Dietary fat types and 4-year cognitive change in community-dwelling older women

BETA-HYDROXYBUTYRATE COUNTERACTS THE DELETERIOUS EFFECTS OF A SATURATED HIGH-FAT DIET ON SYNAPTIC AMPA RECEPTORS AND COGNITIVE PERFORMANCE

The ketogenic diet, characterized by high fat and low carbohydrates, has gained popularity not only as a strategy for managing body weight but also for its efficacy in delaying cognitive decline associated with neurodegenerative diseases and the aging process. Since this dietary approach stimulates the liver's production of ketone bodies, primarily β-hydroxybutyrate (BHB), which serves as an alternative energy source for neurons, we investigated whether BHB could mitigate impaired AMPA receptor trafficking, synaptic dysfunction, and cognitive decline induced by metabolic challenges such as saturated fatty acids. Here, we observe that, in cultured primary cortical neurons, exposure to palmitic acid (200μM) decreased surface levels of glutamate GluA1-containing AMPA receptors, whereas unsaturated fatty acids, such as oleic acid and ω-3 docosahexaenoic acid (200μM), and BHB (5mM) increased them. Furthermore, BHB countered the adverse effects of palmitic acid on synaptic GluA1 levels in hippocampal neurons, as well as excitability and plasticity in hippocampal slices. Additionally, daily intragastric administration of BHB (100 mg/kg/day) for two months reversed cognitive impairment induced by a saturated high-fat diet (49% of calories from fat) in a mouse experimental model of obesity. In summary, our findings underscore the significant impact of fatty acids and ketone bodies on AMPA receptors abundance, synaptic function and neuroplasticity, shedding light on the potential use of BHB to delay cognitive impairments associated with metabolic diseases.

The relationship between different fatty acids intake and the depressive symptoms: A population-based study

BACKGROUND

Depression is a common psychological disorder worldwide, affecting mental and physical health. Previous studies have explored the benefits of polyunsaturated fatty acids (PUFAs) intake in depressive symptoms; however, few studies have focused on the association between all types of fatty acids intake and depressive symptoms. Therefore, we explored the relationship between the intake of different fatty acids intake and the risk of depressive symptoms.

METHODS

The study was based on the data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES), a large US-based database. We used a nutrient residual model and multi-nutrient density model for the analysis. We calculated the nutrient density and residual in men and women separately, and the fatty acids intake was divided into quartiles based on the sex distribution. The relationship between the depressive symptoms and the intake of different fatty acids was examined using logistic regression; furthermore, we explored the relationships separately in men and women.

RESULTS

The intake of monounsaturated fatty acids (MUFAs) and PUFAs, particularly n-3 and n-6 PUFAs, were associated with reduced odds ratios for depressive symptoms. The inverse relationship between the intake of MUFAs, PUFAs, n-3, and n-6 PUFAs and depressive symptoms was stronger in women. The inverse relationship between total fatty acid (TFAs) intake and depressive symptoms existed only in a single model. In contrast, saturated fatty acid (SFAs) intake was not related to depressive symptoms.

CONCLUSION

Consuming MUFAs and PUFAs can counteract the depressive symptoms, especially in women.

Effects of saturated and monounsaturated fatty acids on cognitive impairment: evidence from Mendelian randomization study

BACKGROUND

Prior observational studies have suggested correlations between saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) with cognitive function. However, causal relationships remains unclear.

METHODS

We assessed the causal impact of two SFAs (palmitic acid [PA] and stearic acid [SA]) and two MUFAs (oleic acid [OA] and palmitoleic acid [POA]) on cognitive function-related traits, and dementia-related traits by univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) analyses.

RESULTS

UVMR indicated β of 0.060 (P = 4.05E-06) for cognitive performance score and 0.066 (P = 4.21E-04) for fluid intelligence per standard deviation (SD) increase in OA level. MVMR indicated: (i) β of -0.608 (P = 8.37E-05) for fluid intelligence score per SD increase in POA; (ii) β of 0.074 (P = 0.018) for fluid intelligence score per SD increase in OA; (iii) β of 0.029 (P = 0.033) for number of incorrect matches in round per SD increase in PA; and (iv) β of 0.039 (P = 0.032) for number of incorrect matches in round per SD increase in SA. In addition, a secondary MVMR analysis after excluding the effect of polyunsaturated fatty acids suggested that: (i) β of -0.043 (P = 1.97E-02) for cognitive performance score per SD increase in PA and (ii) β of -0.079 (P = 1.79E-03) for cognitive performance score per SD increase in SA.

CONCLUSIONS

Overall, UVMR and MVMR suggest that OA may be beneficial for cognitive function, while POA, PA, and SA may have detrimental effects on cognitive function.

Relationship between dietary macronutrients intake and biological aging: a cross-sectional analysis of NHANES data

PURPOSE

This study aimed to investigate the association between macronutrient intake and biological age.

METHODS

Data were collected from 26,381 adults who participated in the United States National Health and Nutrition Examination Survey (NHANES). Two biological ages were estimated using the Klemera-Doubal method (KDM) and PhenoAge algorithms. Biological age acceleration (AA) was computed as the difference between biological age and chronological age. The associations between macronutrient intakes and AA were investigated.

RESULTS

After fully adjusting for confounding factors, negative associations were observed between AA and fiber intake (KDM-AA: β - 0.53, 95% CI - 0.62, - 0.43, P < 0.05; PhenoAge acceleration: β - 0.30, 95% CI - 0.35, - 0.25, P < 0.05). High-quality carbohydrate intake was associated with decreased AA (KDM-AA: β - 0.57, 95% CI - 0.67, - 0.47, P < 0.05; PhenoAge acceleration: β - 0.32, 95% CI - 0.37, - 0.26, P < 0.05), while low-quality carbohydrate was associated with increased AA (KDM-AA: β 0.30, 95% CI 0.21, 0.38, P < 0.05; PhenoAge acceleration: β 0.16, 95% CI 0.11, 0.21, P < 0.05). Plant protein was associated with decreased AA (KDM-AA: β - 0.39, 95% CI - 0.51, - 0.27, P < 0.05; PhenoAge acceleration: β - 0.21, 95% CI - 0.26, - 0.15, P < 0.05). Long-chain SFA intake increased AA (KDM-AA: β 0.16, 95% CI 0.08, 0.24, P < 0.05; PhenoAge acceleration: β 0.11, 95% CI 0.07, 0.15, P < 0.05). ω-3 PUFA was associated with decreased KDM-AA (β - 0.18, 95% CI - 0.27, - 0.08, P < 0.05) and PhenoAge acceleration (β - 0.09, 95% CI - 0.13, - 0.04, P < 0.05).

CONCLUSION

Our findings suggest that dietary fiber, high-quality carbohydrate, plant protein, and ω-3 PUFA intake may have a protective effect against AA, while low-quality carbohydrate and long-chain SFA intake may increase AA. Therefore, dietary interventions aimed at modifying macronutrient intakes may be useful in preventing or delaying age-related disease and improving overall health.

Association between erythrocyte membrane fatty acids and gut bacteria in obesity-related cognitive dysfunction

Obesity increases the risk of cognitive impairment and dementia, and the gut microbiota can affect brain cognitive function and obesity through a variety of pathways such as the gut-brain axis. This study aimed to discover how fatty acid affect cognitive function by regulating intestinal flora in obesity. Obese subjects were recruited for cognitive function assessment, and participants were divided into obese group with cognitive impairment (MCI, n = 49) and obese cognitively normal group (Non_MCI, n = 55). In the erythrocyte membrane, the proportion of polyunsaturated fatty acids (PUFA), linoleic acid (C18:2 n-6) and arachidonic acid (C20:4 n-6) and n-6/n-3 ratio was higher in the MCI group than in the Non_MCI group. However, the α-linolenic acid (C18:3 n-3) percentage of the erythrocyte membrane was lower in the MCI group. We found that Coriobacteriales_Incertae_Sedis was positively correlated with erythrocyte membrane C20:4 n-6 and n-6 PUFA and negatively correlated with cognitive scores in obese patients. In addition, several of the functional pathways we predicted were significantly different in the MCI and Non_MCI groups. Higher levels of n-6/n-3 polyunsaturated fatty acids ratio in the erythrocyte membranes may influence the inflammatory response in the organism causing obesity induced cognitive damage. Moreover, high levels of n-6/n-3 polyunsaturated fatty acids ratio may also affect the intestinal flora of obese patients, which in turn may affect the cognitive function of obese patients.

Gender-specific moderating role of abdominal obesity in the relationship between handgrip strength and cognitive impairment

BACKGROUND & AIMS

Both low handgrip strength (HGS) and abdominal obesity (AO) are associated with cognitive impairment. However, it remains unclear whether low HGS and AO interact to affect cognition, and whether the synergistic effect varies by gender. This study aimed to examine whether the association between low HGS and incident cognitive impairment was moderated by AO among Chinese older men and women.

