'Metabolic syndrome' in the brain: deficiency in omega-3 fatty acid exacerbates dysfunctions in insulin receptor signalling and cognition

Development and validation of dietary depression index in Chinese adults

OBJECTIVE

Previous studies have suggested diet was associated with depressive symptoms. We aimed to develop and validate Dietary Depression Index (DDI) based on dietary prediction of depression in a large Chinese cancer screening cohort.

METHODS

In the training set (n = 2729), we developed DDI by using intake of 20 food groups derived from a food frequency questionnaire to predict depression as assessed by Patient Health Questionnaire-9 based on the reduced rank regression method. Sensitivity, specificity, positive predictive value, and negative predictive value were used to assess the performance of DDI in evaluating depression in the validation dataset (n = 1176).

RESULTS

Receiver operating characteristic analysis was constructed to determine the best cut-off value of DDI in predicting depression. In the study population, the DDI ranged from -3.126 to 1.810. The discriminative ability of DDI in predicting depression was good with the AUC of 0.799 overall, 0.794 in males and 0.808 in females. The best cut-off values of DDI for depression prediction were 0.204 overall, 0.330 in males and 0.034 in females. DDI was a validated method to assess the effects of diet on depression.

CONCLUSION

Among individual food components in DDI, fermented vegetables, fresh vegetables, whole grains and onions were inversely associated, whereas legumes, pickled vegetables and rice were positively associated with depressive symptoms.

Dietary EPA and DHA enrichment of a high fat diet during doxorubicin-based chemotherapy attenuated neuroinflammatory gene expression in the brain of C57bl/6 ovariectomized mice

Chemotherapy agents in breast cancer are associated with chemotherapy-related cognitive impairments (CRCI). Mechanisms are not fully clear, but alterations of glucose and lipid metabolism, neuroinflammation and neurodegeneration may contribute to CRCI. The aim of this study was to investigate the combined effects of a high fat (HF) diet combined with doxorubicin-based chemotherapy on glucose and lipid metabolism, neuroinflammation, and neurodegeneration in mice. Additionally, we examined the therapeutic potential of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to attenuate these effects. Female C57Bl/6 mice (n = 42) were fed HF, HFn-3 (2 % kcals as EPA + DHA) or Low Fat (LF) diets for seven weeks, with and without chemotherapy. In this study, two chemotherapy injections led to weight and body fat loss associated with a decrease in insulin resistance measured by HOMA-IR. HOMA-IR was significantly greater in HF versus LF groups; but HOMA-IR in HFn-3 group did not significantly differ from either HF or LF groups. Chemotherapy resulted in higher brain concentrations of the inflammatory chemokine KC/GRO. Compared to LF diet plus chemotherapy, HF diet plus chemotherapy upregulated multiple genes involved in neuroinflammation and neurodegeneration pathways. HFn-3 diet plus chemotherapy attenuated gene expression by downregulating multiple genes involved in neuroinflammation and blood brain barrier regulation, including Mapkapk2, Aqp4, and s100b, and upregulating Kcnb1 and Atxn3, genes involved in reduction of oxidative stress and anxiety, respectively. Overall, a HF diet combined with chemotherapy is associated with neuroinflammatory and neurodegenerative gene expression changes in this mouse model; dietary enrichment of EPA and DHA attenuated these effects. Further studies are needed to understand how diet impacts behavioral outcomes of CRCI.

Dietary menhaden fish oil supplementation suppresses lipopolysaccharide-induced neuroinflammation and cognitive impairment in diabetic rats

CONTEXT

Menhaden fish oil (FO) is widely recognized for inhibiting neuroinflammatory responses and preserving brain function. Nevertheless, the mechanisms of FO influencing brain cognitive function in diabetic states remain unclear.

OBJECTIVE

This study examines the potential role of FO in suppressing LPS-induced neuroinflammation and cognitive impairment in diabetic animals (DA).

MATERIALS AND METHODS

Thirty male Wistar rats were divided into 5 groups: i) DA received LPS induction (DA-LPS); ii) DA received LPS induction and 1 g/kg FO (DA-LPS-1FO); iii) DA received LPS induction and 3 g/kg FO (DA-LPS-3FO); iv) animals received normal saline and 3 g/kg FO (NS-3FO) and v) control animals received normal saline (CTRL). Y-maze test was used to measure cognitive performance, while brain samples were collected for inflammatory markers and morphological analysis.

RESULTS

DA received LPS induction, and 1 or 3 g/kg FO significantly inhibited hyperglycaemia and brain inflammation, as evidenced by lowered levels of pro-inflammatory mediators. Additionally, both DA-LPS-1FO and DA-LPS-3FO groups exhibited a notable reduction in neuronal damage and glial cell migration compared to the other groups. These results were correlated with the increasing number of entries and time spent in the novel arm of the Y-maze test.

DISCUSSION AND CONCLUSION

This study indicates that supplementation of menhaden FO inhibits the LPS signaling pathway and protects against neuroinflammation, consequently maintaining cognitive performance in diabetic animals. Thus, the current study suggested that fish oil may be effective as a supporting therapy option for diabetes to avoid diabetes-cognitive impairment.

Low sucrose diets protect long-term memory and EPA & DHA enriched diets alter insulin resistance in a mouse model of chemotherapy

Chemotherapy-related cognitive impairment (CRCI) and affective symptoms negatively impact quality of life in breast cancer survivors. The aim of this study was to determine the efficacy of high eicosapentaenoic acid + docosahexaenoic acid (EPA+DHA) and low sucrose diets to alleviate these symptoms in a mouse model of chemotherapy. Potential mechanisms involving insulin resistance were explored. We hypothesized that diets enriched in EPA+DHA and low amounts of sucrose would protect against the impact of chemotherapy on measures of CRCI. Female C57Bl/6 mice were randomized to 1 of 4 diets (2% kcal eicosapentaenoic acid + docosahexaenoic acid [EPA+DHA]/high or low sucrose, low omega-3/high or low sucrose) for 6 weeks and treated with two injections of doxorubicin-based chemotherapy or vehicle during week 2 and 4. Behavioral tests were performed 7 days after second injection. Chemotherapy increased serum insulin and decreased body weight, locomotion and exploratory behavior (all p < .05). Low sucrose consumption resulted in better long-term memory regardless of chemotherapy or vehicle injection (p < .05). 2% EPA+DHA consumption lessened insulin resistance (p < .05); however, controlling for body weight attenuated this effect (p = .08). There were no significant differences by diet or injection on liver lipid content; however, liver lipid content was positively correlated with insulin resistance scores (p < .05). Low sucrose diets may protect long-term memory during chemotherapy. The effect of EPA+DHA on insulin resistance and affective side effects during chemotherapy requires further investigation.

Short-term dietary changes are reflected in the cerebral content of adult ring-billed gulls

Omega-3 long-chain polyunsaturated fatty acids (n3-LCPUFAs) are produced primarily in aquatic ecosystems and are considered essential nutrients for predators given their structural role in vertebrates' cerebral tissues. Alarmingly, with urbanization, many aquatic animals now rely on anthropogenic foods lacking n3-LCPUFAs. In this study undertaken in Newfoundland (Canada), we tested whether recent or longer term diet explains the cerebral fatty acid composition of ring-billed gulls (Larus delawarensis), a seabird that now thrives in cities. During the breeding season, cerebral levels of n3-LCPUFAs were significantly higher for gulls nesting in a natural habitat and foraging on marine food (mean ± s.d.: 32 ± 1% of total identified fatty acids) than for urban nesters exploiting rubbish (27 ± 1%). Stable isotope analysis of blood and feathers showed that urban and natural nesters shared similar diets in autumn and winter, suggesting that the difference in cerebral n3-LCPUFAs during the breeding season was owing to concomitant and transient differences in diet. We also experimentally manipulated gulls' diets throughout incubation by supplementing them with fish oil rich in n3-LCPUFAs, a caloric control lacking n3-LCPUFAs, or nothing, and found evidence that fish oil increased urban nesters' cerebral n3-LCPUFAs. These complementary analyses provide evidence that the brain of this seabird remains plastic during adulthood and responds to short-term dietary changes.

