Association of Dietary Intake of Flavonols With Changes in Global Cognition and Several Cognitive Abilities

Nutrition for dementia prevention: a state of the art update for clinicians

BACKGROUND AND OBJECTIVES

Dementia prevalence continues to rise. It is therefore essential to provide feasible and effective recommendations to encourage healthy brain ageing and reduce dementia risk across the population. Appropriate nutrition represents a potential strategy to mitigate dementia risk and could be recommended by clinicians as part of mid-life health checks and other health initiatives to reduce dementia prevalence. The purpose of this review is to provide a clinician-focused update on the current state of the knowledge on nutrition and dementia prevention.

METHODS

Narrative review.

RESULTS

Strong evidence exists to support the consumption of healthy, plant-based dietary patterns (e.g. Mediterranean, MIND or Nordic diet) for maintaining cognitive function and reducing dementia risk in later life and is supported by dementia prevention guideline from leading public health bodies (e.g. World Health Organization). Emerging evidence suggests potential cognitive benefits of consuming specific nutrients/foods (e.g. n-3 fatty acids or fish, flavonols and B-vitamins) and multi-nutrient compounds (e.g. Fortasyn Connect). Challenges and opportunities for integrating nutritional/dietary interventions for dementia prevention into clinical practice are explored in this review.

CONCLUSIONS

Appropriate nutrition represents an important factor to help facilitate healthy cognitive ageing and allay dementia risk. The information provided in this article can help clinicians provide informed opinions on appropriate nutritional strategies as part of mid-life Health Checks and other risk reduction initiatives.

Kaempferol improves Pb-induced cognitive impairments via inhibiting autophagy

Kaempferol (Kam) is a flavonoid antioxidant found in fruits and vegetables, which was discovered as neuroprotective antioxidants. Lead (Pb), an environmental pollution, could induce learning and memory deficits. Nevertheless, little is known about the mechanisms underlying Kam actions in Pb-induced learning and memory deficits. In this study, we investigated the effects of Kam on Pb-induced cognitive deficits. Pb-exposed rats were treated with 50 mg/kg Kam from postnatal day (PND) 30 to PND 60. Then, Y-maze and Morris water maze have been used to detect the spatial memory in all groups of rats. Hematoxylin and eosin (HE) staining and Nissl staining were used to analyze the neuronal structure damages. The results found Kam treatment improved the learning and memory ability and alleviated hippocampal neuronal pathological damages. Besides, Kam could significantly reverse the synaptic transmission related protein expression including PSD95 and NMDAR2B. Further research found that Kam downregulated autophagy markers, P62, ATG5, Beclin1, and LC3-II. Furthermore, 3-MA, autophagy inhibitor, increased the levels of NMDAR2B and PSD95 in Pb-induced PC12 cells, indicating Kam alleviated Pb-induced neurotoxicity through inhibiting autophagy activation. Our results showed that Kam could ameliorate Pb-induced cognitive impairments and neuronal damages by decreasing Pb-induced excess autophagy accumulation.

Association between dietary flavonol intake and mortality risk in the U.S. adults from NHANES database