METHODS

We used the data of participants (≥60 years) from four waves (2011-2018) of the China Health and Retirement Longitudinal Study. We defined low HGS as the maximal HGS of <28 kg in men and <18 kg in women, and AO as waist circumference of ≥90 cm for men and ≥80 cm for women. Cognitive impairment was defined as a global cognitive score in the lowest 10th percentile. For each gender, we used subdistribution hazards model to estimate subdistribution hazard ratios (SHRs) for the association of low HGS and AO with incident cognitive impairment, treating mortality as the competing event and controlling for other covariates. Multiplicative interaction was assessed through a cross-product interaction term of low HGS and AO in the model. Additive interaction between low HGS and AO was evaluated by calculating the relative excess risk due to interaction (RERI) and attributable proportion due to interaction (AP).

RESULTS

We included 3704 participants (Mean age: 66.9 ± 5.81; 54.9% male). During the 7-year follow-up, 1133 events of interest occurred (731 cognitive impairments and 402 deaths). Incidence rates of cognitive impairment and mortality were 4.1 (95% CI: 3.8 to 4.4) and 2.2 (95% CI: 2.0 to 2.5) per 100 person-years. There were positive multiplicative (SHR for the product term = 1.974, 95% CI: 1.114 to 3.500) and additive interactions (RERI = 1.056, 95% CI: 0.027 to 2.086, AP = 0.454, 95% CI: 0.158 to 0.750) of low HGS and AO on the risk of cognitive impairment among older men. Male participants with both low HGS and AO showed an increased risk of cognitive impairment (SHR = 2.325, 95% CI: 1.498 to 3.609) compared with those without either. There was no evidence of interaction among older women (SHR for the product term = 1.151, 95% CI: 0.725 to 1.825; RERI = 0.044, 95% CI: -0.524 to 0.613; AP = 0.039, 95% CI: -0.458 to 0.536).

CONCLUSIONS

Low HGS and AO may interact to synergistically increase the risk of cognitive impairment among Chinese older men. Screening the highest-risk subpopulation, who may benefit most from neurocognitive prevention strategies, may maximize potential public health gains.

Association of dietary fiber with subjective sleep quality in hemodialysis patients: a cross-sectional study in China

BACKGROUND

Poor sleep quality is a common problem among hemodialysis (HD) patients. Dietary fiber is a key component of a healthy diet and is beneficial for a variety of health outcomes; however, evidence of an association between dietary fiber consumption and subjective sleep quality has not been established among HD patients. Therefore, we determined the association between dietary fiber consumption and the subjective sleep quality in Chinese maintenance HD patients, taking into account fiber type and source.

METHODS

Dietary intake was assessed with a validated food frequency questionnaire in a cross-sectional study including 741 maintenance HD patients between December 2021 and January 2022. The daily intake of dietary fiber was categorized into three groups. The lowest tertile was used as the reference category. Sleep quality of patients was accurately calculated using the Pittsburgh sleep quality index standard questionnaire. Multivariable logistic regression model and restricted cubic spline analysis were performed to assess the relationship between dietary fiber consumption and poor sleep quality.

RESULTS

Compared with the lowest tertile group of dietary fiber intake, the highest tertile group had a lower prevalence of poor sleep quality. After adjustment for potential confounders, a higher intake of total dietary fiber (OR_{tertile 3 (T3) to tertile 1 (T1)}= 0.51, 95% CI: 0.31-0.85), total insoluble dietary fiber (OR_{T3 to T1} =0.54, 95% CI: 0.33-0.89), and soluble dietary fiber in vegetables (OR_{T3 to T1} =0.61, 95% CI: 0.40-0.93) were associated with a lower prevalence of poor sleep quality. Furthermore, significant linear trends were also observed (p < 0.05). No significant interactions were observed in subgroup analyses.

CONCLUSION

A higher intake of dietary fiber was inversely associated with the poor sleep quality. These findings support the current recommendations that dietary fiber is essential for health and well-being.Key messagesThis study was conducted because there was not prior evidence connecting sleep quality and dietary fiber consumption in hemodialysis patients.In the present study a cross-sectional design was used to assess the association between dietary fiber consumption and poor sleep quality.Intake of total dietary fiber, total insoluble dietary fiber, and soluble dietary fiber in vegetables were negatively associated with poor sleep quality among maintenance hemodialysis patients.

Proposed solutions to anthropogenic climate change: A systematic literature review and a new way forward

Humanity is now facing what may be the biggest challenge to its existence: irreversible climate change brought about by human activity. Our planet is in a state of emergency, and we only have a short window of time (7-8 years) to enact meaningful change. The goal of this systematic literature review is to summarize the peer-reviewed literature on proposed solutions to climate change in the last 20 years (2002-2022), and to propose a framework for a unified approach to solving this climate change crisis. Solutions reviewed include a transition toward use of renewable energy resources, reduced energy consumption, rethinking the global transport sector, and nature-based solutions. This review highlights one of the most important but overlooked pieces in the puzzle of solving the climate change problem - the gradual shift to a plant-based diet and global phaseout of factory (industrialized animal) farming, the most damaging and prolific form of animal agriculture. The gradual global phaseout of industrialized animal farming can be achieved by increasingly replacing animal meat and other animal products with plant-based products, ending government subsidies for animal-based meat, dairy, and eggs, and initiating taxes on such products. Failure to act will ultimately result in a scenario of irreversible climate change with widespread famine and disease, global devastation, climate refugees, and warfare. We therefore suggest an "All Life" approach, invoking the interconnectedness of all life forms on our planet. The logistics for achieving this include a global standardization of Environmental, Social, and Governance (ESG) or similar measures and the introduction of a regulatory body for verification of such measures. These approaches will help deliver environmental and sustainability benefits for our planet far beyond an immediate reduction in global warming.

Association between dairy intake and risk of incident dementia: the Ohsaki Cohort 2006 Study

PURPOSE

To investigate the association between dairy intake and risk of incident dementia in older adults.

METHODS

A longitudinal analysis of dairy intake with incident dementia was conducted using a cohort study of 11,637 non-disabled Japanese older adults aged ≥ 65 years followed-up for up to 5.7 years (mean: 5.0 years). Data on milk, yogurt, and cheese intake were collected using a validated food frequency questionnaire. Total dairy intake was calculated as the sum of the daily intake of milk, yogurt, and cheese, which was sex-specifically categorized in quintiles. Dementia cases were retrieved from the public long-term care insurance database. Cox proportional hazards model was used to estimate multivariable hazard ratios (HRs) and 95% confidence intervals (95% CIs) for incident dementia.

RESULTS

During 58,013 person-years of follow-up, 946 persons developed dementia. In the primary analysis, compare to the lowest quintile of total dairy intake, Q2 showed a slightly decreased incident dementia risk (HR for Q2 vs Q1: 0.90, 95% CI: 0.73-1.10) after fully adjusted for demographic, lifestyle, psychological, and nutritional factors, and diseases history. Compared to non-consumers of milk, those consuming for 1-2 times/month showed a lower risk of incident dementia (fully-adjusted HR: 0.76, 95% CI: 0.57-1.02). Daily yogurt consumers also had a reduced risk (fully-adjusted HR: 0.89, 95% CI: 0.74-1.09). But daily cheese consumers showed an increased risk of dementia (fully-adjusted HR: 1.28, 95% CI: 0.91-1.79). In the sensitivity analysis where we excluded dementia cases ascertained in the first 2 years, results were consistent with those from the primary analysis and we further found that yogurt intake might be inversely associated with dementia risk (p for trend = 0.025).

CONCLUSION

Low total dairy intake or low milk intake frequency might be associated with lower incident dementia risk, however daily cheese consumers seemed to have an increased risk. Our study also suggested a possible inverse dose-response association between yogurt consumption and dementia risk, but further studies are needed to confirm whether this benefit was from yogurt intake itself or as a part of a healthy dietary pattern.

Self-reported intake of high-fat and high-sugar diet is not associated with cognitive stability and flexibility in healthy men

Animal studies indicate that a high-fat/high-sugar diet (HFS) can change dopamine signal transmission in the brain, which could promote maladaptive behavior and decision-making. Such diet-induced changes may also explain observed alterations in the dopamine system in human obesity. Genetic variants that modulate dopamine transmission have been proposed to render some individuals more prone to potential effects of HFS. The objective of this study was to investigate the association of HFS with dopamine-dependent cognition in humans and how genetic variations might modulate this potential association. Using a questionnaire assessing the self-reported consumption of high-fat/high-sugar foods, we investigated the association with diet by recruiting healthy young men that fall into the lower or upper end of that questionnaire (low fat/sugar group: LFS, n = 45; high fat/sugar group: HFS, n = 41) and explored the interaction of fat and sugar consumption with COMT Val¹⁵⁸Met and Taq1A genotype. During functional magnetic resonance imaging (fMRI) scanning, male participants performed a working memory (WM) task that probes distractor-resistance and updating of WM representations. Logistic and linear regression models revealed no significant difference in WM performance between the two diet groups, nor an interaction with COMT Val¹⁵⁸Met or Taq1A genotype. Neural activation in task-related brain areas also did not differ between diet groups. Independent of diet group, higher BMI was associated with lower overall accuracy on the WM task. This cross-sectional study does not provide evidence for diet-related differences in WM stability and flexibility in men, nor for a predisposition of COMT Val¹⁵⁸Met or Taq1A genotype to the hypothesized detrimental effects of an HFS diet. Previously reported associations of BMI with WM seem to be independent of HFS intake in our male study sample.

