Dietary fat intake and cognitive decline in women with type 2 diabetes

High-fat diet consumption negatively influences closed-head traumatic brain injury in a pediatric rodent model

Traumatic brain injury (TBI) is one of the most common causes of emergency room visits in children, and it is a leading cause of death in juveniles in the United States. Similarly, a high proportion of this population consumes diets that are high in saturated fats, and millions of children are overweight or obese. The goal of the present study was to assess the relationship between diet and TBI on cognitive and cerebrovascular outcomes in juvenile rats. In the current study, groups of juvenile male Long Evans rats were subjected to either mild TBI via the Closed-Head Injury Model of Engineered Rotational Acceleration (CHIMERA) or underwent sham procedures. The animals were provided with either a combination of high-fat diet and a mixture of high-fructose corn syrup (HFD/HFCS) or a standard chow diet (CH) for 9 days prior to injury. Prior to injury, the animals were trained on the Morris water maze for three consecutive days, and they underwent a post-injury trial on the day of the injury. Immediately after TBI, the animals' righting reflexes were tested. Four days post-injury, the animals were euthanized, and brain samples and blood plasma were collected for qRT-PCR, immunohistochemistry, and triglyceride assays. Additional subsets of animals were used to investigate cerebrovascular perfusion using Laser Speckle and perform immunohistochemistry for endothelial cell marker RECA. Following TBI, the righting reflex was significantly increased in TBI rats, irrespective of diet. The TBI worsened the rats' performance in the post-injury trial of the water maze at 3 h, p(injury) < 0.05, but not at 4 days post-injury. Reduced cerebrovascular blood flow using Laser Speckle was demonstrated in the cerebellum, p(injury) < 0.05, but not foci of the cerebral cortices or superior sagittal sinus. Immunoreactive staining for RECA in the cortex and corpus callosum was significantly reduced in HFD/HFCS TBI rats, p < 0.05. qRT-PCR showed significant increases in APOE, CREB1, FCGR2B, IL1B, and IL6, particularly in the hippocampus. The results from this study offer robust evidence that HFD/HFCS negatively influences TBI outcomes with respect to cognition and cerebrovascular perfusion of relevant brain regions in the juvenile rat.

Multi-nutrient interventions and cognitive ageing: are we barking up the right tree?

As we continue to elucidate the mechanisms underlying age-related brain diseases, the reductionist strategy in nutrition–brain function research has focused on establishing the impact of individual foods. However, the biological processes connecting diet and cognition are complex. Therefore, consideration of a combination of nutritional compounds may be most efficacious. One barrier to establishing the efficacy of multi-nutrient interventions is that the area lacks an established set of evidence-based guidelines for studying their effect on brain health. This review is an output of the International Life Sciences Institute (ILSI) Europe. A multi-disciplinary expert group was assembled with the aim of developing a set of considerations to guide research into the effects of multi-nutrient combinations on brain functions. Consensus recommendations converged on six key issues that should be considered to advance research in this area: (1) establish working mechanisms of the combination and contributions of each individual compound; (2) validate the relevance of the mechanisms for the targeted human condition; (3) include current nutrient status, intake or dietary pattern as inclusion/exclusion criteria in the study design; (4) select a participant population that is clinically and biologically appropriate for all nutritional components of the combination; (5) consider a range of cognitive outcomes; (6) consider the limits of reductionism and the ‘gold standard’ randomised controlled trial. These guiding principles will enhance our understanding of the interactive/complementary activities of dietary components, thereby strengthening the evidence base for recommendations aimed at delaying cognitive decline.

The Dietary Carbohydrate/Fat-Ratio and Cognitive Performance: Panel Analyses in Older Adults at Risk for Dementia

Background

Roughly 80% of total energy intake (TEI) in most human diets originates from digestible carbohydrates (eCarb) and fat (eFat), but the impact of their proportions on cognitive performance is poorly understood.

Objectives

Our primary aim was to investigate estimates of global cognition in relation to macronutrient intake, with the log-ratio eCarb/eFat (CFr) as the primary predictor variable of interest. Secondary predictors were protein and the saturated/total fat ratio. Exploratory comparisons of CFr with eCarb and eFat as separate predictors were an additional aim.

Methods

The observations were made on panel data (years 0, 1, 2) from the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, n = 1251; age 60-77 y; 47% females; selected by risk factors for dementia. Self-reported diet was assessed by 3-d food records. Global cognition was measured using a modified Neuropsychological Test Battery. A mixed linear regression model was used, adjusted for age, sex, education, body-mass index, cholesterol-lowering drugs, TEI, time, time × intervention/control group, with study site and subject as random factors. Estimates were standardized (mean = 0; SD = 1) with 95% CI.

Results

CFr had a negative estimate to global cognition (β = -0.022, CI: -0.039, -0.005; P = 0.011). The point estimate for protein was β = 0.013 (P = 0.41), and for the saturated/total fat ratio, associations with cognition were nonlinear. CFr correlated highly with eCarb (Pearson's r = 0.92) and eFat (r = -0.94). The point estimate for CFr fell between eCarb (β = -0.026, P < 0.001) and (inversely) eFat (β = 0.017, P = 0.090).

Conclusions

A lower CFr was associated with better global cognition among older adults at risk for dementia. Because this is an important target group for preventive interventions, clinical trials are warranted to further investigate the impact of macronutritional composition on cognitive health. The potential role of CFr as a predictor for cognitive health should be further studied.

Nutrient intake in low-carbohydrate diets in comparison to the 2020-2025 Dietary Guidelines for Americans: a cross-sectional study

The percentage of US adults following low-carbohydrate diets (LCD) doubled in the last decade. Some researchers observed this trend with concern and highlighted the potential for nutritional deficiencies and impaired overall diet quality with LCD. The present study investigated nutrient intake in a nationally representative sample of 307 US adults following an LCD. Using cross-sectional data from the National Health and Nutrition Examination Surveys, we compared nutrient intake profiles in said individuals with the daily nutritional goals specified in the current 2020-2025 Dietary Guidelines for Americans (DGA). Results were then compared with the general population consuming a standard American diet. Almost 57 % of low-carbohydrate dieters were female, and the mean age was 48·67 (1·35) years. Individuals consuming LCD exceeded the recommendations for saturated fat, total lipid and sodium intake (both sexes). An insufficient intake was observed for fibre, Mg, potassium and several other vitamins (vitamins A, E, D in both sexes as well as vitamin C in men and folate in women). Neither men nor women met the recommendations for fibre intake. A comparable picture was found for the general population. The potentially insufficient intake of several essential nutrients in LCD warrants consideration and a careful assessment with regard to the current DGA.

Type 2 diabetes mellitus-associated cognitive dysfunction: Advances in potential mechanisms and therapies

Type 2 diabetes (T2D) and its target organ injuries cause distressing impacts on personal health and put an enormous burden on the healthcare system, and increasing attention has been paid to T2D-associated cognitive dysfunction (TDACD). TDACD is characterized by cognitive dysfunction, delayed executive ability, and impeded information-processing speed. Brain imaging data suggest that extensive brain regions are affected in patients with T2D. Based on current findings, a wide spectrum of non-specific neurodegenerative mechanisms that partially overlap with the mechanisms of neurodegenerative diseases is hypothesized to be associated with TDACD. However, it remains unclear whether TDACD is a consequence of T2D or a complication that co-occurs with T2D. Theoretically, anti-diabetes methods are promising neuromodulatory approaches to reduce brain injury in patients with T2D. In this review, we summarize potential mechanisms underlying TDACD and promising neurotropic effects of anti-diabetes methods and some neuroprotective natural compounds. Constructing screening or diagnostic tools and developing targeted treatment and preventive strategies would be expected to reduce the burden of TDACD.

