The role of homocysteine in multisystem age-related problems: a systematic review

Potential inflammatory targets in the integrative health care of patients with sickle cell disease

Inflammation plays an integral role in the complications of sickle cell disease (SCD), which can lead to vaso-occlusive crisis and extreme pain. SCD is accompanied by numerous complications, including cardiovascular disease, cognitive decline and endothelial dysfunction, contributing to mortality. As disease severity increases with age, the present study aimed to assess if age is also correlated with a definite pattern of progression of the two inflammatory markers, high-sensitivity C-reactive protein (hsCRP) and total homocysteine (tHCY). The findings of the present study could lead to an improved understanding of the threshold levels of these inflammatory markers and timely interventions to delay complications. In an observational study, levels of hsCRP and tHCY were analyzed in 70 patients (35 male and 35 female patients) with SCD aged between 5 and 16 years. hsCRP levels were in the high-risk range in 64.29% (n=45) of all male and female patients. A sex-wise distribution showed that, of the 35 male patients, 74.28% (n=26) were in the high-risk range, and of the 35 female patients, 54.28% (n=19) were in the high-risk range. An age-wise distribution showed that of the 41 patients in the 5-10-years age group, 70.73% (n=29), were in the high-risk range. In comparison, of the 29 patients in the 11-16-years age group, 55.17% (n=16) were in the high-risk range. tHCY levels were observed to be in the normal range in 98.57% (n=69) of all children, as compared with 1.43% (n=1) in the high-risk range. Furthermore, a sex-wise distribution showed that female patients in the high-risk group of hsCRP had higher concentrations of tHCY as compared with the male patients in that risk group. An age-wise distribution of hsCRP concentration also showed that the risk of CVD in patients in the 11-16-years age group was higher with increased concentrations of tHCY. A weak negative correlation was observed between age and hsCRP concentrations (r-value=-0.280; P=0.026) and a weak positive correlation was detected between tHCY and age (r-value=0.259; P=0.036). In conclusion, the results of the present study indicated that higher levels of hsCRP could be a useful marker in children with SCD, and levels of tHCY may be an adjunct marker as the disease progresses with age.

Modulation of DNA methylation by one-carbon metabolism: a milestone for healthy aging

Healthy aging can be defined as an extended lifespan and health span. Nutrition has been regarded as an important factor in healthy aging, because nutrients, bioactive food components, and diets have demonstrated beneficial effects on aging hallmarks such as oxidative stress, mitochondrial function, apoptosis and autophagy, genomic stability, and immune function. Nutrition also plays a role in epigenetic regulation of gene expression, and DNA methylation is the most extensively investigated epigenetic phenomenon in aging. Interestingly, age-associated DNA methylation can be modulated by one-carbon metabolism or inhibition of DNA methyltransferases. One-carbon metabolism ultimately controls the balance between the universal methyl donor S-adenosylmethionine and the methyltransferase inhibitor S-adenosylhomocysteine. Water-soluble B-vitamins such as folate, vitamin B6, and vitamin B12 serve as coenzymes for multiple steps in one-carbon metabolism, whereas methionine, choline, betaine, and serine act as methyl donors. Thus, these one-carbon nutrients can modify age-associated DNA methylation and subsequently alter the age-associated physiologic and pathologic processes. We cannot elude aging per se but we may at least change age-associated DNA methylation, which could mitigate age-associated diseases and disorders.

Identification of Factors Affecting the Increased Percentage of CGA Recommendations among Patients on Geriatric Ward

In Poland, the elderly population is noticeably increasing every year. Therefore, the current healthcare system has to rise to the challenge of treatment and prevention strategies targeting elderly persons. Based on the Vulnerable Elders Survey (VES-13 scale), consisting of international and validated scales, we put effort into identifying the factors affecting the increased percentage of CGA (Comprehensive Geriatric Assessment) recommendations by healthcare system physicians. The study group involved 78 patients from the Department of Geriatrics, Wroclaw Medical University, Poland, aged 60-91 (median Me = 81 years old). Of the studied patients, 51 were recommended for CGA (51/78; 64.6%). A statistically significant association was observed between CGA recommendation and age (p < 0.001); the likelihood of a CGA recommendation increased with age. Furthermore, the increased CGA recommendation was observed among geriatric patients with: (a) frailty syndrome (OR = 11.2, CI95% 2.88-43.5, p < 0.001), (b) high risk of malnutrition or malnutrition (OR = 3.87; CI95%, 1.00-14.9, p = 0.04), (c) low mental status (OR = 3.32, CI95% 1.22-9.09, p = 0.029), (d) low ability to perform basic daily duties (according to ADL scale-OR = 12.6, CI95% 1.57-101, p = 0.004 and IADL scale-OR = 4.71, CI95% 1.72-12.9, p = 0.003), and (e) fall risk (OR = 15.0, CI95% 4.67-48.3, p < 0.001). Moreover, homocysteine levels increased with age (p = 0.003) and decreased with sleep duration (p = 0.043). Taken together, all these factors seem to be important when implementing treatment programs adjusted to the individual geriatric patient.

Vitamin B status and its impact in post-menopausal women: A review

Menopause is an age-related naturally occurring phenomenon in women. Women generally attain menopause between the 40-58 years of age, during which they undergo several physiological changes that have an impact on their daily activities. The deficiency of B vitamins occurs mainly due to the dietary pattern, absorption and blood loss which may leads to health problems such as cognitive decline, osteoporosis, physical and mental imbalance.  This review evaluated the published evidence on the vitamin B status and its impact in post-menopausal women. Selected data sources were searched for relevant literature (2010-2020) and included as per the set criteria using Prisma guidelines. The NIH quality questionnaire tool was used to rate the articles. Finally eleven articles were included for full length review having reports on the impact of B vitamins on bone loss, cognitive decline and physical activity. Existing evidences show that there is no association between B vitamins and bone loss. Very few studies are available which concluded association of B vitamin with cognitive decline and physical health.  More studies are required to address this research gap.

Modern Concepts in Cardiovascular Disease: Inflamm-Aging

The improvements in healthcare services and quality of life result in a longer life expectancy and a higher number of aged individuals, who are inevitably affected by age-associated cardiovascular (CV) diseases. This challenging demographic shift calls for a greater effort to unravel the molecular mechanisms underlying age-related CV diseases to identify new therapeutic targets to cope with the ongoing aging "pandemic". Essential for protection against external pathogens and intrinsic degenerative processes, the inflammatory response becomes dysregulated with aging, leading to a persistent state of low-grade inflammation known as inflamm-aging. Of interest, inflammation has been recently recognized as a key factor in the pathogenesis of CV diseases, suggesting inflamm-aging as a possible driver of age-related CV afflictions and a plausible therapeutic target in this context. This review discusses the molecular pathways underlying inflamm-aging and their involvement in CV disease. Moreover, the potential of several anti-inflammatory approaches in this context is also reviewed.

Rivastigmine Reverses the Decrease in Synapsin and Memory Caused by Homocysteine: Is There Relation to Inflammation?