Mechanisms Underlying Memory Impairment Induced by Fructose

Fructose consumption has increased over the years, especially in adolescents living in urban areas. Growing evidence indicates that daily fructose consumption leads to some pathological conditions, including memory impairment. This review summarizes relevant data describing cognitive deficits after fructose intake and analyzes the underlying neurobiological mechanisms. Preclinical experiments show sex-related deficits in spatial memory; that is, while males exhibit significant imbalances in spatial processing, females seem unaffected by dietary supplementation with fructose. Recognition memory has also been evaluated; however, only female rodents show a significant decline in the novel object recognition test performance. According to mechanistic evidence, fructose intake induces neuroinflammation, mitochondrial dysfunction, and oxidative stress in the short term. Subsequently, these mechanisms can trigger other long-term effects, such as inhibition of neurogenesis, downregulation of trophic factors and receptors, weakening of synaptic plasticity, and long-term potentiation decay. Integrating all these neurobiological mechanisms will help us understand the cellular and molecular processes that trigger the memory impairment induced by fructose.

Butyrate reduction and HDAC4 increase underlie maternal high fructose-induced metabolic dysfunction in hippocampal astrocytes in female rats

Maternal nutrient intake influences the health of the offspring via microenvironmental systems in digestion and absorption. Maternal high fructose diet (HFD) impairs hippocampus-dependent memory in adult female rat offspring. However, the underlying mechanisms remain largely unclear. Maternal HFD causes microbiota dysbiosis. In this study, we find that the plasma level of butyrate, a major metabolite of microbiota, is significantly decreased in the adult female maternal HFD offspring. In these rats, GPR43, a butyrate receptor was downregulated in the hippocampus. Moreover, the expressions of mitochondrial transcription factor A (TFAM), and peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) were downregulated in the hippocampus. The decreases of these functional proteins were reversed by fructooligosaccharides (FOS, a probiotic) treatment in adulthood. Astrocytes are critical for energy metabolism in the brain. Primary astrocyte culture from female maternal HFD offspring indicated that GPR43 and the mitochondrial biogenesis were significantly suppressed, which was reversed by supplemental butyrate incubation. The oxygen consumption rate (OCR) was reduced in the HFD group and rescued by butyrate. Intriguingly, the nuclear histone deacetylase 4 (HDAC4) was enhanced in the HFD group, suggesting an inhibitory role of butyrate on histone deacetylase activity. Inhibition of HDAC4 effectively restored the OCR, bioenergetics, and biogenesis of mitochondria. Together, these results suggested that the impaired butyrate signaling by maternal HFD could underlie the reduced mitochondrial functions in the hippocampus via HDAC4-mediated epigenetic changes.

Fish oil supplementation and risk of dementia among diabetic patients: a prospective study of 16,061 older patients

BACKGROUND

Although n-3 Polyunsaturated fatty acids (PUFAs) may benefit cognitive performance, the association of n-3 PUFA intake with dementia risk under dysglycemia has not been examined. We aimed to evaluate the relationship between fish oil supplement use or fish consumption and dementia risk among older patients with diabetes.

METHOD

A total of 16,061 diabetic patients aged over 60 years were followed up in the UK Biobank. Fish oil supplements use (yes or no) was collected by the touch screen questionnaire. The diagnosis of dementia was ascertained by the UK Biobank Outcome Adjudication Group. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) were estimated using Cox proportional hazards models.

RESULTS

A total of 337 cases of dementia were confirmed after a mean duration of 7.7 years (123,486 person-years) of follow-up. Habitual use of fish oil supplements showed a 24% lower dementia risk among older diabetic patients [HRs (95% CIs): 0.76 (0.60-0.98) (P = 0.031)] compared with non-users. Such inverse association was not modified by the APOE ε4 genotype. However, the consumption of both oily fish (≥2 times/week) and non-oily fish (≥2 times/week) had no significant association with dementia risk (p-trend = 0.271 and p-trend = 0.065) compared with non-consumers.

CONCLUSION

In summary, fish oil supplementation may play a protective role in cognitive function across all APOE genotypes, while non-oily fish and oily fish consumption have no protective association among older diabetic patients.

Effects of the ApoE genotype on cognitive function in aging mice fed with a high-fat diet and the protective potential of n-3 polyunsaturated fatty acids

The ApoE4 allele is the strongest genetic determinant for Alzheimer's disease (AD), while obesity is a strong environmental risk for AD. The modulatory effect of the ApoE genotype on aging-related cognitive function in tandem with a high-fat diet (HFD) remains uncertain. This study aimed to elucidate the effects of ApoE3/ApoE4 genotypes in aged mice exposed to a HFD, and the benefits of n-3 polyunsaturated fatty acids (PUFAs) from fish oil. Remarkably, the HFD led to weight gain and lipid accumulation, more pronounced in ApoE3 mice, while ApoE4 mice experienced exacerbated cerebral insulin resistance, neuroinflammation, and oxidative stress. Critically, n-3 PUFAs modulated the cerebral insulin signaling via the IRS-1/AKT/GLUT4 pathway, mitigated microglial hyperactivity, and reduced IL-6 and MDA levels, thereby counteracting cognitive deficits. These findings highlight the contrasting impacts of ApoE genotypes on aging mice exposed to a HFD, supporting n-3 PUFAs as a strategic nutritional intervention for brain health, especially for ApoE4 carriers.

Association between serum omega-3 PUFAs levels and cognitive impairment in never medically treated first-episode patients with geriatric depression: A cross-sectional study

BACKGROUND

Geriatric depression increases the public health burden and health care costs, reduces quality of life. Studies have shown the association between ω-3 PUFAs levels and inflammatory markers levels and depression, but few have explored the relationship between omega-3 PUFAs, inflammatory markers, and cognitive function in geriatric depression. This study aimed to compare the differences in ω-3 PUFAs levels and inflammatory markers between geriatric depression with cognitive impairment (CI) and those without CI.

METHODS

A total of three hundred and five elderly patients were recruited. In addition to collecting basic information, their blood specimens were collected to detect serum EPA, DHA, AA, TC, LDL-C, IL-6, TNF-α, and hs-CRP levels. The Hamilton depression scale (HAMD), Hamilton anxiety scale (HAMA), and The Montreal cognitive assessment (MoCA) were used to assess their depression, anxiety, and cognitive function, respectively.

RESULTS

Compared to those without CI, geriatric depression patients with CI had higher serum TC, LDL-C levels, lower EPA, DHA, and AA levels, and more elevated IL-6, TNF-α, and hs-CRP levels (all P < 0.05). Further linear regression analysis showed that EPA, DHA, and TNF-α, hs-CRP levels were significantly associated with the occurrence and the severity of CI.

LIMITATIONS

No causal relationship could be drawn due to the cross-sectional design.

CONCLUSIONS

Omega-3 PUFAs and inflammatory factors levels may predict CI in elderly patients with MDD in the future. Our findings suggest that ω-3 PUFAs (EPA and DHA) and inflammatory factors (TNF-α and CRP) may predict the occurrence and the severity of CI among elderly MDD patients.