Sex Differences in Cognition Across Aging

Sex and gender differences are seen in cognitive disturbances in a variety of neurological and psychiatry diseases. Men are more likely to have cognitive symptoms in schizophrenia whereas women are more likely to have more severe cognitive symptoms with major depressive disorder and Alzheimer's disease. Thus, it is important to understand sex and gender differences in underlying cognitive abilities with and without disease. Sex differences are noted in performance across various cognitive domains - with males typically outperforming females in spatial tasks and females typically outperforming males in verbal tasks. Furthermore, there are striking sex differences in brain networks that are activated during cognitive tasks and in learning strategies. Although rarely studied, there are also sex differences in the trajectory of cognitive aging. It is important to pay attention to these sex differences as they inform researchers of potential differences in resilience to age-related cognitive decline and underlying mechanisms for both healthy and pathological cognitive aging, depending on sex. We review literature on the progressive neurodegenerative disorder, Alzheimer's disease, as an example of pathological cognitive aging in which human females show greater lifetime risk, neuropathology, and cognitive impairment, compared to human males. Not surprisingly, the relationships between sex and cognition, cognitive aging, and Alzheimer's disease are nuanced and multifaceted. As such, this chapter will end with a discussion of lifestyle factors, like education and diet, as modifiable factors that can alter cognitive aging by sex. Understanding how cognition changes across age and contributing factors, like sex differences, will be essential to improving care for older adults.

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.

Threshold Effects of Total Copper Intake on Cognitive Function in US Older Adults and the Moderating Effect of Fat and Saturated Fatty Acid Intake

BACKGROUND

Evidence for a relationship between total copper intake and cognition is lacking, and few studies have assessed the moderating effect of dietary fat and saturated fatty acid (SFA) intake on this relationship.

OBJECTIVE

Our aim was to explore the curvilinear association between total copper intake and cognitive function in older adults, and to clarify the moderating effect of dietary fat and SFA intake on the association.

DESIGN

This was a cross-sectional analysis of data from National Health and Nutrition Examination Surveys 2011-2014.

PARTICIPANTS

The analysis included 2,483 participants aged 60 years and older.

MAIN OUTCOME MEASURES

Cognitive function was evaluated by the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) Word Learning subtest, the Animal Fluency Test, and the Digit Symbol Substitution Test (DSST).

STATISTICAL ANALYSES PERFORMED

Smooth curve fitting and two-piecewise linear regression models were performed to address the nonlinear association between total copper intake and cognitive function. Multivariable quadratic regression models and analyses stratified by total fat or SFA intake were used to assess the effects of the interaction between copper and fat intake and between copper and SFA intake on cognitive function.

RESULTS

There was a nonlinear association between total copper intake and cognitive test scores. The inflection point of copper was 0.8 mg/d for the Consortium to Establish a Registry for Alzheimer's Disease Word Learning subtest and 1.4 mg/d for both the Animal Fluency test and the DSST. When copper intake was below the inflection point, positive associations were apparent for copper intake and Consortium to Establish a Registry for Alzheimer's Disease Word Learning subtest scores (β = 3.9; 95% CI 1.2 to 6.5), Animal Fluency test scores (β = 1.7, 95% CI .9 to 2.6), and DSST scores (β = 6.0, 95% CI 3.8 to 8.3). When copper intake was above the inflection point, a nonsignificant downward trend was found. Interactive effects between total copper and total fat intake (P interaction = .000) and between total copper and SFA intake (P interaction = .011) on the DSST scores were observed. In the low fat intake and low SFA intake groups, DSST scores first increased and then decreased with increasing copper. However, in the high fat intake and high SFA intake groups, DSST scores first increased and then flattened with increasing copper.

CONCLUSIONS

The present study suggests a nonlinear association between copper intake and cognitive function and identifies threshold effects of copper intake on cognitive function. Copper intake below the inflection point was positively and independently associated with cognitive function. High fat and high SFA intake may protect older adults against a decline in DSST scores related to high copper intake.

Dietary intake is associated with neuropsychological impairment in women with HIV

BACKGROUND

Diet is a modifiable risk factor that may influence cognition in people with HIV.

OBJECTIVES

We examined the association between dietary intake and cognition in women with HIV (WWH) and HIV-seronegative women.

METHODS

An 18-item dietary National Cancer Institute screener was completed by 729 WWH and 346 HIV-seronegative Women's Interagency HIV Study participants. Daily intake frequencies of processed meats, sweet beverages, fish, whole milk, and vegetables were calculated. Participants completed biennial neuropsychological (NP) testing. NP domains included attention/working memory, executive function, processing speed, memory, learning, fluency, and motor function. NP impairment was defined as demographically adjusted T-scores (mean = 50; SD = 10) ≤40 at ≥1 visit after completing the dietary screener. Multivariable logistic regression, stratified by HIV serostatus, examined associations between intake frequency tertile (referent = lowest intake) and NP performance.

RESULTS

Dietary intake frequencies of individual food line items were similar between WWH and HIV-seronegative women, except for sweet beverages, for which HIV-seronegative women reported higher intake frequencies than WWH (P values < 0.05). In WWH, multivariable-adjusted models indicated higher odds of NP impairment with higher intake frequencies of processed meat [P = 0.006; ORupper tertile = 1.91 (95% CI: 1.23-2.95; P = 0.003); ORmiddle tertile = 1.66 (95% CI: 1.14-2.42; P = 0.01)], sweet beverages [P = 0.02; ORupper tertile = 1.75 (95% CI: 1.17-2.64; P = 0.007)], fish [P = 0.01; ORupper tertile = 1.70 (95% CI: 1.10-2.64; P = 0.02)], and whole milk [P = 0.029; ORupper tertile = 1.66 (95% CI: 1.14-2.42; P = 0.008)]. Lower odds of NP impairment [P = 0.005; ORupper tertile = 0.65 (95% CI: 0.45-0.95; P = 0.02); ORmiddle tertile = 0.42 (95% CI: 0.24-0.73; P = 0.002)] were associated with higher vegetable intakes. In HIV-seronegative women, multivariable-adjusted models did not show associations between food line items/diet quality score and NP outcomes.

CONCLUSIONS

Intakes of processed meat, sweet beverages, whole milk, fish, and vegetables may be associated with NP functions among WWH. Associations among WWH are not directly comparable to those among HIV-seronegative women, because models were conducted on each group separately given controls for HIV-specific covariates in WWH. Further studies are needed using more rigorous dietary assessment methods and lengthier longitudinal follow-ups.