Elevated levels of homocysteine (Hcy) in the blood, called hyperhomocysteinemia (HHcy), is a prevalent risk factor for it has been shown that Hcy induces oxidative stress and increases microglial activation and neuroinflammation, as well as causes cognitive impairment, which have been linked to the neurodegenerative process. This study aimed to evaluate the effect of mild hyperhomocysteinemia with or without ibuprofen and rivastigmine treatments on the behavior and neurochemical parameters in male rats. The chronic mild HHcy model was chemically induced in Wistar rats by subcutaneous administration of Hcy (4055 mg/kg body weight) twice daily for 30 days. Ibuprofen (40 mg/kg) and rivastigmine (0.5 mg/kg) were administered intraperitoneally once daily. Motor damage (open field, balance beam, rotarod, and vertical pole test), cognitive deficits (Y-maze), neurochemical parameters (oxidative status/antioxidant enzymatic defenses, presynaptic protein synapsin 1, inflammatory profile parameters, calcium binding adapter molecule 1 (Iba1), iNOS gene expression), and cholinergic anti-inflammatory pathway were investigated. Results showed that mild HHcy caused cognitive deficits in working memory, and impaired motor coordination reduced the amount of synapsin 1 protein, altered the neuroinflammatory picture, and caused changes in the activity of catalase and acetylcholinesterase enzymes. Both rivastigmine and ibuprofen treatments were able to mitigate this damage caused by mild HHcy. Together, these neurochemical changes may be associated with the mechanisms by which Hcy has been linked to a risk factor for AD. Treatments with rivastigmine and ibuprofen can effectively reduce the damage caused by increased Hcy levels.

The Relationship between F2-Isoprostanes Plasma Levels and Depression Symptoms in Healthy Older Adults

The increasing proportion of older citizens in our society reflects a need to better understand age-related biological underpinnings of mood, as depression in older age may be under-diagnosed. Pre-clinical and human studies evidence a relationship between oxidative stress (OS) biomarkers in depression symptoms, and an influence of biological factors such as Body Mass Index (BMI), but focus has been clinical or younger samples, and less is known about patterns in healthy older adults. We investigated these associations with data derived from the Australian Research Council Longevity Study (ARCLI; ANZCTR12611000487910), in 568 healthy adults aged 60–75 years using F₂-Isoprostanes plasma levels, and controlling for demographic factors, in assessing mood via the Beck Depression Inventory-II, Chalder Fatigue Scale, and General Health Questionnaire 12. Elevated F₂-Isoprostanes contributed to depressed mood on the BDI-II and reduced general health on the GHQ-12. BMI was positively associated with Chalder Fatigue scores, yet better ratings on the GHQ-12. Females had significantly higher F₂-Isoprostanes than males. The results suggest that in otherwise healthy older adults, mood and mental health are reduced with increases in oxidative stress markers, exhibiting similar patterns observed in clinical groups. Sex as a factor should be considered when assessing OS levels in systemic pathologies. BMI as a modifiable risk factor for maintenance of mental health, and OS modification through nutrient supplementation, are discussed. The findings contribute to understanding oxidative stress marker patterns in healthy older adults and their potential role in mood symptoms and mental health.

Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs

H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.

Biological Features of the Outcome-Based Intrinsic Capacity Composite Scores From a Population-Based Cohort Study: Pas de Deux of Biological and Functional Aging

Introduction

This study aims to develop and validate an integrative intrinsic capacity (IC) scoring system, to investigate its associations with a wide spectrum of biomarkers and to explore the predictive value of the integrative IC score on 4-year mortality among community dwelling people aged 50 years and older.

Methods

We included 839 adults aged ≥50 years from the Social Environment and Biomarkers of Aging Study (SEBAS) and randomly divided them into derivation and validation cohorts to develop the IC scoring system. The multivariate logistic regression model was used to weight each subdomain (locomotion, sensory, vitality, psychological, and cognition) of IC according to its association with impairments in instrumental activities of daily living (IADL) and to construct the integrative IC score. Age-related biomarkers and genetic markers were compared between IC groups by ordinal logistic regression. A Cox proportional hazard model was used to examine the association between IC and mortality, and subgroup analysis was used to assess the robustness of the results among participants aged 60 years and older.

Results

A 12-score IC scoring system (AUROC = 0.83; Hosmer–Lemeshow goodness-of-fit test p = 0.17) was developed, and higher scores indicated better intrinsic capacity. High interleukin (IL)-6, high E-selectin, low serum albumin and low folate were significantly associated with low IC in the whole sample. However, high IL-6, low serum albumin, low folate, high allostatic load, and APOE ε4 genotype were significantly associated with low IC in those aged 60 years old and older. Compared to the high IC group, the low IC group was significantly associated with all-cause mortality (HR: 2.50, 95% CI: 1.22–5.11, p = 0.01 for all participants; HR 2.19, 95% CI 1.03–4.64, p = 0.04 for participants aged 60 years and older).

Conclusions

The conceptually proposed IC can be easily transformed into a scoring system considering different weights of individual subdomains, which not only predicts mortality but also suggests different pathophysiologies across the life course of aging (inflammation, nutrition, stress, and ApoE4 genotype). An intervention study is needed using the composite IC score to promote healthy aging and determine the underlying pathophysiology.

Hydrocephalus presented as the prominent symptom of severe 5,10-methylenetetrahydrofolate reductase deficiency in an infant: A case report

Hyperhomocysteinemia is a common medical condition observed in patients with aminoaciduria. Deficiency in cystathionine beta-synthase, metabolism of cobalamin associated C, peroxiredoxin 1, 5-methyltetrahydrofolate-homocysteine methyltransferase reductase, LMBR1 domain containing 1, 5-methyltetrahydrofolate-homocysteine methyltransferase or 5,10-methylenetetrahydrofolate reductase (MTHFR) all can result in an elevation in plasma homocysteine, which has been reported to be a risk factor of vascular events, such as atherosis, acute myocardial infarction and cerebral stroke. Hyperhomocysteinemia due to the deficiency of 5,10-methylenetetrahydrofolate reductase (MTHFR; also known as 5,10-methyl THR reductase) is an autosomal recessive rare disease caused by defects in the MTHFR gene. The clinical manifestations of this disorder are heterogeneous, ranging from asymptomatic to severe neurological disorders. However, hydrocephalus has seldomly been reported in patients with MTHFR deficiency. The present study thus describes a case of severe MTHFR deficiency in an infant, whose main manifestation was hydrocephalus. The clinical course and genotype of the patient were also examined. Specifically, a 4-month-old boy with hydrocephalus was admitted to hospital. Clinical examinations and genetic sequencing of the patient were performed to determine the probable causative factors. A physical examination revealed that the patient had developmental delay and progressive hydrocephalus. Amino acid analysis of the blood revealed an enhancement in serum homocysteine levels and a decrease in blood methionine and free carnitine levels. The organic acid levels in urine were normal. Therefore, he was diagnosed with hyperhomocysteinemia. Targeted next-generation sequencing was performed to determine the pathogenetic gene in this case. A paternal mutation c.1530G>A (p.K510K) and a maternal mutation c.233C>A (p.S78X) were identified. Previous experimental evidence indicated that these two mutations were all pathogenic; therefore, this patient was ultimately diagnosed with MTHFR deficiency. The patient in described herein study presented with severe progressive hydrocephalus in association with a delayed developmental milestone. According to the clinical and genetic tests, the patient was diagnosed with severe MTHFR deficiency. It thus is recommended that screening for metabolites and performing gene sequencing in infants presenting with undisclosed hydrocephalus.

Isotretinoin and neuropsychiatric side effects: Continued vigilance is needed

Background

Isotretinoin (13-cis-retinoic acid, marketed under the names Accutane, Roaccutane, and others) is an effective treatment for acne that has been on the market for over 30 years, although reports of neuropsychiatric side effects continue to be reported. Isotretinoin is an isomer of the active form of Vitamin A, 13-trans-retinoic acid, which has known psychiatric side effects when given in excessive doses, and is part of the family of compounds called retinoids, which have multiple functions in the central nervous system.

Methods

The literature was reviewed in pubmed and psychinfo for research related to isotretinoin and neuropsychiatric side effects including depression, suicidal thoughts, suicide, mania, anxiety, impulsivity, emotional lability, violence, aggression, and psychosis.

