Intracellular distribution of the vitamin D receptor in the brain: Comparison with classic target tissues and redistribution with development

Effects of vitamin D on brain function in preschool children with autism spectrum disorder: a resting-state functional MRI study

BACKGROUND

Previous studies indicate vitamin D impacts autism spectrum disorder (ASD), but its relationship with brain function is unclear. This study investigated the association between serum 25-hydroxyvitamin D [25(OH)D] levels and brain function in preschool children with ASD using resting-state functional magnetic resonance imaging (rs-fMRI), and explored correlations with clinical symptoms.

METHODS

A total of 226 ASD patients underwent rs-fMRI scanning and serum 25(OH)D testing. Clinical symptoms were assessed using Childhood Autism Rating Scale (CARS) and Autism Behavior Checklist (ABC). Patients were categorized into mild and severe groups based on the CARS, and further divided into normal (NVD), insufficient (VDI), and deficient (VDD) serum 25(OH)D levels. Changes in brain function among these groups were analyzed using regional homogeneity (ReHo), with ABC scores used for correlation analysis.

RESULTS

In mild ASD, ReHo increased in the right postcentral gyrus and left precuneus in the VDI and VDD groups compared to NVD, and decreased in the bilateral middle cingulate gyrus and left superior frontal gyrus in the VDD group compared to VDI. In severe ASD, ReHo decreased in the right middle occipital gyrus and increased in the right insula in the VDI group compared to NVD, and increased in the right superior frontal gyrus in the VDD group compared to VDI. Correlation analysis revealed that in mild ASD, ReHo in the right postcentral gyrus was positively correlated with body and object use scores in the NVD and VDI groups, while ReHo in the right middle cingulate gyrus was negatively correlated with relating scores in the VDD and VDI groups. In severe ASD, ReHo in the right insula was positively correlated with language scores in the NVD and VDI groups.

CONCLUSIONS

ASD patients with lower serum 25(OH)D levels show multiple brain functional abnormalities, with specific brain region alterations linked to symptom severity. These findings enhance our understanding of vitamin D's impact on ASD and suggest that future research may explore its therapeutic potential.

Vitamin D replacement therapy may regulate sleep habits in patients with restless leg syndrome

Aim

The aim of this study is to determine the effect of vitamin D replacement therapy on sleep habits in restless legs syndrome (RLS) patients with vitamin D deficiency.

Methods

The study was conducted between September 1, 2018, and September 1, 2019, at the Pediatrics outpatient clinic of Bezmialem Vakif University. 46 cases with RLS and 43 healthy controls between these dates were included in the study. The Children's Sleep Habits Questionnare was filled out retrospectively by parents.

Results

While vitamin D supplementation was given to 20 children with RLS who were found to have vitamin D deficiency, the 26 patients without vitamin D deficiency did not receive supplementation. There was no significant difference between the treatment groups in terms of gender, age, and pre-treatment sleep habits. Compared to the pre-treatment period, post-treatment bedtime resistance, sleep onset delay, sleep anxiety, parasomnias, daytime sleepiness, and CSHQ total score were significantly improved in RLS cases with vitamin D deficiency. There were no significant differences in RLS patients without vitamin D supplementation. Other comparisons also showed no difference between groups.

Conclusion

There was no difference between the sleep habits of RLS cases with and without vitamin D deficiency. Sleep habits improved positively after vitamin D supplementation in patients with vitamin D deficiency compared to the pre-treatment period. There was no difference in the sleeping habits of RLS patients without vitamin D deficiency during the same period. Vitamin D supplementation can improve sleep habits in patients with RLS.

Pediatric Headache Patients Are at High Risk of Vitamin D Insufficiency

BACKGROUND

Vitamin D deficiency has been associated with headaches in adults, but data for children with headaches are sparse.

OBJECTIVE

To describe vitamin D levels in children with headaches.

METHODS

We retrospectively analyzed serum 25(OH)D concentrations in children aged 2-17 years with headaches compared to children with epilepsy at the Children's Hospital of Eastern Ontario between October 1, 2014, and August 19, 2021. Serum 25(OH)D <50 nmol/L was classified as insufficient.