Long-chain polyunsaturated fatty acids and brain functions - literature review

Long-chain ω-3 PUFAs such as DHA and EPA are often present in high amounts in algae and fish. DHA in particular is crucial for the proper development and functioning of the brain because it is the main structural component of ω-3 PUFA in the brain. This makes it an indispensable element of the phospholipids of the nervous membrane. The purpose of this article is to present the benefits of Omega-3 acids in the functioning of the nervous system. The text discusses a literature review focusing on the impact of omega-3 fatty acids. Polyunsaturated fatty acids (PUFAs) are essential for overall health and have been extensively studied for their contributions to human well-being and disease management. Recent research indicates their effectiveness in preventing and treating various diseases. Omega-3 PUFAs have been identified as therapeutic agents, particularly in combating inflammatory conditions like cardiovascular and neurodegenerative diseases. The aim of this article is to present the benefits of omega-3 fatty acids supplementation. Publications outlining properties of polyunsaturated fatty acids on the brain and articles presenting the effects of polyunsaturated fatty acids were reviewed using the Pubmed platform. The review included the keywords "Omega-3 fatty acids" "DHA" "EPA" "PUFA.

Factors that can influence neurocognitive performance: a case study in a controlled environment

This is a case study of a patient in her 50s who presents with severe malnutrition, alcohol dependence, and untreated Bipolar Affective Disorder. She was hospitalized multiple times and placed in a group home 1 year after symptom onset. Cognitive and functional improvements are observed over a 6-year period, as demonstrated by 3 comprehensive neuropsychological evaluations. Residing in a monitored and structured environment for 6 years, with stability in psychiatric medications, monitored nutrition and abstinence from alcohol are attributed to this improvement. This study provides unique evidence of the impact of balanced nutrition and improvements in psychiatric symptoms on cognition.

Liver acts as a metabolic gate for the traumatic brain injury pathology: Protective action of thyroid hormone

Clinical evidence indicates that injury to the brain elicits systemic metabolic disturbances that contributes to the brain pathology. Since dietary fructose is metabolized in the liver, we explored mechanisms by which traumatic brain injury (TBI) and dietary fructose influence liver function and their possible repercussions to brain. Consumption of fructose contributed to the detrimental effects of TBI on liver operation, in terms of glucose and lipid metabolism, de novo lipogenesis, lipid peroxidation. Thyroid hormone (T4) is metabolized in the liver and found that T4 supply improved lipid metabolism by reducing de novo lipogenesis, lipid accumulation, lipogenic enzymes (ACC, AceCS1, FAS), lipid peroxidation in liver in response to fructose and fructose-TBI. T4 supply also helped to normalize glucose metabolism and improve insulin sensitivity. Furthermore, T4 counteracted elevations of the pro-inflammatory cytokines, Tnfα and Mcp-1 after TBI and/or fructose intake in liver and circulation. T4 also exerted an effect on isolated primary hepatocytes by potentiating phosphorylation of AMPKα and AKT substrate, AS160, leading to increased glucose uptake. In addition, T4 restored the metabolism of DHA in the liver disrupted by TBI and fructose, adding important information to optimize the action of DHA in therapeutics. The overall evidence seems to indicate that the liver works as a gate for the regulation of the effects of brain injury and foods on brain pathologies.

Bibliometric mapping of the landscape and structure of nutrition and depression research: visualization analysis

BACKGROUND

Numerous epidemiological studies have examined the relationship between dietary intake of specific foods or nutrients and the incidence of depression and have noted that nutrition has a significant impact on mental health. Therefore, the purpose of this study is to assess the state of research, the frontiers of research, and development trends in the field of nutrition and depression using bibliometric and visual analysis.

METHODS

We collected publications on the topic of nutrition and depression from Scopus between 2002 and 2021. Subsequently, we utilized VOSviewer 1.6.18 and Microsoft Excel 2013 to perform bibliometric analysis and visualization. Bibliometric analysis involves retrieving documents from a singular database, such as SciVerse Scopus or Web of Knowledge, and subjecting them to quantitative and qualitative analysis. Notably, gray literature is not considered in bibliometric analysis.

RESULTS

A total of 2171 publications on nutrition and depression were found between 2002 and 2021, namely 1855 (85.44%) original articles, 190 (8.75%) reviews, 38 (1.75%) letters, and 88 (4.05%) other types of publications. The most productive country was found to be the USA (n = 726; 33.44%), followed by Australia (n = 172; 7.92%), the United Kingdom (n = 158; 7.28%), China (n = 132; 6.08%), and Canada (n = 131; 6.03%). The remaining publications were from other countries (n = 852; 39.25%). According to the citation analysis, the retrieved papers were cited on an average of 26.6 times and had an h-index of 105 with 57,781 citations. The most frequent terms on the map include those related to (a) fatty acid links to depression and brain inflammation, (b) depression and eating disorders, and finally, (c) adherence to the Mediterranean diet and risk of depression.

CONCLUSIONS

The current study was the first novel bibliometric analysis of nutrition and depression research that used data extracted from Scopus for visualization network mapping. In recent years, the theme "Mediterranean diet adherence and risk of depression" has been identified more frequently, indicating that studies in this field have garnered considerable attention and reflect the most recent scientific advances. Researchers should continue to investigate nutrition and depression, and we believe this study provides significant information for researchers, nutritionists, and clinicians.

Early life exposure to high fructose diet induces metabolic dysregulation associated with sex-specific cognitive impairment in adolescent rats

The incidence of adolescent mental health disorders is on the rise. Epidemiological studies suggest that poor nutrition is a significant contributor to this public health crisis, specifically through exposure to high level of dietary sugar, including fructose, during critical periods of development. Previous studies have shown that elevated fructose exposure during adolescence disrupts mental health. Despite these data, it is currently unknown how fructose exposure, specifically during infancy, may impact adolescent mental health. We developed a rat experimental protocol to investigate the effects of fructose exposure during infancy on behavioral, cognitive and metabolic endpoints in adolescence. We found that exposing rats to high fructose from birth to weaning resulted in higher circulating glucose, insulin and leptin levels in adolescence. High fructose during infancy also increased bodyweight, disrupted metabolic homeostasis in the basolateral amygdala (BLA) as indicated by decreased activity of the cellular energy sensor AMPK, and impaired attention and impulsivity in a male-specific manner. This impaired attention observed in adolescent male rats following neonatal fructose exposure was partially rescued by viral-mediated, in vivo expression of a constitutively active form of AMPK in principal neurons of the BLA. Our results suggest that exposure to high level of fructose during infancy may impact adolescent mental health in a male-specific manner and that manipulation of AMPK activity may mitigate this impact.

Flaxseed supplementation significantly reduces hemoglobin A1c in patients with type 2 diabetes mellitus: A systematic review and meta-analysis

Flaxseed is a functional food because of its high content of alpha-linolenic acid, lignans, and dietary fiber. We hypothesized that flaxseed supplementation would improve cardiometabolic parameters in patients with type 2 diabetes mellitus (T2DM); however, clinical trials have shown conflicting results. Therefore, this systematic review and meta-analysis was conducted to determine the impact of flaxseed supplementation in patients with T2DM. Randomized controlled trials were systematically searched in PubMed, Web of Science, Scopus, Cochrane Library, and Embase until 25 March 2022. A total of 13 studies were included, and the results showed that flaxseed supplementation significantly reduced hemoglobin A1c (HbA1c) in participants with T2DM compared with the control group. In contrast, it had no effects on body weight, body mass index, blood pressure, fasting blood glucose (FBG), homeostatic model assessment for insulin resistance, quantitative insulin sensitivity check index, and lipid parameters. In the subgroup analyses, FBG was significantly reduced with supplementation of flaxseed in participants with baseline FBG ≥8.0 mmol/L or baseline HbA1c ≥7.0%. And a significant decrease in HbA1c in participants with baseline HbA1c ≥7.0% after flaxseed supplementation. In addition, subgroup analyses indicated that whole flaxseed supplementation significantly increased high-density lipoprotein cholesterol and reduced total cholesterol or low-density lipoprotein cholesterol in participants with T2DM. In conclusion, flaxseed supplementation significantly reduced HbA1c in participants with T2DM, especially those with poorly controlled blood sugar levels. However, larger scale studies with better designs are needed to confirm insignificant and/or ambiguous findings.