Results

Multiple case series have shown that successful treatment of acne with isotretinoin results in improvements in measures of quality of life and self esteem However, studies show individual cases of clinically significant depression and other neuropsychiatric events that, although not common, are persistent in the literature. Since the original cases of depression were reported to the United States Food and Drug Administration, numerous cases have been reported to regulatory agencies in the United Kingdom, France, Ireland, Denmark, Australia, Canada, and other countries, making isotretinoin one of the top five medications in the world associated with depression and other neuropsychiatric side effects. Clinicians are advised to warn patients of the risks of neuropsychiatric side effects with isotretinoin which may arise from the medication itself, and not just as a side effect of acne or youth.

Plasma homocysteine concentrations and depression: A twin study

Background

Homocysteine is an amino acid formed during metabolism of the essential amino acid methionine that plays an important role in energy metabolism and neurotransmitter synthesis. High levels of homocysteine have been linked to both depression and cardiovascular disease, however studies of depression have not always been consistent, possibly related to differences in methodology among studies. The study of twins in clinical research can be useful in controlling for confounding factors. The purpose of this study was to assess the relationship between depression and plasma homocysteine in a study of twins.

Methods

Homocysteine concentration was assessed in twins (N = 202) from the Vietnam Era Twin Registry, including twin pairs discordant for the diagnosis of Major Depressive Disorder (MDD) and twin pairs without MDD. Self reported depressive symptom levels were also measured as a continous variable using the Beck Depression Inventory (BDI).

Results

The average homocysteine concentration was 7.9 μmol/L (2.1 μmol/L SD, range of 2.0-17.1 μmol/L). There were no within twin pair differences in homocysteine concentration within twin pairs discordant for MDD and within twin pairs that differed for BDI score. There was a significant pair-level relationship between depressive symptoms as measured by mean BDI score and homocysteine concentration, such that the higher the mean BDI score of the twin pair, the higher the mean homocystein of the pair (p < .001). Every 10 point increase in BDI score was associated with an 0.8 μmol/L increase in homocysteine concentration at the pair level.

Conclusions

These findings are not consistent with a causal role for elevated homocysteine in the development of depression, but rather point to familial confounding or other factors that are shared by twin brothers and that contribute to both depression and homocysteine levels.

Using data mining technology to explore homocysteine at low levels

A high homocysteine level is known to be an independent risk factor for cardiovascular diseases; however, whether or not low homocysteine level contributes to any damage to the body has not been extensively studied. Furthermore, acquiring healthy subject databases from domestic studies on homocysteine is not trivial. Therefore, we aimed to investigate the causality between serum homocysteine levels and health status and lifestyle factors, particularly with a focus on low serum homocysteine levels. Additionally, we discussed a systematic methodical platform for data collection and statistical analysis, using the descriptive analysis of the chi-square test, t test, multivariate analysis of variance, and logistic regression.This study was a cross-sectional analysis of 5864 subjects (i.e., clients of a health examination clinic) in Taipei, Taiwan during a general health check-up in 2017. The patients' personal information and associated links were excluded. A sample group was selected as per the health criteria defined for this research whose data were processed using SPSS for descriptive statistical analysis using chi-square test, t test, multivariate analysis of variance, and logistic regression analysis.Those working for >12 hours/day had a higher homocysteine level than those working for <12 hours/day (P < .001). The average serum homocysteine level was 7.9 and 8.6 mol/L for people with poor sleep quality and good sleep quality, respectively (P = .003). The homocysteine value of people known to have cancer was analyzed using the logistic regression analysis, revealing a Δodds value of 0.898. The percentage of subjects with a homocysteine value of ≤6.3 μmol/L, who perceived their health status as "not very good" or "very bad," was higher than those with a higher homocysteine level. The number of subjects who perceived their health as poor was higher than expected.The results suggest that the homocysteine level could be an effective health management indicator. We conclude that normal homocysteine level should not be ≤6.3 μmol/L. Moreover, homocysteine should not be considered as harmful and its fluctuations from the normal range could be utilized to infer a person's physical status for health management.

The association between serum homocysteine and depression: A systematic review and meta-analysis of observational studies

BACKGROUND

Hyperhomocysteinaemia is known to interfere with neurological functions; however, there is a controversy regarding the relationship between homocysteine and depression.

MATERIALS AND METHODS

Science Direct, MEDLINE and ISI Web of Science were searched to find relevant articles, published up to August 2020. Studies were included if they compared homocysteine levels in healthy subjects with subjects with depression. Also, articles that reported the association between hyperhomocysteinaemia and risk of depression were included. Odds ratios of depression and means of homocysteine were used to ascertain the overall effect size.

RESULTS

Homocysteine level was higher in subjects with depression in comparison with healthy controls (weight mean difference = 2.53 µmol/L, 95% confidence interval: 1.77, 3.30), and the depression diagnostic tool was a source of heterogeneity. Homocysteine level was significantly higher in subjects with depression in studies that used Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV), Geriatric Depression Scale (GDS), Zung Self-Rating Depression Scale (ZDRS) and Beck Depression Index II (BDI-II) as depression diagnostic tools. Also, participants with hyperhomocysteinaemia had a higher chance of depression (Pooled risk = 1.34, 95% confidence interval: 1.19, 1.52), where the depression diagnostic tool was a source of heterogeneity. In contrast to ZDRS and Patient Health Questionnaire (PHQ) subgroups, hyperhomocysteinaemia yielded a significantly higher risk of depression in DSM-IV, GDS and 'other' subgroups.

CONCLUSION

Homocysteinemia level is higher in individuals with depression. However, the depression diagnostic tool used is instrumental in influencing their association, and thus, future studies should focus on the tools for depression assessment.

The role of B vitamins in stroke prevention

Elevated plasma levels of homocysteine (Hcy) are a recognized risk factor for stroke. This relationship represents one aspect of the debated `Hcy hypothesis'. Elevated Hcy may be an independent and treatable cause of atherosclerosis and thrombotic vascular diseases. Further observations indicate that proper dietary supplementation with B-vitamins decreases total plasma Hcy concentrations and may be an effective intervention for stroke prevention. Metabolic vitamin B₁₂ deficiency is a nutritional determinant of total Hcy and stroke risk. Genetic factors may link B vitamins with stroke severity due to the impact on Hcy metabolism of polymorphism in the genes coding for methylenetetrahydrofolate reductase, methionine-synthase, methionine synthase reductase, and cystathionine β-synthase. Several meta-analyses of large randomized controlled trials exist. However, they are not completely in agreement about B vitamins' role, particularly folic acid levels, vitamin B₁₂, and B₆, in lowering the homocysteine concentrations in people at high stroke risk. A very complex relationship exists between Hcy and B vitamins, and several factors appear to modify the preventive effects of B vitamins in stroke. This review highlights the regulating factors of the active role of B vitamins active in stroke prevention. Also, inputs for further large, well-designed studies, for specific, particularly sensitive subgroups are given.