Using updated National Health and Nutrition Examination Survey (NHANES) follow-up data, and a large nationwide representative sample of adult U.S. citizens, the aim of this study was to explore the relationship between dietary flavonol intake, all-cause and cause-specific mortality risks. In this prospective cohort study based on NHANES (2007-2008, 2009-2010, and 2017-2018), a total of 11,679 participants aged 20 years and above were evaluated. The amount and type of food taken during a 24-h dietary recall were used to estimate dietary flavonol intake, which includes total flavonol, isorhamnetin, kaempferol, myricetin, and quercetin. Each analysis of the weighted data was dealt with in accordance with the NHANES reporting requirements' intricate stratification design. The Cox proportional risk regression model or Fine and Gray competing risks regression model were applied to evaluate all-cause and cause-specific mortality risks, respectively. The follow-up period was calculated using the time interval between the baseline and the death date or December 31, 2019 (whichever occurs first). Each data analysis was performed between October 1, 2023, and October 22, 2023. Dietary flavonol intake included total flavonol, isorhamnetin, kaempferol, myricetin, and quercetin. Up to December 31, 2019, National Death Index (NDI) mortality data were used to calculate mortality from all causes as well as cause-specific causes. A total of 11,679 individuals, which represents 44,189,487 U.S. non-hospitalized citizens, were included in the study; of these participants, 49.78% were male (n = 5816), 50.22% were female (n = 5, 863); 47.56% were Non-Hispanic White (n = 5554), 18.91% were Non-Hispanic Black (n = 2209), 16.23% were Mexican American (n = 1895), and 17.30% were other ethnicity (n = 2021); The mean [SE] age of the sample was 46.93 [0.36] years, with a median follow-up of 7.80 years (interquartile range, 7.55-8.07 years). After adjusting covariates, Cox proportional hazards models and fine and gray competing risks regression models for specific-cause mortality demonstrated that total flavonol intake was associated with all-cause (HR 0.64, 95% CI 0.54-0.75), cancer-specific (HR 0.45, 95% CI 0.28-0.70) and CVD-specific (HR 0.67, 95% CI 0.47-0.96) mortality risks; isorhamnetin intake was associated with all-cause (HR 0.72, 95% CI 0.60-0.86), and cancer-specific (HR 0.62, 95% CI 0.46-0.83) mortality risks; kaempferol intake was associated with all-cause (HR 0.74, 95% CI 0.63-0.86), and cancer-specific (HR 0.62, 95% CI 0.40-0.97) mortality risks; myricetin intake was associated with all-cause (HR 0.77, 95% CI 0.67-0.88), AD-specific (HR 0.34, 95% CI 0.14-0.85), and CVD-specific (HR 0.61, 95% CI 0.47-0.80) mortality risks; quercetin intake was associated with all-cause (HR 0.66, 95% CI 0.54-0.81), cancer-specific (HR 0.54, 95% CI 0.35-0.84), and CVD-specific (HR 0.61, 95% CI 0.40-0.93) mortality risks; there was no correlation observed between dietary flavonol intake and DM-specific mortality. According to the current study, all-cause, AD, cancer, and CVD mortality risks declined with increased dietary flavonoid intake in the U.S. adults. This finding may be related to the anti-tumor, anti-inflammatory, and anti-oxidative stress properties of flavonol.

Integrating Lifestyle Factor Science into Neuropsychological Practice: A National Academy of Neuropsychology Education Paper

OBJECTIVE

The primary aim of this paper is to review evidence and clinical implications related to lifestyle activities associated with promoting brain and cognitive health. Our review targets four key lifestyle factors: physical activity and exercise, social engagement, cognitively stimulating activity, and consuming Mediterranean-style diets.

METHOD

We conducted a critical review of the lifestyle factor literature in the four domains listed earlier. We contextualize this literature review by translating findings, when possible, into evidence-based recommendations to consider when providing neuropsychological services.

RESULTS

There is significant current evidence supporting the role of physical activity and exercise, social engagement, cognitively stimulating activity, and consuming Mediterranean-style diets on positive brain and cognitive health outcomes. While some null findings are present in all four areas reviewed, the weight of the evidence supports the notion that engaging in these activities may promote brain and cognitive functioning.

CONCLUSIONS

Clinical neuropsychologists can have confidence in recommending engagement in physical activity, social activity, and cognitively stimulating activity, and adhering to a Mediterranean-style diet to promote brain and cognitive health. We discuss limitations in existing lifestyle factor research and future directions to enhance the existing evidence base, including additional research with historically underrepresented groups and individuals with neurological conditions.

Effects of the active botanical blend "WKUP GT" on attention and cognitive functions after lunch in healthy volunteers

OBJECTIVES

"WKUP GT", a low caffeine beverage consisting of carob, Guarana, Green Tea and Elderberry extracts was studied on attention and cognitive functions post-lunch in a pilot randomized double blind placebo controlled trial.

METHODS

Thirty healthy volunteers were included in a crossover design trial, presenting five beverages randomly assigned to the following groups: placebo, "WKUP GT" (single, double or triple doses), or "caffeine" as an active control. Hemodynamic measurements were assessed as safety outcomes. The Cambridge Neuropsychological Test Automated Battery (CANTAB), was used to evaluate the patients when beverages were consumed 30 and 120 min after lunch (respectively Delta30 and Delta120 considering baseline).

RESULTS

Drinking "caffeine" or "WKUP GT" after lunch, showed significant improvement (p < 0.05) in rapid visual information processing compared to placebo (Delta120 of "caffeine", "WKUP" single and double). In addition, improvement in Multitasking Test (Delta30 for "WKUP" double, and Delta120 for "caffeine" and "WKUP" triple compared to placebo) was observed. "WKUP" triple also showed significant improvement for "memory" when compared to placebo (Delta120). Compared to "caffeine", WKUP GT did not increase systolic blood pressure.

