity in adolescence, intervention studies inspecting a causal relationship between diet quality and attention are warranted. [NPID: cognition, macros, macronutrients, Mediterranean diet, Med diet, attention, diet quality]

This 1999 review discusses some of the most significant findings on nutrition and neurodevelopment in the last three decades, and particularly in the last few years. While randomized intervention studies have indicated how crucial early nutrition is on cognitive development later in life, recent epidemiological findings revealed that both genetics and environment are risk factors for schizophrenia. Early nutrition is particularly important for hippocampal development (hippocampus is a brain structure vital in learning, memory, and cognitive performance). Future research should focus on enhancing our knowledge on the