Gender- and age-related differences in homocysteine concentration: a cross-sectional study of the general population of China

The primary goals of this study were to evaluate the gender- and age-related differences in homocysteine concentration in the general population of China and possible influencing factors. A total of 7872 subjects, divided into male and female groups, participated in this retrospective study. The average homocysteine level, prevalence of hyperhomocysteinemia, and independent factors affecting homocysteine concentration were analyzed. The homocysteine level was significantly higher in males than in females in each age range (aged 20–30, aged 30–40, aged 40–50, aged 50–60, aged 60–80, aged over 80) (P < 0.0001), and the trend did not abate with age. The homocysteine concentration first decreased and then increased, being lowest at 30–50 years of age and significantly increased after 50 years of age. Factors associated with homocysteine concentration in males were smoking status (current smokers versus ex-smokers: β: 0.112), estimated glomerular filtration rate (β =  − 0.192), blood urea nitrogen (β =  − 0.14), diastolic blood pressure (β =  − 0.113), free triiodothyronine (β =  − 0.091), serum potassium (β =  − 0.107) and cystatin C (β = 0.173). In females, independent factors associated with homocysteine concentration were cystatin C (β = 0.319), albumin (β = 0.227), free thyroxine (β = 0.179), age (β = 0.148), free triiodothyronine (β =  − 0.217) and serum potassium (β =  − 0.153). The homocysteine level was significantly higher in males than in females and increased markedly after 50 years of age in both groups. The independent factors associated with increased homocysteine concentration differed between males and females.

Microglial-associated responses to comorbid amyloid pathology and hyperhomocysteinemia in an aged knock-in mouse model of Alzheimer's disease

BACKGROUND

Elevated blood homocysteine levels, termed hyperhomocysteinemia (HHcy), is a prevalent risk factor for Alzheimer's disease (AD) in elderly populations. While dietary supplementation of B-vitamins is a generally effective method to lower homocysteine levels, there is little if any benefit to cognition. In the context of amyloid pathology, dietary-induced HHcy is known to enhance amyloid deposition and certain inflammatory responses. Little is known, however, about whether there is a more specific effect on microglia resulting from combined amyloid and HHcy pathologies.

METHODS

The present study used a knock-in mouse model of amyloidosis, aged to 12 months, given 8 weeks of B-vitamin deficiency-induced HHcy to better understand how microglia are affected in this comorbidity context.

RESULTS

We found that HHcy-inducing diet increased amyloid plaque burden, altered the neuroinflammatory milieu, and upregulated the expression of multiple damage-associated and "homeostatic" microglial genes.

CONCLUSIONS

Taken together, these data indicate complex effects of comorbid pathologies on microglial function that are not driven solely by increased amyloid burden. Given the highly dynamic nature of microglia, their central role in AD pathology, and the frequent occurrence of various comorbidities in AD patients, it is increasingly important to understand how microglia respond to mixed pathological processes.

The Evolving Applications of Creatine Supplementation: Could Creatine Improve Vascular Health?

Creatine is a naturally occurring compound, functioning in conjunction with creatine kinase to play a quintessential role in both cellular energy provision and intracellular energy shuttling. An extensive body of literature solidifies the plethora of ergogenic benefits gained following dietary creatine supplementation; however, recent findings have further indicated a potential therapeutic role for creatine in several pathologies such as myopathies, neurodegenerative disorders, metabolic disturbances, chronic kidney disease and inflammatory diseases. Furthermore, creatine has been found to exhibit non-energy-related properties, such as serving as a potential antioxidant and anti-inflammatory. Despite the therapeutic success of creatine supplementation in varying clinical populations, there is scarce information regarding the potential application of creatine for combatting the current leading cause of mortality, cardiovascular disease (CVD). Taking into consideration the broad ergogenic and non-energy-related actions of creatine, we hypothesize that creatine supplementation may be a potential therapeutic strategy for improving vascular health in at-risk populations such as older adults or those with CVD. With an extensive literature search, we have found only four clinical studies that have investigated the direct effect of creatine on vascular health and function. In this review, we aim to give a short background on the pleiotropic applications of creatine, and to then summarize the current literature surrounding creatine and vascular health. Furthermore, we discuss the varying mechanisms by which creatine could benefit vascular health and function, such as the impact of creatine supplementation upon inflammation and oxidative stress.

Implication of Hyperhomocysteinemia in Blood Retinal Barrier (BRB) Dysfunction

Elevated plasma homocysteine (Hcy) level, known as hyperhomocysteinemia (HHcy) has been linked to different systemic and neurological diseases, well-known as a risk factor for systemic atherosclerosis and cardiovascular disease (CVD) and has been identified as a risk factor for several ocular disorders, such as diabetic retinopathy (DR) and age-related macular degeneration (AMD). Different mechanisms have been proposed to explain HHcy-induced visual dysfunction, including oxidative stress, upregulation of inflammatory mediators, retinal ganglion cell apoptosis, and extracellular matrix remodeling. Our previous studies using in vivo and in vitro models of HHcy have demonstrated that Hcy impairs the function of both inner and outer blood retinal barrier (BRB). Dysfunction of BRB is a hallmark of vision loss in DR and AMD. Our findings highlighted oxidative stress, ER stress, inflammation, and epigenetic modifications as possible mechanisms of HHcy-induced BRB dysfunction. In addition, we recently reported HHcy-induced brain inflammation as a mechanism of blood–brain barrier (BBB) dysfunction and pathogenesis of Alzheimer’s disease (AD). Moreover, we are currently investigating the activation of glutamate receptor N-methyl-d-aspartate receptor (NMDAR) as the molecular mechanism for HHcy-induced BRB dysfunction. This review focuses on the studied effects of HHcy on BRB and the controversial role of HHcy in the pathogenesis of aging neurological diseases such as DR, AMD, and AD. We also highlight the possible mechanisms for such deleterious effects of HHcy.

Association Between Dietary Intakes of B Vitamins in Midlife and Cognitive Impairment in Late-Life: The Singapore Chinese Health Study

BACKGROUND

Dietary intakes of B vitamins (eg, folate) are related to cognitive function according to epidemiological studies in western countries. But prospective studies in Asian populations are scarce. This study evaluated the relationships of dietary intakes of six B vitamins in midlife with cognitive impairment in old age in a Chinese population living in Singapore.

METHODS

This study included 16,948 participants from the Singapore Chinese Health Study, a population-based prospective cohort. Baseline dietary intakes of B vitamins were assessed using a validated 165-item food frequency questionnaire when the participants were aged 45-74 years (1993-1998). After an average follow-up of 20 years, cognitive function was examined using a Singapore-modified version of Mini-Mental State Examination scale in 2014-2016, and cognitive impairment was defined using education-specific cutoffs. Logistic regression models were applied to estimate the association between B vitamins and cognitive impairment. All the six B vitamins were mutually adjusted in the final model.

RESULTS

In the 2014-2016 interview, 2,443 participants were defined as cognitive impairment. Riboflavin and folate were significantly and independently associated with cognitive impairment in a dose-dependent manner: the odds ratio (95% confidence interval) comparing the highest with the lowest quartile was 0.82 (0.69, 0.97) for riboflavin and 0.83 (0.70, 0.98) for folate (both p-trend <.05). Dietary intakes of thiamine, niacin, vitamin B-6, and B-12 were not significantly associated with risk of cognitive impairment.

CONCLUSIONS

Higher dietary intakes of riboflavin and folate in midlife were associated with a lower risk of cognitive impairment in late-life in the Chinese population.

Homocysteine: Its Possible Emerging Role in At-Risk Population Groups

Increased plasma homocysteine is a risk factor for several pathological disorders. The present review focused on the role of homocysteine (Hcy) in different population groups, especially in risk conditions (pregnancy, infancy, old age), and on its relevance as a marker or etiological factor of the diseases in these age groups, focusing on the nutritional treatment of elevated Hcy levels. In pregnancy, Hcy levels were investigated in relation to the increased risk of adverse pregnancy outcomes such as small size for gestational age at birth, preeclampsia, recurrent abortions, low birth weight, or intrauterine growth restriction. In pediatric populations, Hcy levels are important not only for cardiovascular disease, obesity, and renal disease, but the most interesting evidence concerns study of elevated levels of Hcy in autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD). Finally, a focus on the principal pathologies of the elderly (cardiovascular and neurodegenerative disease, osteoporosis and physical function) is presented. The metabolism of Hcy is influenced by B vitamins, and Hcy-lowering vitamin treatments have been proposed. However, clinical trials have not reached a consensus about the effectiveness of vitamin supplementation on the reduction of Hcy levels and improvement of pathological condition, especially in elderly patients with overt pathologies, suggesting that other dietary and non-dietary factors are involved in high Hcy levels. The importance of novel experimental designs focusing on intra-individual variability as a complement to the typical case-control experimental designs and the study of interactions between different factors it should be emphasized.

