Effect of Vitamin B Supplementation on Cognitive Function in the Elderly: A Systematic Review and Meta-Analysis

Vitamin B12 Supplementation in Psychiatric Practice

PURPOSE OF REVIEW

Vitamin B12 (B12, cobalamin) deficiency has been associated with neuropsychiatric symptoms, suggesting a role for B12 supplementation both as a treatment for psychiatric symptoms due to B12 deficiency and as an augmentation strategy for pharmacological treatments of psychiatric disorders. This critical review discusses the major causes of B12 deficiency, the range of psychiatric and non-psychiatric manifestations of B12 deficiency, the indications for testing B12 levels, and the evidence for B12 supplementation for major psychiatric disorders.

RECENT FINDINGS

We find that high-quality evidence shows no benefit to routine B12 supplementation for mild depressive symptoms or to prevent depression. There is very limited evidence on the role of B12 supplementation to augment antidepressants. No high-quality evidence to date suggests a role for routine B12 supplementation in any other major psychiatric disorder. No formal guidelines indicate when clinicians should test B12 levels for common psychiatric symptoms, in the absence of major risk factors for deficiency or cardinal symptoms of deficiency. No robust evidence currently supports routine B12 supplementation for major psychiatric disorders. However, psychiatrists should be aware of the important risk factors for B12 deficiency and should be able to identify symptoms of B12 deficiency, which requires prompt testing, medical workup, and treatment. Testing for B12 deficiency should be considered for atypical or severe psychiatric presentations.

Prevention, Assessment, and Management of Malnutrition in Older Adults with Early Stages of Cognitive Disorders

Malnutrition is common in older adults, and its risk is greater in those living with dementia. Relative to cognitively healthy peers, the prevalence of malnutrition is also increased in individuals with early stages of cognitive disorders owing to pathophysiological, cognitive, and psychosocial changes related to cognitive impairment. Malnutrition is associated with adverse health outcomes, including faster cognitive and functional decline. Here, we provide an overview of the prevention, assessment, and management of malnutrition in older adults, with a special focus on the aspects that are important to consider in individuals with early stages of cognitive disorders. Strategies to prevent malnutrition include systematic screening for malnourishment using validated tools to detect those at risk. If the screening reveals an increased risk of malnutrition, a detailed assessment including the individual's nutritional, medical, and functional status as well as dietary intake should be performed. The management of malnutrition in the early stages of cognitive disorders should be based on the findings of a comprehensive assessment and be personalized according to the individual's specific characteristics. In the article, we also provide an overview of the evidence on vitamin supplements and specific dietary patterns to prevent cognitive decline or attenuate its progression.

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.

Elevated homocysteine levels may moderate and mediate the association between HIV and cognitive impairment among middle-aged and older adults in an underserved population in Baltimore, Maryland

Background: In the antiretroviral therapy (ART) era, HIV-associated neurocognitive disorders (HAND) remain a considerable challenge for people with HIV, yet not all such disorders can be attributed to HIV alone. This study aimed to: (1) identify factors influencing neurocognitive impairment (NCI) utilizing the NIH Toolbox Cognition Battery (NIHTB-CB) as per the revised research criteria for HAND; (2) ascertain the moderating role of high homocysteine levels in the association between NCI and HIV; and (3) assess the mediating effect of elevated homocysteine levels on this association.Methods: We analyzed data from 788 adults (≥45 years) participating in a study on HIV-related comorbidities in underserved Baltimore communities, using NIHTB-CB to gauge neurocognitive performance. Special attention was given to results from the Dimensional Change Card Sort (DCCS) test within the executive function domain during causal mediation analysis.Results: Overall, HIV was not associated with NCI presence. However, HIV was associated with NCI among individuals with homocysteine >14 μmol/L. Furthermore, HIV was both directly and indirectly associated with NCI in DCCS test scores. Notably, the mediating role of elevated homocysteine in DCCS scores was only observable among individuals who had never used cocaine or had used it for ≤ 10 years, suggesting that extended cocaine use may have a substantial influence on cognitive performance.Conclusions: The findings from this study suggest elevated homocysteine levels may moderate and mediate the association between HIV and neurocognitive impairment.

A Combinational Therapy for Preventing and Delaying the Onset of Alzheimer's Disease: A Focus on Probiotic and Vitamin Co-Supplementation

Alzheimer's disease is a progressive neurodegenerative disorder with a complex etiology, and effective interventions to prevent or delay its onset remain a global health challenge. In recent years, there has been growing interest in the potential role of probiotic and vitamin supplementation as complementary strategies for Alzheimer's disease prevention. This review paper explores the current scientific literature on the use of probiotics and vitamins, particularly vitamin A, D, E, K, and B-complex vitamins, in the context of Alzheimer's disease prevention and management. We delve into the mechanisms through which probiotics may modulate gut-brain interactions and neuroinflammation while vitamins play crucial roles in neuronal health and cognitive function. The paper also examines the collective impact of this combinational therapy on reducing the risk factors associated with Alzheimer's disease, such as oxidative stress, inflammation, and gut dysbiosis. By providing a comprehensive overview of the existing evidence and potential mechanisms, this review aims to shed light on the promise of probiotic and vitamin co-supplementation as a multifaceted approach to combat Alzheimer's disease, offering insights into possible avenues for future research and clinical application.

Biological age as estimated by baseline circulating metabolites is associated with incident diabetes and mortality

OBJECTIVES

It is unclear how metabolomic assessment of biological aging performs in non-White populations and whether such an approach can predict future mortality. We aimed to evaluate the application of serum metabolomics combined with machine learning methodologies to predict incident diabetes and mortality in a Thai population.

DESIGN, SETTING AND PARTICIPANTS

We analyzed serum samples and mortality data over 11 years from among 454 participants with no previous history of diabetes and with a fasting plasma glucose ≥85th percentile (5.4 mmol/L) but <7 mmol/L.

MEASUREMENTS

Untargeted serum metabolomics were assessed using liquid chromatography/mass spectrometry. A deep artificial neural network was used to predict biological age based on serum metabolite profiles and chronological age.

RESULTS

The mean age of participants was 40.5 ± 6.4 years, and 70.8% were men. We found a significant positive correlation between metabolomic age and chronological age (r = 0.71, P < 0.001). After 5 years, 61 of 404 participants with available glycated hemoglobin status (15.1%) progressed to diabetes. Chronological age was associated with incident diabetes but was not significant (P = 0.08), after adjusting for BMI and sex. Metabolomic age was significantly related to incident diabetes after controlling for BMI and sex (P < 0.05). Over the 11-year follow-up, 10 participants died owing to non-accidental causes. When metabolomic age and chronological age were included together in the model, metabolomic age (but not chronological age) was associated with mortality, independent of age, sex, and BMI. Among all identifiable metabolites, beta-D-mannosylphosphodecaprenyl and phosphatidylserines were the five leading metabolites associated with mortality.

CONCLUSION

We concluded that serum metabolomic profile was associated with incident diabetes as well as mortality over our 11-year study period, which may render it potentially useful in assessing biological aging in humans.

Nutrition, Immunity and Aging: Current Scenario and Future Perspectives in Neurodegenerative Diseases

Aging is a gradual decline of physiological function and tissue homeostasis and, in many instances, is related to increased (neuro)-degeneration, together with inflammation, becoming one of the most important risks for developing neurodegenerative diseases. Certain individual nutrients or foods in combination may counteract aging and associated neurodegenerative diseases by promoting a balance between the pro- and anti-inflammatory responses. Thus, nutrition could represent a powerful modulator of this fine balance, other than a modifiable risk factor to contrast inflammaging. This narrative review explores from a broad perspective the impact of nutrition on the hallmarks of aging and inflammation in Alzheimer's disease (AD), Parkinson's disease (PD) and Amyotrophic Lateral Sclerosis Syndrome (ALS), starting from nutrients up to single foods and complex dietary patterns.

The effects of the interplay between vitamins, antibiotics, and gut microbiota on the pathogenesis and progression of dementia: A systematic review and meta-analysis

Background

Given that there is already evidence of a neural network that connects the brain and gut and that the gut microbiota actively modulates gut health, it is crucial to know which foods, supplements, and medications to use or avoid when treating any disease that causes dementia or cognitive impairment. Previous research has examined the relationships between vitamins, antibiotics, and gut microbiota and the correlations between these factors and dementia. The question arises of how these three factors interact together and if evidence suggests one element is more important than the others in the pathogenesis and development of dementia.