RESULTS

Vitamin D concentrations of 353 children (117 with headaches; 236 with epilepsy) were analyzed. The median age in years was 10 (interquartile range [IQR] 5, 14); 50.4% of subjects were female. The median serum 25(OH)D was 56 nmol/L (IQR 41, 69) in children with headaches and 70 nmol/L (IQR 50, 95) in children with epilepsy. Vitamin D insufficiency was present in 42% of children with headaches and 25% of children with epilepsy (P = .002). In a multivariable linear regression model adjusting for age, sex and seasonality, children with headaches had serum 25(OH)D concentrations that were on average 9 nmol/L (95% CI-16.76, -0.96) lower compared to children with epilepsy (P = .029).

CONCLUSION

The prevalence of vitamin D insufficiency is higher in children with headaches compared to children with epilepsy. Prospective studies are needed to assess if vitamin D supplementation may have a therapeutic effect on pediatric headaches.

Vitamin D deficiency may accelerate cognitive decline in female apolipoprotein E ε4 non-carriers

BACKGROUND & AIMS

The impact of vitamin D deficiency (VDD) on cognition remains controversial. Evidences suggest that variability based on apolipoprotein E (APOE) ε4 status and gender, given APOE ε4's influence on vitamin D metabolism and women's heightened vitamin D sensitivity. We investigated the interplay between APOE ε4, gender, and VDD in cognitive decline among older adults.

METHODS

In a population-based cohort of 1547 cognitively normal Koreans aged ≥60 years, Mini Mental State Examination (MMSE) changes were tracked biennially (2010-2020). VDD was defined as serum 25-hydroxyvitamin D < 10 ng/mL. Linear mixed models analyzed VDD effects, with subgroup analyses for APOE ε4 status and gender.

RESULTS

VDD was present in 21.3 % at baseline and was linked to faster MMSE decline (estimate = -0.054, 95 % CI [-0.091, -0.017], p = 0.004), particularly in APOE ε4 non-carriers (estimate = -0.070, 95 % CI [-0.112, -0.029], p = 0.001). A gender-based analysis revealed that this effect was significant only in female non-carriers (estimate = -0.097, 95 % CI [-0.156, -0.038], p = 0.001). Conversely, male non-carriers demonstrated an absence of a statistically significant association (estimate = -0.017, 95 % CI [-0.076, 0.041], p = 0.562).

CONCLUSIONS

VDD accelerates cognitive decline in cognitively normal APOE ε4 non-carriers, particularly women, underscoring the importance of tailored prevention strategies.

Association between 25(OH) vitamin D and schizophrenia: shared genetic correlation, pleiotropy, and causality

Background

This study delves into the complex interplay between genetics, 25-hydroxyvitamin D (25OHD), and schizophrenia (SCZ). It leverages extensive sample data derived from Genome-Wide Association Studies (GWAS) to uncover genetic correlations.

Methods

Employing Linkage Disequilibrium Score Regression (LDSC) and S-LDSC, this study investigates genetic connections between 25OHD and SCZ. It examines Single Nucleotide Polymorphism (SNP) heritability in specific tissues and incorporates diverse immune cell datasets for genetic enrichment analysis. Local genetic correlations were analyzed using HESS software, and pleiotropy analysis identified shared genetic loci in brain tissues. Hyprcoloc analysis was used to explore shared genetic factors between 25OHD, immune cells, and SCZ, complemented by a bidirectional Mendelian Randomization (MR) to probe potential causal links.

Results

We identified a significant negative genetic correlation between 25OHD levels and SCZ. PLACO analysis revealed 35 pleiotropic loci with strong enrichment in brain regions, particularly the cerebellum, frontal cortex, and hippocampus. Eight loci (1p34.2, 2p23.3, 3p21.1, 5q31.2, 12q23.2, 14q32.33, 16p13.3, and 16q24.3) exhibited strong colocalization, highlighting potential drug targets. Gene and tissue enrichment analyses emphasized neurological and immune-related mechanisms, including hyaluronan metabolism. Bidirectional MR analysis supported a causal effect of SCZ on 25OHD levels.

Conclusion

Our study identifies NEK4 as a potential therapeutic target and highlights the involvement of hyaluronan metabolism in the genetic association between 25OHD and SCZ. These findings provide valuable insights into shared genetic pathways, immune-related connections, and causal interactions in the context of SCZ.