Relationship between Homocysteine and Muscle Strength Decline: The Baltimore Longitudinal Study of Aging

Background

Decreased muscle strength is strongly associated with future mobility limitations in older adults. Homocysteine is a risk factor for vascular disease and may exacerbate muscle strength decline. The present study aimed to examine the association between homocysteine levels and muscle strength in adults aged 50 years or older.

Methods

Data were from 1,101 participants of The Baltimore Longitudinal Study of Aging between December 2004 and March 2015. Muscle strength was measured using grip strength. Mixed effects linear regression was used to estimate the association between homocysteine and muscle strength in men and women, separately.

Results

Total mean follow-up time was 4.7 ± 3.1 years, range from 0 to 10.1 years. Baseline mean grip strength was 39.9 kg for men and 25.5 kg for women. Grip strength declined over the follow-up time for both men and women. Among women, there was a significant inverse relationship between homocysteine and grip strength, where grip strength declined as a function of increasing homocysteine over time (β = -0.05, p = .031). Among men, an increase of 1 μmol/L in homocysteine was associated with -0.10 kg decrease in grip strength, though not significantly.

Conclusions

In this study of healthy older adults aged 50 years or older, higher homocysteine was related to lower muscle strength in women. This is the first study to characterize the relationship over a long follow-up period. Future research should focus on assessing homocysteine as a marker of physical function decline and translating the relationship into clinical and public health practice.

Impaired Homocysteine Metabolism Associated with High Plasma Interleukin-17A Levels, a Pro-Atherogenic Marker, in an Endogamous Population of North India

Background

Impaired homocysteine metabolism (IHM; hyperhomocysteinemia) has been linked with many complex disorders like cardiovascular diseases and immunological disturbances. However, studies understanding IHM in light of pro- and anti- atherogeneic markers like Interleukin-17A & -10 (IL-17A & IL-10) and Forkhead box p3 (Foxp3, a master transcription factor) are scarce.

Aim

In our present study, we aimed to understand the relation of IHM with plasma IL-17A and IL-10 levels and Foxp3 mRNA expression in peripheral blood mononuclear cells (PBMCs) from an endogamous population (Jats of Haryana, North India) with high prevalence of IHM without the concurrence of significant adverse cardiovascular outcomes.

Methods

Forty (40) clinically healthy individuals, unrelated up to first cousins, were recruited and were subjected to demographic, physiological and anthropometric profiling, followed by intravenous blood sample collection (fasting) and lipid profiling. Plasma homocysteine levels were estimated and individuals with homocysteine levels ≥ 15umol/L and <15umol/L were categorized as the impaired homocysteine metabolism group (IHM, n=30) and normal homocysteine metabolism group (NHM, n=10) respectively. Plasma folate and vitamin B12 and MTHFR C677T (methylenetetrahydrofolate reductase) polymorphism were detected. Relative mRNA expression of Foxp3 in PBMCs (normalized to 18S) was quantitated using SyBR green technology. Plasma IL-10 & 17 levels were estimated by ELISA assays.

Results and Conclusions

None of the physiological, anthropometric and lipid variables were different between the two groups. Foxp3 mRNA expression levels were relatively lower, and plasma IL-10 levels were found to be comparable among IHM and NHM group. However, significantly higher IL-17A levels and relatively high LDL cholesterol levels were present in the IHM group as compared with NHM. Our findings suggest that the Jats of Haryana, North India, exhibiting high levels of homocysteine, might also carry the high IL-17A -pro-atherogenic marker, suggesting an increasing burden of pre-morbid condition. This apparently does not reach to significant mortality/morbidity attributed to the counter action or balancing act of IL-10 (an anti-atherogenic marker). This further suggests environment-influenced epigenetic control mechanisms of the targeted genes in the present population.

MTHFR 677C → T genotype modulates the effect of a 5-year supplementation with B-vitamins on homocysteine concentration: The SU.FOL.OM3 randomized controlled trial

AIMS

To study how MTHFR 677C→T genotype modulates the effect of supplementation with B-vitamins on total homocysteine (tHcy) and B-vitamin concentrations.

METHODS

2381 patients with a personal history of cardiovascular disease were randomly assigned to one of four groups: 1) B-vitamins alone (560 μg of 5-methyl-THF, 3 mg of vitamin B6 and 20 μg of vitamin B12), 2) n-3 fatty acids alone (600 mg of EPA and DHA in a 2:1 ratio), 3) B-vitamins and n-3 fatty acids, and 4) placebo. Participants were followed up for 4.7 years. At baseline and annually thereafter, biological parameters were assessed. Multivariate and linear mixed models were fit to study the interaction between B-vitamins and MTHFR genotype.

RESULTS

Among supplemented participants, concentrations of all three B-vitamins increased during the first year (all p<0.0001) across MTHFR genotype categories. tHcy decreased by 26.3% during the first year (p<0.0001), then steadily increased throughout the 5 years (ptrend<0.001). However, at the end of follow-up, that increase was smaller among TT than among CT or CC subjects (pinteraction<0.02). At baseline, the difference in tHcy concentrations between TT homozygous and CC homozygous subjects was 2.33 μmol/l (p<0.001). After 5 years, that difference was reduced to 1.06 μmol/l and remained statistically significant (p<0.001).

CONCLUSION

Participants with the TT genotype exhibited a lower 5-year decrease in tHcy concentrations following a B-vitamin supplementation than did participants with the CC or CT genotype.

CLINICAL TRIAL REGISTRATION

Current Controlled Trials # ISRCTN41926726.

Nutrition and Ageing

The ageing trajectory is plastic and can be slowed down by lifestyle factors, including good nutrition, adequate physical activity and avoidance of smoking. In humans, plant-based diets such as the Mediterranean dietary pattern are associated with healthier ageing and lower risk of age-related disease, whereas obesity accelerates ageing and increases the likelihood of most common complex diseases including CVD, T2D, dementia, musculoskeletal diseases and several cancers. As yet, there is only weak evidence in humans about the molecular mechanisms through which dietary factors modulate ageing but evidence from cell systems and animal models suggest that it is probable that better dietary choices influence all 9 hallmarks of ageing. It seems likely that better eating patterns retard ageing in at least two ways including (i) by reducing pervasive damaging processes such as inflammation, oxidative stress/redox changes and metabolic stress and (ii) by enhancing cellular capacities for damage management and repair. From a societal perspective, there is an urgent imperative to discover, and to implement, cost-effective lifestyle (especially dietary) interventions which enable each of us to age well, i.e. to remain physically and socially active and independent and to minimise the period towards the end of life when individuals suffer from frailty and multi-morbidity.

Vitamin B12 and Homocysteine Associations with Gait Speed in Older Adults: The Baltimore Longitudinal Study of Aging

OBJECTIVES

This study aimed to assess the independent associations of serum levels of vitamin B12 and plasma concentrations of homocysteine with gait speed decline.

DESIGN, SETTING, PARTICIPANTS

This study utilized longitudinal analysis of participants 50 years or older from The Baltimore Longitudinal Study of Aging, N=774.

MEASUREMENTS

Gait speed (m/s) was assessed using the 6-meter usual pace test. Vitamin B12 and homocysteine concentrations were collected using standard clinical protocols. Linear mixed effects regression was stratified by baseline age category (50-69, 70-79, and ≥80 years old).