Different Sources of Sugar Consumption and Cognitive Performance in Older Adults: Data From the National Health and Nutrition Examination Survey 2011-2014

OBJECTIVES

Excess sugar consumption, particularly in sugar-sweetened beverages (SSBs), has been linked to poor cognitive performance. We aimed to assess the association of consumption of total sugar, as well as the consumption of SSBs, solid desserts, and 100% fruit juice with cognitive performance among older adults.

METHODS

Consumption of total sugar, SSBs, solid desserts, and 100% fruit juice were obtained from the 24-hr recall interview. Cognitive performance was evaluated using the Consortium to Establish a Registry for Alzheimer's Disease word list, the Animal Fluency Test, and the Digit Symbol Substitution Test. Binary logistic regression models were used to evaluate the association between consumption of sugar (total and from different sources) and cognitive performance.

RESULTS

A total of 1,938 participants aged 60 years or older from the National Health and Nutrition Examination Survey 2011-2014 were included. Compared to the lowest tertile, the highest tertile of total sugar consumption was independently associated with higher odds of low memory performance (odds ratio [OR] = 1.87, 95% confidence interval [CI] = 1.00; 3.50, p = .049). Consumption of SSBs was associated with higher risk of low memory (OR = 1.58, 95% CI = 1.11; 2.25, p = .014), whereas consumption of solid desserts was associated with lower risk of low verbal fluency performance (OR = 0.62, 95% CI = 0.41; 0.95, p = .032).

DISCUSSION

Higher consumption of total sugars and SSBs was associated with lower memory performance, while consumption of solid desserts was associated with higher verbal fluency performance.

Investigation of fructose consumption on hippocampal insulin and glucagon-like peptide-1 receptors, and metabolic effects in rats

Objectives

The detrimental effects of high fructose consumption on metabolic health have been extensively studied. However, limited research has focused on the impact of fructose intake on neuroprotective mechanisms, specifically the expression of insulin receptor (INSR) and glucagon-like peptide-1 receptor (GLP-1R) in the hippocampus. Understanding the effects of fructose on these neuroprotective molecules can provide valuable insights into the potential role of fructose in hippocampal dysfunction. The goal of this study is to aim at the basal plasma levels of lipid profile, insulin, GLP-1, and HOMA-IR, as well as the mRNA and protein expression of neuroprotective molecules such as INSR and GLP-1R in Wistar rats fed a high fructose diet.

Materials and Methods

Rats were separated into control (C) and high fructose (HF) groups. The HF group was given 20% fructose water to drink for 16 weeks.

Results

Fructose ingestion significantly increased abdominal fat (C=1.24±0.08 g, HF=1.79±0.19 g, P<0.05) and plasma triglyceride levels (C=179.22±22.85 µg/ml, HF=242.45±14.45 µg/ml, P<0.05), but had no statistically significant effect on body weight and plasma HDL, LDL, total cholesterol, insulin, and GLP-1 levels (P>0.05). Although INSR mRNA expression in the hippocampus was significantly lower in the HF group compared to the control group (P<0.05), GLP-1R mRNA expression did not differ significantly across the groups (P>0.05). Furthermore, whereas INSR and GLP-1R protein levels in the experimental group were on a declining trend, this trend was not substantially different (P>0.05).

Conclusion

These data suggest that fructose consumption may be harmful to the hippocampus by lowering the expression of INSR.

Lifestyle Adjustment: Influential Risk Factors in Cognitive Aging

Cognitive aging is inevitable. However, researchers have demonstrated that lifestyle adjustments can reduce the risk of cognitive impairment. A healthy diet style, the Mediterranean diet, has been proven to benefit the elderly. Oil, salt, sugar, and fat are, on the contrary, risk factors for cognitive dysfunction because of the resultant high caloric intake. Physical and mental exercises, especially cognitive training, are also beneficial for aging. At the same time, several risk factors need to be noted, such as smoking, alcohol consumption, insomnia, and excessive daytime sleeping, which are highly relative to cognitive impairment, cardiovascular diseases, and dementia.

Effects of plant-based versus marine-based omega-3 fatty acids and sucrose on brain and liver fatty acids in a mouse model of chemotherapy

Chemotherapy can result in toxic side effects in the brain. Intake of marine-based omega-3 polyunsaturated fatty acids (n-3 PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), alter brain fatty acids, potentially improving brain function. However, it is unclear if alpha-linolenic acid (ALA), the plant-based n-3, affects brain PUFAs during chemotherapy. The objective of this study was to examine the effects of dietary ALA, EPA and DHA, with high or low sucrose, on brain PUFAs in a mouse model of chemotherapy. Secondarily, the use of liver PUFAs as surrogate measures of brain PUFAs was examined. Lipid peroxidation (4-HNE) and neurotrophic markers (BDNF) were assessed. Female C57Bl/6 mice (n = 90) were randomized to 1 of 5 diets (high EPA + DHA/high or low sucrose, high ALA/high or low sucrose, or control with no EPA + DHA/low ALA/low sucrose) and injected with doxorubicin-based chemotherapy or saline. Brain EPA and DHA were greater (p < 0.0001) with high EPA + DHA diets, regardless of sucrose; there were no significant differences in brain PUFAs between high ALA diets and control. Chemotherapy-treated mice had higher brain and liver DHA (p < 0.05) and lower brain and liver linoleic acid (p < 0.0001). Brain n-3 and n-6 PUFAs were strongly correlated with liver n-3 (r = 0.8214, p < 0.0001) and n-6 PUFAs (r = 0.7568, p < 0.0001). BDNF was correlated with brain total PUFAs (r = 0.36; p < 0.05). In conclusion, dietary ALA in proportions approximately two times greater than consumed by humans did not appreciably increase brain n-3 PUFAs compared to low ALA intake. Liver PUFAs may be a useful surrogate marker of brain PUFAs in this mouse model.

Nutritional intervention for diabetes mellitus with Alzheimer's disease

The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.

Eicosanoid lipidome activation in post-mortem brain tissues of individuals with APOE4 and Alzheimer's dementia

BACKGROUND

Chronic neuroinflammation is one of the hallmarks of late-onset Alzheimer's disease (AD) dementia pathogenesis. Carrying the apolipoprotein ε4 (APOE4) allele has been associated with an accentuated response to brain inflammation and increases the risk of AD dementia progression. Among inflammation signaling pathways, aberrant eicosanoid activation plays a prominent role in neurodegeneration.

METHODS

Using brains from the Religious Order Study (ROS), this study compared measures of brain eicosanoid lipidome in older persons with AD dementia to age-matched controls with no cognitive impairment (NCI), stratified by APOE genotype.

RESULTS

Lipidomic analysis of the dorsolateral prefrontal cortex demonstrated lower levels of omega-3 fatty acids eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and DHA-derived neuroprotectin D1 (NPD-1) in persons with AD dementia, all of which associated with lower measures of cognitive function. A significant interaction was observed between carrying the APOE4 allele and higher levels of both pro-inflammatory lipids and pro-resolving eicosanoid lipids on measures of cognitive performance and on neuritic plaque burden. Furthermore, analysis of lipid metabolism pathways implicated activation of calcium-dependent phospholipase A2 (cPLA2), 5-lipoxygenase (5-LOX), and soluble epoxide hydrolase (sEH) enzymes.

CONCLUSION

These findings implicate activation of the eicosanoid lipidome in the chronic unresolved state of inflammation in AD dementia, which is increased in carriers of the APOE4 allele, and identify potential therapeutic targets for resolving this chronic inflammatory state.

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.