Dietary Fats and Cognitive Status in Italian Middle-Old Adults

The increase in life expectancy led to a significant rise in the prevalence of age-related neurological diseases, such as cognitive impairment, dementia, and Alzheimer’s disease. Although genetics certainly play a role, nutrition emerged as a key factor in maintaining optimal cognitive function among older adults. Therefore, the study aimed to investigate whether specific categories and subcategories of dietary fats, based on carbon-chain length, are associated with cognitive status in a cohort of 883 Italian participants over the age of 50. Methods: The intake of total, single class of dietary fat, such as saturated fatty acids (SFA), monounsaturated fatty acid (MUFA), and polyunsaturated fatty acid (PUFA), and also single fatty acids grouped according to carbon-chain length, were evaluated by food frequency questionnaires (FFQs). Cognitive health was assessed using the short portable mental status questionnaire (SPMSQ). Results: After adjustment for potential confounding factors subjects with a moderate consumption of both short-chain SFA (for Q2 vs. Q1, OR = 0.23, 95% CI: 0.08, 0.66) and middle-chain SFA specifically lauric acid (C12:0) intake (for Q2 vs. Q1, OR = 0.27, 95% CI: 0.09, 0.77) were less likely to suffer from cognitive impairment. Among single MUFAs, erucic acid (C22:1) intake resulted in an inverse association, in a linear way, with cognitive impairment (for Q4 vs. Q1, OR = 0.04, 95% CI: 0.00, 0.39). Conversely, moderate intake of linoleic acid (C18:2) was associated with cognitive impairment (Q3 vs. Q1, OR = 4.59, 95% CI: 1.51, 13.94). Regarding other PUFAs, individuals consuming moderate intake alpha linolenic acid (C18:3) were less likely to have cognitive impairment (for Q3 vs. Q1, OR = 0.19, 95% CI: 0.06, 0.64). Conclusions: Total SFA intake appeared to be inversely associated with cognitive impairment. Regarding specific subtypes of fatty acids, the results mostly referred to short- and middle-chain SFA. Further studies are needed to validate the results of the present study.

Are We What We Eat? The Moral Imperative of the Medical Profession to Promote Plant-Based Nutrition

The typical Western diet, high in processed and animal-based foods, is nutritionally and ethically problematic. Beyond the well-documented cruelty to animals that characterizes the practices of the factory-farming industry, current patterns of meat consumption contribute to medical and moral harm in humans on both an individual level and a public health scale. We aim to deconstruct, by highlighting their fallacies, the common positive and normative arguments that are used to defend current nutritional patterns. Animal-based foods promote the mechanisms that underlie chronic cardiometabolic disease, whereas whole-food plant-based nutrition can reverse them. Factory farming of animals also contributes to climate change, antibiotic resistance, and the spread of infectious diseases. Finally, the current allocation of nutritional resources in the United States is unjust. A societal shift toward more whole-food plant-based patterns of eating stands to provide significant health benefits and ethical advantages, and the medical profession has a duty to advocate accordingly. Although it remains important for individuals to make better food choices to promote their own health, personal responsibility is predicated on sound advice and on resource equity, including the availability of healthy options. Nutrition equity is a moral imperative and should be a top priority in the promotion of public health.

Feeding the Brain: Effect of Nutrients on Cognition, Synaptic Function, and AMPA Receptors

In recent decades, traditional eating habits have been replaced by a more globalized diet, rich in saturated fatty acids and simple sugars. Extensive evidence shows that these dietary factors contribute to cognitive health impairment as well as increase the incidence of metabolic diseases such as obesity and diabetes. However, how these nutrients modulate synaptic function and neuroplasticity is poorly understood. We review the Western, ketogenic, and paleolithic diets for their effects on cognition and correlations with synaptic changes, focusing mainly (but not exclusively) on animal model studies aimed at tracing molecular alterations that may contribute to impaired human cognition. We observe that memory and learning deficits mediated by high-fat/high-sugar diets, even over short exposure times, are associated with reduced arborization, widened synaptic cleft, narrowed post-synaptic zone, and decreased activity-dependent synaptic plasticity in the hippocampus, and also observe that these alterations correlate with deregulation of the AMPA-type glutamate ionotropic receptors (AMPARs) that are crucial to neuroplasticity. Furthermore, we explored which diet-mediated mechanisms modulate synaptic AMPARs and whether certain supplements or nutritional interventions could reverse deleterious effects, contributing to improved learning and memory in older people and patients with Alzheimer’s disease.

Association between the Erythrocyte Membrane Fatty Acid Profile and Cognitive Function in the Overweight and Obese Population Aged from 45 to 75 Years Old

Dietary fatty acid intake is closely related to the cognitive function of the overweight and obese population. However, few studies have specified the correlation between exact fatty acids and cognitive functions in different body mass index (BMI) groups. We aimed to explain these relationships and reference guiding principles for the fatty acid intake of the overweight and obese population. Normal weight, overweight, and obese participants were recruited to receive a cognitive function assessment and dietary survey, dietary fatty acids intake was calculated, and the erythrocyte membrane fatty acid profile was tested by performing a gas chromatography analysis. The percentages of saturated fatty acids (SFAs) in the obese group were higher, while monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) were lower than in the normal weight and overweight groups. In the erythrocyte membrane, the increase of n-3 PUFAs was accompanied by cognitive decline in the overweight group, which could be a protective factor for cognitive function in the obese group. High n-6 PUFAs intake could exacerbate the cognitive decline in the obese population. Dietary fatty acid intake had different effects on the cognitive function of overweight and obese people, especially the protective effect of n-3 PUFAs; more precise dietary advice is needed to prevent cognitive impairment.

Markers of a plant-based diet relate to memory and executive function in older adults

BACKGROUND

Although it is known that plant-based foods are important for physical health, little is known about the relationship between plant-based foods and cognitive health. Emerging evidence suggests that some macronutrients may influence cognition, but it is unclear which domains of cognition are involved; more importantly, it is unknown how a plant-based diet relates to cognition.

OBJECTIVE

To examine associations between a plant-based dietary pattern and cognitive functioning.

METHODS

Participants were 3,039 older adults who participated in the 2011-2014 waves of the National Health and Nutrition Examination Survey (NHANES). The present cross-sectional study used data on macronutrient intake from 24-hour dietary interviews, as well as performance on tests of long-term memory and executive function (i.e., delayed word recall, digit symbol substitution test, and animal fluency). Principal component analysis was used to extract a dietary pattern consistent with a plant-based diet.

RESULTS

Greater adherence to a dietary pattern consistent with a plant-based diet was related to better performance on all cognitive tasks. Secondary analyses indicated that the associations between a plant-based dietary pattern and executive function accounted for the association between a plant-based dietary pattern and memory. Furthermore, this same plant-based dietary pattern was associated with reduced baseline inflammation in a separate dataset.

CONCLUSIONS

Experimental manipulations are needed to determine the potential causal relations of these associations, but these results suggest that a plant-based diet relates to better cognition, especially through improved executive control. Future work should also attempt to extend these results by examining potential mechanisms underlying these associations, such as reduced inflammation.

Long-term intake of total energy and fat in relation to subjective cognitive decline

Diet is one of the modifiable risk factors for cognitive decline. However, human studies on total energy intake and cognitive function have remained limited and studies on fat intake and cognitive decline have been inconclusive. We aimed to examine prospectively the associations between long-term intakes of total energy and fat with subsequent subjective cognitive decline (SCD). A total of 49,493 women from the Nurses' Health Study and 27,842 men from the Health Professionals Follow-up Study were followed for over 20 years. Average dietary intake was calculated based on repeated food frequency questionnaires (SFFQs), and Poisson regression was used to evaluate associations. Higher total energy intake was significantly associated with greater odds of SCD in both cohorts. Comparing the highest with lowest quintiles of total energy intake, the pooled multivariable-adjusted ORs (95% CIs) for a 3-unit increment in SCD, corresponding to poor versus normal SCD, was 2.77 (2.53, 2.94). Each 500 kcal/day greater intake of total energy was associated with 48% higher odds of SCD. Intakes of both total fat and total carbohydrate appeared to contribute to the positive association between total energy intake and SCD although for the same percent of energy, the association was stronger for total fat. In conclusion, higher intakes of total energy, total fat, and total carbohydrate were adversely associated with SCD. Whether these associations are causal is unclear and deserves further investigation.