Cholecalciferol Supplementation Impacts Behavior and Hippocampal Neuroglial Reorganization in Vitamin D-Deficient Rats

Vitamin D deficiency (VDD) is widespread around the world and has been extensively documented to affect various health conditions, including the cognitive functioning of the brain. Serum 25-hydroxylated forms of vitamin D are traditionally used to determine vitamin D status. However, there is now evidence that cholecalciferol activation can occur and be controlled by locally expressed enzymes in the brain. This study aimed to investigate the effects of cholecalciferol supplementation on cognitive function in rats who underwent transient VDD in adulthood. Thirty-six adult Wistar rats were administered paricalcitol (seven doses of 32 ng injected every other day) along with a "vitamin D-free" diet to induce VDD, which was confirmed using a LC-MS/MS serum analysis of the cholecalciferol and 25-hydroxyvitamin D3 levels. Treatment was performed by including 1000 IU/kg and 10,000 IU/kg cholecalciferol in the diet. Cognitive performance was evaluated using the novel object recognition (NOR), Morris water maze (MWM), and radial arm maze (RAM) tests. An immunohistochemical analysis of the brain regions involved in learning and memory was performed by quantifying the neurons, astrocytes, and microglia labelled with anti-neuronal nuclei (NeuN), glial fibrillary acidic protein (GFAP), and ionized calcium-binding adaptor molecule 1 (Iba-1) antibodies, respectively. The vitamin D deficient group showed the lowest performance in both the MWM and RAM tests. In contrast, the cholecalciferol-treated groups exhibited a faster learning curve. However, no difference was detected between the groups in the NOR test. On the other hand, differences in the cellular organization of the hippocampus and amygdala were observed between the groups. Cholecalciferol supplementation decreased the density of the Iba-1- and GFAP-labeled cells in the hilus and cornu Ammonis 3 (CA3) regions of the hippocampus and in the amygdala. These results support vitamin D's substantial role in learning and memory. They also highlight that subtle changes of cognitive function induced by transient VDD could be reversed by cholecalciferol supplementation. Further studies are needed to better understand VDD and cholecalciferol's effects on the brain structure and function.

Current Aspects of Selected Factors to Modulate Brain Health and Sports Performance in Athletes

This review offers a comprehensive evaluation of current aspects related to nutritional strategies, brain modulation, and muscle recovery, focusing on their applications and the underlying mechanisms of physiological adaptation for promoting a healthy brain, not only in athletes but also for recreationally active and inactive individuals. We propose that applying the rule, among others, of good sleep, regular exercise, and a properly balanced diet, defined as "SPARKS", will have a beneficial effect on the function and regeneration processes of the gut-brain-muscle axis. However, adopting the formula, among others, of poor sleep, stress, overtraining, and dysbiosis, defined as "SMOULDER", will have a detrimental impact on the function of this axis and consequently on human health as well as on athletes. Understanding these dynamics is crucial for optimizing brain health and cognitive function. This review highlights the significance of these factors for overall well-being, suggesting that adopting the "SPARKS" approach may benefit not only athletes but also older adults and individuals with health conditions.

Knockdown of vitamin D receptor affects early stages of pectoral fin development in zebrafish

The vitamin D receptor (VDR) signalling has been implicated in vertebrate limb or fin formation. However, the involvement of VDR signalling in the early stages of limb/fin development remains to be elucidated. In this study, the role of VDR signalling in pectoral fin development was investigated in zebrafish embryos. Knockdown of vdr induced the severe impairment of pectoral fin development. The zebrafish larvae lacking vdr exhibited reduced pectoral fins with no skeletal elements. In situ hybridization revealed depletion of vdr downregulated fibroblast growth factor 24 (fgf24), a marker of early pectoral fin bud mesenchyme, in the presumptive fin field even before fin buds were visible. Moreover, a perturbed expression pattern of bone morphogenetic protein 4 (bmp4), a marker of the pectoral fin fold, was observed in the developing fin buds of zebrafish embryos that lost the vdr function. These findings suggest that VDR signalling is crucial in the early stages of fin development, potentially influencing the process by regulating other signalling molecules such as Fgf24 and Bmp4.

Triggering multiple sclerosis at conception and early gestation: The variation in ultraviolet radiation is as important as its intensity

Background and objectives

Medical science needs to further elucidate the role of ultraviolet radiation (UVR), geographic latitude, and the role of vitamin D in the autoimmune disease multiple sclerosis (MS). We separated several papers into categories out of the thousands published and used their conclusions to explore the relationship between UVR and MS.

Relevance

MS is increasing in incidence, particularly in women where MS is two to three times that in men and particularly severe in African Americans.

Methods

We collected UVR data at our observatory in Central Maine and calculated the average coefficient of variation (CVUVR) for each month for 15 years (2007-2021, inclusive).