Hippocampal Endoplasmic Reticulum Stress Hastens Motor and Cognitive Decline in Adult Male Rats Sustainedly Exposed to High-Sucrose Diet

Metabolic dysfunctions, such as hyperglycemia and insulin resistance, have been associated to cognitive impairment and dementia regardless of advanced age, although the underlying mechanisms are still elusive. Thus, this study investigates the deleterious effects of metabolic syndrome (MetS) induced by long-term exposure to a high-sucrose diet on motor and cognitive functions of male adult rats and its relationship with hippocampal endoplasmic reticulum (ER) stress. Weaned Wistar male rats were fed a high-sucrose diet until adulthood (HSD; 6 months old) and compared to both age-matched (CTR; 6 months old) and middle-aged chow-fed rats (OLD; 20 months old). MetS development, serum redox profile, behavioral, motor, and cognitive functions, and hippocampal gene/protein expressions for ER stress pro-adaptive and pro-apoptotic pathways, as well as senescence markers were assessed. Prolonged exposure to HSD induced MetS hallmarked by body weight gain associated to central obesity, hypertriglyceridemia, insulin resistance, and oxidative stress. Furthermore, HSD rats showed motor and cognitive decline similar to that in OLD animals. Noteworthy, HSD rats presented marked hippocampal ER stress characterized by failure of pro-adaptive signaling and increased expression of Chop, p21, and Parp-1 cleavage, markers of cell death and aging. This panorama resembles that found in OLD rats. In toto, our data showed that early and sustained exposure to a high-sucrose diet induced MetS, which subsequently led to hippocampus homeostasis disruption and premature impairment of motor and cognitive functions in adult rats.

Fenofibrate Improves Cognitive Impairment Induced by High-Fat High-Fructose Diet: A Possible Role of Irisin and Heat Shock Proteins

A high-fat, high-fructose diet (HFFD) impairs cognitive functions and increases susceptibility to neurodegenerative disorders. Irisin and heat shock protein 70 (HSP70) are well known for their role in neuroprotection. The possible neuroprotective effects of fenofibrate on HFFD-induced cognitive dysfunction and the involvement of irisin and HSP70 in these effects were investigated in this study. Rats were divided into normal control, HFFD, dimethylsulfoxide+HFFD, and fenofibrate+HFFD groups. At the end of the experiment, fenofibrate treatment restored hippocampus histological characteristics to almost normal and improved HFFD-induced cognitive deficit. It reduced body weight gain and had hypolipidemic effects by significantly lowering total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels while increasing high-density lipoprotein cholesterol levels. It has antioxidant and anti-inflammatory effects as it significantly reduced the hippocampal malondialdehyde, interleukin-6, and tumor necrosis factor-alpha levels, while significantly increasing the reduced glutathione level. It prevented HFFD-induced hypoxia by significantly lowering hippocampal vascular endothelial growth factor and hypoxia-inducible factor-1 alpha levels. It significantly activated the hippocampal peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α)/irisin/brain-derived neurotrophic factor pathway. It significantly increased hippocampal HSP70 while decreasing the HSP90 levels. It enhanced synaptic plasticity by significantly upregulating the hippocampal relative GluR1 gene expression. Furthermore, hippocampal irisin levels in the HFFD group were found to be positively correlated with cognitive function, hippocampal HSP70, and relative GluR1 gene expression levels, while negatively correlated with hippocampal HSP90 and HIF1α levels. Therefore, fenofibrate may be used as a potential medication to treat HFFD-induced neurodegenerative disorders.

TLR4 mutation protects neurovascular function and cognitive decline in high-fat diet-fed mice

Background

Metabolic syndrome (MS) is defined as a low-grade proinflammatory state in which abnormal metabolic and cardiovascular factors increase the risk of developing cardiovascular disease and neuroinflammation. Events, such as the accumulation of visceral adipose tissue, increased plasma concentrations of free fatty acids, tissue hypoxia, and sympathetic hyperactivity in MS may contribute to the direct or indirect activation of Toll-like receptors (TLRs), specifically TLR4, which is thought to be a major component of this syndrome. Activation of the innate immune response via TLR4 may contribute to this state of chronic inflammation and may be related to the neuroinflammation and neurodegeneration observed in MS. In this study, we investigated the role of TLR4 in the brain microcirculation and in the cognitive performance of high-fat diet (HFD)-induced MS mice.

Methods

Wild-type (C3H/He) and TLR4 mutant (C3H/HeJ) mice were maintained under a normal diet (ND) or a HFD for 24 weeks. Intravital video-microscopy was used to investigate the functional capillary density, endothelial function, and endothelial–leukocyte interactions in the brain microcirculation. Plasma concentrations of monocyte chemoattractant protein-1 (MCP-1), adipokines and metabolic hormones were measured with a multiplex immunoassay. Brain postsynaptic density protein-95 and synaptophysin were evaluated by western blotting; astrocytic coverage of the vessels, microglial activation and structural capillary density were evaluated by immunohistochemistry.

Results

The HFD-induced MS model leads to metabolic, hemodynamic, and microcirculatory alterations, as evidenced by capillary rarefaction, increased rolling and leukocyte adhesion in postcapillary venules, endothelial dysfunction, and less coverage of astrocytes in the vessels, which are directly related to cognitive decline and neuroinflammation. The same model of MS reproduced in mice deficient for TLR4 because of a genetic mutation does not generate such changes. Furthermore, the comparison of wild-type mice fed a HFD and a normolipid diet revealed differences in inflammation in the cerebral microcirculation, possibly related to lower TLR4 activation.

Conclusions

Our results demonstrate that TLR4 is involved in the microvascular dysfunction and neuroinflammation associated with HFD-induced MS and possibly has a causal role in the development of cognitive decline.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02465-3.

Simultaneous exposure to electromagnetic field from mobile phone and unimpeded fructose drinking during pre-, peri-, and post-pubertal stages perturbs the hypothalamic and hepatic regulation of energy homeostasis by early adulthood: experimental evidence

The present-day children-adolescents ubiquitously use the mobile phones and unrestrictedly consume fructose-laden diet. Unfortunately, a rise in the incidence of insulin resistance and fatty liver syndrome in young adults has also been recorded. To delineate a possible correlate, the effect of exposure to electromagnetic field (EMF) from the mobile phone and unrestricted fructose intake during pre-, peri-, and post-pubertal stages of development on orexigenic and anorexigenic signals arising from the hypothalamus and liver of rats is investigated here. The study design included four arms, i.e., "Normal", "Exposure Only (ExpO)", "Fructose Only (FruO)", and "Exposure with Fructose (EF)", wherein weaned rats received either "normal chow and drinking water" or "normal chow and fructose (15%) drinking solution" in presence and absence of EMF exposure (2 h/day) for 8 weeks. The results indicate that the total calories consumed by the EF were higher by early adulthood than normal, possibly under the influence of the raised levels of the orexigenic hormone, i.e., ghrelin, and it reflected as raised rate of weight gain. At early adulthood, the EF recorded mitigated response and sensitivity of insulin. Despite EF being a "fed-state", both centrally and peripherally, the glycolysis was restrained, but the gluconeogenesis was raised. Additionally, the altered lipid profile and the glycogen levels indicate that the EF developed fatty liver. The energy homeostasis of the EF was compromised as evidenced by (a) reduced expression of the glucosensors-GLUT2 and glucokinase in the hypothalamus and liver and (b) reduced expression of the cellular energy regulator-AMPK, orexigenic peptide-NPY, and anorexigenic peptide-POMC in the hypothalamus. Taken together, the present study evidences that the exposure to EMFfrom the mobile phone and unrestricted fructose intake during childhood-adolescence impairs the central and peripheral pathways that mediate the glucosensing, glucoregulation, feeding, and satiety behavior by early adulthood.