Memory and eating: A bidirectional relationship implicated in obesity

This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.

Crème de la Créature: Dietary Influences on Behavior in Animal Models

In humans, alterations in cognitive, motivated, and affective behaviors have been described with consumption of processed diets high in refined sugars and saturated fats and with high body mass index, but the causes, mechanisms, and consequences of these changes remain poorly understood. Animal models have provided an opportunity to answer these questions and illuminate the ways in which diet composition, especially high-levels of added sugar and saturated fats, contribute to brain physiology, plasticity, and behavior. Here we review findings from invertebrate (flies) and vertebrate models (rodents, zebrafish) that implicate these diets with changes in multiple behaviors, including eating, learning and memory, and motivation, and discuss limitations, open questions, and future opportunities.

Dietary Insights in Neurological Diseases

PURPOSE OF REVIEW

Dietary interventions may play a role in the pathophysiology of common neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, migraines, multiple sclerosis, and epilepsy. This article describes the most common and impactful dietary regimens for commonly encountered neurological disorders.

RECENT FINDINGS

Plant-based, low-fat, high-fiber diets, rich in antioxidants and other lifestyle interventions may reduce the burden and disability of common neurological disorders. The ketogenic diet, the diet of choice for the treatment of refractory epilepsy, is such an example. Diverse neurological disorders demonstrate several common pathophysiological mechanisms including increased oxidative stress, neuroinflammation, and disrupted metabolism. Dietary interventions can potentially influence these pathophysiological processes and thus favorably alter clinical outcomes. Adequate dietary choices should be considered as part of a continuum of healthy lifestyle choices.

The impact of saturated fat, added sugar and their combination on human hippocampal integrity and function: A systematic review and meta-analysis

Paralleling animal research, there is emerging evidence that a Western-style (WS) diet - high in saturated fat and added sugar - impairs human hippocampal functioning. However, the conditions under which this occurs are not fully understood and there have been published failures to detect such effects. To date, there has been no systematic review or meta-analysis of relevant human studies. We undertook a systematic database search and review. Twenty studies were identified, two experimental, with the remainder correlational. The latter were included in a meta-analyses on the impact of WS-diet and its macronutrient components on human hippocampal function. Effects of age and sex were also examined. A WS-diet adversely impacted human hippocampal volume and functioning, with a small-pooled effect size. No effects were found for individual macronutrients. There was a high-level of study heterogeneity, which was not fully explained by study/sample characteristics. This may arise via the wide range of assessment tools used to measure both dietary intake and hippocampal functioning. Overall, a WS-diet clearly impacts human hippocampal functioning as in animals.

Case-cohort study of plasma phospholipid fatty acid profiles, cognitive function, and risk of dementia: a secondary analysis in the Ginkgo Evaluation of Memory Study

BACKGROUND

Phospholipids are biomarkers of dietary fat intake and metabolism, linked to several cardiometabolic disorders. Few prospective studies have assessed plasma phospholipids in relation to dementia risk and cognitive function.

OBJECTIVES

We aimed to evaluate the association between a decrease in linoleic acid accompanied with an increase in other fatty acids and cognitive function and dementia risk.

METHODS

We conducted a case-cohort study nested within the Ginkgo Evaluation of Memory Study. We included 1252 participants, 498 of whom who developed dementia during a mean of 5 y of follow-up. We measured 45 individual plasma phospholipids (as a percentage of total plasma phospholipid fatty acids) by GC and related these to Modified Mini-Mental State Examination (3MSE) scores at baseline and neurologist-adjudicated incidence of all-cause dementia and Alzheimer disease (AD), adjusting for sociodemographic and clinical characteristics.

RESULTS

Substitution of 1% of SFAs for 1% of linoleic acid, the predominant polyunsaturated n-6 (ɷ-6) fatty acid, was associated with higher risk of dementia (HR per 1% of SFAs instead of linoleic acid = 1.03; 95% CI: 1.00, 1.07) and a 0.08 point lower 3MSE score at baseline (95% CI: -0.12, -0.03), signifying worse cognitive function. When compared with linoleic acid, we found no associations of total monounsaturated, n-3 polyunsaturated, or trans fatty acids with risk of dementia or AD. However, the substitution of 1% of the marine n-3 PUFA DHA for linoleic acid was associated with lower risk of dementia (HR = 0.86 per 1% of DHA instead of linoleic acid; 95% CI: 0.76, 0.96). These associations were not modified by apolipoprotein E genotype, mild cognitive impairment at baseline, age, or sex.

CONCLUSIONS

Specific elements of diet may be associated with late-life dementia, a hypothesis that requires formal testing in randomized controlled trials and that represents a possible preventive intervention.

Consumption of dietary nuts in midlife and risk of cognitive impairment in late-life: the Singapore Chinese Health Study

BACKGROUND

evidence from prospective studies investigating the association between consumption of nuts in midlife and risk of cognitive impairment in late life is limited.

METHODS

this study analysed data from 16,737 participants in a population-based cohort, the Singapore Chinese Health Study. Intake of nuts was assessed using a validated food-frequency questionnaire at baseline (1993-1998), when participants were 45-74 years old (mean age = 53.5 years). Cognitive function was tested using the Singapore modified Mini-Mental State Examination during the third follow-up visit (2014-2016), when participants were 61-96 years old (mean age = 73.2 years). Cognitive impairment was defined using education-specific cut-off points. Logistic regression models were used to estimate the odds ratio (OR) and the 95% confidence interval (CI) for the association between intake and risk of cognitive impairment.

RESULTS

cognitive impairment was identified in 2,397 (14.3%) participants. Compared with those who consumed <1 serving/month of nuts, participants who consumed 1-3 servings/month, 1 serving/week and ≥2 servings/week had 12% (95% CI 2-20%), 19% (95% CI 4-31%) and 21% (2-36%) lower risk of cognitive impairment, respectively (P-trend = 0.01). Further adjustment for intake of unsaturated fatty acids attenuated the association to non-significance. Mediation analysis showed that the 50.8% of the association between nuts and risk of cognitive impairment was mediated by the intake of total unsaturated fatty acids (P < 0.001).

CONCLUSION

higher intake of nuts in midlife was related to a lower risk of cognitive impairment in late life, which was partly mediated by unsaturated fatty acids.

Dietary fatty acids and risk for Alzheimer's disease, dementia, and mild cognitive impairment: A prospective cohort meta-analysis

The association between dietary fatty acid intake and Alzheimer's disease (AD), dementia, and mild cognitive impairment (MCI) risk is inconsistent. This meta-analysis examined the effect of dietary fatty acid intake in prospective cohort studies including patients with AD, dementia, and MCI. PubMed, China Biology Medicine (CBM), China National Knowledge Infrastructure (CNKI), Wanfang Data, and VIP Database were systematically searched through September 2020. The random-effects model was used to combine the highest and lowest categories of multivariable adjusted relative risk (RR). Prospective cohort studies that included associations between dietary fatty acid intake and the risk for AD, dementia, or MCI were included. Fourteen studies were included, comprising 54 177 participants: 1696 patients with AD, 1118 patients with dementia, and 2889 with MCI. The pooled RR showed a significant association only between ω-3 polyunsaturated fatty acid (PUFA) intake and MCI risk (RR, 0.86; 95% CI, 0.75-0.98), with no heterogeneity between studies (I² = 0%). The intake of total fatty acids, saturated fatty acids (SFAs), cholesterol, monounsaturated fatty acids (MUFAs), PUFAs, ω-3 PUFAs, ω-6 PUFAs, docosahexaenoic acids (DHAs), and eicosapentaenoic acids (EPAs) was not significantly associated with AD risk. The intake of total fatty acids, SFAs, MUFAs, PUFAs, and ω-3 PUFAs was not significantly associated with dementia risk. This meta-analysis provided evidence that ω-3 PUFA intake may be negatively associated with MCI risk.

Effects of very low-carbohydrate vs. high-carbohydrate weight loss diets on psychological health in adults with obesity and type 2 diabetes: a 2-year randomized controlled trial

AIMS

Very low-carbohydrate (LC) diets are popular for type 2 diabetes (T2DM) management; however, long-term effects on psychological health remain largely unknown. This study reports the effects of a LC diet on mood and cognitive function after 2 years and explores the potential predictors of changes in psychological health.

METHODS

115 adults (57% males; age: 58.5 ± 7.1 years) with obesity and T2DM were randomized to consume an energy reduced (~ 500 to 1000 kcal/day deficit), LC diet [14% energy as carbohydrate, 28% protein, 58% fat (< 10% saturated fat)] or an isocaloric high unrefined carbohydrate, low-fat diet [HC: 53% carbohydrate, 17% protein, 30% fat (< 10% saturated fat)] for 2 years. Both diets were combined with aerobic/resistance exercise (1 h, 3 days/week). Mood/well-being [Beck Depression Inventory (BDI), Spielberger State Anxiety Inventory (SAI), Profile of Mood States (POMS)], diabetes-related quality of life [Diabetes-39 (D-39)] and distress [Problem Areas in Diabetes (PAID) Questionnaire], and cognitive function were assessed during and post-intervention.