Results

The month of conception (MOC) is more important than the month of birth (MOB) in explaining how UVR triggers the variable genetic predisposition to MS. We hypothesize that the rapidly increasing CVUVR is important in preventing an increase in the activity of the vitamin D receptor (VDR) from August to December, which then requires a higher intensity of UVR later in life to suppress the immune system, therefore predisposing to more MS.

Limitations

One observatory at about 44° latitude.

Conclusions

While variation in UVR is important at the MOC if UVR exceeds a threshold (e.g., if the sunspot number equals or is greater than 90, usually at a solar cycle MAX, or at elevations above approximately 3,000 feet above sea level), the MS mitigating vitamin D-VDR mechanism is overwhelmed and the genotoxic effects of higher-intensity UVR promote MS in those with a genetic predisposition.

What is new in this research

This paper offers a new concept in MS research.

Vitamin D and Probability of Developmental Disorders among Perinatally HIV-Affected and Unaffected Ugandan Children

We tested the hypothesis that vitamin D deficiency (VDD) is associated with higher developmental disorder probability in 604 children with perinatal HIV infection (CPHIV, n = 199), HIV exposed and uninfected (CHEU, n = 196), and HIV unexposed uninfected (CHUU, n = 201). Children at 6-18 years old and their adult caregivers were assessed at enrollment, 6, and 12-month follow-ups. Serum 25-hydroxyvitamin-D (25OHD) levels in children quantified per the NHANES protocol were used to define VD categories as VDD (25OHD < 20 ng/mL), VD insufficient (VDI, 20 ≤ 25OHD ≤ 25 ng/mL), and VD sufficient (VDS = reference group if 25OHD > 25 ng/mL). Perinatal HIV status per DNA polymerase chain reaction/HIV rapid diagnostic tests included: CPHIV, CHEU, and CHUU. Developmental stage was defined as pre-adolescent (age < 11) vs. adolescent (age ≥ 11) years. Caregiver responses to standardized questions from Behavioral Assessment System for Children, Third Edition (BASC-3), were used to calculate probability scores for four disorders, namely: autism (ASD), attention deficit & hyperactivity (ADHD), emotional behavioral disorder (EBD), functional impairment (FI), and resiliency at 0, 6 and 12 months. Multivariable longitudinal models estimated VD-associated standardized mean difference (SMD) and corresponding 95% confidence intervals (95% CI) in respective probability scores in Statistical Analysis Software (v.9.4). Baseline VDD vs. VDS predicted higher probability scores of moderate clinical importance for ASD, ADHD, EBD, and higher FI among pre-adolescents (SMD = 0.32 to 0.40, 95% CI: 0.00 to 0.74). VDD was not associated with resiliency or any developmental disorders among adolescents. VDD predicted higher developmental disorder and FI scores over 12 months in a developmental stage-dependent manner. This relationship requires further understanding to appropriately target future interventions.

Nutritional metabolism and cerebral bioenergetics in Alzheimer's disease and related dementias

Disturbances in the brain's capacity to meet its energy demand increase the risk of synaptic loss, neurodegeneration, and cognitive decline. Nutritional and metabolic interventions that target metabolic pathways combined with diagnostics to identify deficits in cerebral bioenergetics may therefore offer novel therapeutic potential for Alzheimer's disease (AD) prevention and management. Many diet-derived natural bioactive components can govern cellular energy metabolism but their effects on brain aging are not clear. This review examines how nutritional metabolism can regulate brain bioenergetics and mitigate AD risk. We focus on leading mechanisms of cerebral bioenergetic breakdown in the aging brain at the cellular level, as well as the putative causes and consequences of disturbed bioenergetics, particularly at the blood-brain barrier with implications for nutrient brain delivery and nutritional interventions. Novel therapeutic nutrition approaches including diet patterns are provided, integrating studies of the gut microbiome, neuroimaging, and other biomarkers to guide future personalized nutritional interventions.

Liver's influence on the brain through the action of bile acids

The liver partakes as a sensor and effector of peripheral metabolic changes and a regulator of systemic blood and nutrient circulation. As such, abnormalities arising from liver dysfunction can influence the brain in multiple ways, owing to direct and indirect bilateral communication between the liver and the brain. Interestingly, altered bile acid composition resulting from perturbed liver cholesterol metabolism influences systemic inflammatory responses, blood-brain barrier permeability, and neuron synaptic functions. Furthermore, bile acids produced by specific bacterial species may provide a causal link between dysregulated gut flora and neurodegenerative disease pathology through the gut-brain axis. This review will cover the role of bile acids-an often-overlooked category of active metabolites-in the development of neurological disorders associated with neurodegeneration. Further studies into bile acid signaling in the brain may provide insights into novel treatments against neurological disorders.