Ginger and turmeric lipid-solubles attenuate heated oil-induced oxidative stress in the brain via the upregulation of NRF2 and improve cognitive function in rats

In this study, we elucidated the modulatory potentials of lipid-solubles from ginger and turmeric that may migrate to oils during heating on the brain antioxidant defense and cognitive response in rats. Male Wistar rats were fed with control diet [including native canola oil (N-CNO), and native sunflower oil (N-SFO)], or experimental diets [including heated canola oil (H-CNO), heated sunflower oil (H-SFO), heated canola oil with ginger (H-CNO + GI), heated canola oil with turmeric (H-CNO + TU), heated sunflower oil with ginger (H-SFO + GI), heated sunflower oil with turmeric (H-SFO + TU)] for 90 days. Memory parameters [Morris water maze, elevated plus maze, novel object recognition test, T-maze (spontaneous alteration)], locomotor skills (open field test and rotarod test), antioxidant defense enzymes, reactive oxygen species, NOS2, ICAM-1, and NRF-2 level in the brain were assessed. Compared to their respective controls, heated oil-fed rats, but not those fed oils heated with ginger or turmeric, showed significant (p < 0.05) reduction in the memory, motor coordination skills, antioxidant defense enzymes, and NRF-2 activation in the brain. Compared to their respective controls, the brain NOS-2 and ICAM-1 were significantly (p < 0.05) increased in heated oil-fed rats, but not those fed oils heated with ginger or turmeric. Chronic intake of repeatedly heated oil causes brain dysfunction by inducing oxidative stress through NRF-2 downregulation. Lipid-solubles from ginger and turmeric that may migrate to oil during heating prevent the oxidative stress and cognitive dysfunction triggered by heated oils in rats.

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 Management in Older Adults with Diabetes: A Review on the Importance of Shifting Prevention Strategies from Metabolic Syndrome to Frailty

The increasing prevalence of older adults with diabetes has become a major social burden. Diabetes, frailty, and cognitive dysfunction are closely related to the mechanisms of aging. Insulin resistance, arteriosclerosis, chronic inflammation, oxidative stress, and mitochondrial dysfunction may be common mechanisms shared by frailty and cognitive impairment. Hyperglycemia, hypoglycemia, obesity, vascular factors, physical inactivity, and malnutrition are important risk factors for cognitive impairment and frailty in older adults with diabetes. The impact of nutrients on health outcomes varies with age; thus, shifting diet therapy strategies from the treatment of obesity/metabolic syndrome to frailty prevention may be necessary in patients with diabetes who are over 75 years of age, have frailty or sarcopenia, and experience malnutrition. For the prevention of frailty, optimal energy intake, sufficient protein and vitamin intake, and healthy dietary patterns should be recommended. The treatment of diabetes after middle age should include the awareness of proper glycemic control aimed at extending healthy life expectancy with proper nutrition, exercise, and social connectivity. Nutritional therapy in combination with exercise, optimal glycemic and metabolic control, and social participation/support for frailty prevention can extend healthy life expectancy and maintain quality of life in older adults with diabetes mellitus.

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.

Diabetic Cognitive Dysfunction: From Bench to Clinic

Type 2 diabetes increases the risk of developing cognitive dysfunction in the elderly in the form of short-term memory and executive function impairment. Genetic and diet-induced models of type 2 diabetes further support this link, displaying deficits in working memory, learning, and memory performance. The risk factors for diabetic cognitive dysfunction include vascular disease, hypoglycaemia, hyperlipidaemia, adiposity, insulin resistance, lifestyle factors, and genetic factors. Using neuronal imaging technologies, diabetic patients with cognitive dysfunction show atrophy of the whole brain, particularly the grey matter, hippocampus and amygdala; increased volume of the ventricular and white matter; brain infarcts; impaired network integrity; abnormal microstructure; and reduced cerebral blood flow and amplitude of low-frequency fluctuations. The pathogenesis of type 2 diabetes with cognitive dysfunction involves hyperglycaemia, macrovascular and microvascular diseases, insulin resistance, inflammation, apoptosis, and disorders of neurotransmitters. Large clinical trials may offer further proof of biomarkers and risk factors for diabetic cognitive dysfunction. Advanced neuronal imaging technologies and novel disease animal models will assist in elucidating the precise pathogenesis and to provide better therapeutic interventions and treatment.

Sex differences in cardio-metabolic and cognitive parameters in rats with high-fat diet-induced metabolic dysfunction

IMPACT STATEMENT

Excessive dietary fat intake plays important roles in the process of metabolic dysfunction and increases susceptibilities to chronic diseases such as hypertension. Few previous studies, however, have accurately reflected real-world medical conditions. In addition, studies performed to date have not examined detailed sex-differences in cardio-metabolic and cognitive parameters, precluding the development of sex-tailored interventions for patients with metabolic dysfunction who are susceptible to hypertension and cognitive impairment. In this study, using rats with HFD-induced metabolic dysfunction that made them susceptible to hypertension and cognitive impairment, we demonstrate that male rats show greater impairment of acetylcholine-induced vasorelaxation of the carotid artery and systolic blood pressure compared to female rats. These findings may provide a basis for the early detection of carotid artery dysfunction and systolic blood pressure increase, especially in males.

Chronic high fat feeding paradoxically attenuates cerebral capillary dysfunction and neurovascular inflammation in Senescence-Accelerated-Murine-Prone Strain 8 mice

Background: A body of epidemiological, clinical and preclinical studies suggest increased risk for cerebro- and cardio-vascular disease associated with dietary ingestion of long-chain saturated fatty acids (LCSFA). In wild-type rodent models, chronic ingestion of LCSFA diets are associated with increased cerebral capillary permeability, heightened neurovascular inflammation and poorer cognitive performance. However, recent studies suggest that diets enriched in fat may paradoxically attenuate elements of the ageing phenotype via a caloric support axis.Objective: The purpose of this study was to explore the effects of dietary LCSFA on cerebral capillary integrity and neurovascular inflammation in an established model of accelerated ageing, Senescence-Accelerated-Murine-Prone Strain 8 (SAMP8) mice.Methods: From 6 weeks of age, SAMP8 mice and age-matched controls were randomised to either normal chow, or to an LCSFA-enriched diet, for either 12 or 34 weeks. An additional group of SAMP8 mice were provided the LCSFA-enriched diet for 12 weeks followed by the provision of ordinary low-fat chow for 22 weeks. Ex vivo measures of cerebrovascular integrity, neurovascular inflammation and astrocytic activation, were determined via 3-dimensional immunofluorescent confocal microscopy methodologies.Results: LCSFA-fed SAMP8 mice had markedly attenuated cerebral capillary dysfunction concomitant with reduced microglial activation. In SAMP8 mice transiently maintained on an LCSFA diet for 12 weeks, suppression of neurovascular inflammation persisted. Marked hippocampal astrogliosis was evident in LCSFA-fed mice when compared to SAMP8 mice maintained on ordinary chow.Conclusion: The findings from this study support the notion that high-fat, potentially ketogenic diets, may confer neuroprotection in SAMP8 mice through a vascular-support axis.

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.

Mild cognitive impairment and progression to dementia in people with diabetes, prediabetes and metabolic syndrome: a systematic review and meta-analysis

PURPOSE

We aimed to quantify the relative risk of progression from mild cognitive impairment (MCI) to dementia in people with and without diabetes, and with and without the MetS (MetS); and to identify potential modifiers of the risk of progression from MCI to dementia in people with diabetes or MetS.

METHODS

We searched Medline, Embase, PsycINFO, PsycArticles and Web of Science from inception through to 20th March 2018. Where possible, the results from three or more studies were pooled in a meta-analysis, while other findings have been described narratively.

RESULTS

We included 15 articles reporting 12 studies (6865 participants). The overall unadjusted pooled odds ratio for the progression of MCI to dementia in people with diabetes/MetS was 1.67 (95% CI 1.27-2.19); the pooled odds ratio for progression in diabetes + MCI was 1.53 (95% CI 1.20-1.97) and in people with MetS + MCI was 2.95 (95% CI 1.23-7.05). There was moderate heterogeneity in the included studies (I² < 60%). In diabetes, a longer duration of diabetes and the presence of retinopathy were associated with an increased risk of progression, while the use of statins and oral hypoglycaemic agents reduced the risk. Having multiple cardiovascular risk factors was a significant risk factor for progression from MCI to dementia in people with MetS.