RESULTS

61 (LC: 33, HC: 28) participants completed the study. Weight loss was 9.1% after 12 months and 6.7% after 2 years with no difference between diet groups. There were no differences between the groups for the changes in any psychological health outcome (smallest p ≥ 0.19 for all time x diet interactions). Overtime, improvements in BDI, POMS [Total Mood Disturbance (TMD); four subscales], PAID, and D-39 (three subscales) scores occurred (p ≤ 0.05, time). Stepwise regression analysis showed improvements in BDI, POMS (TMD; two subscales), D-39, SAI, and PAID scores were significantly (p < 0.05) correlated with reductions in body weight and glycated hemoglobin.

CONCLUSION

In adults with obesity and T2DM, energy-restricted LC and HC diets produced comparable long-term improvements on a comprehensive range of psychological health outcomes. The findings suggest both diets can be used as a diabetes management strategy as part of a holistic lifestyle modification program without concern of negative effects on mental well-being or cognition.

TRIAL REGISTRATION

ACTRN12612000369820, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=362168&isReview=true . Data described in the manuscript, code book, and analytic code will not be made available because approval has not been granted by participants.

Alzheimer's disease and gut microbiota: does trimethylamine N-oxide (TMAO) play a role?

Alzheimer's disease (AD) is a neurodegenerative disease that affects memory and cognitive function. Clinical evidence has put into question our current understanding of AD development, propelling researchers to look into further avenues. Gut microbiota has emerged as a potential player in AD pathophysiology. Lifestyle factors, such as diet, can have negative effects on the gut microbiota and thus host health. A Western-type diet has been highlighted as a risk factor for both gut microbiota alteration as well as AD development. The gut-derived trimethylamine N-oxide (TMAO) has been previously implied in the development of cardiovascular diseases with recent evidence suggesting a plausible role of TMAO in AD development. Therefore, the main goal of the present review is to provide the reader with potential mechanisms of action through which consumption of a Western-type diet could increase AD risk, by acting through microbiota-produced TMAO. Although a link between TMAO and AD is far from definitive, this review will serve as a call for research into this new area of research.

The impact of dietary macronutrient intake on cognitive function and the brain

Macronutrients - carbohydrates, fats, and proteins - supply the nutrients required for optimal functioning. Inadequate intake compromises both physical and brain health. We synthesized research on macronutrients from whole meals on cognitive function in healthy adults and identified underlying mechanisms. Intake of simple carbohydrates ('sugars') is consistently associated with decreased global cognition whereas consumption of complex carbohydrates correlates with successful brain aging and improved memory both in the short- and long-term. Saturated fatty acid intake correlates with decreased memory and learning scores whereas omega-3 intake correlates positively with memory scores. Protein intake boosts executive function and working memory when task-demands are high. Individual differences affecting the macronutrient-cognition relationship are age, physical activity, and glucose metabolism. Neural correlates reflect findings on cognitive functions: cortical thickness and cerebral amyloid burden correlate with sugar intake, inflammatory status and cerebral glucose metabolism correlate with fatty acid intake. Key mechanisms by which dietary macronutrients affect the brain and cognition include glucose and insulin metabolism, neurotransmitter actions, and cerebral oxidation and inflammation. In conclusion, macronutrient intake affects cognitive function both acutely and in the long-term, involving peripheral and central mechanisms. A healthy diet supports brain integrity and functionality, whereas inadequate nutrition compromises it. Studying diet can be key to nutritional recommendations, thereby improving the landscape of mental health and healthy brain aging.

Changes in dietary fat intake and associations with mental health in a UK public sample during the COVID-19 pandemic

Background

Consumption of unhealthy foods may have changed during the COVID-19 pandemic. This study explored how dietary fat intake was impacted in a sample of the UK public who were social distancing during the COVID-19 pandemic.

Methods

Data were collected from a UK COVID-19 online survey. Fat intake was measured using the Dietary Instrument for Nutrition Education questionnaire. Anxiety and depressive symptoms were assessed using Becks’ Anxiety and Depression Inventories, while the short-form Warwick-Edinburgh Mental Well-being Scale assessed mental well-being. Differences between individuals who increased versus decreased fat intake were explored using chi-square or independent sample t-tests. Association between fat intake and mental health was explored using adjusted linear regression models.

Results

Eight hundred and eighty-seven adults were included. Approximately, 34% recorded medium-to-high levels of fat consumption during social distancing. Around 48% reported decreased fat intake during social distancing compared to usual levels, while 41.3% documented increased fat intake. Fat intake was not significantly associated (P > 0.05) with any measures of mental health.

Conclusions

A higher proportion of a sample of UK adults social distancing during the COVID-19 pandemic recorded decreased fat intake when compared to levels prior to social distancing. There appeared to be no associations between fat intake and mental health.

Resveratrol confers neuroprotection against high-fat diet in a mouse model of Alzheimer's disease via modulation of proteolytic mechanisms

Cumulative evidence indicates that excessive consumption of calories from saturated fat contributes to the development of Alzheimer's disease (AD). Here, we assess the triggering and progression of AD pathology induced by a high-fat diet (HFD), and the effects of resveratrol, a polyphenol found in common dietary sources with pleiotropic neuroprotective activities. Over 16 weeks, male wild type (WT) and AD transgenic 5XFAD mice were fed a control diet, HFD (60% kcal from fat), or HFD supplemented with 0.1% resveratrol. Resveratrol protected against HFD-induced memory loss in WT mice and prevented memory loss in 5XFAD mice. Resveratrol also reduced the amyloid burden aggravated by HFD in 5XFAD, and protected against HFD-induced tau pathology in both WT and 5XFAD strains. At the mechanistic level, resveratrol inhibited the HFD-increased amyloidogenic processing of the amyloid precursor protein in both strains; it also restored abnormal high levels in the proteolytic activity of the ubiquitin-proteasome system induced by HFD, suggesting the presence of a compensatory mechanism to counteract the accumulation of aberrant proteins. Thus, our data suggest that resveratrol can correct the harmful effects of HFD in the brain and may be a potential therapeutic agent against obesity-related disorders and AD pathology.

Dietary Fatty Acid Factors in Alzheimer's Disease: A Review

Alzheimer's disease (AD) is an irreversible neurodegenerative disease characterized by brain function disorder and chronic cognitive function impairment. The onset of AD is complex and is mostly attributed to interactions between genetic factors and environmental factors. Lifestyle, dietary habits, and food consumption are likely to play indispensable functions in aged-related neurodegenerative diseases in elderly people. An increasing number of epidemiological studies have linked dietary fatty acid factors to AD, raising the point of view that fatty acid metabolism plays an important role in AD initiation and progression as well as in other central nervous system disorders. In this paper, we review the effects of the consumption of various dietary fatty acids on AD onset and progression and discuss the detrimental and beneficial effects of some typical fatty acids derived from dietary patterns on the pathology of AD. We outline these recent advances, and we recommend that healthy dietary lifestyles may contribute to preventing the occurrence and decreasing the pathology of AD.

Nutrition and the ageing brain: Moving towards clinical applications

The global increases in life expectancy and population have resulted in a growing ageing population and with it a growing number of people living with age-related neurodegenerative conditions and dementia, shifting focus towards methods of prevention, with lifestyle approaches such as nutrition representing a promising avenue for further development. This overview summarises the main themes discussed during the 3^rd Symposium on "Nutrition for the Ageing Brain: Moving Towards Clinical Applications" held in Madrid in August 2018, enlarged with the current state of knowledge on how nutrition influences healthy ageing and gives recommendations regarding how the critical field of nutrition and neurodegeneration research should move forward into the future. Specific nutrients are discussed as well as the impact of multi-nutrient and whole diet approaches, showing particular promise to combatting the growing burden of age-related cognitive decline. The emergence of new avenues for exploring the role of diet in healthy ageing, such as the impact of the gut microbiome and development of new techniques (imaging measures of brain metabolism, metabolomics, biomarkers) are enabling researchers to approach finding answers to these questions. But the translation of these findings into clinical and public health contexts remains an obstacle due to significant shortcomings in nutrition research or pressure on the scientific community to communicate recommendations to the general public in a convincing and accessible way. Some promising programs exist but further investigation to improve our understanding of the mechanisms by which nutrition can improve brain health across the human lifespan is still required.

Plasma fatty acid profile is related to cognitive function in obese Chinese populations (35-64 years): A cross-sectional study

BACKGROUND

A fast-growing body of evidence suggests that dietary lipids influence cognition, but the effects of dietary fatty acid (FA) intake and plasma FA profile on cognitive function in obese populations are currently unclear. The present study aimed to investigate the dietary FA intakes and plasma FA composition and their association with cognitive functions in obese and overweight populations aged 35-64 years.