RESULTS

Mean follow-up time for the total study sample was 5.4 ± 2.0 years. No association between vitamin B12 and gait speed decline over the follow-up time for any age group was found. Elevated homocysteine concentrations were associated with decline in gait speed after adjustment for covariates (50-69: β= -0.005, p=.057; 70-79: β= -0.013, p<.001, ≥80: β= -0.007, p=.054).

CONCLUSION

Homocysteine and vitamin B12 are inversely related, yet only homocysteine was associated with gait speed decline in this population of healthy older adults. Given these results, future research should be directed towards investigating the relationship in populations with greater variation in vitamin B12 concentrations and other mechanisms influencing homocysteine concentrations.

Low sulfide levels and a high degree of cystathionine β-synthase (CBS) activation by S-adenosylmethionine (SAM) in the long-lived naked mole-rat

Hydrogen sulfide (H₂S) is a gaseous signalling molecule involved in many physiological and pathological processes. There is increasing evidence that H₂S is implicated in aging and lifespan control in the diet-induced longevity models. However, blood sulfide concentration of naturally long-lived species is not known. Here we measured blood sulfide in the long-lived naked mole-rat and five other mammalian species considerably differing in lifespan and found a negative correlation between blood sulfide and maximum longevity residual. In addition, we show that the naked mole-rat cystathionine β-synthase (CBS), an enzyme whose activity in the liver significantly contributes to systemic sulfide levels, has lower activity in the liver and is activated to a higher degree by S-adenosylmethionine compared to other species. These results add complexity to the understanding of the role of H₂S in aging and call for detailed research on naked mole-rat transsulfuration.

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Blood sulfide levels are low in long-lived species.

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Naked mole-rat CBS harbours a mutation at an evolutionarily conserved cysteine C412L.

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Naked mole-rat CBS is activated to an unusually high degree by SAM.

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C431L, in contrast to C431S, in human CBS does not confer constitutive activation.

Aging and DNA methylation

In this Opinion article, we summarize how changes in DNA methylation occur during aging in mammals and discuss examples of how such events may contribute to the aging process. We explore mechanisms that could facilitate DNA methylation changes in a site-specific manner and highlight a model in which region-specific DNA hypermethylation during aging is facilitated in a competitive manner by destabilization of the Polycomb repressive complex.

Higher intake of vitamin B-6 and dairy products and lower intake of green and oolong tea are independently associated with lower serum homocysteine concentration in young Japanese women

Little is known about the relation of modifiable dietary factors to circulating homocysteine concentrations, particularly in young adults and non-Western populations. We investigated the hypothesis that intakes of nutrients and foods are associated with serum homocysteine concentration in a group of young Japanese women. This cross-sectional study included 1050 female Japanese dietetic students aged 18 to 22 years. Dietary intake was assessed using a validated, self-administered, comprehensive diet history questionnaire. Fasting blood samples were collected, and serum homocysteine concentrations were measured. Adjustment was made for survey year, region, municipality level, current smoking, current alcohol drinking, dietary supplement use, physical activity, body mass index, energy intake, and intakes of other nutrients or foods. After adjustment for nondietary confounding factors, intakes of all B vitamins (folate, vitamin B-6, vitamin B-12, and riboflavin) were inversely associated with homocysteine concentration. However, only vitamin B-6 remained significant after further adjustment for other B vitamins. Marine-origin n-3 polyunsaturated fatty acid intake showed an inverse association, but this was not independent of intakes of B vitamins. For foods, pulses, fish and shellfish, and vegetables were independently and inversely associated with homocysteine concentration, but these associations disappeared after adjustment for intakes of other foods. Conversely, an inverse association for dairy products and a positive association for green and oolong tea remained even after adjustment for other foods. To conclude, in a group of young Japanese women, higher intake of vitamin B-6 and dairy products and lower intake of green and oolong tea were independently associated with lower serum homocysteine concentration.

Homocysteine, folate, vitamin B-12, and physical function in older adults: cross-sectional findings from the Singapore Longitudinal Ageing Study

BACKGROUND

There is a paucity of studies, as well as inconsistent findings, on the associations of homocysteine, folate, and vitamin B-12 with physical function and decline in older persons.

OBJECTIVE

We investigated the independent associations of homocysteine, folate, and vitamin B-12 with gait and balance performance and Instrumental Activities of Daily Living (IADL) in community-living older persons.

DESIGN

We performed cross-sectional analyses on baseline data of 796 respondents in the Singapore Longitudinal Ageing Study who had laboratory measurements of fasting homocysteine folate and vitamin B-12 and completed Performance Oriented Mobility Assessment (POMA) of gait and balance and self-reports of IADLs.

RESULTS

In multivariate analyses in which sex, age, education, housing type, comorbidities, hospitalization, depression and global cognitive scores, BMI, creatinine, arthritis and hip fracture, serum albumin and hemoglobin, and physical activities were controlled for, we showed that homocysteine, independently of folate and vitamin B-12, showed significant negative associations with POMA balance (P = 0.02), POMA gait scores (P < 0.01), and IADL (P < 0.01). Serum folate showed a significant positive association only with POMA balance scores (P < 0.045). No significant independent associations for vitamin B-12 were observed.

CONCLUSIONS

The independent association of elevated homocysteine and low folate, but not vitamin B-12, on physical and functional decline was supported in this study. Interventional studies of the physical functional effects of folate and vitamin B-12 status in different populations are needed.

Systematic reviews on behavioural and psychological symptoms in the older or demented population

Introduction

Behavioural and psychological symptoms of dementia (BPS) include depressive symptoms, anxiety, apathy, sleep problems, irritability, psychosis, wandering, elation and agitation, and are common in the non-demented and demented population.

Methods

We have undertaken a systematic review of reviews to give a broad overview of the prevalence, course, biological and psychosocial associations, care and outcomes of BPS in the older or demented population, and highlight limitations and gaps in existing research. Embase and Medline were searched for systematic reviews using search terms for BPS, dementia and ageing.

Results

Thirty-six reviews were identified. Most investigated the prevalence or course of symptoms, while few reviewed the effects of BPS on outcomes and care. BPS were found to occur in non-demented, cognitively impaired and demented people, but reported estimates vary widely. Biological factors associated with BPS in dementia include genetic factors, homocysteine levels and vascular changes. Psychosocial factors increase risk of BPS; however, across studies and between symptoms findings are inconsistent. BPS have been associated with burden of care, caregiver's general health and caregiver depression scores, but findings are limited regarding institutionalisation, quality of life and disease outcome.

Conclusions

Limitations of reviews include a lack of high quality reviews, particularly of BPS other than depression. Limitations of original studies include heterogeneity in study design particularly related to measurement of BPS, level of cognitive impairment, population characteristics and participant recruitment. It is our recommendation that more high quality reviews, including all BPS, and longitudinal studies with larger sample sizes that use frequently cited instruments to measure BPS are undertaken. A better understanding of the risk factors and course of BPS will inform prevention, treatment and management and possibly improve quality of life for the patients and their carers.