Omega-3 polyunsaturated fatty acids promote SNAREs mediated GLUT4 vesicle docking and fusion

Glucose homeostasis imbalance and insulin resistance (IR) are major contributors to the incidence of type 2 diabetes. Omega-3 polyunsaturated fatty acids (PUFAs) are key ingredients for maintaining cellular functions and improving insulin sensitivity. However, how omega-3 PUFAs modulate the dynamic process of glucose transport at the cellular level remains unclear. Here we unraveled eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may regulate the glucose transporter 4 (GLUT4) vesicle trafficking in both normal and IR adipocytes. Both omega-3 PUFAs significantly increase glucose consumption within a range of 10-32% in the basal state. Furthermore, both EPA (200 μM) and DHA (100 μM) may significantly promote the serine/threonine protein kinase (Akt) phosphorylation by 70% and 40% in the physiological state of adipocytes, respectively. Both omega-3 PUFAs significantly advanced the Akt phosphorylation in a dose-dependent way and showed a ∼2-fold increase at the dose of 200 μM in the IR pathological state. However, they could not up-regulate the expression of GLUT4 and insulin-regulated aminopeptidase protein. We further revealed that both omega-3 PUFAs dynamically promote insulin-stimulated GLUT4 vesicle translocation and soluble N-ethylmaleimide-sensitive factor attachment protein receptor mediated vesicle docking and fusion to the plasma membrane via specifically modulating the expression of vesicle-associated membrane protein 2. Understanding the mechanisms by which omega-3 PUFAs modulate cellular metabolism and IR in peripheral tissues may provide novel insights into the potential impact of omega-3 PUFAs on the metabolic function and the management of IR.

Fructose-rich diet and walnut supplementation differently regulate rat hypothalamic and hippocampal glucose transporters expression

BACKGROUND

Nutritional modulations may be considered a strategy to protect mental health. Neuronal homeostasis is highly dependent on the availability of glucose, which represents the primary energy source for the brain. In this study, we evaluated the effects of walnut intake and fructose-rich diet on the expression of glucose transporters (GLUTs) in two rat brain regions: hypothalamus and hippocampus.

RESULTS

Our results show that walnut supplementation of fructose-fed animals restored the hypothalamic content of GLUT1 and GLUT3 protein. Furthermore, walnut intake did not affect increased hypothalamic GLUT2 content upon fructose consumption. These effects were accompanied by distinctive alterations of hippocampal GLUTs levels. Specifically, walnut intake increased GLUT1 content, whereas GLUT2 protein was decreased within the rat hippocampus after both individual and combined treatments.

CONCLUSION

Overall, our study suggests that walnut supplementation exerted modulatory effects on the glucose transporters within specific brain regions in the presence of developed metabolic disorder. © 2021 Society of Chemical Industry.

Lifestyle-dependent microglial plasticity: training the brain guardians

Lifestyle is one of the most powerful instruments shaping mankind; the lifestyle includes many aspects of interactions with the environment, from nourishment and education to physical activity and quality of sleep. All these factors taken in complex affect neuroplasticity and define brain performance and cognitive longevity. In particular, physical exercise, exposure to enriched environment and dieting act through complex modifications of microglial cells, which change their phenotype and modulate their functional activity thus translating lifestyle events into remodelling of brain homoeostasis and reshaping neural networks ultimately enhancing neuroprotection and cognitive longevity.

Neural mechanisms underlying the role of fructose in overfeeding

Fructose consumption has been linked with metabolic syndrome and obesity. Fructose-based sweeteners like high fructose corn syrup taste sweeter, improve food palatability, and are increasingly prevalent in our diet. The increase in fructose consumption precedes the rise in obesity and is a contributing driver to the obesity epidemic worldwide. The role of dietary fructose in obesity can be multifactorial by promoting visceral adiposity, hypertension, and insulin resistance. Interestingly, one emergent finding from human and animal studies is that dietary fructose promotes overfeeding. As the brain is a critical regulator of food intake, we reviewed the evidence that fructose can act in the brain and elucidated the major brain systems underlying fructose-induced overfeeding. We found that fructose acts on multiple interdependent brain systems to increase orexigenic drive and the incentive salience of food while decreasing the latency between food bouts and reducing cognitive control to disinhibit feeding. We concluded that the collective actions of fructose may promote feeding behavior by producing a hunger-like state in the brain.

Brain on food: The neuroepigenetics of nutrition

Humans have known for millennia that nutrition has a profound influence on health and disease, but it is only recently that we have begun mapping the mechanisms via which the dietary environment impacts brain physiology and behavior. Here we review recent evidence on the effects of energy-dense and methionine diets on neural epigenetic marks, gene expression, and behavior in invertebrate and vertebrate model organisms. We also discuss limitations, open questions, and future directions in the emerging field of the neuroepigenetics of nutrition.

The association of metabolic syndrome and cognitive impairment in Jidong of China: a cross-sectional study

BACKGROUND

Metabolic syndrome (Mets) is prevalent in the general population and has been reported to be an independent risk factor for cognitive impairment. This study aimed to investigate the association of Mets with the risk of cognitive impairment.

METHODS

We studied 5854 participants from the Jidong community. Cognitive function was assessed by the Mini-Mental State of Examination (MMSE) scale. Mets was diagnosed according to the International Diabetes Federation criteria. We used logistic regression analysis to investigate the association of metabolic syndrome with the risk of cognitive impairment.

RESULT

Among the 5854 adults included in the study, the age mean (SD) of age was 44 (13.57) years, and 2916 (50.34%) were male. There was a higher (56.03%) cognitive impairment incidence rate among participants with Mets than among those without Mets. In addition, there was a significant association between Mets and cognitive impairment (OR: 2.39, 95% CI: 2.00-2.86, P < 0.05) after adjusting for potential confounders, including age, gender, education level, marital status, smoking and alcohol consumption status. Regarding the 5 Mets components, abdominal obesity and elevated blood pressure were associated with the risk of Mets (OR: 1.36, 95% CI: 1.09-1.70, P < 0.001; OR: 1.32, 95% CI: 1.07-1.63, P < 0.05). Moreover, the strongest statistical correlation (adjusted OR: 1.86, 95% CI: 1.22-2.83, P < 0.05) was found when the number of Mets components was three.

CONCLUSION

Our study suggested that Mets was associated with cognitive impairment and that abdominal obesity and hypertension were associated with an increased risk of cognitive impairment.

High Fructose Diet Induces Sex-specific Modifications in Synaptic Respiration and Affective-like Behaviors in Rats

The consequences of excessive fructose intake extend beyond those of metabolic disorder to changes in emotional regulation and cognitive function. Long-term consumption of fructose, particularly common when begun in adolescence, is more likely to lead to deleterious consequences than acute consumption. These long-term consequences manifest differently in males and females, suggesting a sex-divergent mechanism by which fructose can impair physiology and neural function. The purpose of the current project was to investigate a possible sex-specific mechanism by which elevated fructose consumption drives behavioral deficits and accompanying metabolic symptoms - specifically, synaptic mitochondrial function. Male and female rats were fed a high fructose diet beginning at weaning and maintained into adulthood. Measures of physiological health across the diet consumption period indicated that females were more likely to gain weight than males while both displayed increased circulating blood glucose. As adults, females fed the high fructose diet displayed increased floating behavior in the forced swim task while males exhibited increased exploratory behavior in the open field. Synaptic respiration was altered by diet in both females and males but the effect was sex-divergent - fructose-fed females had increased synaptic respiration while males showed a decrease. When exposed to an acute energetic challenge, the pattern was reversed. Taken together, these data indicate that diet-induced alterations to neural function and physiology are sex-specific and highlight the need to consider sex as a biological variable when treating metabolic disease. Furthermore, these data suggest that synaptic mitochondrial function may contribute directly to the behavioral consequences of elevated fructose consumption.