CONCLUSION

"WKUP GT" showed improvements for attention, memory, psychomotor and executive function tasks after lunch without increase in pulse rate.

Effect of Polyphenol Supplementation on Memory Functioning in Overweight and Obese Adults: A Systematic Review and Meta-Analysis

Negative health consequences of obesity include impaired neuronal functioning and cell death, thus bringing the risk of impaired cognitive functioning. Antioxidant properties of polyphenols offer a possible intervention for overweight people, but evidence for their effectiveness in supporting cognitive functioning is mixed. This review examined evidence from randomized controlled trials concerning the effect of polyphenols on tasks requiring either immediate or delayed retrieval of learned information, respectively, thus controlling for differences in cognitive processes and related neural substrates supporting respective task demands. Searches of the PubMed/Medline, PsycInfo, and Scopus databases identified 24 relevant primary studies with N = 2336 participants having a BMI ≥ 25.0 kg/m2. The participants' mean age for the 24 studies exceeded 60 years. Respective meta-analyses produced a significant summary effect for immediate retrieval but not for delayed retrieval. The present findings support a potential positive effect of chronic supplementation with polyphenols, most notably flavonoids, on immediate retrieval in participants aged over 60 years with obesity being a risk factor for cognitive impairment. We recommend further investigation of this potential positive effect in participants with such risk factors. Future research on all populations should report the phenolic content of the supplementation administered and be specific regarding the cognitive processes tested.

Dietary (Poly)phenols and Cognitive Decline: A Systematic Review and Meta-Analysis of Observational Studies

SCOPE

This study aims to systematically review observational studies investigating the relation between dietary (poly)phenol consumption and various cognitive outcomes.

METHODS AND RESULTS

Embase and PubMed databases are searched from inception to April 2023 for observational studies investigating the relation between dietary (poly)phenol intake and cognitive outcomes. For quantitative analyses, random effects models, subgroup analyses, and dose-response analyses are performed. A total of 37 studies are included in the systematic review. Among (poly)phenols, a higher intake of flavonoids is associated with better cognitive function and lower odds of cognitive decline (although with some exceptions). A quantitative meta-analysis shows an overall inverse association with cognitive impairment and reduced association with the incidence of dementia or related disorders for total flavonoids (relative risk (RR) = 0.83, 95% confidence interval (CI): 0.76, 0.89), anthocyanins (RR = 0.73, 95% CI: 0.60, 0.89), flavones (RR = 0.77, 95% CI: 0.63, 0.94), flavan-3-ols (RR = 0.86, 95% CI: 0.82, 0.91), and flavonols (RR = 0.88, 95% CI: 0.80, 0.96). Data on other (poly)phenolic compounds (i.e., phenolic acids) are promising but too preliminary.

CONCLUSION

Habitual inclusion of flavonoids in the diet may play a preventive role against cognitive disorders.

The role of Caenorhabditis elegans in the discovery of natural products for healthy aging

Covering: 2012 to 2023The human population is aging. Thus, the greatest risk factor for numerous diseases, such as diabetes, cancer and neurodegenerative disorders, is increasing worldwide. Age-related diseases do not typically occur in isolation, but as a result of multi-factorial causes, which in turn require holistic approaches to identify and decipher the mode of action of potential remedies. With the advent of C. elegans as the primary model organism for aging, researchers now have a powerful in vivo tool for identifying and studying agents that effect lifespan and health span. Natural products have been focal research subjects in this respect. This review article covers key developments of the last decade (2012-2023) that have led to the discovery of natural products with healthy aging properties in C. elegans. We (i) discuss the state of knowledge on the effects of natural products on worm aging including methods, assays and involved pathways; (ii) analyze the literature on natural compounds in terms of their molecular properties and the translatability of effects on mammals; (iii) examine the literature on multi-component mixtures with special attention to the studied organisms, extraction methods and efforts regarding the characterization of their chemical composition and their bioactive components. (iv) We further propose to combine small in vivo model organisms such as C. elegans and sophisticated analytical approaches ("wormomics") to guide the way to dissect complex natural products with anti-aging properties.