Methods

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards were followed when conducting this review. The papers' publication dates varied from (2012-2022). Cochrane/EMBASE, PEDro, and PubMed/Medline databases were searched. The precise terms "gut microbiota," vitamins," antibiotics," and "dementia" were included in the search method, along with the conjunctions "OR" and "AND."

Results

Gut dysbiosis has a significant impact on cognition, brain function, and the development and progression of dementia. The two most popular probiotics used in studies linked to cognition benefits were Lactobacillus and Bifidobacterium. Numerous scales were used to evaluate cognition, but the mini-mental state examination was the most popular, and the most prevalent impairment was Alzheimer's disease. The supplements with the most significant impact on gut microbiota were vitamin B-12 and folic acid.

Conclusion

This systematic review concluded that vitamins, gut microbiota and antibiotics have a close association with the development of dementia. More research is required to establish causality and elucidate the underlying mechanisms because there is still little evidence connecting the interactions of vitamins, medications, and microbiota with dementia. The complexity of interactions between genetics, lifestyle factors, and comorbidities, as well as the heterogeneity of dementia, may make it more challenging to interpret the findings.

Intermittent Fasting on Neurologic Diseases: Potential Role of Gut Microbiota

As the global population ages, the prevalence of neurodegenerative diseases is surging. These disorders have a multifaceted pathogenesis, entwined with genetic and environmental factors. Emerging research underscores the profound influence of diet on the development and progression of health conditions. Intermittent fasting (IF), a dietary pattern that is increasingly embraced and recommended, has demonstrated potential in improving neurophysiological functions and mitigating pathological injuries with few adverse effects. Although the precise mechanisms of IF's beneficial impact are not yet completely understood, gut microbiota and their metabolites are believed to be pivotal in mediating these effects. This review endeavors to thoroughly examine current studies on the shifts in gut microbiota and metabolite profiles prompted by IF, and their possible consequences for neural health. It also highlights the significance of dietary strategies as a clinical consideration for those with neurological conditions.

Four-week administration of an energy and protein dense oral nutritional supplement improves micronutrient concentrations but does not completely correct deficiencies in institutionalized malnourished older adults

Introduction

Poor food intake is common among elderly living in nursing homes, leading to micronutrient deficiency (MD). There are no recommendations for the management of MD in malnourished older adults.

Methods

We conducted a single arm, open-label, multicenter interventional study in institutionalized malnourished older adults to describe the effect of a 4-week daily energy and protein dense oral nutritional supplementation (ONS, 600 kcal, 30 g protein per unit) containing 50% of the recommended daily micronutrient intake on micronutrient status. Plasma concentrations of vitamins (A, B9, B12, C, E), magnesium (Mg), selenium (Se) and zinc (Zn), and erythrocyte vitamin B9 were measured at baseline and after 4 weeks.

Results

Forty-six participants completed the study (age 87.4 ± 6.6). At baseline, the most frequent MD were Se (48%), Zn (35%), Mg (24%) and vitamin C (24%). Plasma concentrations of vitamins B9, B12, C and E, Mg, Se and Zn significantly increased and the proportion of subjects with at least one MD decreased (p = 0.006). However, after 4 weeks, 40% of subjects still had at least one MD.

Discussion

ONS consumption improved micronutrient status but did not correct MD in all participants. Our data suggest that the prescription of vitamin, mineral and trace element supplementation should be considered in institutionalized malnourished older adults in addition to high energy and high protein ONS.

Alzheimer's Disease Treatment: The Search for a Breakthrough

As the search for modalities to cure Alzheimer's disease (AD) has made slow progress, research has now turned to innovative pathways involving neural and peripheral inflammation and neuro-regeneration. Widely used AD treatments provide only symptomatic relief without changing the disease course. The recently FDA-approved anti-amyloid drugs, aducanumab and lecanemab, have demonstrated unclear real-world efficacy with a substantial side effect profile. Interest is growing in targeting the early stages of AD before irreversible pathologic changes so that cognitive function and neuronal viability can be preserved. Neuroinflammation is a fundamental feature of AD that involves complex relationships among cerebral immune cells and pro-inflammatory cytokines, which could be altered pharmacologically by AD therapy. Here, we provide an overview of the manipulations attempted in pre-clinical experiments. These include inhibition of microglial receptors, attenuation of inflammation and enhancement of toxin-clearing autophagy. In addition, modulation of the microbiome-brain-gut axis, dietary changes, and increased mental and physical exercise are under evaluation as ways to optimize brain health. As the scientific and medical communities work together, new solutions may be on the horizon to slow or halt AD progression.

The Effects of Methylfolate on Cognitive Decline and Dementia: A Protocol for Systematic Review and Meta-Analysis

INTRODUCTION

Dementia and cognitive decline are highly prevalent in later life and are growing public health concerns worldwide due to the increasing aging population. Individuals diagnosed with dementia have reduced mental function, resulting in social and cognitive skill deficits, increased dependence, and reduced autonomy-all of which are conditions associated with higher mortality rates. This systematic review aims to assess the effectiveness of treating dementia and cognitive decline with methylfolate. The main outcomes analyzed will be dementia and changes in cognitive function measured by different instruments in older adults treated with methylfolate. Secondary outcomes, such as inflammatory markers, plasma folic-acid levels, and total homocysteine, will also be assessed.

METHODS AND ANALYSIS

This study will be carried out in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This protocol is registered in the International Prospective Registry of Systematic Reviews, under the code CRD42021275755. We will include clinical trials conducted with older adults diagnosed with dementia or cognitive decline and treated with folic acid. The searches will be conducted on the PubMed, Scopus, and Embase databases, and the articles will be selected by reading their titles and abstracts first, followed by the full text. The quality of the selected studies will be assessed using GRADE and the risk of bias will be assessed using the Downs-and-Black method.

ETHICS AND DISSEMINATION

The results will be presented at scientific conferences and disseminated by publishing a scientific article in an international English-language journal. We hope to find robust and significant evidence regarding the effectiveness of methylfolate supplementation in improving dementia symptoms and cognitive decline among older adults. By systematizing this evidence and possibly performing a meta-analysis study, we expect to significantly contribute to the treatment of this health problem, reduce mortality, and improve the quality of life and health of this population, boosting the development of medical protocols capable of reducing the financial effects of public health.

Physiological Associations between Vitamin B Deficiency and Diabetic Kidney Disease

The number of people living with chronic kidney disease (CKD) is growing as our global population continues to expand. With aging, diabetes, and cardiovascular disease being major harbingers of kidney disease, the number of people diagnosed with diabetic kidney disease (DKD) has grown concurrently. Poor clinical outcomes in DKD could be influenced by an array of factors-inadequate glycemic control, obesity, metabolic acidosis, anemia, cellular senescence, infection and inflammation, cognitive impairment, reduced physical exercise threshold, and, importantly, malnutrition contributing to protein-energy wasting, sarcopenia, and frailty. Amongst the various causes of malnutrition in DKD, the metabolic mechanisms of vitamin B (B1 (Thiamine), B2 (Riboflavin), B3 (Niacin/Nicotinamide), B5 (Pantothenic Acid), B6 (Pyridoxine), B8 (Biotin), B9 (Folate), and B12 (Cobalamin)) deficiency and its clinical impact has garnered greater scientific interest over the past decade. There remains extensive debate on the biochemical intricacies of vitamin B metabolic pathways and how their deficiencies may affect the development of CKD, diabetes, and subsequently DKD, and vice-versa. Our article provides a review of updated evidence on the biochemical and physiological properties of the vitamin B sub-forms in normal states, and how vitamin B deficiency and defects in their metabolic pathways may influence CKD/DKD pathophysiology, and in reverse how CKD/DKD progression may affect vitamin B metabolism. We hope our article increases awareness of vitamin B deficiency in DKD and the complex physiological associations that exist between vitamin B deficiency, diabetes, and CKD. Further research efforts are needed going forward to address the knowledge gaps on this topic.

Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial

INTRODUCTION

Dietary supplements are touted for cognitive protection, but supporting evidence is mixed. COSMOS-Mind tested whether daily administration of cocoa extract (containing 500 mg/day flavanols) versus placebo and a commercial multivitamin-mineral (MVM) versus placebo improved cognition in older women and men.