CONCLUSIONS

Diabetes and MetS were both associated with an increased incidence of dementia when co-existing with MCI. Intensive cardiovascular risk reduction and lifestyle changes for patients presenting with MCI and diabetes, prediabetes or MetS may be important in reducing incidence of dementia in this high risk population.

Ginsenoside Rb1 improves leptin sensitivity in the prefrontal cortex in obese mice

AIM

Obesity impairs leptin-induced regulation of brain-derived neurotrophic factor (BDNF) expression and synaptogenesis, which has been considered to be associated with the incidence of neuronal degenerative diseases, cognitive decline, and depression. Ginsenoside Rb1 (Rb1), a major bioactive component of ginseng, is known to have an antiobesity effect and improve cognition. This study examined whether Rb1 can improve central leptin effects on BDNF expression and synaptogenesis in the prefrontal cortex during obesity using an in vivo and an in vitro model.

RESULT

Ginsenoside Rb1 (Rb1) chronic treatment improved central leptin sensitivity, leptin-JAK2-STAT3 signaling, and leptin-induced regulation of BDNF expression in the prefrontal cortex of high-fat diet-induced obese mice. In cultured prefrontal cortical neurons, palmitic acid, the saturated fat, impaired leptin-induced BDNF expression, reduced the immunoreactivity and mRNA expression of synaptic proteins, and impaired leptin-induced neurite outgrowth and synaptogenesis. Importantly, Rb1 significantly prevented these pernicious effects induced by palmitic acid.

CONCLUSION

These results indicate that Rb1 reverses central leptin resistance and improves leptin-BDNF-neurite outgrowth and synaptogenesis in the prefrontal cortical neurons. Thus, Rb1 supplementation may be a beneficial avenue to treat obesity-associated neurodegenerative disorders.

APP Function and Lipids: A Bidirectional Link

Extracellular neuritic plaques, composed of aggregated amyloid-β (Aβ) peptides, are one of the major histopathological hallmarks of Alzheimer's disease (AD), a progressive, irreversible neurodegenerative disorder and the most common cause of dementia in the elderly. One of the most prominent risk factor for sporadic AD, carrying one or two aberrant copies of the apolipoprotein E (ApoE) ε4 alleles, closely links AD to lipids. Further, several lipid classes and fatty acids have been reported to be changed in the brain of AD-affected individuals. Interestingly, the observed lipid changes in the brain seem not only to be a consequence of the disease but also modulate Aβ generation. In line with these observations, protective lipids being able to decrease Aβ generation and also potential negative lipids in respect to AD were identified. Mechanistically, Aβ peptides are generated by sequential proteolytic processing of the amyloid precursor protein (APP) by β- and γ-secretase. The α-secretase appears to compete with β-secretase for the initial cleavage of APP, preventing Aβ production. All APP-cleaving secretases as well as APP are transmembrane proteins, further illustrating the impact of lipids on Aβ generation. Beside the pathological impact of Aβ, accumulating evidence suggests that Aβ and the APP intracellular domain (AICD) play an important role in regulating lipid homeostasis, either by direct effects or by affecting gene expression or protein stability of enzymes involved in the de novo synthesis of different lipid classes. This review summarizes the current literature addressing the complex bidirectional link between lipids and AD and APP processing including lipid alterations found in AD post mortem brains, lipids that alter APP processing and the physiological functions of Aβ and AICD in the regulation of several lipid metabolism pathways.

Nutrition and Cognition in Older Adults With Heart Failure: A Systematic Review

Cognitive impairment is commonly observed in older adults with heart failure; nutrition is a possible contributing factor. The purpose of the current systematic review is to examine the relationship between nutrition and cognition in older adults with heart failure. A literature review was performed through August 2015 that examined published, peer-reviewed studies from PubMed, PsycINFO, CINAHL, and Web of Science. Four articles were selected for inclusion. Findings revealed that poorer nutritional habits were associated with poorer attention, executive functioning, and memory in older adults with heart failure. Nutritional biomarkers, including anemia, hyponatremia, hypokalemia, hyperglycemia, and hypoalbuminemia, were also associated with cognitive impairment. More research is needed to explore the relationship between nutrition and cognition in this population. Descriptive studies will inform scientists as they design and test nutritional interventions to optimize cognitive function in older adults with heart failure.

Diet and Inflammation in Alzheimer's Disease and Related Chronic Diseases: A Review

Inflammation is one of the pathological features of the neurodegenerative disease, Alzheimer's disease (AD). A number of additional disorders are likewise associated with a state of chronic inflammation, including obesity, cardiovascular disease, and type-2 diabetes, which are themselves risk factors for AD. Dietary components have been shown to modify the inflammatory process at several steps of the inflammatory pathway. This review aims to evaluate the published literature on the effect of consumption of pro- or anti-inflammatory dietary constituents on the severity of both AD pathology and related chronic diseases, concentrating on the dietary constituents of flavonoids, spices, and fats. Diet-based anti-inflammatory components could lead to the development of potent novel anti-inflammatory compounds for a range of diseases. However, further work is required to fully characterize the therapeutic potential of such compounds, including gaining an understanding of dose-dependent relationships and limiting factors to effectiveness. Nutritional interventions utilizing anti-inflammatory foods may prove to be a valuable asset in not only delaying or preventing the development of age-related neurodegenerative diseases such as AD, but also treating pre-existing conditions including type-2 diabetes, cardiovascular disease, and obesity.

Cognitive disorders in diabetic patients

This chapter gives an overview of the literature on cognitive dysfunction in adults with type 1 or type 2 diabetes. First, methods to evaluate cognitive functioning and the pattern and severity of cognitive dysfunction in relation to diabetes will be discussed. The reader will note that diabetes is associated with worse cognitive functioning and an increased dementia risk. Next, diabetes-associated abnormalities on brain MRI, including reductions in brain volume - i.e., cerebral atrophy - and vascular lesions, will be addressed. At the group level there are clear relations between these imaging abnormalities and cognitive dysfunction, but at the level of the individual patient these relations are often less clear. Subsequently, risk factors for cognitive performance will be discussed. Evidently, these risk factors are related to diabetes type and the age of the patients involved. For type 1 diabetes, an early age at diabetes onset is the most consistent risk factor, whereas in type 2 diabetes, vascular risk factors and vascular comorbidities are consistent indicators of increased risk. The final section of the chapter addresses possible preventive and treatment measures and implications for daily care.

Association of Long-Term Dietary Fat Intake, Exercise, and Weight with Later Cognitive Function in the Finnish Diabetes Prevention Study

OBJECTIVES

To investigate associations of long-term nutrient intake, physical activity and obesity with later cognitive function among the participants in the Finnish Diabetes Prevention Study, in which a lifestyle intervention was successful in diabetes prevention.

DESIGN

An active lifestyle intervention phase during middle age (mean duration 4 years) and extended follow-up (additional 9 years) with annual lifestyle measurements, followed by an ancillary cognition assessment.

SETTING

5 research centers in Finland.

PARTICIPANTS

Of the 522 middle-aged, overweight participants with impaired glucose tolerance recruited to the study, 364 (70%) participated in the cognition assessment (mean age 68 years).