Homocysteine, folate, and vitamin B12 levels and vertebral fracture risk in postmenopausal women

The objective of this study was to examine the influence of homocysteine, vitamin B(12), and folate on the prevalence of asymptomatic osteoporotic vertebral fractures (VFs) using vertebral fracture assessment (VFA) in postmenopausal women. The study cohort consisted of 188 consecutive postmenopausal women (mean age, weight, and body mass index of 57.9 ± 8.5 [41-91]yr, 74.4 ± 13.5 [38-150]kg, and 30.4 ± 5.2 [17.1-50.7]kg/m(2), respectively). Lateral VFA images and scans of the lumbar spine and proximal femur were obtained using a Lunar Prodigy Vision densitometer (GE Healthcare Inc., Waukesha, WI). VFs were defined using a combination of Genant's semiquantitative approach and morphometry. Fifty-eight (30.9%) patients had densitometric osteoporosis. VFs were identified using VFA in 76 (40.4%) patients: 61 women had grade 1 VFs and 15 had grade 2 or 3 VFs. No statistical difference was shown between the 3 groups (absence of VFs, VFs grade 1, and VFs grade 2/3) concerning the biological parameters. Comparison of patients according to quartiles of homocysteine levels showed that women in the highest quartile were older and had a lower bone mineral density (BMD); however, the prevalence of VFs was not statistically different from that of women in the other quartile groups. Stepwise regression analysis showed that homocysteine was not independently associated with the presence of VFs, which was mainly related to the osteoporotic status. Although a weak association was observed between hyperhomocysteinemia and low BMD and a trend to higher prevalence of grade 2/3 VFs was observed, our study did not confirm that homocysteine, vitamin B(12), and folate status are important determinants of prevalent asymptomatic VFs in postmenopausal women.

Retinoic acid and affective disorders: the evidence for an association

OBJECTIVE

Isotretinoin (13-cis-retinoic acid), approved by the US Food and Drug Administration for the treatment of acne, carries a black box warning related to the risk of depression, suicide, and psychosis. Retinoic acid, the active form of vitamin A, regulates gene expression in the brain, and isotretinoin is its 13-cis isomer. Retinoids represent a group of compounds derived from vitamin A that perform a large variety of functions in many systems, in particular the central nervous system, and abnormal retinoid levels can have neurologic effects. Although infrequent, proper recognition and treatment of psychiatric side effects in acne patients is critical given the risk of death and disability. This article reviews the evidence for isotretinoin's relationships with depression and suicidality.

DATA SOURCES

The PsycINFO, MEDLINE, and PubMed searchable database indexes were searched for articles published in the English language from 1960 to June 2010 using the key words isotretinoin, retinoids, retinoic acid, depression, depressive disorders, and vitamin A. Evidence examined includes (1) case reports; (2) temporal association between onset of depression and exposure to the drug; (3) challenge-rechallenge cases; (4) class effect (other compounds in the same class, like vitamin A, having similar neuropsychiatric effects); (5) dose response; and (6) biologically plausible mechanisms.

STUDY SELECTION

All articles in the literature related to isotretinoin, depression, and suicide were reviewed, as well as articles related to class effect, dose response, and biologic plausibility.

DATA EXTRACTION

Information from individual articles in the literature was extracted, including number of episodes of depression, suicidality, suicide, psychosis, violence and aggression, past psychiatric history, time of onset in relation to isotretinoin usage, medication dosage, duration of treatment, and dechallenge and challenge history.

RESULTS

The literature reviewed is consistent with associations of isotretinoin administration with depression and with suicide in a subgroup of vulnerable individuals.

CONCLUSIONS

The relationship between isotretinoin and depression may have implications for a greater understanding of the neurobiology of affective disorders.

Vitamin B12 and homocysteine levels and 6-year change in peripheral nerve function and neurological signs

BACKGROUND

Low vitamin B12 and high homocysteine (Hcy) levels are common in older adults and may be associated with worse neurological function. The aim of this study is to determine whether changes in B12 or Hcy levels are associated with longitudinal changes in peripheral nerve function and clinical neurological signs and symptoms.

METHODS

Participants aged 60 years and older at baseline (n = 678; 72.2 ± 6.2 years; 43.5% male) were from the InCHIANTI Study. Low B12 (<260 pmol/L) and high Hcy (≥13 μmol/L) were measured at baseline and 3-year follow-up. Neurological function was assessed by peroneal nerve conduction amplitude (compound motor action potential) and velocity, neurological examination, and peripheral neuropathy symptoms at baseline, 3-year, and 6-year follow-up.

RESULTS

At baseline, 43.8% had low B12 levels and 58.6% had high Hcy levels. Over 6 years, 12.4% declined to poor compound motor action potential (<1 mV) and 42.1% declined to poor nerve conduction velocity (<40 m/s). In mixed models analyses, sustained high Hcy was associated with worse compound motor action potential compared with sustained normal Hcy (p = .04), adjusting for demographics, diabetes, and folate level. Participants whose Hcy level became high at follow-up were more likely to become unable to detect monofilament at 6-year follow-up compared with those with sustained normal Hcy (odds ratio: 5.4; 95% CI: 1.5-19.0), adjusting for demographics, diabetes, body mass index, and peripheral arterial disease. There was no association with vitamin B12 level or with symptoms.

CONCLUSIONS

High Hcy may be associated with worse sensory and motor peripheral nerve function. Because poor nerve function has been associated with lower strength and physical performance, these results have important implications for disability in older adults.

Methyl Vitamin B12 but not methylfolate rescues a motor neuron-like cell line from homocysteine-mediated cell death

Homocysteine is an excitatory amino acid implicated in multiple diseases including amyotrophic lateral sclerosis (ALS). Information on the toxicity of homocysteine in motor neurons is limited and few studies have examined how this toxicity can be modulated. In NSC-34D cells (a hybrid cell line derived from motor neuron-neuroblastoma), homocysteine induces apoptotic cell death in the millimolar range with a TC₅₀ (toxic concentration at which 50% of maximal cell death is achieved) of 2.2 mM, confirmed by activation of caspase 3/7. Induction of apoptosis was independent of short-term reactive oxygen species (ROS) generation. Methyl Vitamin B12 (MeCbl) and methyl tetrahydrofolate (MTHF), used clinically to treat elevated homocysteine levels, were tested for their ability to reverse homocysteine-mediated motor neuron cell death. MeCbl in the micromolar range was able to provide neuroprotection (2 h pretreatment prior to homocysteine) and neurorescue (simultaneous exposure with homocysteine) against millimolar homocysteine with an IC₅₀ (concentration at which 50% of maximal cell death is inhibited) of 0.6 μM and 0.4 μM, respectively. In contrast, MTHF (up to 10 μM) had no effect on homocysteine-mediated cell death. MeCbl inhibited caspase 3/7 activation by homocysteine in a time- and dose-dependent manner, whereas MTHF had no effect. We conclude that MeCbl is effective against homocysteine-induced cell death in motor neurons in a ROS-independent manner, via a reduction in caspase activation and apoptosis. MeCbl decreases Hcy induced motor neuron death in vitro in a hybrid cell line derived from motor neuron-neuroblastoma and may play a role in the treatment of late stage ALS where HCy levels are increased in animal models of ALS.

Perinatal folate supply: relevance in health outcome parameters

The importance of physiological supply of folate is well recognized in human health; the crucial roles of folate in one-carbon metabolism for physiological DNA synthesis and cell division, as well as in the conversion of homocysteine (Hcy) to methionine, and subsequently, to S-adenosylmethionine, have been convincingly demonstrated. Improved folate status may reduce the risk of macrocytic anaemia, cardiovascular diseases, neuropsychiatric disorders and adverse pregnancy outcomes. Inadequate folate status results in a decrease in the methylation cycle and in increased blood levels of the neurotoxic Hcy. The aim of this review is to provide insight into the influence of folate status on pregnancy health outcomes, and to consider increasing evidence of a link between the extent of genome/epigenome damage and elevated risk for adverse obstetrical endpoints. Pregnant women are at risk for folate insufficiency because of the increased need for folate for rapid fetal growth, placental development and enlargement of the uterus. Inadequate folate status may cause fetal malformations, impaired fetal growth, pre-term delivery and maternal anaemia. Even some diseases of the placenta may arise from folate deficiencies. Fetal growth seems to be vulnerable to maternal folate status during the periconception period, because it has the potential to affect both the closure of the neural tube and several epigenetic mechanisms within the placenta and the fetus. Mainly on the basis of the well recognized link between maternal folate status and fetal neural tube defects, women are advised to receive folic acid supplement during the periconceptional period. Because an adequate folate supply seems to play an important role in the implantation and development of the placenta and in improving endothelial function, folic acid supplementation in the late first trimester or early second trimester might also be beneficial.