METHODS

COSMOS-Mind, a large randomized two-by-two factorial 3-year trial, assessed cognition by telephone at baseline and annually. The primary outcome was a global cognition composite formed from mean standardized (z) scores (relative to baseline) from individual tests, including the Telephone Interview of Cognitive Status, Word List and Story Recall, Oral Trail-Making, Verbal Fluency, Number Span, and Digit Ordering. Using intention-to-treat, the primary endpoint was change in this composite with 3 years of cocoa extract use. The pre-specified secondary endpoint was change in the composite with 3 years of MVM supplementation. Treatment effects were also examined for executive function and memory composite scores, and in pre-specified subgroups at higher risk for cognitive decline.

RESULTS

A total of 2262 participants were enrolled (mean age = 73y; 60% women; 89% non-Hispanic White), and 92% completed the baseline and at least one annual assessment. Cocoa extract had no effect on global cognition (mean z-score = 0.03, 95% CI: -0.02 to 0.08; P = .28). Daily MVM supplementation, relative to placebo, resulted in a statistically significant benefit on global cognition (mean z = 0.07, 95% CI 0.02 to 0.12; P = .007), and this effect was most pronounced in participants with a history of cardiovascular disease (no history: 0.06, 95% CI 0.01 to 0.11; history: 0.14, 95% CI -0.02 to 0.31; interaction, nominal P = .01). Multivitamin-mineral benefits were also observed for memory and executive function. The cocoa extract by MVM group interaction was not significant for any of the cognitive composites.

DISCUSSION

Cocoa extract did not benefit cognition. However, COSMOS-Mind provides the first evidence from a large, long-term, pragmatic trial to support the potential efficacy of a MVM to improve cognition in older adults. Additional work is needed to confirm these findings in a more diverse cohort and to identify mechanisms to account for MVM effects.

HIGHLIGHTS

COSMOS-Mind was a large simple pragmatic randomized clinical trial in older adults conducted by mail and telephone. The trial used a two-by-two factorial design to assess treatment effects of two different interventions within a single large study. We found no cognitive benefit of daily cocoa extract administration (containing 500 mg flavanols) for 3 years. Daily multivitamin-mineral (MVM) supplementation for 3 years improved global cognition, episodic memory, and executive function in older adults. The MVM benefit appeared to be greater for adults with cardiovascular disease.

Effectiveness of vitamin-B supplements on cognition in older adults: A meta-analysis

OBJECTIVES

We aimed to investigate the efficacy of B-vitamin and folic acid supplementation in slowing down cognitive function decline among older adults.

METHODS

We searched databases for trials comparing B-vitamin and folate supplementation versus placebo in older adults identified with or without impaired cognition.

RESULTS

23 articles were eligible and included in this meta-analysis. The mean difference (MD) in homocysteine levels was significant between the compared groups (MD:-4.52; 95%CI:-5.41 to 3.63, P < 0.001). However, the difference in the Mini-Mental State Examination (MMSE) was non-significant between the compared groups with or without cognitive impairment (MD:0.19; 95%CI: -0.148 to 0.531, P = 0.27), and (MD:0.04; 95%CI:-0.1 to 0.18, P = 0.59), respectively. The difference in Clinical Dementia Rating-sum of box (CDR-SOB) scores was non-significant (MD:-0.16; 95%CI:-0.49 to 0.18; P = 0.36).

CONCLUSIONS

B-vitamin and folate supplementations significantly reduced homocysteine levels. However, it failed to provide significant benefits over placebo in preventing or slowing the decline in cognitive function.

The role of diet in managing menopausal symptoms: A narrative review

Menopause is a natural stage that occurs when women stop menstruating, during which many women experience physical and psychological symptoms that can affect their quality of life and ability to work. Dietary modifications and food supplements may be explored by some women as alternatives to hormone replacement therapy, although existing reviews and expert position statements have given this limited consideration. This narrative review summarises the current evidence for dietary patterns, and botanical and food supplements, in the management of common menopausal symptoms, including vasomotor symptoms (VMS; hot flushes; night sweats), changes in bodyweight and composition, psychological symptoms (depression; anxiety; cognitive changes), sleep disturbances, joint pain, skin changes and urogenital symptoms. Soy isoflavones may reduce the frequency and/or severity of VMS, although results are inconsistent, and it is unclear whether dietary and supplemental sources have comparable effects. Adopting a healthier dietary pattern may support a healthy bodyweight and benefit VMS. However, evidence suggesting dietary patterns may benefit depression, anxiety, and cognition remains largely observational. While some botanicals, such as black cohosh and St John's Wort, have been reported in some studies to alleviate symptoms (such as VMS and depression), these are not currently recommended due to uncertainty about the appropriate dose and preparation, and potential safety concerns. Evidence for other symptoms is currently too limited to draw conclusions. While further trials at different menopausal stages are needed, adopting a healthier dietary pattern in accordance with dietary guidelines is likely to help support women's health before, during and after the menopausal transition.

Folic acid ameliorates synaptic impairment following cerebral ischemia/reperfusion injury via inhibiting excessive activation of NMDA receptors

Folic acid, a water-soluble B-vitamin, has been demonstrated to decrease the risk of first stroke and improve its poor prognosis. However, the molecular mechanisms responsible for the beneficial effect of folic acid on recovery from ischemic insult remain largely unknown. Excessive activation of the N-methyl-d-aspartate receptors (NMDARs) has been shown to trigger synaptic dysfunction and excitotoxic neuronal death in ischemic brains. Here, we hypothesized that the effects of folic acid on cognitive impairment may involve the changes in synapse loss and NMDAR expression and function following cerebral ischemia/reperfusion injury. The ischemic stroke models were established by middle cerebral artery occlusion/reperfusion (MCAO/R) and by oxygen-glucose deprivation and reperfusion (OGD/R)-treated primary neurons. The results showed that folic acid supplemented diets (8.0 mg/kg for 28 days) improved cognitive performances of rats after MCAO/R. Folic acid also caused a reduction in the number of neuronal death, an increase in the number of synapses and the expressions of synapse-related proteins including SNAP25, Syn, GAP-43 and PSD95, and a decrease in p-CAMKII expression in ischemic brains. Similar changes in synaptic functions were observed in folic acid (32 µM)-treated OGD/R neurons. Furthermore, NMDA treatment reduced folic acid-induced upregulations of synapse-associated proteins and Ca²⁺ influx, whereas downregulations of NMDARs by NR1 or both NR2A and NR2B siRNA further enhanced the expressions of synapse-related proteins raised by folic acid in OGD/R neurons. Our findings suggest that folic acid improves cognitive dysfunctions and ameliorates ischemic brain injury by strengthening synaptic functions via the NMDARs.

Vitamin B12: For more than just the treatment of megaloblastic anemia?

Vitamin B12, or cobalamin, belongs to the group of water-soluble vitamins and is ingested through food of animal origin such as eggs, milk, red meat and poultry, fish, and shellfish. Its clinical indication is the treatment of hypovitaminosis B12 administered orally or intramuscularly in the form of hydroxocobalamin. Hypovitaminosis B12 is mainly caused by deficient dietary intake (individuals with malnutrition, vegetarians or vegans, older adults, pregnant people, individuals with alcohol use disorder); when intestinal absorption is reduced (atrophic gastritis, malabsorption syndrome, gastrointestinal surgery); and for causes associated with the intake of drugs (antacids, metformin). Hypervitaminosis B12 has been associated with renal failure; liver diseases such as cirrhosis and acute-phase hepatitis; alcohol use disorder with or without liver involvement; solid tumors of the lung, liver, esophagus, pancreas, and colorectum; and in hematological malignancies such as leukemia and bone marrow dysplasia.

B vitamin intakes modify the association between particulate air pollutants and incidence of all-cause dementia: Findings from the Women's Health Initiative Memory Study

INTRODUCTION

Particulate air pollutants may induce neurotoxicity by increasing homocysteine levels, which can be lowered by high B vitamin intakes. Therefore, we examined whether intakes of three B vitamins (folate, B12 , and B6 ) modified the association between PM2.5 exposure and incidence of all-cause dementia.

METHODS

This study included 7183 women aged 65 to 80 years at baseline. B vitamin intakes from diet and supplements were estimated by food frequency questionnaires at baseline. The 3-year average PM2.5 exposure was estimated using a spatiotemporal model.

RESULTS

During a mean follow-up of 9 years, 342 participants developed all-cause dementia. We found that residing in locations with PM2.5 exposure above the regulatory standard (12 μg/m3 ) was associated with a higher risk of dementia only among participants with lower intakes of these B vitamins.

DISCUSSION

This is the first study suggesting that the putative neurotoxicity of PM2.5 exposure may be attenuated by high B vitamin intakes.