MEASUREMENTS

A cognitive assessment was executed with the CERAD test battery and the Trail Making Test A on average 13 years after baseline. Lifestyle measurements included annual clinical measurements, food records, and exercise questionnaires during both the intervention and follow-up phase.

RESULTS

Lower intake of total fat (p=0.021) and saturated fatty acids (p=0.010), and frequent physical activity (p=0.040) during the whole study period were associated with better cognitive performance. Higher BMI (p=0.012) and waist circumference (p=0.012) were also associated with worse performance, but weight reduction prior to the cognition assessment predicted worse performance as well (decrease vs. increase, p=0.008 for BMI and p=0.002 for waist).

CONCLUSIONS

Long-term dietary fat intake, BMI, and waist circumference have an inverse association with cognitive function in later life among people with IGT. However, decreases in BMI and waist prior to cognitive assessment are associated with worse cognitive performance, which could be explained by reverse causality.

Exercise reduces diet-induced cognitive decline and increases hippocampal brain-derived neurotrophic factor in CA3 neurons

BACKGROUND

Previous studies have shown that a western diet impairs, whereas physical exercise enhances hippocampus-dependent learning and memory. Both diet and exercise influence expression of hippocampal brain-derived neurotrophic factor (BDNF), which is associated with improved cognition. We hypothesized that exercise reverses diet-induced cognitive decline while increasing hippocampal BDNF.

METHODS

To test the effects of exercise on hippocampal-dependent memory, we compared cognitive scores of Sprague-Dawley rats exercised by voluntary running wheel (RW) access or forced treadmill (TM) to sedentary (Sed) animals. Memory was tested by two-way active avoidance test (TWAA), in which animals are exposed to a brief shock in a specific chamber area. When an animal avoids, escapes or has reduced latency to do either, this is considered a measure of memory. In a second experiment, rats were fed either a high-fat diet or control diet for 16 weeks, then randomly assigned to running wheel access or sedentary condition, and TWAA memory was tested once a week for 7 weeks of exercise intervention.

RESULTS

Both groups of exercised animals had improved memory as indicated by reduced latency to avoid and escape shock, and increased avoid and escape episodes (p<0.05). Exposure to a high-fat diet resulted in poor performance during both the acquisition and retrieval phases of the memory test as compared to controls. Exercise reversed high-fat diet-induced memory impairment, and increased brain-derived neurotrophic factor (BDNF) in neurons of the hippocampal CA3 region.

CONCLUSIONS

These data suggest that exercise improves memory retrieval, particularly with respect to avoiding aversive stimuli, and may be beneficial in protecting against diet induced cognitive decline, likely via elevated BDNF in neurons of the CA3 region.

Dietary fat composition and dementia risk

This is a qualitative review of the evidence linking dietary fat composition to the risk of developing dementia. The review considers laboratory and animal studies that identify underlying mechanisms as well as prospective epidemiologic studies linking biochemical or dietary fatty acids to cognitive decline or incident dementia. Several lines of evidence provide support for the hypothesis that high saturated or trans fatty acids increase the risk of dementia and high polyunsaturated or monounsaturated fatty acids decrease risk. Dietary fat composition is an important factor in blood-brain barrier function and the blood cholesterol profile. Cholesterol and blood-brain barrier function are involved in the neuropathology of Alzheimer's disease, and the primary genetic risk factor for Alzheimer's disease, apolipoprotein E-ε4, is involved in cholesterol transport. The epidemiologic literature is seemingly inconsistent on this topic, but many studies are difficult to interpret because of analytical techniques that ignored negative confounding by other fatty acids, which likely resulted in null findings. The studies that appropriately adjust for confounding by other fats support the dietary fat composition hypothesis.

Dietary and lifestyle guidelines for the prevention of Alzheimer's disease

Risk of developing Alzheimer's disease is increased by older age, genetic factors, and several medical risk factors. Studies have also suggested that dietary and lifestyle factors may influence risk, raising the possibility that preventive strategies may be effective. This body of research is incomplete. However, because the most scientifically supported lifestyle factors for Alzheimer's disease are known factors for cardiovascular diseases and diabetes, it is reasonable to provide preliminary guidance to help individuals who wish to reduce their risk. At the International Conference on Nutrition and the Brain, Washington, DC, July 19-20, 2013, speakers were asked to comment on possible guidelines for Alzheimer's disease prevention, with an aim of developing a set of practical, albeit preliminary, steps to be recommended to members of the public. From this discussion, 7 guidelines emerged related to healthful diet and exercise habits.

Dementia and cognitive decline in type 2 diabetes and prediabetic stages: towards targeted interventions

Type 2 diabetes is associated with dementia, and also with more slight cognitive decrements. In this Review we discuss trajectories from normal cognition to dementia in people with type 2 diabetes, and explore opportunities for treatment. Slight diabetes-associated cognitive decrements and dementia affect different age groups and show a different evolution. These cognitive entities should therefore not be regarded as a continuum, although their effects might be additive. Vascular damage is a key underlying process in both entities. Glucose-mediated processes and other metabolic disturbances might also have a role. No treatment has been established, but management of vascular risk factors and optimisation of glycaemic control could have therapeutic benefit. We identify possible opportunities for intervention to improve cognitive outcomes in people with type 2 diabetes, and suggest how treatment can be tailored to individual risk profiles and comorbidities.

Microglial cell activation increases saturated and decreases monounsaturated fatty acid content, but both lipid species are proinflammatory

Neuroinflammation is a component of age-related neurodegenerative diseases and cognitive decline. Saturated (SFA) and monounsaturated (MUFA) fatty acids are bioactive molecules that may play different extrinsic and intrinsic roles in neuroinflammation, serving as exogenous ligands for cellular receptors, or endogenous components of cell structural, energetic and signaling pathways. We determined the fatty acyl profile of BV2 microglial cells before and after acute activation with lipopolysaccharide (LPS). We also investigated the effect of SFA and MUFA pretreatment on the production of an invasive, neurotoxic phenotype in BV2 cells. Acute activation of BV2 microglia resulted in an increase in the relative content of SFA (12:0, 16:0, 18:0, 20:0, 22:0, and 24:0 increased significantly), and a relative decrease in the content of MUFA (16:1n7, 18:1n7, 18:1n9, 20:1n9, 24:1n9 decreased significantly). In agreement, the major stearoyl-CoA desaturase (SCD) isoform in BV2 cells, SCD2, was significantly down-regulated by LPS. We next treated cells with SFA (16:0 or 18:0) or MUFA (16:1n7 or 18:1n9), and found that levels of secreted IL6 were increased, as was secreted MMP9-mediated proteolytic activity. To test the functional significance, we treated SH-SY5Y neuronal cells with conditioned medium from BV2 cells pretreated with fatty acids, and found a small but significant induction of cell death. Our findings suggest differential intrinsic roles for SFA and MUFA in activated microglial cells, but similar extrinsic roles for these fatty acid species in inducing activation. Expansion of SFA is important during microglial cell activation, but either supplemental SFA or MUFA may contribute to chronic low-grade neuroinflammation.