METHODS

A total of 672 subjects were recruited and divided into normal-weight, overweight, and obese groups based on their body mass index (BMI). Dietary information was collected using a semiquantified food frequency questionnaire. Plasma FAs composition was examined using gas chromatography. The mini-mental state examination and Montreal Cognitive Assessment scales were carried out to assess the cognitive performance of each participant. Dietary FA intake and plasma FA composition were compared with rank transformation followed by one-way ANOVA analysis across different BMI groups. Spearman rank correlation analysis was used to investigate the correlation between dietary FA intake and plasma FA composition and cognitive functions in normal-weight, overweight, and obese subjects, respectively.

RESULTS

Overweight and obese subjects consumed larger amounts of saturated fatty acids (SFAs) compared to normal-weight participants (p < .05). Obese populations also had higher plasma levels of total SFAs and total monounsaturated fatty acid (MUFAs) than normal-weight subjects (both p < .05). In addition, plasma levels of SFAs, polyunsaturated fatty acids (PUFAs), and MUFAs were negatively correlated with cognitive functions in obese subjects but showed no correlation in normal-weight and overweight subjects.

CONCLUSIONS

From current data, we found higher plasma levels of SFA, PUFA, and MUFA in obese populations, which were associated with declined cognition. Lowering plasma FA levels may help maintaining normal cognitive functions in obese people.

Midlife Dietary Intakes of Monounsaturated Acids, n-6 Polyunsaturated Acids, and Plant-Based Fat Are Inversely Associated with Risk of Cognitive Impairment in Older Singapore Chinese Adults

BACKGROUND

Previous studies have shown inconsistent results for the relation between dietary fat intake and cognitive function in the elderly. Furthermore, prospective studies on this topic among the Chinese population are scarce.

OBJECTIVES

We aimed to examine the association between midlife dietary fat intake and risk of cognitive impairment in the elderly.

METHODS

Prospective cohort analysis was conducted among 16,736 participants from the Singapore Chinese Health Study. Dietary information was assessed by a validated FFQ at baseline (1993-1998) when participants aged 45-74 y (mean: 53.5; SD: 6.22). Cognitive impairment was identified using the Singapore modified Mini-Mental State Examination at the third follow-up visit (2014-2016) when participants aged 61-96 y (mean: 73.2; SD: 6.41). Multivariable logistic regression models were used to calculate ORs and 95% CIs.

RESULTS

Cognitive impairment was presented in 2397 participants. When substituted for total carbohydrate, dietary fat intake was inversely related to cognitive impairment (OR comparing extreme quartiles: 0.80; 95% CI: 0.67, 0.94; P-trend = 0.003). The OR (95% CI) comparing extreme quartiles of specific dietary fats was 1.08 (0.89, 1.31; P-trend = 0.51) for SFAs, 0.80 (0.64, 0.99; P-trend = 0.02) for MUFAs, 0.84 (0.72, 0.99; P-trend = 0.02) for PUFAs, 0.92 (0.77, 1.09; P-trend = 0.49) for n-3 PUFAs, and 0.83 (0.70, 0.98; P-trend = 0.01) for n-6 PUFAs. An inverse association was found for plant-based fat (OR: 0.84; 95% CI: 0.72, 0.98; P-trend = 0.02), but not for animal-based fat (OR: 0.96; 95% CI: 0.81, 1.15; P-trend = 0.76). When substituted for SFAs, the OR (95% CI) was 0.77 (0.61, 0.97; P-trend = 0.02) for MUFAs and 0.82 (0.70, 0.95; P-trend = 0.003) for PUFAs.

CONCLUSIONS

We found that substitution of total carbohydrate or SFAs with MUFAs and PUFAs, particularly n-6 PUFAs, was related to a lower risk of cognitive impairment in elderly Chinese participants. In addition, an inverse association with cognitive impairment was found for plant-based fat.

A Preliminary Investigation of the Effects of a Western Diet on Hippocampal Volume in Children

Introduction: Over the course of the 20th century, there has been a sharp increase in the consumption of saturated fat and refined sugars. This so-called "western diet" (WD) has been extensively linked to biological alterations and associated functional deficits in the hippocampus of animals. However, the effects of a WD on the human hippocampus are less well-characterized. This preliminary study aimed to extend prior animal work by investigating the effects of a WD on hippocampal volume in children. Methods: Twenty-one healthy children (ages 5-9) completed a structural T1-weighted magnetic resonance imaging scan. Bilateral hippocampal volumes (as regions-of-interest) and bilateral amygdala volumes (as medial temporal lobe control regions-of-interest) were calculated. WD variables were derived from the parent-completed Youth/Adolescent Food Frequency Questionnaire. Specifically, variables were calculated as percent of daily calories consumed from sugars, fats, or a combination of these (WD). Results: While the relationships between overall WD consumption and bilateral hippocampal volumes were not significant, increased fat consumption was significantly related to decreased left hippocampal volume. Sugar consumption was not related to hippocampal size. Control region volumes were not related to any diet variables. Discussion: This study is the first to directly link diet-specifically fat consumption-to decreased left hippocampal volume in children. This extends previous work showing smaller left hippocampal volume related to obesity in pediatric samples. Though preliminary, findings represent an important step toward understanding the impact of diet on child brain development.

Low-fat dietary pattern and global cognitive function: Exploratory analyses of the Women's Health Initiative (WHI) randomized Dietary Modification trial

BACKGROUND

Meta-analyses of observational studies associate adherence to several dietary patterns with cognitive health. However, limited evidence from full scale, randomized controlled trials precludes causal inference regarding dietary effects on cognitive function.

METHODS

The Women's Health Initiative (WHI) Dietary Modification (DM) randomized trial, in 48,835 postmenopausal women, included a subset of 1,606 WHI Memory Study (WHIMS) participants >= 65 years old, to assess low-fat dietary pattern influence on global cognitive function, evaluated with annual screening (Modified Mini-Mental State Examinations [3MSE]). Participants were randomized by a computerized, permuted block algorithm, stratified by age group and center, to a dietary intervention (40%) to reduce fat intake to 20% of energy and increase fruit, vegetable and grain intake or usual diet comparison groups (60%). The study outcome was possible cognition impairment (failed cognitive function screening) through the 8.5 year (median) dietary intervention. Those failing screening received a comprehensive, multi-phase cognitive function assessment to classify as: no cognitive impairment, mild cognitive impairment, or probable dementia. Exploratory analyses examined the composite endpoint of death after possible cognitive impairment through 18.7 years (median) follow-up. The WHI trials are registered at ClinicalTrials.gov:NCT00000611.

FINDINGS

Among the 1,606 WHIMS participants, the dietary intervention statistically significantly reduced the incidence of possible cognitive impairment (n = 126; hazard ratio [HR] 0.59 95% confidence interval [CI] 0.38-0. 91, P = 0.01) with HR for dietary influence on subsequent mild cognitive impairment of 0.65 (95% CI 0.35-1.19) and HR of 0.63 (95% CI 0.19-2.10) for probable dementia (PD). Through 18.7 years, deaths from all-causes after possible cognitive impairment were non-significantly lower in the dietary intervention group (0.56% vs 0.77%, HR 0.83 95% CI 0.35 to 2.00, P = 0.16).

INTERPRETATION

Adoption of a low-fat eating pattern, representing dietary moderation, significantly reduced risk of possible cognitive impairment in postmenopausal women.

FUNDING

Several Institutes of the US National Institutes of Health.

Sex and Gender Driven Modifiers of Alzheimer's: The Role for Estrogenic Control Across Age, Race, Medical, and Lifestyle Risks

Research indicates that after advanced age, the major risk factor for late-onset Alzheimer’s disease (AD) is female sex. Out of every three AD patients, two are females with postmenopausal women contributing to over 60% of all those affected. Sex- and gender-related differences in AD have been widely researched and several emerging lines of evidence point to different vulnerabilities that contribute to dementia risk. Among those being considered, it is becoming widely accepted that gonadal steroids contribute to the gender disparity in AD, as evidenced by the “estrogen hypothesis.” This posits that sex hormones, 17β-estradiol in particular, exert a neuroprotective effect by shielding females’ brains from disease development. This theory is further supported by recent findings that the onset of menopause is associated with the emergence of AD-related brain changes in women in contrast to men of the same age. In this review, we discuss genetic, medical, societal, and lifestyle risk factors known to increase AD risk differently between the genders, with a focus on the role of hormonal changes, particularly declines in 17β-estradiol during the menopause transition (MT) as key underlying mechanisms.