Diet, Polyphenols, and Human Evolution

Although diet has contributed significantly to the evolution of human beings, the composition of the diet that has most affected this phenomenon is still an open issue. Diet has undoubtedly participated in the acquisition of the skills that underlie the differentiation of humans from other animal species and in this context the development of the nervous system has played a primary role. This paper aimed to: (1) outline the relationship between diet and human evolution; (2) evaluate how a variation in food consumption may have contributed to the enhancement of cognitive and adaptive capacities. The most widespread diet among the ancient populations that showed the highest levels of civilization (that is well-organized societies, using advanced technical tools, and promoting art and science) was very close to what is now defined as the Mediterranean diet. This suggests that a dietary approach typical of the Mediterranean basin (little meat and some fish; abundant cereals, legumes, fruit, vegetables and wine) significantly increased the intake of antioxidant molecules, including polyphenols, which along with other factors may have modulated the cognitive evolution of humans.

Plants, Plants, and More Plants: Plant-Derived Nutrients and Their Protective Roles in Cognitive Function, Alzheimer’s Disease, and Other Dementias

Background and Objectives: Alzheimer’s disease (AD) is the most common form of dementia, with the risk of developing it attributed to non-modifiable and modifiable factors. Currently, there is no cure for AD. A plant-based diet may protect against cognitive decline, due to the effects of plant-based nutrients such as vitamins, antioxidants, and fiber. The aim of the review is to summarize current literature on plant-based nutrients and their impact on cognition. Materials and Methods: A search was conducted on PubMed for clinical and murine studies, using combinations of the following words: “Alzheimer’s disease”, “dementia”, “cognition”, “plant-based diet”, “mild cognitive impairment”, “vitamin B”, “vitamin C”, “vitamin E, “beta carotene”, “antioxidants”, “fiber”, “vitamin K”, “Mediterranean diet”, “vitamin D”, and “mushrooms”. Results and Conclusions: A diet rich in vitamin B and antioxidants can benefit the cognitive functions of individuals as shown in randomized clinical trials. Vitamin K is associated with improved cognition, although large randomized controlled trials need to be done. Fiber has been shown to prevent cognitive decline in animal studies. Vitamin D may contribute to cognitive health via anti-inflammatory processes. Several medical organizations have recommended a plant-based diet for optimizing cognitive health and potentially helping to prevent dementia.

Nonalcoholic Fatty Liver Disease and Altered Neuropsychological Functions in Patients with Subcortical Vascular Dementia

NAFLD is the most common cause of abnormality in liver function tests. NAFLD is considered a potential cardiovascular risk factor and is linked to cardiovascular risk factors such as obesity, hypertension, type 2 diabetes, and dyslipidemia. Few previous studies have investigated whether NAFLD could be independently associated with cognitive impairment. The current study aims to find a possible role of NAFLD in the development of subcortical vascular dementia (sVaD). We considered NAFLD as a possible independent vascular risk factor or, considering its metabolic role, associated with other commonly accepted sVaD risk factors, i.e., lack of folate, vitamin B12, and vitamin D-OH25, and increased levels of homocysteine. We studied 319 patients diagnosed with sVaD. All patients underwent an abdominal ultrasound examination to classify steatosis into four levels (1-none up to 4-severe). sVaD patients were divided into two groups according to the presence or absence of NAFLD. Our results demonstrated a strong correlation between NAFLD and sVaD. Patients with the two comorbidities had worse neuropsychological outcomes and a worse metabolic profile. We also found a robust relationship between NAFLD and severe vitamin B12, folate, vitamin D hypovitaminosis, and higher hyperhomocysteinemia levels. This way, it is evident that NAFLD contributes to a more severe metabolic pathway. However, the strong relationship with the three parameters (B12, folate and vitamin D, and homocysteinemia) suggests that NAFLD can contribute to a proinflammatory condition.

The potential role of beef and nutrients found in beef on outcomes of wellbeing in healthy adults 50 years of age and older: A systematic review of randomized controlled trials

Shifts in wellbeing and health occur as we age. As life expectancy increases, maintenance of wellbeing and health becomes increasingly important. Nutrients found in beef are associated with outcomes of wellbeing such as physical and cognitive function, lean body mass, and mood in older adults and individuals with chronic disease. However, it is unclear how beef and nutrients found in beef impact wellbeing in healthy adults ≥50 years of age. This study systematically reviewed evidence linking the intake of beef and nutrients found in beef to markers of wellbeing in healthy adults. PubMed, CINAHL, and Web of Science were searched up to August 31, 2021 for eligible randomized controlled trials (RCTs). Nutrients included in the analysis were beef, red meat, dietary protein, essential amino acids, branched chain amino acids, tryptophan, arginine, cysteine, glycine, glutamate, vitamin B6, vitamin B12, choline, zinc, and iron. We identified nine RCTs with results from 55 measurements of markers of wellbeing. An overall positive effect was found of beef and beef's nutrients on wellbeing. There was an overall positive effect of amino acids and protein on wellbeing, with no effect of arginine, vitamin B-12, leucine, and zinc. Physical function was also influenced by beef and nutrients found in beef. Eight of the studies found focused on specific nutrients found in beef, and not beef itself in older adults with one or more chronic diseases. This study identified a need for further research regarding the effect of beef and nutrients found in beef on defined functional outcomes of wellbeing in healthy adults ≥50 years of age.

Non-Linear Association between Folate/Vitamin B12 Status and Cognitive Function in Older Adults

Although folate and vitamin B12 status have long been implicated in cognitive function, there is no consensus on the threshold of folate and vitamin B12 for assessing their impacts on cognition. The goal of this study was to detail the association between folate and vitamin B12 with cognitive performance. We analyzed cross-sectional data of older adults (≥60 y; n = 2204) from the NHANES (National Health and Nutrition Examination Surveys) cohort from 2011–2014. The restricted cubic spline model was used for describing the associations between serum total folate, RBC folate, 5-methyltetrahydrofolate, and vitamin B12 and the Consortium to Establish a Registry for Alzheimer’s Disease Word Learning (CERAD-WL) and Delayed Recall (CERAD-DR) tests, the Animal Fluency (AF) test, and the Digit Symbol Substitution Test (DSST), respectively. Older adults with a different folate and vitamin B12 status were clustered by artificial intelligence unsupervised learning. The statistically significant non-linear relationships between the markers of folate or vitamin B12 status and cognitive function were found after adjustments for potential confounders. Inverse U-shaped associations between folate/vitamin B12 status and cognitive function were observed, and the estimated breakpoint was described. No statistically significant interaction between vitamin B12 and folate status on cognitive function was observed in the current models. In addition, based on the biochemical examination of these four markers, older adults could be assigned into three clusters representing relatively low, medium, and high folate/vitamin B12 status with significantly different scores on the CERAD-DR and DSST. Low or high folate and vitamin B12 status affected selective domains of cognition, and was associated with suboptimal cognitive test outcomes.

The Roles of Long-Term Hyperhomocysteinemia and Micronutrient Supplementation in the AppNL–G–F Model of Alzheimer’s Disease

A causal contribution of hyperhomocysteinemia to cognitive decline and Alzheimer’s disease (AD), as well as potential prevention or mitigation of the pathology by dietary intervention, have frequently been subjects of controversy. In the present in vivo study, we attempted to further elucidate the impact of elevated homocysteine (HCys) and homocysteic acid (HCA) levels, induced by dietary B-vitamin deficiency, and micronutrient supplementation on AD-like pathology, which was simulated using the amyloid-based App^NL–G–F knock-in mouse model. For this purpose, cognitive assessment was complemented by analyses of ex vivo parameters in whole blood, serum, CSF, and brain tissues from the mice. Furthermore, neurotoxicity of HCys and HCA was assessed in a separate in vitro assay. In confirmation of our previous study, older App^NL–G–F mice also exhibited subtle phenotypic impairment and extensive cerebral amyloidosis, whereas dietary manipulations did not result in significant effects. As revealed by proximity extension assay-based proteome analysis, the App^NL–G–F genotype led to an upregulation of AD-characteristic neuronal markers. Hyperhomocysteinemia, in contrast, indicated mainly vascular effects. Overall, since there was an absence of a distinct phenotype despite both a significant amyloid-β burden and serum HCys elevation, the results in this study did not corroborate the pathological role of amyloid-β according to the “amyloid hypothesis,” nor of hyperhomocysteinemia on cognitive performance. Nevertheless, this study aided in further characterizing the App^NL–G–F model and in elucidating the role of HCys in diverse biological processes. The idea of AD prevention with the investigated micronutrients, however, was not supported, at least in this mouse model of the disease.