Habitual fat intake predicts memory function in younger women

High intakes of fat have been linked to greater cognitive decline in old age, but such associations may already occur in younger adults. We tested memory and learning in 38 women (25 to 45 years old), recruited for a larger observational study in women with polycystic ovary syndrome. These women varied in health status, though not significantly between cases (n = 23) and controls (n = 15). Performance on tests sensitive to medial temporal lobe function (CANTABeclipse, Cambridge Cognition Ltd, Cambridge, UK), i.e., verbal memory, visuo-spatial learning, and delayed pattern matching (DMS), were compared with intakes of macronutrients from 7-day diet diaries and physiological indices of metabolic syndrome. Partial correlations were adjusted for age, activity, and verbal IQ (National Adult Reading Test). Greater intakes of saturated and trans fats, and higher saturated to unsaturated fat ratio (Sat:UFA), were associated with more errors on the visuo-spatial task and with poorer word recall and recognition. Unexpectedly, higher UFA intake predicted poorer performance on the word recall and recognition measures. Fasting insulin was positively correlated with poorer word recognition only, whereas higher blood total cholesterol was associated only with visuo-spatial learning errors. None of these variables predicted performance on a DMS test. The significant nutrient–cognition relationships were tested for mediation by total energy intake: saturated and trans fat intakes, and Sat:UFA, remained significant predictors specifically of visuo-spatial learning errors, whereas total fat and UFA intakes now predicted only poorer word recall. Examination of associations separately for monounsaturated (MUFA) and polyunsaturated fats suggested that only MUFA intake was predictive of poorer word recall. Saturated and trans fats, and fasting insulin, may already be associated with cognitive deficits in younger women. The findings need extending but may have important implications for public health.

Diet assessment in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil): Development of a food frequency questionnaire

OBJECTIVE: The objective of this article is to present the development of the Food Frequency Questionaire used in the Longitudinal Study of Adult Health-Brazil and analyze how diet exposes individuals to cardiovascular diseases and type 2 diabetes Mellitus. METHODS: The Longitudinal Study of Adult Health-Brazil dietary assessment instrument is based on a previously validated Food Frequency Questionaire and the final list of items took into consideration a study done in the six Longitudinal Study of Adult Health-Brazil investigation centers. RESULTS: New foods/preparations were included in the Food Frequency Questionaire with their respective portions, totaling 114 items. The perspectives of dietary analysis and cardiovascular diseases and diabetes are presented in Longitudinal Study of Adult Health-Brazil. CONCLUSION: A new instrument was developed to cover the regional particularities of the study population.

The association of antioxidants and cognition in the Nurses' Health Study

The authors examined long-term antioxidant intake in relation to cognitive decline among older women. Beginning in 1980, Nurses' Health Study (NHS) participants completed dietary assessments every 4 years; in 1995-2001, 16,010 participants aged ≥70 years completed initial cognitive assessments, which were repeated 3 times at 2-year intervals. Long-term antioxidant intake was averaged from 1980 through the time of initial cognitive interviews. Multivariable-adjusted linear regression was used to estimate mean differences in rates of cognitive decline across categories of vitamin E, vitamin C, and carotenoid intake; statistical tests were 2-sided. No associations were evident for vitamin E or total carotenoid intake and cognitive decline (e.g., after multivariable adjustment, P-trend = 0.44 and P-trend = 0.51, respectively, for a global composite score averaging all 6 cognitive tests), although higher lycopene intake and lower vitamin C intake were related to slower cognitive decline. In alternative analyses of overall cognitive status at older ages (averaging all 4 cognitive assessments), results for vitamins E and C were generally null, but higher carotenoid intake was related to better cognition. Overall, long-term vitamin E and C intakes were not consistently related to cognition, although greater consumption of carotenoids may have cognitive benefits in older adults.

Dietary habits moderate the association between heart failure and cognitive impairment

Cognitive impairment is common in heart failure patients. Poor dietary habits are associated with reduced neurocognitive function in other medical populations, including diabetes and Alzheimer's disease. This study examined whether dietary habits help moderate the relationship between heart failure severity and cognitive function. A total of 152 persons with heart failure completed neuropsychological testing and a fitness assessment. Dietary habits were assessed using the Starting the Conversation-Diet questionnaire, a nutrition measure suggested for use in primary care settings. Moderation analyses showed that better dietary habits attenuated the adverse impact of heart failure severity on frontal functioning (b = 1.28, p < 0.05). Follow-up analyses revealed consumption of foods high in sodium was associated with reduced cognitive function (p < 0.05). This study suggests dietary habits can moderate the association between heart failure and performance on tests of attention and executive function. Longitudinal studies are needed to confirm and clarify the mechanisms for our findings.

Mediterranean diet and cognitive decline in women with cardiovascular disease or risk factors

BACKGROUND

Cardiovascular disease and vascular risk factors increase rates of cognitive impairment, but very little is known regarding prevention in this high-risk group. The heart-healthy Mediterranean-type dietary pattern may beneficially influence both vascular and cognitive outcomes.

OBJECTIVES

We examined the association between Mediterranean-style diet and cognitive decline in women with prevalent vascular disease or ≥3 coronary risk factors.

DESIGN/PARTICIPANTS/SETTING

Prospective cohort study among 2,504 women participants in the Women's Antioxidant Cardiovascular Study (WACS), a cohort of female health professionals. Adherence to a Mediterranean-style diet was determined at WACS baseline (1995-1996) using a 0- to 9-point scale with higher scores indicating higher adherence. In 1998-2000, participants aged ≥65 years underwent a telephone cognitive battery including five tests of global cognition, verbal memory, and category fluency. Tests were administered three additional times across 5.4 years.

STATISTICAL ANALYSES PERFORMED

We used multivariable-adjusted generalized linear models for repeated measures to compare the annual rates of cognitive score changes across tertiles of Mediterranean diet score, as assessed at WACS baseline.

RESULTS

In both basic- and multivariable-adjusted models, consuming a Mediterranean-style diet was not related to cognitive decline. No effect modification was detected by age, education, depression, cardiovascular disease severity at WACS baseline, or level of cognition at initial assessment.

CONCLUSIONS

In women at higher risk of cognitive decline due to vascular disease or risk factors, adherence to a Mediterranean-style diet was not associated with subsequent 5-year cognitive change.

Cognitive enhancement by omega-3 fatty acids from child-hood to old age: findings from animal and clinical studies

Omega-(n)-3 polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are major components of neuronal membranes and have a wide range of functions, from modulating synaptic plasticity and neurochemistry, to neuroimmune-modulation and neuroprotection. Thus, it is not surprising that n-3 PUFA are widely acknowledged to have cognitive-enhancing effects. Although clinical evidence is somewhat conflicting, probably in large part due to methodological issues, animal studies have consistently demonstrated that n-3 PUFA are indispensable for proper brain development, may enhance cognitive function in healthy, adult individuals and attenuate cognitive impairment in aging and age-related disorders, such as dementia. This review discusses and integrates up to date evidence from clinical and animal studies investigating the cognitive-enhancing effects of n-3 PUFA during development, child- and adult-hood, as well as old-age with associated neurodegenerative diseases, such as Alzheimer's disease. Furthermore, we cover the major underlying biochemical and neurophysiological mechanisms by which n-3 PUFA mediate these effects on cognition. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

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

OBJECTIVE

A study was undertaken to relate dietary fat types to cognitive change in healthy community-based elders.

METHODS

Among 6,183 older participants in the Women's Health Study, we related intake of major fatty acids (saturated [SFA], monounsaturated [MUFA], total polyunsaturated [PUFA], trans-unsaturated) to late-life cognitive trajectory. Serial cognitive testing, conducted over 4 years, began 5 years after dietary assessment. Primary outcomes were global cognition (averaging tests of general cognition, verbal memory, and semantic fluency) and verbal memory (averaging tests of recall). We used analyses of response profiles and logistic regression to estimate multivariate-adjusted differences in cognitive trajectory and risk of worst cognitive change (worst 10%) by fat intake.