The Association between Vitamin D Deficiency and Changes in Cognitive Functions in Chinese Older Adults: A Prospective Cohort Study

BACKGROUND

Along with the problem of population aging, the prevalence of dementia is gradually increasing. Associations between vitamin D deficiency (VDD) and cognitive functions remain unclear.

OBJECTIVES

We aimed to determine the relationship between VDD and changes in cognitive performance in community-dwelling older adults.

METHODS

In this longitudinal cohort study, participants aged ≥65 years were enrolled in March, 2016. The serum level of 25-hydroxy-vitamin D was analyzed by liquid-chromatography-tandem-- mass-spectrometry at baseline. VDD was defined as less than 20 ng/mL. All participants completed a health status questionnaire. Cognitive functions were evaluated by the Wechsler Adult Intelligence Scale-Revised in China at baseline and each visit. The linear mixed-effects model was utilized to examine the association between baseline VDD and changes in cognitive functions.

RESULTS

In total, 866 participants were included in our study, with a mean duration of 3 years. VDD was markedly associated with lower full intelligence quotient (FIQ) (β: -3.355, 95% confidence interval [CI]:-4.165,-2.545), verbal intelligence quotient (VIQ) (β: -3.420, 95%CI: -4.193,-2.647), performance intelligence quotient (PIQ) (β: -2.610, 95%CI: -3.683,-1.537), comprehension (β: -0.630, 95%CI: -1.022,-0.238), information (β: -0.354, 95%CI: -0.699,-0.008), arithmetic (β: -1.065, 95%CI: -1.228,-0.902), digit span (β: -0.370, 95%CI: -0.547,-0.192), vocabulary (β: -0.789, 95%CI: -1.084,-0.493), picture completion (β: -0.391, 95%CI: -0.761,-0.022), block design (β: -0.412, 95%CI: -0.697,-0.127), picture arrangement (β: -0.542, 95%CI: -0.909,-0.174), and object assembly (β: -0.492, 95%CI: -0.818,-0.165) than those with adequacy.

CONCLUSION

A higher frequency of VDD was associated with lower scores of FIQ, VIQ, PIQ and subtests on memory and executive function. Future randomized controlled trials are warranted to further verify the conclusions.

Low Serum Vitamin D Status Is Associated with Incident Alzheimer's Dementia in the Oldest Old

Background. Vitamins A, D and E and beta-carotene may have a protective function for cognitive health, due to their antioxidant capacities. Methods. We analyzed data from 1334 non-demented participants (mean age 84 years) from the AgeCoDe study, a prospective multicenter-cohort of elderly general-practitioner patients in Germany, of whom n = 250 developed all-cause dementia and n = 209 developed Alzheimer’s dementia (AD) during 7 years of follow-up. We examined whether concentrations of vitamins A (retinol), D (25-hydroxycholecalciferol) and E (alpha-tocopherol) and beta-carotene, would be associated with incident (AD) dementia. Results. In our sample, 33.7% had optimum vitamin D concentrations (≥50 nmol/L). Higher concentrations of vitamin D were associated with lower incidence of all-cause dementia and AD (HR 0.99 (95%CI 0.98; 0.99); HR0.99 (95%CI 0.98; 0.99), respectively). In particular, subjects with vitamin D deficiency (25.3%, <25 nmol/L) were at increased risk for all-cause dementia and AD (HR1.91 (95%CI 1.30; 2.81); HR2.28 (95%CI 1.47; 3.53), respectively). Vitamins A and E and beta-carotene were unrelated to (AD) dementia. Conclusions. Vitamin D deficiency increased the risk to develop (AD) dementia. Our study supports the advice for monitoring vitamin D status in the elderly and vitamin D supplementation in those with vitamin D deficiency. We observed no relationships between the other vitamins with incident (AD) dementia, which is in line with previous observational studies.

Bile acids and neurological disease

This review will focus on how bile acids are being used in clinical trials to treat neurological diseases due to their central involvement with the gut-liver-brain axis and their physiological and pathophysiological roles in both normal brain function and multiple neurological diseases. The synthesis of primary and secondary bile acids species and how the regulation of the bile acid pool may differ between the gut and brain is discussed. The expression of several bile acid receptors in brain and their currently known functions along with the tools available to manipulate them pharmacologically are examined, together with discussion of the interaction of bile acids with the gut microbiome and their lesser-known effects upon brain glucose and lipid metabolism. How dysregulation of the gut microbiome, aging and sex differences may lead to disruption of bile acid signalling and possible causal roles in a number of neurological disorders are also considered. Finally, we discuss how pharmacological treatments targeting bile acid receptors are currently being tested in an array of clinical trials for several different neurodegenerative diseases.