Effects of Leisure-Time Physical Activity on Cognitive Reserve Biomarkers and Leisure Motivation in the Pre-Diabetes Elderly

The purpose of this study was to investigate the change in cognitive reserve biomarkers of the pre-diabetic individual according to the types of leisure-time physical activity (aerobic or resistance physical activity). The research subjects (n = 184) who participated in the survey were pre-diabetic and diabetic patients who were visiting university hospitals and welfare centers. The intervention subjects (n = 36) who were elderly females with pre-diabetes volunteered to participate in the study by performing regular physical exercise (aerobic or resistance exercise). The study participants were 65 years of age or older with pre-diabetes defined by a glycated hemoglobin (HbA1c) level of (5.7−6.4)%. All research subjects performed motivation and stress questionnaire survey. All intervention subjects participated in leisure-time physical activity (LTPA) for 12 weeks. Body composition, HbA1c, and cognitive reserve biomarkers were measured at baseline, and at 6 and 12 weeks. LTPA motivation confirmed that the LTPA participants had a high level of motivation. Stress confirmed that the stress level of LTPA participants was low. Two-way within-factor ANOVA revealed significant group × time interaction for weight (p < 0.05), BMI (p < 0.01), % fat (p < 0.001), SBP (p < 0.05), HbA1c (p < 0.001), BDNF (p < 0.001), and Beta-Amyloid 1−42 (p < 0.001). In both physical activity groups, HbA1c (p < 0.001), NGF (p < 0.05), BDNF (p < 0.05), and Cathepsin B (p < 0.05) improved significantly at 12 weeks, compared to baseline and 6 weeks. In the resistance physical activity group, Beta-Amyloid 1−42 (p < 0.01) and Homocysteine (p < 0.05) significantly decreased at 12 weeks, compared to baseline and at 6 weeks. The LTPA showed high levels of integrated and identified regulation among leisure motive types, and the level of stress was found to be low. The LTPA is effective in reducing the HbA1c levels of the pre-diabetes elderly. In addition, the pre-diabetes elderly were found to have increased NGF, BDNF, and cathepsin B, and decreased Beta-Amyloid 1−42 and homocysteine. Regular leisure-time physical activity has a positive effect on cognitive reserve biomarkers through improving glycemic control by reducing weight and % fat in the pre-diabetes elderly.

Influences of Vitamin B12 Supplementation on Cognition and Homocysteine in Patients with Vitamin B12 Deficiency and Cognitive Impairment

Vitamin B12 deficiency is associated with cognitive impairment, hyperhomocysteinemia, and hippocampal atrophy. However, the recovery of cognition with vitamin B12 supplementation remains controversial. Of the 1716 patients who visited our outpatient clinic for dementia, 83 had vitamin B12 deficiency. Among these, 39 patients (mean age, 80.1 ± 8.2 years) had undergone Mini-Mental State Examination (MMSE) and laboratory tests for vitamin B12, homocysteine (Hcy), and folic acid levels. The hippocampal volume was estimated using the z-score of the MRI-voxel-based specific regional analysis system for Alzheimer’s disease. This is multi-center, open-label, single-arm study. All the 39 patients were administered vitamin B12 and underwent reassessment to measure the retested for MMSE and Hcy after 21−133 days (median = 56 days, interquartile range (IQR) = 43−79 days). After vitamin B12 supplementation, the mean MMSE score improved significantly from 20.5 ± 6.4 to 22.9 ± 5.5 (p < 0.001). Hcy level decreased significantly from 22.9 ± 16.9 nmol/mL to 11.5 ± 3.9 nmol/mL (p < 0.001). Significant correlation was detected between the extent of change in MMSE scores and baseline Hcy values. The degree of MMSE score was not correlated with hippocampal atrophy assessed by the z-score. While several other factors should be considered, vitamin B12 supplementation resulted in improved cognitive function, at least in the short term, in patients with vitamin B12 deficiency.

Can Nutrients and Dietary Supplements Potentially Improve Cognitive Performance Also in Esports?

Factors influencing brain function and cognitive performance can be critical to athletic performance of esports athletes. This review aims to discuss the potential beneficial effects of micronutrients, i.e., vitamins, minerals and biologically active substances on cognitive functions of e-athletes. Minerals (iodine, zinc, iron, magnesium) and vitamins (B vitamins, vitamins E, D, and C) are significant factors that positively influence cognitive functions. Prevention of deficiencies of the listed ingredients and regular examinations can support cognitive processes. The beneficial effects of caffeine, creatine, and probiotics have been documented so far. There are many plant products, herbal extracts, or phytonutrients that have been shown to affect precognitive activity, but more research is needed. Beetroot juice and nootropics can also be essential nutrients for cognitive performance. For the sake of players’ eyesight, it would be useful to use lutein, which, in addition to improving vision and protecting against eye diseases, can also affect cognitive functions. In supporting the physical and mental abilities of e-athletes the base is a well-balanced diet with adequate hydration. There is a lack of sufficient evidence that has investigated the relationship between dietary effects and improved performance in esports. Therefore, there is a need for randomized controlled trials involving esports players.

Low folate predicts accelerated cognitive decline: 8-year follow-up of 3140 older adults in Ireland

OBJECTIVE

To examine associations of plasma folate concentrations and risk of global and domain-specific cognitive decline in older people.

METHODS

Data of 3140 participants from The Irish Longitudinal Study on Ageing (TILDA), a nationally-representative cohort of adults aged ≥50 years were used over 8-year follow-up. Biannual cognitive assessments included the Mini-Mental State Examination (MMSE), verbal fluency and immediate and delayed word recall tests (Waves 1-5) and the Montreal Cognitive Assessment, (MoCA) (Waves 1 and 3). Plasma folate concentrations were measured in stored blood collected at baseline. Mixed effects Poisson and linear regression determined associations between baseline folate concentrations and cognition.

RESULTS

In multivariable-adjusted models of those aged ≥50 years at baseline, low folate at baseline (<11.2 nmol/L) was associated with higher proportions of MMSE errors (incidence rate ratio [IRR] = 1.10; 95% confidence interval [CI] (1.00, 1.21), lowest vs. highest quintile) over 8 years. Plasma folate <21.8 nmol/L predicted declines in episodic memory for immediate (beta [β] = -0.26; 95% CI (-0.48, -0.03), β = -0.29; 95% CI (-0.50, 0.08) and β = -0.29; (-0.50, -0.08), for lowest three vs. highest quintile) and delayed recall (β = -0.20; 95% CI (-0.38, -0.01), β = -0.18; 95% CI (-0.37, -0.01) and β = -0.19; (-0.36, -0.01) lowest three vs. highest quintile). There were no significant associations in a subsample aged ≥65 years.

CONCLUSION

In those aged ≥50 years, lower concentrations of folate may have differential relationships with cognitive domains. Folate <11.2 nmol/L predicted a decline in global cognitive function, while <21.8 nmol/L predicted poorer episodic memory. Low folate was associated with accelerated decline in cognitive function and is an important marker for cognitive decline among older people.

Cognitive Impairment and Its Associated Factors in Older Adults Living in High and Low Altitude Areas: A Comparative Study

BACKGROUND

Cognitive impairment is a major health concern in older adults. Few studies have examined the association between environmental factors and cognitive impairment, especially in high altitude areas. In this study, the prevalence of cognitive impairment in older adults living in high altitude was compared with those living in low altitude areas.

METHODS

This was a comparative study conducted at Qinghai (high altitude group), and Guangzhou (low altitude group), China. Cognition, depressive symptoms and quality of life (QOL) were assessed using the Montreal Cognitive Assessment (MoCA), Patient Health Questionnaire (PHQ-9) and WHO Quality of Life brief version-WHOQOL-BREF, respectively.