RESULTS

Higher SFA intake was associated with worse global cognitive (p for linear trend = 0.008) and verbal memory (p for linear trend = 0.01) trajectories. There was a higher risk of worst cognitive change, comparing highest versus lowest SFA quintiles; the multivariate-adjusted odds ratio (OR) with 95% confidence interval (CI) was 1.64 (1.04-2.58) for global cognition and 1.65 (1.04-2.61) for verbal memory. By contrast, higher MUFA intake was related to better global cognitive (p for linear trend < 0.001) and verbal memory (p for linear trend = 0.009) trajectories, and lower OR (95% CI) of worst cognitive change in global cognition (0.52 [0.31-0.88]) and verbal memory (0.56 [0.34-0.94]). Total fat, PUFA, and trans-fat intakes were not associated with cognitive trajectory.

INTERPRETATION

Higher SFA intake was associated with worse global cognitive and verbal memory trajectories, whereas higher MUFA intake was related to better trajectories. Thus, different consumption levels of the major specific fat types, rather than total fat intake itself, appeared to influence cognitive aging.

Trans fatty acids enhance amyloidogenic processing of the Alzheimer amyloid precursor protein (APP)

Hydrogenation of oils and diary products of ruminant animals leads to an increasing amount of trans fatty acids in the human diet. Trans fatty acids are incorporated in several lipids and accumulate in the membrane of cells. Here we systematically investigate whether the regulated intramembrane proteolysis of the amyloid precursor protein (APP) is affected by trans fatty acids compared to the cis conformation. Our experiments clearly show that trans fatty acids compared to cis fatty acids increase amyloidogenic and decrease nonamyloidogenic processing of APP, resulting in an increased production of amyloid beta (Aβ) peptides, main components of senile plaques, which are a characteristic neuropathological hallmark for Alzheimer's disease (AD). Moreover, our results show that oligomerization and aggregation of Aβ are increased by trans fatty acids. The mechanisms identified by this in vitro study suggest that the intake of trans fatty acids potentially increases the AD risk or causes an earlier onset of the disease.

The 2-minute step test is independently associated with cognitive function in older adults with heart failure

BACKGROUND AND AIMS

Cognitive impairment is common in persons with heart failure (HF), and measures like the 6-minute walk test (6MWT) are known to correspond to level of impairment. The 2- minute step test (2MST) has been suggested as a more practical alternative to the 6MWT, though no study has examined whether it is associated with cognitive impairment in persons with HF. This study examined whether the 2MST is associated with cognitive function in older adults with HF.

METHODS

Older adults with HF (n=145; 68.97±9.31 yrs) completed the 2MST and a neuropsychological test battery that assessed function in multiple cognitive domains.

RESULTS

Consistent with past work, HF patients exhibited high rates of cognitive impairment. Hierarchical regression analyses adjusting for demographic and medical characteristics found that the 2MST accounted for unique variance in global cognitive function (ΔR²=0.09, p<0.001), executive function (ΔR²=0.03, p<0.05), and language (ΔR²=0.10, p<0.001). A trend emerged for attention (ΔR²=0.02, p=0.09). Follow-up tests indicated that better 2MST performance was significantly correlated with better global cognitive function, attention, executive, and language test performance.

CONCLUSION

The current results indicate that the 2MST is associated with cognitive function in older adults with HF. Further work is needed to clarify underlying mechanisms for this association and the value of implementing the 2MST during routine visits.

Short-term effects of liraglutide on visceral fat adiposity, appetite, and food preference: a pilot study of obese Japanese patients with type 2 diabetes

Background

To examine the effects of liraglutide, a glucagon-like peptide-1 (GLP-1) analogue, on visceral fat adiposity, appetite, food preference, and biomarkers of cardiovascular system in Japanese patients with type 2 diabetes.

Methods

The study subjects were 20 inpatients with type 2 diabetes treated with liraglutide [age; 61.2 ± 14.0 years, duration of diabetes; 16.9 ± 6.6 years, glycated hemoglobin (HbA1c); 9.1 ± 1.2%, body mass index (BMI); 28.3 ± 5.2 kg/m², mean ± SD]. After improvement in glycemic control by insulin or oral glucose-lowering agents, patients were switched to liraglutide. We assessed the estimated visceral fat area (eVFA) by abdominal bioelectrical impedance analysis, glycemic control by the 75-g oral glucose tolerance test (OGTT) and eating behavior by the Japan Society for the Study of Obesity questionnaire.

Results

Treatment with liraglutide (dose range: 0.3 to 0.9 mg/day) for 20.0 ± 6.4 days significantly reduced waist circumference, waist/hip ratio, eVFA. It also significantly improved the scores of eating behavior, food preference and the urge for fat intake and tended to reduce scores for sense of hunger. Liraglutide increased serum C-peptide immunoreactivity and disposition index.

Conclusions

Short-term treatment with liraglutide improved visceral fat adiposity, appetite, food preference and the urge for fat intake in obese Japanese patients with type 2 diabetes.

Nutritional determinants of cognitive aging and dementia

The objective of this review is to provide an overview of nutritional factors involved in cognitive aging and dementia with a focus on nutrients that are also important in neurocognitive development. Several dietary components were targeted, including antioxidant nutrients, dietary fats and B-vitamins. A critical review of the literature on each nutrient group is presented, beginning with laboratory and animal studies of the underlying biological mechanisms, followed by prospective epidemiological studies and randomised clinical trials. The evidence to date is fairly strong for protective associations of vitamin E from food sources, the n-3 fatty acid, DHA, found in fish, a high ratio of polyunsaturated to saturated fats, and vitamin B12 and folate. Attention to the level of nutrient intake is crucial for interpreting the literature and the inconsistencies across studies. Most of the epidemiological studies that observe associations have sufficient numbers of individuals who have both low and adequate nutrient status. Few of the randomised clinical trials are designed to target participants who have low baseline status before randomising to vitamin supplement treatments, and this may have resulted in negative findings. Post-hoc analyses by some of the trials reveal vitamin effects in individuals with low baseline intakes. The field of diet and dementia is a relatively young area of study. Much further work needs to be done to understand dietary determinants of cognitive aging and diseases. Further, these studies must be particularly focused on the levels of nutrient intake or status that confer optimum or suboptimal brain functioning.

Changes in emerging cardiac biomarkers after an intensive lifestyle intervention

The present study evaluated the changes in emerging cardiac biomarkers, cognitive function, and social support measures after a comprehensive lifestyle intervention that included a low-fat, whole-foods, plant-based diet, exercise, stress management, and group support meetings. We conducted a prospective cohort study of 131 participants (59.2% women and 43.1% with diabetes mellitus), 56 with coronary heart disease (CHD) (37.5% women and 27.3% diabetes mellitus), and 75 at high risk with ≥3 CHD risk factors and/or diabetes mellitus (76% women and 54.7% diabetes mellitus). The measurements were taken at baseline and 3 months after the intervention. Improvement in all targeted health behaviors was seen in both high-risk and CHD groups (all p <0.001) at 3 months, with reductions in body mass index, systolic and diastolic blood pressure, waist/hip ratio, C-reactive protein, insulin, low-density lipoprotein, high-density and total cholesterol, apolipoproteins A1 and B (all p <0.009) were observed. Nuclear magnetic resonance spectroscopy analysis of lipoprotein subclass particle concentrations and diameters showed a reduction in large very-low-density lipoprotein particles, size of the very-low-density lipoprotein particles, total low-density lipoprotein particles; total, large, and small high-density lipoprotein particles (all p <0.009) and small very-low-density lipoprotein particles (p <0.02). Increases in fibrinogen (p <0.03) and B-type natriuretic peptide (p <0.001) were seen, and these changes correlated inversely with the changes in the body mass index. The observed increase in B-type natriuretic peptide can be explained by the metabolic changes related to adipose tissue lipolysis. The quality of life, cognitive functioning, and social support measures significantly improved. In conclusion, lifestyle changes can be followed by favorable changes in traditional and emerging coronary heart disease biomarkers, quality of life, social support, and cognitive function among those with, or at high risk, of CHD.