Vitamin D and the Central Nervous System: Causative and Preventative Mechanisms in Brain Disorders

Twenty of the last one hundred years of vitamin D research have involved investigations of the brain as a target organ for this hormone. Our group was one of the first to investigate brain outcomes resulting from primarily restricting dietary vitamin D during brain development. With the advent of new molecular and neurochemical techniques in neuroscience, there has been increasing interest in the potential neuroprotective actions of vitamin D in response to a variety of adverse exposures and how this hormone could affect brain development and function. Rather than provide an exhaustive summary of this data and a listing of neurological or psychiatric conditions that vitamin D deficiency has been associated with, here, we provide an update on the actions of this vitamin in the brain and cellular processes vitamin D may be targeting in psychiatry and neurology.

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.

Shift Work and Serum Vitamin D Levels: A Systematic Review and Meta-Analysis

Vitamin D deficiency and insufficiency are highly prevalent conditions worldwide due to several factors, including poor sun exposure. Shift workers may be exposed to the risk of hypovitaminosis D due to fewer opportunities for sunlight exposure compared to day workers. A systematic review of the PubMed, SCOPUS, and EMBASE databases was conducted according to the Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) statement to investigate the effect of shift work on vitamin D levels. Mean differences (MD) and 95% confidence intervals (CI) of serum 25-OH-D levels in shift workers and non-shift workers were calculated. A total of 13 cross-sectional studies were included in the meta-analysis. We found significantly lower levels of serum 25-OH-D in shift workers compared with non-shift workers (MD: −1.85, 95% CI [−2.49 to −1.21]). Heterogeneity among included studies was high (I2 = 89%, p < 0.0001), and neither subgroup analysis nor meta-regression were able to identify specific sources of the heterogeneity that may be related to the different characteristics of shift work among studies. The monitoring of serum vitamin D levels and prompt correction of any deficiencies should be considered in shift workers. Notably, since a large part of the observations are derived from Koreans, larger epidemiological studies are needed in other populations.

Full spectrum of vitamin D immunomodulation in multiple sclerosis: mechanisms and therapeutic implications

Vitamin D deficiency has been associated with the risk of multiple sclerosis, disease activity and progression. Results from in vitro experiments, animal models and analysis of human samples from randomized controlled trials provide comprehensive data illustrating the pleiotropic actions of Vitamin D on the immune system. They globally result in immunomodulation by decreasing differentiation of effector T and B cells while promoting regulatory subsets. Vitamin D also modulates innate immune cells such as macrophages, monocytes and dendritic cells, and acts at the level of the blood–brain barrier reducing immune cell trafficking. Vitamin D exerts additional activity within the central nervous system reducing microglial and astrocytic activation. The immunomodulatory role of Vitamin D detected in animal models of multiple sclerosis has suggested its potential therapeutic use for treating multiple sclerosis. In this review, we focus on recent published data describing the biological effects of Vitamin D in animal models of multiple sclerosis on immune cells, blood–brain barrier function, activation of glial cells and its potential neuroprotective effects. Based on the current knowledge, we also discuss optimization of therapeutic interventions with Vitamin D in patients with multiple sclerosis, as well as new technologies allowing in-depth analysis of immune cell regulations by vitamin D.

The role of sleep in PCOS: what we know and what to consider in the future

INTRODUCTION

Sleep disturbance and clinical sleep conditions disrupt endocrine signals, energy expenditure and nutritional intake. Women with polycystic ovary syndrome (PCOS) are at higher risk of sleep disturbances and clinical conditions. It is possible that sleep may contribute to the exacerbation of PCOS. This review aims to explore the relationship between sleep and chronic disease, particularly in women with PCOS.

AREAS COVERED

This review narratively explores what sleep is, how to measure sleep and the possible mechanisms that support the link between sleep in adipose tissue deposition, insulin resistance and the presentation of PCOS.