RESULTS

Altogether, 644 older adults (207 in Qinghai and 437 in Guangzhou) completed the assessment. The prevalence rate of cognitive impairment was 94.7% (95% CI: 91.6-97.7%) in older adults living in the high altitude area, while the corresponding figure was 89.2% (95% CI: 86.3-92.1%) in the low altitude area. After controlling for covariates, the high altitude group appeared more likely to have cognitive impairment (OR = 2.92, 95% CI: 1.23-6.91, P = 0.015) compared with the low altitude group. Within the high altitude group sample, multinomial logistic regression analysis revealed that older age (aged 74 and above) was significantly associated with higher risk of severe cognitive impairment (OR = 3.58, 95%CI: 1.44-8.93, P = 0.006), while higher education level (secondary school and above) was associated with decreased risk of moderate cognitive impairment (OR = 0.43, 95%CI: 0.22-0.85, P = 0.006). Within the high altitude group, QOL did not differ significantly between normal/mild, moderate and severe cognitive impairment subgroups across physical [F _{(1, 207)} = 1.83, P = 0.163], psychological [F _{(1, 207)} = 1.50, P = 0.225], social [F _(1,207) = 2.22, P = 0.111] and environmental domains [F _(1,207) = 0.49, P = 0.614].

CONCLUSION

This study found that cognitive impairment was more common among older adults living in the high altitude area. Regular screening and appropriate interventions should be provided to older adults in need.

Protocol for thiamine and folic acid in the treatment of cognitive impairment in maintenance haemodialysis patients: a prospective, randomised, placebo-controlled, double-blind, multicentre study

INTRODUCTION

Cognitive impairment (CI) is the common complications in maintenance haemodialysis (MHD) patients. Recently, the pathogenesis of CI has been discussed and oxidative stress is one of the main mechanisms in these patients. Thiamine and folic acid, which play an important role in relieving the production of reactive oxygen species, reducing homocysteine levels, improving oxidative stress in the nervous system. In pilot study, cognitive function was significantly improved in the group with thiamine and folic supplementation. Based on this result, we hypothesise that thiamine combined with folic acid supplementation may improve cognitive function in patients with MHD.

METHODS AND ANALYSIS

In this prospective, randomised, placebo-controlled, double-blind, multicentre study, we will enrol patients undergoing haemodialysis who has the Montreal Cognitive Assessment score lower than 26 to treatment group (thiamine 90 mg/day combined with folic acid 30 mg/day) or control group (thiamine placebo 90 mg/day combined with folic acid placebo 30 mg/day). All subjects will be followed up for 96 weeks. The primary endpoint is the comparison of Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) score between treatment group and control group at 96 weeks of follow-up. The secondary endpoints include serum thiamine, folate, homocysteine levels, cranial functional MRI and survival. The central randomisation method will be adopted and the principles of placebo-controlled, double-blind randomised control will be followed. The comparisons among ADAS-Cog scores and other secondary endpoints over time within subjects is conducted by using repeated measure analysis of variance (ANOVA) or generalised estimating equations (GEE). Pairwise t-test with Bonferroni adjustment is performed for multiple comparisons. On the other hand, for comparisons between treatment and control group, simple one-way ANOVA, GEE or Wilcoxon rank sum test is used. The χ² method is used for statistical analysis of the categorical data. Kaplan-Meier survival curve is used for survival analysis. A p<0.05 is considered statistically significant difference.

ETHICS AND DISSEMINATION

This trial has been approved by Shanghai Jiao Tong University School of Medicine, Renji Hospital Ethics Committee (KY2019-199). After publication of study results, trial report will be published in peer-reviewed journals and/or in national or international conferences.

TRIAL REGISTRATION NUMBER

ChiCTR2000029297.

The dihydrofolate reductase 19-bp deletion modifies the beneficial effect of B-vitamin therapy in mild cognitive impairment: Pooled study of two randomized placebo-controlled trials

BACKGROUND

Higher serum homocysteine is associated with cognitive decline in older people. But homocysteine-lowering trials including folic acid (FA) show inconsistent results on cognitive decline. The reduction of FA to dihydrofolate by dihydrofolate reductase (DHFR) is slow in humans.

OBJECTIVE

We examined the effects of the DHFR 19-bp deletion/insertion (del/ins) polymorphism on FA-containing treatment on cognitive decline and brain atrophy in older people with mild cognitive impairment (MCI).

METHODS

This study used pooled data from two randomized B-vitamin trials on 545 MCI subjects who received either FA-containing B vitamins or placebo for 24 months. Subjects were typed for the DHFR genotype. Primary outcome was the Clinical Dementia Rating scale-global score (CDR-global). Secondary outcomes were CDR-sum of boxes score (CDR-SOB), memory and executive Z-scores, and whole brain atrophy rate by serial MRI.

RESULTS

The proportion of subjects with del/del, del/ins and ins/ins genotype were 29.5%, 44.3% and 26.1%, respectively. DHFR genotypes modified the effects of B vitamins on CDR-global, CDR-SOB and executive function Z-score (Pinteraction = 0.017, 0.014 and 0.052, respectively), with significant benefits being observed only in those with ins/ins genotype (Beta = -1.367, -0.614 and 0.315, P = 0.004, 0.014 and 0.012, respectively). The interaction was not significant for memory Z-score and whole brain atrophy rate. Notably, the supplements only slowed brain atrophy in members of the 'ins/ins' group who were not using aspirin.

CONCLUSIONS

Our data indicate that the beneficial effects of B vitamins including FA on cognitive function are only apparent in those with ins/ins genotype, i.e. relatively better preserved DHFR activity.

Hyperhomocysteinemia: Metabolic Role and Animal Studies with a Focus on Cognitive Performance and Decline-A Review

Disturbances in the one-carbon metabolism are often indicated by altered levels of the endogenous amino acid homocysteine (HCys), which is additionally discussed to causally contribute to diverse pathologies. In the first part of the present review, we profoundly and critically discuss the metabolic role and pathomechanisms of HCys, as well as its potential impact on different human disorders. The use of adequate animal models can aid in unravelling the complex pathological processes underlying the role of hyperhomocysteinemia (HHCys). Therefore, in the second part, we systematically searched PubMed/Medline for animal studies regarding HHCys and focused on the potential impact on cognitive performance and decline. The majority of reviewed studies reported a significant effect of HHCys on the investigated behavioral outcomes. Despite of persistent controversial discussions about equivocal findings, especially in clinical studies, the present evaluation of preclinical evidence indicates a causal link between HHCys and cognition-related- especially dementia-like disorders, and points out the further urge for large-scale, well-designed clinical studies in order to elucidate the normalization of HCys levels as a potential preventative or therapeutic approach in human pathologies.

The neuropsychiatric effects of nitrous oxide and low vitamin B12

This narrative review article aims to update knowledge on the neuropsychiatric complications of nitrous oxide use and low vitamin B12. We consider common forms and uses of nitrous oxide (N2O) and review its mechanism of action, and then explore the potential impacts of use. In particular, neuropsychiatric effects mediated by low vitamin B12 are considered and the correct interpretation of laboratory results explored. This is of particular importance as where vitamin B12 is inactivated by chronic nitrous oxide use, blood test levels of vitamin B12 may not reflect the quantity of functional B12 in patients.

Vitamin B12 impacts amyloid beta-induced proteotoxicity by regulating the methionine/S-adenosylmethionine cycle

Alzheimer's disease (AD) is a devastating neurodegenerative disorder with no effective treatment. Diet, as a modifiable risk factor for AD, could potentially be targeted to slow disease onset and progression. However, complexity of the human diet and indirect effects of the microbiome make it challenging to identify protective nutrients. Multiple factors contribute to AD pathogenesis, including amyloid beta (Aβ) deposition, energy crisis, and oxidative stress. Here, we use Caenorhabditis elegans to define the impact of diet on Aβ proteotoxicity. We discover that dietary vitamin B12 alleviates mitochondrial fragmentation, bioenergetic defects, and oxidative stress, delaying Aβ-induced paralysis without affecting Aβ accumulation. Vitamin B12 has this protective effect by acting as a cofactor for methionine synthase, impacting the methionine/S-adenosylmethionine (SAMe) cycle. Vitamin B12 supplementation of B12-deficient adult Aβ animals is beneficial, demonstrating potential for vitamin B12 as a therapy to target pathogenic features of AD triggered by proteotoxic stress.

The Role of Vitamins in Neurodegenerative Disease: An Update

Acquiring the recommended daily allowance of vitamins is crucial for maintaining homeostatic balance in humans and other animals. A deficiency in or dysregulation of vitamins adversely affects the neuronal metabolism, which may lead to neurodegenerative diseases. In this article, we discuss how novel vitamin-based approaches aid in attenuating abnormal neuronal functioning in neurodegeneration-based brain diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and Prion disease. Vitamins show their therapeutic activity in Parkinson's disease by antioxidative and anti-inflammatory activity. In addition, different water- and lipid-soluble vitamins have also prevented amyloid beta and tau pathology. On the other hand, some results also show no correlation between vitamin action and the prevention of neurodegenerative diseases. Some vitamins also exhibit toxic activity too. This review discusses both the beneficial and null effects of vitamin supplementation for neurological disorders. The detailed mechanism of action of both water- and lipid-soluble vitamins is addressed in the manuscript. Hormesis is also an essential factor that is very helpful to determine the effective dose of vitamins. PubMed, Google Scholar, Web of Science, and Scopus were employed to conduct the literature search of original articles, review articles, and meta-analyses.