Monounsaturated, trans, and saturated Fatty acids and cognitive decline in women

OBJECTIVES

To prospectively assess effects of select dietary fats on cognitive decline.

DESIGN

Prospective observational; 3-year follow-up.

SETTING

Northwestern University.

PARTICIPANTS

Four hundred eighty-two women aged 60 and older who participated in the Women's Health Initiative (WHI) Observational Study or in the control group of the WHI Diet Modification arm.

MEASUREMENTS

Dietary intake from a validated food frequency questionnaire (FFQ) administered twice (mean 2.7 years apart) before baseline cognitive assessment (mean 2.9 years after second FFQ) was averaged. Testing of memory, vision, executive function, language, and attention was performed twice, 3 years apart. A global Z-score was created for both time points by averaging all Z-scores for each participant, and global cognitive change was defined as the difference between follow-up and baseline Z-scores.

RESULTS

Median intake of saturated fat (SFA), trans-fat, (TFA), dietary cholesterol (DC), and monounsaturated fat (MUFA) was 18.53, 3.45, 0.201, and 19.39 g/d, respectively. There were no associations between degree of cognitive decline and intake of SFA (P=.69), TFA (P=.54), or DC (P=.64) after adjusting for baseline cognition, total energy intake, age, education, reading ability, apolipoprotein E ɛ4 allele, body mass index, estrogen and beta-blocker use, and intake of caffeine and other fatty acids. In contrast, MUFA intake was associated with lower cognitive decline in fully adjusted linear regression models, with mean decline (standard error) of 0.21 (0.05) in the lowest and 0.05 (0.05) in the highest quartiles (P=.02). This effect of MUFA intake was primarily in the visual and memory domains (P=.03 for both).

CONCLUSION

Greater intake of SFA, TFA, and DC was not associated with cognitive decline, whereas greater MUFA intake was associated with less cognitive decline.

Polyunsaturated fatty acids and reduced odds of MCI: the Mayo Clinic Study of Aging

Mono- and polyunsaturated fatty acids (MUFA, PUFA) have been associated with a reduced risk of dementia. The association of these fatty acids with mild cognitive impairment (MCI) is not fully established. The objective of the study was to investigate the cross-sectional association of dietary fatty acids with MCI in a population-based sample. Participants aged >or= 70 years on October 1, 2004, were evaluated using the Clinical Dementia Rating Scale (participant and informant), a neurological evaluation, and neuropsychological testing. A panel of nurses, physicians, and neuropsychologists reviewed the data for each participant in order to establish a diagnosis of MCI, normal cognition, or dementia by consensus. Participants also completed a 128-item food-frequency questionnaire. Among 1,233 non-demented subjects, 163 (13.2%) had MCI. The odds ratio (OR) of MCI decreased with increasing PUFA and MUFA intake. Compared to the lowest tertile, the OR (95% confidence interval) for the upper tertiles were 0.44 (0.29-0.66; p for trend = 0.0004) for total PUFA; 0.44 (0.30-0.67; p for trend = 0.0004) for omega-6 fatty acids; 0.62 (0.42-0.91; p for trend = 0.012) for omega-3 fatty acids; and 0.56 (0.38-0.83; p for trend = 0.01) for (MUFA+PUFA):saturated fatty acid ratio after adjustment for age, sex, number of years of education, and caloric intake. In this study, higher intake of PUFA and MUFA was associated with a reduced likelihood of MCI among elderly persons in the population-based setting.

Dietary fat intake in relation to cognitive change in high-risk women with cardiovascular disease or vascular factors

BACKGROUND/OBJECTIVES

Dietary fat intake may influence the rate of cognitive change among those at high risk due to vascular disease or risk factors.

SUBJECTS/METHODS

Women's Antioxidant Cardiovascular Study began in 1995-1996 as a randomized trial of antioxidants and B vitamin supplementation for secondary prevention in women with cardiovascular disease or ≥3 coronary risk factors. From 1998-1999, eligible participants aged ≥65 years were administered a telephone cognitive battery including five tests of general cognition, memory and category fluency (n=2551). Tests were administered four times over 5.4 years. The primary outcome was a global composite score averaging z-scores of all tests. Multivariable generalized linear models for repeated measures were used to evaluate the difference in cognitive decline rates across tertiles of total fat and various types of fat.

RESULTS

Total fat intake or different types of fat were not related to cognitive decline. However, older age significantly modified the association: among the oldest participants, higher intakes of mono- and polyunsaturated fat were inversely related to cognitive decline (P-interaction: 0.06 and 0.04, respectively), and the rate differences between the highest and lowest tertiles were cognitively equivalent to the rate differences observed with being 4-6 years younger.

CONCLUSIONS

In women at high risk of cognitive decline due to vascular disease or risk factors, dietary fat intake was not associated with 5-year cognitive change. However, a possible protective relation of unsaturated fats with cognitive decline in the oldest women warrants further study.

Insulin resistance, diabetes and cognitive function: consequences for preventative strategies

Cognitive decline and dementia both place a heavy burden on patients and their relatives, and any means of preventing such age-related changes are worthy of consideration. Those who have the metabolic syndrome with or without diabetes suffer more often from dysexecutive problems and slower psychomotor speed than do other patients. In epidemiological studies, diabetes has appeared to be a risk factor for all types of dementia, including vascular dementia, although the role of the metabolic syndrome in the risk of Alzheimer's disease is still a matter of debate. The possible mechanisms of cognitive alterations are multiple, and may differ according to age group and duration of diabetes or the metabolic syndrome. Drug interventional trials addressing the prevention of cognitive decline through action on the metabolic syndrome are disappointing-albeit scarce at this time. Lifestyle interventions in middle-aged or younger-elderly subjects should also be implemented in the general population.

More than the sum of its parts? Nutrition in Alzheimer's disease

The aim of this article is to emphasize the importance of malnutrition and micronutrient deficiencies in Alzheimer's disease and discuss recent supplementation trials. Alzheimer's disease (AD) is a devastating neurodegenerative disease with increasing socio-economic impact. It leads to cognitive decline over the years, finally resulting in brain atrophy and gradually destroying a person's ability to learn, reason, make judgments, and communicate. Most of the cases are sporadic and risk factors evolve. There is evidence that malnutrition, oxidative stress, and homocysteine-related vitamins play a role in the pathogenesis of AD. A plethora of epidemiologic studies have explored the associations between nutrients and AD. In addition, more and more data from recent trials are evolving to analyze the impact of micronutrient supplementation in AD and incipient AD concerning B vitamin status and antioxidants. Available data do not support definitive conclusions regarding specific recommendations on micronutrient supplementation for the prevention or treatment of AD; however, more data from prospective trials are needed. Approaches with multiple nutritional components might be promising.