EXPERT OPINION

Research shows that disturbed sleep and clinical sleep conditions disrupt energy expenditure. This may increase adipose tissue deposition and exacerbate insulin resistance which are known to worsen the presentation of PCOS. Further, sleep disturbance in women with PCOS may ameliorate any positive lifestyle changes made after diagnosis. Cognitive behavioural therapy interventions for sleep are a successful strategy for the management of sleep disturbances in the general population. However, such interventions are yet to be trialled in women with PCOS. Given the proposed implications, interventions to improve sleep could provide additional support for women with PCOS to successfully implement lifestyle strategies and should be further investigated.

Nuclear hormone receptors in demyelinating diseases

Demyelination results from the pathological loss of myelin and is a hallmark of many neurodegenerative diseases. Despite the prevalence of demyelinating diseases, there are no disease modifying therapies that prevent the loss of myelin or promote remyelination. This review aims to summarize studies in the field that highlight the importance of nuclear hormone receptors in the promotion and maintenance of myelination and the relevance of nuclear hormone receptors as potential therapeutic targets for demyelinating diseases. These nuclear hormone receptors include the estrogen receptor, progesterone receptor, androgen receptor, vitamin D receptor, thyroid hormone receptor, peroxisome proliferator-activated receptor, liver X receptor, and retinoid X receptor. Pre-clinical studies in well-established animal models of demyelination have shown a prominent role of these nuclear hormone receptors in myelination through their promotion of oligodendrocyte maturation and development. The activation of the nuclear hormone receptors by their ligands also promotes the synthesis of myelin proteins and lipids in mouse models of demyelination. There are limited clinical studies that focus on how the activation of these nuclear hormone receptors could alleviate demyelination in patients with diseases such as multiple sclerosis (MS). However, the completed clinical trials have reported improved clinical outcome in MS patients treated with the ligands of some of these nuclear hormone receptors. Together, the positive results from both clinical and pre-clinical studies point to nuclear hormone receptors as promising therapeutic targets to counter demyelination.

Decreased vitamin D levels in children with primary mono-symptomatic nocturnal enuresis

Background

Nocturnal enuresis (NE) is a common voiding problem in pediatric populations. Relatively, few studies have investigated the 25-Hydroxyvitamin D and NE associations in children, which may open up a new research area on the effect of vitamin D as nutritional therapy in the treatment of NE. The aim of this study was to determine the level of 25-hydroxyl vitamin D among children and adolescents with nocturnal enuresis in comparison to non-enuretic Egyptian children.

Results

Fifty children (24 females, 26 males) who presented with primary mono-symptomatic nocturnal enuresis (PMNE) and 50 healthy children (23 females, 27 males) were recruited in this study. A structured questionnaire focusing on demographic, socioeconomic, and frequency of bed-wetting were collected, and vitamin D serum levels were assessed in all children. In the NE group, the mean value of serum vitamin D levels was lower than the control (19.0 ± 6.5 versus 23.89 ± 4.19; P < 0.0001). Serum 25-hydroxyvitamin D levels were abnormal (< 20 ng/mL) in 46% of children with NE and 16% of controls (P < 0.001). The higher bed-wetting frequencies were associated with lower levels of 25(OH) D (Every night: 7.0 ± 1.4, 3–5 time/week: 11.2 ± 1.7, 1–3 times/week: 17.6 ± 3.7, < 2times/week: 22.4 ± 2.9, Once/6 month: 24.1 ± 4.3 (ng/ml), P < 0.001).

Conclusion

A difference in serum 25-hydroxyvitamin D levels was found between the two study groups. There is a need for more studies to explain vitamin D deficiency in larger series so that this test can be used in regular enuretic child investigations.

Effect of vitamin D deficiency on spatial contrast sensitivity function

CLINICAL RELEVANCE

Vitamin D has regulatory effects on non-skeletal tissues including neurons. The contrast sensitivity function occurs as a result of interaction between retinal neurons.

BACKGROUND

The association between plasma vitamin D deficiency and contrast sensitivity function was investigated.

METHODS

Forty-one eyes of 41 subjects with vitamin D deficiency with plasma vitamin D level <20 ng/mL (Group 1), and 30 eyes of 30 subjects without vitamin D deficiency with plasma vitamin D level ≥20 ng/mL (Group 2), were included in this prospective study. OPTEC 6500 was used to measure the contrast sensitivity function at all spatial frequencies involving 1.5 cpd, 3 cpd, 6 cpd, 12cpd, and 18 cpd. The average and sectorial retinal nerve fibre layer thickness, the average and minimum ganglion cell-inner plexiform thickness and tear meniscus height were measured by using optical coherence tomography.