Dietary fructose as a model to explore the influence of peripheral metabolism on brain function and plasticity

High consumption of fructose has paralleled an explosion in metabolic disorders including obesity and type 2 diabetes. Even more problematic, sustained consumption of fructose is perceived as a threat for brain function and development of neurological disorders. The action of fructose on peripheral organs is an excellent model to understand how systemic physiology impacts the brain. Given the recognized action of fructose on liver metabolism, here we discuss mechanisms by which fructose can impact the brain by interacting with liver and other organs. The interaction between peripheral and central mechanisms is a suitable target to reduce the pathophysiological consequences of neurological disorders.

Most Effective Combination of Nutraceuticals for Improved Memory and Cognitive Performance in the House Cricket, Acheta domesticus

Background: Dietary intake of multivitamins, zinc, polyphenols, omega fatty acids, and probiotics have all shown benefits in learning, spatial memory, and cognitive function. It is important to determine the most effective combination of antioxidants and/or probiotics because regular ingestion of all nutraceuticals may not be practical. This study examined various combinations of nutrients to determine which may best enhance spatial memory and cognitive performance in the house cricket (Acheta domesticus (L.)). Methods: Based on the 31 possible combinations of multivitamins, zinc, polyphenols, omega-3 polyunsaturated fatty acids (PUFAs), and probiotics, 128 house crickets were divided into one control group and 31 experimental groups with four house crickets in each group. Over eight weeks, crickets were fed their respective nutrients, and an Alternation Test and Recognition Memory Test were conducted every week using a Y-maze to test spatial working memory. Results: The highest-scoring diets shared by both tests were the combination of multivitamins, zinc, and omega-3 fatty acids (VitZncPuf; Alternation: slope = 0.07226, Recognition Memory: slope = 0.07001), the combination of probiotics, polyphenols, multivitamins, zinc, and omega-3 PUFAs (ProPolVitZncPuf; Alternation: slope = 0.07182, Recognition Memory: slope = 0.07001), the combination of probiotics, multivitamins, zinc, and omega-3 PUFAs (ProVitZncPuf; Alternation: slope = 0.06999, Recognition Memory: slope = 0.07001), and the combination of polyphenols, multivitamins, zinc, and omega-3 PUFAs (PolVitZncPuf; Alternation: slope = 0.06873, Recognition Memory: slope = 0.06956). Conclusion: All of the nutrient combinations demonstrated a benefit over the control diet, but the most significant improvement compared to the control was found in the VitZncPuf, ProVitZncPuf, PolVitZncPuf, and ProPolVitZncPuf. Since this study found no significant difference between the performance and improvement of subjects within these four groups, the combination of multivitamins, zinc, and omega-3 fatty acids (VitZncPuf) was concluded to be the most effective option for improving memory and cognitive performance.

The interaction between brain and liver regulates lipid metabolism in the TBI pathology

To shed light on the impact of systemic physiology on the pathology of traumatic brain injury (TBI), we examine the effects of TBI (concussive injury) and dietary fructose on critical aspects of lipid homeostasis in the brain and liver of young-adult rats. Lipids are integral components of brain structure and function, and the liver has a role on the synthesis and metabolism of lipids. Fructose is mainly metabolized in the liver with potential implications for brain function. Lipidomic analysis accompanied by unbiased sparse partial least squares discriminant analysis (sPLS-DA) identified lysophosphatidylcholine (LPC) and cholesterol ester (CE) as the top lipid families impacted by TBI and fructose in the hippocampus, and only LPC (16:0) was associated with hippocampal-dependent memory performance. Fructose and TBI elevated liver pro-inflammatory markers, interleukin-1α (IL-1α), Interferon-γ (IFN-γ) that correlated with hippocampal-dependent memory dysfunction, and monocyte chemoattractant protein-1 (MCP-1) positively correlated with LPC levels in the hippocampus. The effects of fructose were more pronounced in the liver, in agreement with the role of liver on fructose metabolism and suggest that fructose could exacerbate liver inflammation caused by TBI. The overall results indicate that TBI and fructose interact to influence systemic and central inflammation by engaging liver lipids. The impact of TBI and fructose diet on the periphery provides a therapeutic target to counteract the TBI pathogenesis.

Insulin resistance: a connecting link between Alzheimer's disease and metabolic disorder

Recent evidence suggests that Alzheimer's disease (AD) is closely linked with insulin resistance, as seen in type 2 diabetes mellitus (T2DM). Insulin signaling is impaired in AD brains due to insulin resistance, ultimately resulting in the formation of neurofibrillary tangles (NFTs). AD and T2DM are connected at molecular, clinical, and epidemiological levels making it imperative to understand the contribution of T2DM, and other metabolic disorders, to AD pathogenesis. In this review, we have discussed various modalities involved in the pathogenesis of these two diseases and explained the contributing parameters. Insulin is vital for maintaining glucose homeostasis and it plays an important role in regulating inflammation. Here, we have discussed the roles of various contributing factors like miRNA, leptin hormone, neuroinflammation, metabolic dysfunction, and gangliosides in insulin impairment both in AD and T2DM. Understanding these mechanisms will be a big step forward for making molecular therapies that may help maintain or prevent both AD and T2DM, thus reducing the burden of both these diseases.

Effects of dietary n-3 PUFA levels in early life on susceptibility to high-fat-diet-induced metabolic syndrome in adult mice

The maternal nutritional status during pregnancy and lactation was closely related to the growth and development of the fetus and infants, which had a profound impact on the health of the offspring. N-3 polyunsaturated fatty acid (PUFA) had been proved to have beneficial effects on glucolipid metabolism. However, the effects of dietary different n-3 PUFA levels for mother during pregnancy and lactation on susceptibility to high-fat-diet-induced metabolic syndrome for offspring in adulthood are still unclear. The maternal mice were fed with control, n-3 PUFA-deficient or fish oil-contained n-3 PUFA-rich diets during pregnancy and lactation, and the weaned offspring were fed with high-fat or low-fat diet for 13 weeks, then were subjected to oral glucose tolerance tests. The results showed that dietary n-3 PUFA-deficiency in early life could aggravate the high-fat-diet-induced glucolipid metabolism disorders, including glucose intolerance, insulin resistance, obesity, and dyslipidemia, thus increased the susceptibility to metabolic syndrome of adult mice. Notably, nutritional supplementation with n-3 PUFA in early life could significantly alleviate the glucose metabolism disorders by increasing insulin sensitivity, inhibiting gluconeogenesis and promoting glycogenesis. In addition, administration with n-3 PUFA in early life remarkably reduced serum and hepatic lipid profiles by mediating the expression of genes related to lipogenesis and β-oxidation of fatty acids. Dietary n-3 PUFA-deficiency in early life increases the susceptibility to metabolic syndrome of adult offspring, and nutritional supplementation with n-3 PUFA enhances the tolerance to a high-fat diet of adult offspring.

Role of nutraceuticals in cognition during aging and related disorders

Cognitive abilities are compromised with advancing age posing a great risk for the development of dementia and other related brain disorders. Genetic susceptibility as well as environmental exposures determine the fate of cognitive aging and its transition to pathological states. Emerging epidemiological and observational studies have revealed the importance of lifestyle factors including dietary patterns and nutritional intake in the maintenance of cognitive health and reducing the risk of neurodegenerative disorders. In this context, nutraceutical interventions have gained considerable attention in preventing age-related cognitive deficits and counteracting pathological processes. Nutraceuticals include dietary plants and derivatives, food supplements and processed foods with nutritional and pharmaceutical values. The present review highlights the importance of nutraceuticals in attenuating cognitive aging and its progression to dementia, with specific emphasis on chemical constituents, neurocognitive properties and mechanism of action.