Influence of thymidylate synthase gene polymorphisms on total plasma homocysteine concentrations

BACKGROUND

Thymidylate synthase (TS) is a key enzyme that regulates the production of nucleotide synthesis by catalyzing the conversion of deoxyuridylate to thymidylate. Three functional polymorphisms in the TS gene have been identified including: (i) the thymidylate synthase enhancer region (TSER) tandem repeat polymorphism and (ii) the G to C single nucleotide polymorphism (G/C SNP) both of which occur in the 5'untranslated region (UTR) of the TS gene; and (iii) the 6 base pair deletion at base pair 1494 (TS1494del6) located in the 3'UTR.

PURPOSE

The purpose of this research was to investigate the relationship between TS polymorphisms and total plasma homocysteine (tHcy) levels.

METHODS

The study population consisted of 396 healthy male and female volunteers from Kingston, Ontario and Halifax, Nova Scotia, Canada between 2006 and 2008. The effect of each TS polymorphism on tHcy concentrations was investigated and further analyses were conducted on categorization of polymorphisms based on 5' or 3'UTR. The combined effect of TS polymorphisms on tHcy concentration was also investigated, in addition to interactions between polymorphisms in TS and MTHFR 677C>T and interactions between TS polymorphisms and serum folate and vitamin B(12) status.

RESULTS

An association between TS 5'polymorphisms and tHcy concentration was observed (p=0.05). The combined effect of the TS polymorphisms was also found to be associated with tHcy concentration (p=0.05). Additionally, an antagonistic interaction was observed between TS 5'polymorphism and MTHFR 677C>T on tHcy concentrations (p=0.04).

CONCLUSIONS

The findings of this research provide evidence of an association between TS polymorphisms and tHcy concentrations.

Polymorphism of genes encoding homocysteine metabolism-related enzymes and risk for cardiovascular disease

The aim of this review is to present a general overview of the relationships among homocysteine metabolism, polymorphism of the genes encoding homocysteine metabolism-related enzymes, and the nutrients influencing the plasma homocysteine level. Combining these factors creates a profile of an individual's susceptibility to complex diseases associated with hyperhomocysteinemia. Homocysteine is an amino acid derived from the demethylation of methionine. Hyperhomocysteinemia is associated with an increased risk of several complex diseases, including cardiovascular diseases. The level of plasma homocysteine depends on the combined effects of genetic and environmental factors. Polymorphisms of genes encoding homocysteine metabolism-related enzymes, such as methylenetetrahydrofolate reductase, methionine synthase, methionine synthase reductase, and cystathionine beta-synthase, influence plasma homocysteine concentration and thereby cardiovascular health. On the other hand, homocysteine metabolism may be modulated by dietary intake of the nutrients involved in homocysteine metabolism (ie, folates, vitamin B(6), and vitamin B(12)). Thus, the appropriate health-promoting doses of these nutrients may vary among certain groups of individuals, depending on their genotypes and other risk factors for complex diseases. Better understanding of the relationship between genotype and nutrition influencing the plasma total homocysteine level and cardiovascular health may improve the cardiovascular diagnostic tests (ie, measurement of biologic markers). It could be possible to define the level of progression, severity, and susceptibility to disease much earlier than it is done now. In conclusion, the introduction of combined dietary and pharmacologic treatment would be possible at the initial stages of disease.

Cross-sectional analysis of baseline data to identify the major determinants of carotid intima-media thickness in a European population: the IMPROVE study

AIMS

The 'IMPROVE study' was designed to investigate whether cross-sectional carotid artery intima-media thickness (IMT) and overall IMT progression are predictors of new vascular events in European individuals at high risk of cardiovascular diseases. This paper reports the results of the baseline analyses aimed at identifying the major determinants of increased carotid IMT (C-IMT).

METHODS AND RESULTS

IMPROVE is a prospective, multicentre, longitudinal, observational study. A total of 3711 subjects (age range 54-79 years) with at least three vascular risk factors (VRFs) were recruited in seven centres in Finland, France, Italy, the Netherlands, and Sweden. Collected variables included clinical, biochemical, genetic, socioeconomic, psychological, nutritional, and educational data, personal and family history of diseases, drug intake, and physical activity. By multiple linear regression analysis, C-IMT was positively associated with latitude, age, gender, pulse pressure, pack-years, and hypertension, and inversely with educational level (all P < 0.0001 for IMT(mean-max)). Latitude was the strongest independent determinant of C-IMT (partial r(2) for IMT(mean-max) = 0.109, P < 0.0001) and alone accounted for nearly half of the variation explained by the regression model (partial r(2) for IMT(mean-max) = 0.243, P < 0.0001). The geographical gradient for C-IMT paralleled the well-known north-to-south cardiovascular mortality gradient (r(2) for IMT(mean) = 0.96).

CONCLUSION

Latitude is an important determinant of C-IMT, which is not explained by between-country differences in established VRFs. Other unknown contributory mechanisms such as heritable, nutritional, or environmental factors may be important in the genesis of this geographical gradient.

Polygenic association with total homocysteine in the post-folic acid fortification era: the CARDIA study

Elevated plasma concentration of total homocysteine (tHcy) has been linked with many diseases. tHcy is associated with a variety of factors, including polymorphisms in genes involved in homocysteine metabolism. It is not clear whether US-mandated fortification of grain products with folic acid has affected the association of genetic variants with tHcy levels. We determined tHcy concentrations in sera from 997 Caucasians and 692 African Americans participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study before and after folic acid fortification. DNA was genotyped for variants present in four genes involved in homocysteine metabolism: cystathionine beta-synthase (CBS) 844ins68, methionine synthase (MS) 2756A>G; methionine synthase reductase (MTRR) 66A>G and methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C. A greater number of African Americans were homozygous for the MS 2756GG, MTRR 66GG and CBS 844ins68 genotypes compared to Caucasians, while prevalence of MTHFR 677TT and 1298CC genotypes was substantially lower in African Americans compared to Caucasians. The overall variance in tHcy levels at y 0, 7 and 15 that can be explained by the combined presence of all five variants increased slightly over time in Caucasians (17%, y 0; 21%, y 7; and 26%, y 15) and in African Americans (13%, y 0; 17% y 7; and 18% y 15) largely due to decrease in tHcy variance.

Blood homocysteine and risk of depression in the elderly

We studied whether increased blood homocysteine is a predictor for incident depression in a population-based cohort aged >or=65. A total of 240 men and 217 women were identified at baseline and were assessed 4 years later for depression (Geriatric Depression Scale, GDS >or=10 or use of antidepressants). Risk of incident depression was estimated for the highest gender-specific tertile of baseline plasma homocysteine compared to the other tertiles combined in a reference group. As deficiencies of B(12) and folate are the main determinant of increased blood homocysteine in old age, serum concentrations of these vitamins were also measured. In women only, the highest homocysteine tertile was associated with incident depression. However, women with combined serum B(12)/folate deficiency had the highest blood homocysteine but also a lower depression risk than vitamin-replete women. In conclusion, the data only moderately support the hypothesis that blood homocysteine is a predictor of depression.