Analysis of the Impact of Selected Vitamins Deficiencies on the Risk of Disability in Older People

Vitamin deficiencies have a serious impact on healthy aging in older people. Many age-related disorders have a direct or indirect impact on nutrition, both in terms of nutrient assimilation and food access, which may result in vitamin deficiencies and may lead to or worsen disabilities. Frailty is characterized by reduced functional abilities, with a key role of malnutrition in its pathogenesis. Aging is associated with various changes in body composition that lead to sarcopenia. Frailty, aging, and sarcopenia all favor malnutrition, and poor nutritional status is a major cause of geriatric morbidity and mortality. In the present narrative review, we focused on vitamins with a significant risk of deficiency in high-income countries: D, C, and B (B6/B9/B12). We also focused on vitamin E as the main lipophilic antioxidant, synergistic to vitamin C. We first discuss the role and needs of these vitamins, the prevalence of deficiencies, and their causes and consequences. We then look at how these vitamins are involved in the biological pathways associated with sarcopenia and frailty. Lastly, we discuss the critical early diagnosis and management of these deficiencies and summarize potential ways of screening malnutrition. A focused nutritional approach might improve the diagnosis of nutritional deficiencies and the initiation of appropriate clinical interventions for reducing the risk of frailty. Further comprehensive research programs on nutritional interventions are needed, with a view to lowering deficiencies in older people and thus decreasing the risk of frailty and sarcopenia.

Vitamin B12, B6, or Folate and Cognitive Function in Community-Dwelling Older Adults: A Systematic Review and Meta-Analysis

BACKGROUND

Previous studies have indicated that B vitamin deficiencies are an essential cause of neurological pathology. There is a need to provide evidence of the benefit of B vitamins for the prevention of cognitive decline in community-dwelling older adults.

OBJECTIVE

To examine the association between intake and plasma levels of vitamins B12, B6, and folate and cognitive function in older populations through a systematic review and meta-analysis.

METHODS

Medline (PubMed), EMBASE, and Cochrane databases were used to search the literature though August 8, 2019. We included observational population-based studies evaluating the association between concentrations or intake levels of vitamins B6, B12, or folate and cognition in older adults aged ≥45 years. The quality of all studies was assessed by the modified Newcastle-Ottawa Scale. Odds ratios (ORs) and hazard ratios (HRs) were analyzed by the random-effects model. Sensitivity analyses were conducted by excluding the studies with significant heterogeneity.

RESULTS

Twenty-one observational studies with sample sizes ranging from 155-7030 were included in the meta-analysis. Higher levels of vitamin B12 (OR = 0.77, 95% CI = 0.61-0.97) and folate concentration (OR = 0.68, 95% CI = 0.51-0.90) were associated with better cognition in cross-sectional studies, but not in sensitivity analyses or prospective studies. High vitamin B6 concentrations showed no significant benefit on cognition and dementia risk. Prospective studies did not provide substantial evidence for the relationship.

CONCLUSION

The results from our meta-analysis suggest that vitamins B12, B6, and folate may not be modifiable risk factors for slowing cognitive decline among community-dwelling older individuals.

B vitamins and prevention of cognitive decline and incident dementia: a systematic review and meta-analysis

CONTEXT

Elevation of homocysteine (Hcy) levels is well-established as a risk factor for dementia, yet controversy exists regarding whether B-vitamin-mediated reduction of homocysteine levels can benefit cognitive function.

OBJECTIVE

To investigate whether B vitamin supplementation can reduce the risk of cognitive decline and incident dementia.

DATA SOURCES

The PubMed, EMBASE, Cochrane Library, and Web of Science were systematically searched for articles published from the inception dates to March 1, 2020. Randomized controlled trials (RCT) were included if B vitamins were supplied to investigate their effect on the rate of cognitive decline. Cohort studies investigating dietary intake of B vitamins and the risk of incident dementia were eligible. Cross-sectional studies comparing differences in levels of B vitamins and Hcy were included.

DATA EXTRACTION

Two reviewers independently performed data extraction and assessed the study quality.

DATA ANALYSIS

Random-effect or fixed-effect models, depending on the degree of heterogeneity, were performed to calculate mean differences (MDs), hazard ratios (HRs), and odds ratios (ORs).

RESULTS

A total of 95 studies with 46175 participants (25 RCTs, 20 cohort studies, and 50 cross-sectional studies) were included in this meta-analysis. This meta-analysis supports that B vitamins can benefit cognitive function as measured by Mini-Mental State Examination score changes (6155 participants; MD, 0.14, 95%CI 0.04 to 0.23), and this result was also significant in studies where placebo groups developed cognitive decline (4211 participants; MD, 0.16, 95%CI 0.05 to 0.26), suggesting that B vitamins slow cognitive decline. For the > 12 months interventional period stratum, B vitamin supplementation decreased cognitive decline (3814 participants; MD, 0.15, 95%CI 0.05 to 0.26) compared to placebo; no such outcome was detected for the shorter interventional stratum (806 participants; MD, 0.18, 95%CI -0.25 to 0.61). In the non-dementia population, B vitamin supplementation slowed cognitive decline (3431 participants; MD, 0.15, 95%CI 0.04 to 0.25) compared to placebo; this outcome was not found for the dementia population (642 participants; MD, 0.20, 95%CI -0.35 to 0.75). Lower folate levels (but not B12 or B6 deficiency) and higher Hcy levels were significantly associated with higher risks of dementia (folate: 6654 participants; OR, 1.76, 95%CI 1.24 to 2.50; Hcy: 12665 participants; OR, 2.09, 95%CI 1.60 to 2.74) and cognitive decline (folate: 4336 participants; OR, 1.26, 95%CI 1.02 to 1.55; Hcy: 6149 participants; OR, 1.19, 95%CI 1.05 to 1.34). Among the population without dementia aged 50 years and above, the risk of incident dementia was significantly decreased among individuals with higher intake of folate (13529 participants; HR, 0.61, 95%CI 0.47 to 0.78), whereas higher intake of B12 or B6 was not associated with lower dementia risk.

CONCLUSIONS

This meta-analysis suggests that B vitamin supplementation is associated with slowing of cognitive decline, especially in populations who received early intervention and intervention of long duration; the study also indicates that higher intake of dietary folate, but not B12 or B6, is associated with a reduced risk of incident dementia in non-dementia aged population. Given the prevalence of dementia cases in many countries with aging populations, public health policies should be introduced to ensure that subgroups of the population at risk have an adequate B vitamin status.

Dietary Supplement Ingredients for Optimizing Cognitive Performance Among Healthy Adults: A Systematic Review

Background: Dietary supplements promoted for brain health and enhanced cognitive performance are widely available. Claims made for these products are directed not only to the elderly wishing to prevent or mitigate cognitive decline, but also young healthy populations looking to boost their cognitive performance. It is unclear whether these claims made on product bottles and through advertising match the science. Objectives: To explore the evidence on the efficacy and safety of single dietary supplement ingredients frequently marketed with claims of enhanced cognitive performance among healthy adults. Design: A systematic review. Results: Nine of 54 dietary supplement ingredients identified through a scoping review met the eligibility criteria with at least 3 published studies identified per ingredient, yielding 69 unique publications. Ingredients evaluated included Bacopa monnieri, choline, creatine, omega-3 fatty acids, Ginkgo biloba, ginseng, Rhodiola rosea, tyrosine, and valerian root, all in supplement form and compared with a placebo, at various serving sizes and durations of use. Conclusions: The low level of certainty in the state of the science, coupled with not always knowing what is in a dietary supplement product, make weighing risks and benefits difficult; these data hinder the ability to develop recommendations about using such ingredients for consumers interested in boosting their cognitive performance. Whereas certain trends regarding promising serving sizes or duration for use, are pointed to in this synthesis, when combined, studies are inconsistent and imprecise, and many are methodologically flawed. Potential solutions to address research gaps are offered, for future research next steps, which is needed to strengthen the evidence and inform decisions.