Effect of High-Fat Diets on Oxidative Stress, Cellular Inflammatory Response and Cognitive Function

Cognitive dysfunction is linked to chronic low-grade inflammatory stress that contributes to cell-mediated immunity in creating an oxidative environment. Food is a vitally important energy source; it affects brain function and provides direct energy. Several studies have indicated that high-fat consumption causes overproduction of circulating free fatty acids and systemic inflammation. Immune cells, free fatty acids, and circulating cytokines reach the hypothalamus and initiate local inflammation through processes such as microglial proliferation. Therefore, the role of high-fat diet (HFD) in promoting oxidative stress and neurodegeneration is worthy of further discussion. Of particular interest in this article, we highlight the associations and molecular mechanisms of HFD in the modulation of inflammation and cognitive deficits. Taken together, a better understanding of the role of oxidative stress in cognitive impairment following HFD consumption would provide a useful approach for the prevention of cognitive dysfunction.

Serum elaidic acid concentration and risk of dementia: The Hisayama Study

OBJECTIVE

The associations between trans fatty acids and dementia have been unclear. We investigated the prospective association between serum elaidic acid (trans 18:1 n-9) levels, as an objective biomarker for industrial trans fat, and incident dementia and its subtypes.

METHODS

In total, 1,628 Japanese community residents aged 60 and older without dementia were followed prospectively from when they underwent a screening examination in 2002-2003 to November 2012 (median 10.3 years, interquartile range 7.2-10.4 years). Serum elaidic acid levels were measured using gas chromatography/mass spectrometry and divided into quartiles. The Cox proportional hazards model was used to estimate the hazard ratios for all-cause dementia, Alzheimer disease (AD), and vascular dementia by serum elaidic acid levels.

RESULTS

During the follow-up, 377 participants developed some type of dementia (247 AD, 102 vascular dementia). Higher serum elaidic acid levels were significantly associated with greater risk of developing all-cause dementia (p for trend = 0.003) and AD (p for trend = 0.02) after adjustment for traditional risk factors. These associations remained significant after adjustment for dietary factors, including total energy intake and intakes of saturated and polyunsaturated fatty acids (both p for trend <0.05). No significant associations were found between serum elaidic acid levels and vascular dementia.

CONCLUSIONS

The findings suggest that higher serum elaidic acid is a possible risk factor for the development of all-cause dementia and AD in later life. Public health policy to reduce industrially produced trans fatty acids may assist in the primary prevention of dementia.

Three consecutive weeks of nutritional ketosis has no effect on cognitive function, sleep, and mood compared with a high-carbohydrate, low-fat diet in healthy individuals: a randomized, crossover, controlled trial

BACKGROUND

The high-fat ketogenic diet (KD) has become an increasingly popular diet not only in overweight/obese populations, or those with clinical conditions, but also in healthy non-overweight populations.

OBJECTIVE

Because there are concerns about the association between high-fat diets and cognitive decline, this study aimed to determine the effects of a KD compared with an isocaloric high-carbohydrate, low-fat (HCLF) diet on cognitive function, sleep, and mood in healthy, normal-weight individuals.

METHODS

Eleven healthy, normal-weight participants (mean age: 30 ± 9 y) completed this randomized, controlled, crossover study. Participants followed 2 isocaloric diets-an HCLF diet (55% carbohydrate, 20% fat, and 25% protein) and a KD (15% carbohydrate, 60% fat, and 25% protein)-in a randomized order for a minimum of 3 wk, with a 1-wk washout period between diets. Measures of β-hydroxybutyrate confirmed that all participants were in a state of nutritional ketosis during post-KD assessments (baseline: 0.2 ± 0.2 mmol/L; KD: 1.0 ± 0.5 mmol/L; washout: 0.2 ± 0.1 mmol/L; and HCLF: 0.3 ± 0.2 mmol/L). Cognitive function was assessed using a validated, psychological computer-based test battery before and after each diet. Subjective measures of mood and sleep were also monitored throughout the study using validated scales.

RESULTS

Three weeks of sustained nutritional ketosis, compared with the HCLF diet, had no effect on speed and accuracy responses in tasks designed to measure vigilance (speed: P = 0.39, Cohen's d = 0.26; accuracy: P = 0.99, Cohen's d = 0.04), visual learning and memory (speed: P = 0.99, Cohen's d = 0.04; accuracy: P = 0.99, Cohen's d = 0.03), working memory (speed: P = 0.62, Cohen's d = 0.26; accuracy: P = 0.98, Cohen's d = 0.07), and executive function (speed: P = 0.60, Cohen's d = 0.31; accuracy: P = 0.90, Cohen's d = 0.19). Likewise, mood, sleep quality, and morning vigilance did not differ (P > 0.05) between the dietary interventions.

CONCLUSION

The results of our randomized, crossover, controlled study suggest that 3 wk of sustained nutritional ketosis had no effect on cognitive performance, mood, or subjective sleep quality in a sample of healthy individuals. This trial was registered in the Pan African Clinical Trial Registry as PACTR201707002406306.

Preventing Alzheimer's: Our Most Urgent Health Care Priority

Dementia is the fastest growing epidemic in the developed nations, and if not curtailed, it will single handedly collapse our health care system. The prevalence of dementia is 1 in 10 individuals older than 65 years and increases to 50% of all individuals older than 85 years. The prevalence of Alzheimer's dementia (AD), the most common form of dementia, has been increasing rapidly and is projected to reach 16 million individuals by the year 2050. Several prevailing myths about the science of dementia are discussed, such as that AD is inevitable and that it is exclusively a genetic disease. The fact is that AD is dependent on a multitude of genetic, epigenetic, and environmental factors that interact with one another. In fact, 4 core drivers represent 90% of what determines disease progression in AD. These are (1) glucose or energy dysregulation, (2) lipid dysregulation, (3) inflammation, and (4) oxidation. Lifestyle change can significantly alter the course of AD. The authors have created an acronym-NEURO-to help lifestyle practitioners and the public remember the most important lifestyle elements in the treatment and prevention of AD based on the evidence. "N" is for Nutrition, "E" for Exercise, "U" for Unwind (stress management), "R" for Restorative Sleep, and "O" for Optimizing mental and social activity. The evidence base for each of the components is reviewed.

The impact of nutrient-based dietary patterns on cognitive decline in older adults

BACKGROUND & AIMS

The impact of nutrient patterns on cognitive decline is complex and findings are still inconclusive. We aimed to identify major nutrient patterns and to explore their association with cognitive decline over time among older adults.

METHODS

In a population-based cohort, 2250 cognitively healthy people aged ≥60 years were identified at baseline (2001-2004), and followed-up to 9 years. Global cognitive function was tested with the Mini-Mental State Examination (MMSE) at baseline and follow-ups. Nutrients intake was assessed on the basis of food intake using a 98-semi-quantitative food frequency questionnaire at baseline, and nutrient-based patterns were identified by principal components analysis based on 30 nutrients. Mixed-effects linear regression models were used to determine their association with change in cognitive function taking into account potential confounders.

RESULTS

Four major patterns (the plant-, animal-, dairy-derived nutrients and animal/plants-derived fats) were identified. Over the follow-up time, each one unit increment in plant- (β = 0.081, P = 0.002) and animal-derived nutrients pattern scores (β = 0.098, P < 0.001) was associated with slower decline in MMSE score. On the other hand, one-unit higher in dairy-derived nutrients pattern was related to a faster decline in global cognitive function (β = -0.064, P = 0.014). No significant association between animal/plants fats pattern and cognitive decline was observed. In stratified analyses, the association of high scores of plants- and animal-derived nutrient pattern with slower cognitive decline was stronger in APOE ε4 carriers than in ε4 non-carriers.

CONCLUSIONS

Plant- and animal -derived nutrients are associated with preserved cognitive function, especially among the APOE ε4 carriers, whereas nutrients derived from dairy products may accelerate cognitive decline in older adults.

Unsaturated Fatty Acid Intakes During Midlife Are Positively Associated with Later Cognitive Function in Older Adults with Modulating Effects of Antioxidant Supplementation

Background

Given the drastic demographic changes characterized as "population aging," the disease burden related to dementia is a major public health problem. The scientific literature documenting the link between mono- and polyunsaturated fatty acids (MUFAs, PUFAs) and cognitive function during aging is plentiful, but findings are inconsistent.

Objectives

We aimed to evaluate the association between intakes of unsaturated fatty acids at midlife and cognitive performance 13 y later in French adults, and to test for a modulating effect of antioxidant supplementation.

Methods

Fatty acid intakes were estimated with the use of repeated 24-h records (1994-1996) among 3362 subjects (mean ± SD age: 65.5 ± 4.6 y) of the SU.VI.MAX (Supplementation with Antioxidant Vitamins and Minerals) study, including an intervention phase (1994-2002) during which participants were randomly assigned to an "antioxidant supplementation" or placebo group. Cognitive performance was assessed at follow-up only (in 2007-2009) via a battery of 6 standardized neuropsychological tests. A global cognitive score was calculated as the sum of T-scores of the 6 tests. Multivariable-adjusted regression analyses were performed to provide regression coefficients and 95% CIs.