Flavonols as a Potential Pharmacological Intervention for Alleviating Cognitive Decline in Diabetes: Evidence from Preclinical Studies

Diabetes mellitus is a complex metabolic disease associated with reduced synaptic plasticity, atrophy of the hippocampus, and cognitive decline. Cognitive impairment results from several pathological mechanisms, including increased levels of advanced glycation end products (AGEs) and their receptors, prolonged oxidative stress and impaired activity of endogenous mechanisms of antioxidant defense, neuroinflammation driven by the nuclear factor kappa-light-chain enhancer of activated B cells (NF-κB), decreased expression of brain-derived neurotrophic factor (BDNF), and disturbance of signaling pathways involved in neuronal survival and cognitive functioning. There is increasing evidence that dietary interventions can reduce the risk of various diabetic complications. In this context, flavonols, a highly abundant class of flavonoids in the human diet, are appreciated as a potential pharmacological intervention against cognitive decline in diabetes. In preclinical studies, flavonols have shown neuroprotective, antioxidative, anti-inflammatory, and memory-enhancing properties based on their ability to regulate glucose levels, attenuate oxidative stress and inflammation, promote the expression of neurotrophic factors, and regulate signaling pathways. The present review gives an overview of the molecular mechanisms involved in diabetes-induced cognitive dysfunctions and the results of preclinical studies showing that flavonols have the ability to alleviate cognitive impairment. Although the results from animal studies are promising, clinical and epidemiological studies are still needed to advance our knowledge on the potential of flavonols to improve cognitive decline in diabetic patients.

Flavonoids: the use in mental health and related diseases

Given the current increase in mental and neurological disorders, there is an urgent need to develop alternative treatments for patients. Flavonoids exhibit diverse biological activities, including antioxidant, anti-inflammatory and neuroprotective, and has been considered potential therapies for central nervous system diseases, such as Alzheimer's disease, Parkinson's disease, drug addiction, and stroke. Studies have shown that flavonoids protect neurons from oxidative stress, reduce inflammation, improve brain blood flow and enhance cognitive function. Moreover, its modulation of neurotransmission, such as GABAergic, dopaminergic, serotoninergic, and noradrenergic, has been studied for the treatment of mental disorders that require sedative effects, antidepressants, sleep inducers and anxiety reduction. Although more research is needed to fully understand the mechanisms and potential benefits of these compounds, the use of flavonoids for neurological diseases is a promising avenue for future research and development. This review focuses on major flavonoid subclasses and their applications in central nervous system disorders.

Designing plant flavonoids: harnessing transcriptional regulation and enzyme variation to enhance yield and diversity

Plant synthetic biology has emerged as a powerful and promising approach to enhance the production of value-added metabolites in plants. Flavonoids, a class of plant secondary metabolites, offer numerous health benefits and have attracted attention for their potential use in plant-based products. However, achieving high yields of specific flavonoids remains challenging due to the complex and diverse metabolic pathways involved in their biosynthesis. In recent years, synthetic biology approaches leveraging transcription factors and enzyme diversity have demonstrated promise in enhancing flavonoid yields and expanding their production repertoire. This review delves into the latest research progress in flavonoid metabolic engineering, encompassing the identification and manipulation of transcription factors and enzymes involved in flavonoid biosynthesis, as well as the deployment of synthetic biology tools for designing metabolic pathways. This review underscores the importance of employing carefully-selected transcription factors to boost plant flavonoid production and harnessing enzyme promiscuity to broaden flavonoid diversity or streamline the biosynthetic steps required for effective metabolic engineering. By harnessing the power of synthetic biology and a deeper understanding of flavonoid biosynthesis, future researchers can potentially transform the landscape of plant-based product development across the food and beverage, pharmaceutical, and cosmetic industries, ultimately benefiting consumers worldwide.

Honey and Alzheimer's Disease-Current Understanding and Future Prospects

Alzheimer's disease (AD), a leading cause of dementia, has been a global concern. AD is associated with the involvement of the central nervous system that causes the characteristic impaired memory, cognitive deficits, and behavioral abnormalities. These abnormalities caused by AD is known to be attributed by extracellular aggregates of amyloid beta plaques and intracellular neurofibrillary tangles. Additionally, genetic factors such as abnormality in the expression of APOE, APP, BACE1, PSEN-1, and PSEN-2 play a role in the disease. As the current treatment aims to treat the symptoms and to slow the disease progression, there has been a continuous search for new nutraceutical agent or medicine to help prevent and cure AD pathology. In this quest, honey has emerged as a powerful nootropic agent. Numerous studies have demonstrated that the high flavonoids and phenolic acids content in honey exerts its antioxidant, anti-inflammatory, and neuroprotective properties. This review summarizes the effect of main flavonoid compounds found in honey on the physiological functioning of the central nervous system, and the effect of honey intake on memory and cognition in various animal model. This review provides a new insight on the potential of honey to prevent AD pathology, as well as to ameliorate the damage in the developed AD.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.