Gut Microbiota, Probiotic Interventions, and Cognitive Function in the Elderly: A Review of Current Knowledge

Changes in the composition and proportions of the gut microbiota may be associated with numerous diseases, including cognitive impairment. Over the recent years, the growing interest in this relation is observed, but there are still many unknowns, especially in the elderly. To the best of our knowledge, this is the first work that synthesizes and critically evaluates existing evidence on the possible association between human gut microbiota and cognitive function in the elderly. For this purpose, comprehensive literature searches were conducted using the electronic databases PubMed, Google Scholar, and ScienceDirect. The gut microbiota of cognitively healthy and impaired elderly people may differ in the diversity and abundance of individual taxes, but specific taxes cannot be identified. However, some tendencies to changing the Firmicutes/Bacteroidetes ratio can be identified. Currently, clinical trials involving probiotics, prebiotics, and synbiotics supplementation have shown that there are premises for the claim that these factors can improve cognitive functions, however there is no single intervention beneficial to the elderly population. More reliable evidence from large-scale, long-period RCT is needed. Despite proposing several potential mechanisms of the gut microbiota's influence on the cognitive function impairment, prospective research on this topic is extremely difficult to conduct due to numerous confounding factors that may affect the gut microbiota. Heterogeneity of research outcomes impairs insight into these relations.

The preventive efficacy of vitamin B supplements on the cognitive decline of elderly adults: a systematic review and meta-analysis

Background

The irreversibility of cognitive impairment of Alzheimer’s disease (AD) prompts that preventing or delaying the onset of AD should be a public health priority. Vitamin B supplements can lower the serum homocysteine (Hcy) level, but whether it can prevent cognitive decline or not remains unclear. We aimed to evaluate the preventive efficacy of vitamin B supplements on the cognitive decline of elderly adults.

Methods

We searched PubMed, Embase, The Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science, Scopus, Science Direct, PsycINFO from inception to December 1, 2019, and then updated the retrieved results on June 1, 2020. The randomized controlled trials (RCTs) which evaluated the efficacy of vitamin B in mild cognitive impairment (MCI) patients or elderly adults without cognitive impairment were selected. Standardized mean difference (SMD) or mean difference (MD) as well as their 95 % confidence interval (CI) were calculated by performing random effects models or fixed effects models.

Results

A total of 21 RCTs involving 7571 participants were included for meta-analysis. The forest plots showed that there is significant effect in global cognitive function (15 RCTs, SMD: 0.36; 95 % CI: 0.18 to 0.54, P < 0.01) and Hcy (11 RCTs, MD: -4.59; 95 %CI: -5.51 to -3.67, P < 0.01), but there is no effect in information processing speed (10 RCTs, SMD: 0.06; 95 % CI: -0.12 to 0.25, P = 0.49), episodic memory (15 RCTs, SMD: 0.10; 95 % CI: -0.04 to 0.25, P = 0.16), executive function (11 RCTs, SMD: -0.21; 95 % CI: -0.49 to 0.06, P = 0.13). The value of effect size and heterogeneity did not vary apparently when excluding the low-quality studies, so we could believe that the results of meta-analysis were robust.

Conclusions

Vitamin B supplements might delay or maintain the cognitive decline of elderly adults. We can recommend that the vitamin B supplements should be considered as a preventive medication to MCI patients or elderly adults without cognitive impairment. More well-designed RCTs with large sample sizes were required to clarify the preventive efficacy in the future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02253-3.

A pilot study of thiamin and folic acid in hemodialysis patients with cognitive impairment

Objective

This study aimed to explore the effectiveness of thiamin and folic acid supplementation on the improvement of the cognitive function in patients with maintenance hemodialysis.

Method

In the present study, we randomly assigned patients undergoing hemodialysis who had the Montreal Cognitive Assessment (MoCA) score lower than 26 to treatment group (n = 25, thiamin 90 mg/day combined with folic acid 30 mg/day) or control group (n = 25, nonintervention). All subjects were followed up for 96 weeks. The primary outcome was the improvement of the MoCA score. The secondary outcomes included homocysteine level, survival and safety.

Results

Patients in treatment group had an increase of the MoCA score from 21.95 ± 3.81 at baseline to 25.68 ± 1.96 at week 96 (p < 0.001, primary outcome), as compared with the MoCA score from 20.69 ± 3.40 to 19.62 ± 3.58 in control group. Thiamin combined with folic acid treatment also resulted in lower level of serum homocysteine in treatment group compare with control group at week 96 (p < 0.05, secondary outcome). 3 patients and 9 patients died during follow-up period in treatment and control group respectively (p = 0.048). The proportion of adverse events in treatment group was significantly lower than that in control group.

Conclusion

Hemodialysis patients with cognitive impairment treated with thiamin and folic acid had a significant improvement in MoCA score.

Positive effects of folic acid supplementation on cognitive aging are dependent on ω-3 fatty acid status: a post hoc analysis of the FACIT trial

BACKGROUND

Although epidemiological studies suggest a protective role of B vitamins and omega-3 (ω-3) fatty acids in cognitive decline, findings from intervention studies are conflicting. Mechanistic studies suggest that the ω-3 (n-3) fatty acid status can modulate the effects of B vitamins on cognitive decline.

OBJECTIVES

We investigated the interaction between baseline ω-3 fatty acid statuses and folic acid treatment on cognitive decline in a placebo-controlled trial [FACIT (Folic Acid and Carotid Intima-media Thickness)].

METHODS

This post hoc analysis included 791 older adults aged 50-70 y with plasma total homocysteine ≥13 µmol/L and ≤26 µmol/L and serum vitamin B12 ≥200 pmol/L. Participants received 800 µg folic acid or placebo daily for 3 y. Global cognitive functioning and domain-specific functioning (episodic memory, information processing speed, executive functioning) were assessed at baseline and after 3 y. The effect of the folic acid supplementation was analyzed according to tertiles of baseline ω-3 fatty acid concentrations using linear multiple regression.

RESULTS

The mean ± SD age of the study population was 60.2 ± 5.6 y, and the mean ± SD Mini-Mental State Examination score was 28.6 ± 1.5. The treatment effect of folic acid was significantly larger in participants in the low compared to high ω-3 fatty acid tertile for global cognition (difference in z-score: mean ± SE = 0.16 ± 0.059; P < 0.01). Regarding domain-specific functioning, similar results were observed for information processing speed (mean ± SE = 0.167 ± 0.068; P = 0.01). There were no overall interactions between folic acid treatment and ω-3 fatty acid tertiles for episodic memory (P = 0.14) and executive functioning (P = 0.21).

CONCLUSIONS

This post hoc analysis revealed that the efficacy of folic acid treatment on cognitive functioning is dependent on the ω-3 fatty acid status. Individuals with a lower ω-3 fatty acid status at baseline benefited from folic acid treatment, while individuals with a higher ω-3 fatty acid status did not. The results potentially explain the inconsistency in outcomes of B-vitamin supplementation trials and emphasize the importance of a personalized approach. This trial was registered at clinicaltrials.gov as NCT00110604.

Effects of Vitamin B12 Supplementation on Cognitive Function, Depressive Symptoms, and Fatigue: A Systematic Review, Meta-Analysis, and Meta-Regression

Vitamin B12 is often used to improve cognitive function, depressive symptoms, and fatigue. In most cases, such complaints are not associated with overt vitamin B12 deficiency or advanced neurological disorders and the effectiveness of vitamin B12 supplementation in such cases is uncertain. The aim of this systematic review and meta-analysis of randomized controlled trials (RCTs) is to assess the effects of vitamin B12 alone (B12 alone), in addition to vitamin B12 and folic acid with or without vitamin B6 (B complex) on cognitive function, depressive symptoms, and idiopathic fatigue in patients without advanced neurological disorders or overt vitamin B12 deficiency. Medline, Embase, PsycInfo, Cochrane Library, and Scopus were searched. A total of 16 RCTs with 6276 participants were included. Regarding cognitive function outcomes, we found no evidence for an effect of B12 alone or B complex supplementation on any subdomain of cognitive function outcomes. Further, meta-regression showed no significant associations of treatment effects with any of the potential predictors. We also found no overall effect of vitamin supplementation on measures of depression. Further, only one study reported effects on idiopathic fatigue, and therefore, no analysis was possible. Vitamin B12 supplementation is likely ineffective for improving cognitive function and depressive symptoms in patients without advanced neurological disorders.