Results

In multivariable models, total MUFAs, total PUFAs, and n-6 PUFAs (ω-6 PUFAs) were positively associated with overall cognitive functioning. n-3 PUFA (ω-3 PUFA) intakes showed positive associations among supplemented participants only (mean difference Tertile3 versus Tertile1: 1.40; 95% CI: 0.30, 2.51; P-trend = 0.01, P-interaction = 0.01). A detrimental role of arachidonic acid for cognitive functioning was only detected in the placebo group (mean difference Tertile3 versus Tertile1: -1.38; 95% CI: -2.57, -0.18; P-trend = 0.02, P-interaction = 0.07).

Conclusion

Whereas higher total MUFA and n-6 PUFA intakes may be generally beneficial for maintaining cognitive health during aging, a higher consumption of n-3 fatty acids may only be beneficial among individuals with an adequate antioxidant status. These findings underline the importance of not only focusing on specific nutrients for dementia prevention, but also considering the complex interaction between consumed nutrients. This trial was registered at clinicaltrials.gov as NCT00272428.

Dietary patterns derived by factor analysis are associated with cognitive function among a middle-aged and elder Chinese population

The aim of this study was to assess the association of empirically derived dietary patterns with cognitive function among a middle-aged and elder Chinese population. This study comprised 1676 Chinese adults ≥45 years of age, who participated in a Health Survey and completed semi-quantitative food frequency questionnaire (FFQ) and cognitive screening test in the city of Linyi.We performed factor analysis using the principal component analysis method to identify the major dietary patterns. Binary logistic regression models were used to estimate odds ratio(OR) and 95% confidence interval(CI) for cognitive impairment according to quartiles of each dietary pattern score. Three dietary patterns were identified, namely traditional Chinese, Western-style and grains-fruits-vegetable patterns. A total of 362 participants (101 men and 261 women) were classified as cognitive impaired. After controlling for potential confounders, participants in the highest quartile of the Western-style pattern had a greater OR for incident cognitive impairment, compared to participants in the lowest quartile. Compared with the lowest quartile of grains-fruits-vegetable pattern, the highest quartile had a lower OR for incident cognitive impairment. Conclusions: Our findings demonstrate that the Western-style pattern is associated with an elevated risk and the grains-fruits-vegetables pattern is associated with a decreased risk of cognitive impairment.

Rosuvastatin alleviates high-salt and cholesterol diet-induced cognitive impairment in rats via Nrf2-ARE pathway

OBJECTIVE

The objectives of our study were to investigate the possible effect of rosuvastatin in ameliorating high salt and cholesterol diet (HSCD)-induced cognitive impairment and to also investigate its possible action via the Nrf2-ARE pathway.

METHODS

In silico studies were performed to check the theoretical binding of rosuvastatin to the Nrf2 target. HSCD was used to induce cognitive impairment in rats and neurobehavioral studies were performed to evaluate the efficacy of rosuvastatin in enhancing cognition. Biochemical analyses were used to estimate changes in oxidative markers. Western blot and immunohistochemical analyses were done to check Nrf2 translocation. TUNEL and caspase 3 tests were performed to evaluate reversal of apoptosis by rosuvastatin.

RESULTS

Rosuvastatin showed good theoretical affinity to Nrf2, significantly reversed changes in oxidative biomarkers which were induced by HSCD, and also improved the performance of rats in the neurobehavioral test. A rise in nuclear translocation of Nrf2 was revealed through immunohistochemical analysis and western blot. TUNEL staining and caspase 3 activity showed attenuation of apoptosis.

DISCUSSION

We have investigated a novel mechanism of action for rosuvastatin (via the Nrf2-ARE pathway) and demonstrated that it has the potential to be used in the treatment of cognitive impairment.

Omega-3 fatty acids and anxiety: A systematic review of the possible mechanisms at play

Introduction: Anxiety is prevalent, costly, and associated with significant adverse outcomes. The importance of nutrition is underestimated in the management of mental health disorders. In particular, omega-3 fatty acids (ω-3 FAs) are a critical component for healthy development and have been shown to reduce anxiety symptoms. Objective: This paper reviews the current state of the research to identify potential mechanisms underlying the relationship between ω-3 FAs and anxiety reduction. Method: Studies were identified using PubMed, PsycINFO, and CINAHL databases. Results: Of the 197 full-text studies screened, six met criteria for inclusion. Four mechanisms were identified based on primary outcomes reported by each study, Inflammatory Response, Brain-Derived Neurotrophic Factor (BDNF), Cortisol, and Cardiovascular Activity. Conclusion: Five key recommendations are provided to guide future research examining ω-3 FAs and anxiety. They include: (1) standardization of dosage and duration of ω-3 supplementation, (2) more rigorous measurement of variables, (3) effective blinding of participants, (4) designing experiments that test mediation, and (5) increasing sample diversity.

Nutrition and prevention of cognitive impairment

Nutrition is an important lifestyle factor that can modify the risk of future cognitive impairment and dementia. Some, but not conclusive, evidence (mostly from observational studies and infrequently from clinical trials) exists of a protective association between certain nutrients (eg, folate, flavonoids, vitamin D, and certain lipids) or food groups (eg, seafood, vegetables, and fruits, and potentially moderate alcohol and caffeine consumption) and cognitive outcomes in older people. For some nutrients and food groups, protection might be greater in individuals with either deficiencies in certain nutrients or a genetic predisposition to cognitive impairment. Identification of potentially different associations between such subgroups should be a priority for future research. At present, evidence of an association between nutrition and cognitive outcomes is somehow stronger for healthy dietary patterns, such as the Mediterranean-type diet, than for individual nutrients and food groups, possibly because of the cumulative beneficial effects of the many ingredients in these diets. Multidomain interventions (including a nutrition component) might also hold some promise for the prevention of cognitive impairment and dementia, but their effectiveness is still uncertain. Use of advanced technologies for nutrition assessment (eg, metabolomics and innovative methods of dietary intake assessment) and recently identified biomarkers of nutrition and neurobiological outcomes will be important to achieve this goal.

Cognitive impairment in metabolically-obese, normal-weight rats: identification of early biomarkers in peripheral blood mononuclear cells

BACKGROUND

Metabolically-obese, normal-weight (MONW) individuals are not obese in terms of weight and height but have a number of obesity-related features (e.g. greater visceral adiposity, insulin resistance, and increased risk of cardiovascular disease). The MONW phenotype is related to the intake of unbalanced diets, such as those rich in fat. Increasing evidence shows a relationship between high-fat diet consumption and mild cognitive impairment and dementia. Thus, MONW individuals could be at a greater risk of cognitive dysfunction. We aimed to evaluate whether MONW-like animals present gene expression alterations in the hippocampus associated with an increased risk of cognitive impairment, and to identify early biomarkers of cognitive dysfunction in peripheral blood mononuclear cells (PBMC).

METHODS

Wistar rats were chronically fed with a 60% (HF60) or a 45% (HF45) high-fat diet administered isocalorically to control animals to mimic MONW features. Expression analysis of cognitive decline-related genes was performed using RT-qPCR, and working memory was assessed using a T-maze.

RESULTS

High-fat diet consumption altered the pattern of gene expression in the hippocampus, clearly pointing to cognitive decline, which was accompanied by a worse performance in the T-maze in HF60 animals. Remarkably, Syn1 and Sorl1 mRNA showed the same expression pattern in both the hippocampus and the PBMC obtained at different time-points in the HF60 group, even before other pathological signs were observed.

CONCLUSIONS

Our results demonstrate that long-term intake of high-fat diets, even in the absence of obesity, leads to cognitive disruption that is reflected in PBMC transcriptome. Therefore, PBMC are revealed as a plausible, minimally-invasive source of early biomarkers of cognitive impairment associated with increased fat intake.

Interplay Between the Gut-Brain Axis, Obesity and Cognitive Function

Obesity continues to be one of the major public health problems due to its high prevalence and co-morbidities. Common co-morbidities not only include cardiometabolic disorders but also mood and cognitive disorders. Obese subjects often show deficits in memory, learning and executive functions compared to normal weight subjects. Epidemiological studies also indicate that obesity is associated with a higher risk of developing depression and anxiety, and vice versa. These associations between pathologies that presumably have different etiologies suggest shared pathological mechanisms. Gut microbiota is a mediating factor between the environmental pressures (e.g., diet, lifestyle) and host physiology, and its alteration could partly explain the cross-link between those pathologies. Westernized dietary patterns are known to be a major cause of the obesity epidemic, which also promotes a dysbiotic drift in the gut microbiota; this, in turn, seems to contribute to obesity-related complications. Experimental studies in animal models and, to a lesser extent, in humans suggest that the obesity-associated microbiota may contribute to the endocrine, neurochemical and inflammatory alterations underlying obesity and its comorbidities. These include dysregulation of the HPA-axis with overproduction of glucocorticoids, alterations in levels of neuroactive metabolites (e.g., neurotransmitters, short-chain fatty acids) and activation of a pro-inflammatory milieu that can cause neuro-inflammation. This review updates current knowledge about the role and mode of action of the gut microbiota in the cross-link between energy metabolism, mood and cognitive function.