A qualitative study about college students' attitudes, knowledge and perceptions regarding sugar intake

Excessive sugar intake has been associated with multiple health conditions (e.g., higher risk for non-communicable diseases). Hence, health organizations have issued guidelines defining the maximum daily intake of free or added sugars. However, data from several countries suggests that these guidelines are rarely met, particularly by young adults. For example, almost half of Portuguese adolescents and young adults exceed the recommended sugar intake. In this work, we aim to further explore college students' attitudes, knowledge, and perceptions about sugar intake, as well as about sugar intake guidelines. A thematic analysis on data from five focus groups (N = 40) indicated that participants reported difficulty in the comprehension of added/free sugars definition and sugar intake recommendations. Overall, attitudes toward sugar were ambivalent. Sugar was simultaneously perceived as pleasurable and needed, but also as addictive and harmful. Although aware of the potential negative health outcomes associated with excessive sugar intake, most participants did not perceive being at risk due to their youth, exercise habits, or type of diet. The few concerns expressed were mostly associated with the negative impact of high sugar intake on body image (e.g., weight gain). The main barriers to reducing sugar intake identified were environmental (e.g., time restrictions, food available at the university). Still, participants could identify several individual strategies to effectively regulate sugar intake. By identifying knowledge gaps and sources of bias related to sugar consumption, our findings are useful to inform future interventions aiming to address the problem of high sugar intake among university students.

Brain and muscle adaptation to high-fat diets and exercise: Metabolic transporters, enzymes and substrates in the rat cortex and muscle

There is evidence suggesting that the effects of diet and physical activity on physical and mental well-being are the result of altered metabolic profiles. Though the central and peripheral systems work in tandem, the interactions between peripheral and central changes that lead to these altered states of well-being remains elusive. We measured changes in the metabolic profile of brain (cortex) and muscle (soleus and plantaris) tissue in rats following 5-weeks of treadmill exercise and/or a high-fat diet to evaluate peripheral and central interactions as well as identify any common adaptive mechanisms. To characterize changes in metabolic profiles, we measured relative changes in key metabolic enzymes (COX IV, hexokinase, LDHB, PFK), substrates (BHB, FFA, glucose, lactate, insulin, glycogen, BDNF) and transporters (MCT1, MCT2, MCT4, GLUT1, GLUT3). In the cortex, there was an increase in MCT1 and a decrease in glycogen following the high-fat diet, suggesting an increased reliance on monocarboxylates. Muscle changes were dependent muscle type. Within the plantaris, a high-fat diet increased the oxidative capacity of the muscle likely supported by increased glycolysis, whereas exercise increased the oxidative capacity of the muscle likely supported via increased glycogen synthesis. There was no effect of diet on soleus measurements, but exercise increased its oxidative capacity likely fueled by endogenous and exogenous monocarboxylates. For both the plantaris and soleus, combining exercise training and high-fat diet mediated results, resulting in a middling effect. Together, these results indicate the variable adaptions of two main metabolic pathways: glycolysis and oxidative phosphorylation. The results also suggest a dynamic relationship between the brain and body.

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

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

ω-3PUFAs Improve Cognitive Impairments Through Ser133 Phosphorylation of CREB Upregulating BDNF/TrkB Signal in Schizophrenia

Schizophrenia (SZ) is a serious mental condition and is associated with cognitive impairments. Brain-derived neurotrophic factor (BDNF) is one of the learning- and memory-related molecules found in the CNS and its level was reported to be reduced in SZ brain, while ω-3 polyunsaturated fatty acids (ω-3PUFAs) could improve SZ symptoms, but its mechanism of action remains unknown. Using MK801 injection-induced SZ rat model, we here found that supplementation with ω-3PUFAs improved the levels of p-CREB, BDNF, and p-TrkB in the brain of SZ rats, and restore hippocampal neuronal damage, thereby reducing cognitive impairments in SZ rats. However, overexpression of AAV9/CREB S133A (CREB inactivated mutation) downregulated BDNF/TrkB signaling pathway and remarkably abolished the preventive effect of ω-3PUFAs in MK801-induced schizophrenia. Interestingly, AAV9/CREB S133D (CREB activated mutation) improved synaptic dysfunctions and cognitive defects in MK801 rats. In conclusion, these findings indicate that MK801-induced SZ lesions dephosphorylate CREB at Ser133 site, leading to neuron damage, and ω-3PUFAs improve SZ cognitive impairments by upregulating the CREB/BDNF/TrkB pathway, which provides new clues for the mechanism of SZ cognitive impairments, and a basis for therapeutic intervention.

Bioenergetic adaptations to HIV infection. Could modulation of energy substrate utilization improve brain health in people living with HIV-1?

The human brain consumes more energy than any other organ in the body and it relies on an uninterrupted supply of energy in the form of adenosine triphosphate (ATP) to maintain normal cognitive function. This constant supply of energy is made available through an interdependent system of metabolic pathways in neurons, glia and endothelial cells that each have specialized roles in the delivery and metabolism of multiple energetic substrates. Perturbations in brain energy metabolism is associated with a number of different neurodegenerative conditions including impairments in cognition associated with infection by the Human Immunodeficiency Type 1 Virus (HIV-1). Adaptive changes in brain energy metabolism are apparent early following infection, do not fully normalize with the initiation of antiretroviral therapy (ART), and often worsen with length of infection and duration of anti-retroviral therapeutic use. There is now a considerable amount of cumulative evidence that suggests mild forms of cognitive impairments in people living with HIV-1 (PLWH) may be reversible and are associated with specific modifications in brain energy metabolism. In this review we discuss brain energy metabolism with an emphasis on adaptations that occur in response to HIV-1 infection. The potential for interventions that target brain energy metabolism to preserve or restore cognition in PLWH are also discussed.

Association of dietary ω-3 and ω-6 fatty acids intake with cognitive performance in older adults: National Health and nutrition examination Survey (NHANES) 2011-2014

Background

Current evidence on the association of dietary ω-3 and ω-6 fatty acids intake with cognitive performance is inconsistent. Therefore, the aim is to explore the association of dietary ω-3 and ω-6 fatty acids intake with cognitive performance in the U.S. noninstitutionalized population of older adults.

Methods

We used data from the National Health and Nutrition Examination Survey (NHANES) 2011–2014. Intakes of ω-3 and ω-6 fatty acids were obtained through two 24-h dietary recalls and were adjusted by energy. Cognitive performance was evaluated by the Consortium to Establish a Registry for Alzheimer’s disease (CERAD) Word Learning sub-test, Animal Fluency test and Digit Symbol Substitution Test (DSST). For each cognitive test, people who scored lower than the lowest quartile in each age group were defined as having low cognitive performance. Binary logistic regression and restricted cubic spline models were applied to evaluate the association of dietary ω-3 and ω-6 fatty acids intake with cognitive performance.

Results

A total of 2496 participants aged 60 years or older were included. In the full-adjusted model, the odds ratios (ORs) with 95% confidence interval (CI) of CERAD test score, Animal Fluency test score and DSST test score were 0.58 (0.38–0.88), 0.68 (0.47–0.99) and 0.59 (0.37–0.92) for the highest versus lowest tertile of dietary ω-3 fatty acids intake, respectively; the ORs with 95% CI of CERAD test score, Animal Fluency test score and DSST test score were 0.48 (0.31–0.75), 0.60 (0.40–0.92) and 0.50 (0.34–0.75) for the highest versus lowest tertile of dietary ω-6 fatty acids intake, respectively. The association between ω-6: ω-3 ratio and cognitive performance was not statistically significant in three tests. In dose-response relationship analysis, L-shaped associations were apparent for ω-3 and ω-6 fatty acids intake with CERAD test score, Animal Fluency test score and DSST test score.

Conclusions

Dietary ω-3 and ω-6 fatty acids intake might be inversely associated with low cognitive performance.