RESULTS

A significant difference was present between Group 1 and Group 2 regarding the plasma vitamin D level (12.4 ± 4.7 ng/mL in Group 1 versus 27.1 ± 6.7 ng/mL in Group 2 p < 0.001). All spatial frequencies of contrast sensitivity function were significantly greater in Group 2 than those in Group 1, as follows: 45 ± 22.6 in Group 1 versus 57.5 ± 20.9 in Group 2, p = 0.08 in 1.5cpd; 71.3 ± 31.3 in Group 1 versus 91.8 ± 27.8 in Group 2, p = 0.001 in 3cpd; 77.9 ± 39.9 in Group 1 versus 100.4 ± 38.4 in Group 2, p = 0.013 in 6cpd; 32 ± 17.5 in Group 1 versus 48.8 ± 25.2 in Group 2, p = 0.002 in 12cpd; and 12.1 ± 5 in Group 1 versus 17.5 ± 9.5 in Group 2, p = 0.001 in 18cpd. However, there were no significant difference between two groups in terms of retinal fibre layer thicknesses, ganglion cell-inner plexiform layer thicknesses, and tear meniscus height.

CONCLUSION

Vitamin D deficiency can lead to a decrease in contrast sensitivity function that is an indicator of visual quality. This may be an underlying reason for certain visual complaints.

Vitamin D and schizophrenia: 20 years on

Many epidemiological studies have highlighted the link between vitamin D deficiency and schizophrenia. In particular, two prominent studies report an association between neonatal vitamin D deficiency and an increased risk of schizophrenia. In parallel, much has been learnt about the role of vitamin D in the developing central nervous system over the last two decades. Studies in rodent models of developmental vitamin D (DVD)-deficiency describe how brain development is altered leading to a range of neurobiological and behavioral phenotypes of interest to schizophrenia. While glutamate and gamma aminobutyric acid (GABA) systems have been little investigated in these models, alterations in developing dopamine systems are frequently reported. There have been far more studies reporting patients with schizophrenia have an increased risk of vitamin D deficiency compared to well controls. Here we have conducted a systematic review and meta-analysis that basically confirms this association and extends this to first-episode psychosis. However, patients with schizophrenia also have poorer general health, poorer diets, are frequently less active and also have an increased risk of other medical conditions, all factors which reduce circulating vitamin D levels. Therefore, we would urge caution in any causal interpretation of this association. We also summarize the inconsistent results from existing vitamin D supplementation trials in patients with schizophrenia. In respect to animal models of adult vitamin D deficiency, such exposures produce subtle neurochemical alterations and effects on cognition but do not appear to produce behavioral phenotypes of relevance to schizophrenia. We conclude, the hypothesis that vitamin D deficiency during early life may increase the risk of schizophrenia remains plausible and warrants ongoing research.

Impacts of serum vitamin D levels on sleep and daytime sleepiness according to working conditions

STUDY OBJECTIVES

Low serum vitamin D levels are known to be associated with working conditions and poor sleep, but precedent studies on this issue were limited by the absence of objective sleep measurements or clear distinction between daytime and night shift work. Hence, we aimed to examine serum vitamin D levels and sleep in daytime and night-shift workers using actigraphy.

METHODS

A total of 412 night-shift and 432 daytime workers at Seoul National University Bundang Hospital was recruited. All participants completed questionnaires regarding demographic and clinical characteristics. They underwent blood tests for serum vitamin D levels. Objective sleep data were obtained from 150 night-shift workers and 203 daytime workers using actigraphy.

RESULTS

There was no significant difference in serum vitamin D levels between night-shift and daytime workers after controlling for possible confounders. In daytime workers, vitamin D deficiency was closely related to shorter duration of total sleep time (odds ratio [OR]: 3.07, 95% confidence interval [CI]: 1.51-6.26, P = .002) and higher risk of excessive daytime sleepiness (OR: 2.20, 95% CI: 1.30-3.74, P = .003). Deficient vitamin D was also associated with life quality impairment regarding psychological health (OR: 1.83, 95% CI: 1.07-3.29, P = .028) and social relationship (OR: 1.78, 95% CI: 1.10-2.88, P = .020). However, in night-shift workers, no significant association was observed between serum vitamin D level and sleep parameters, depressive/anxiety symptoms, or quality of life.

CONCLUSIONS

The modest adverse impact of poor vitamin D status on sleep could be attenuated by substantial shift work-related sleep disturbances in night-shift workers. Further studies might be needed to clarify the beneficial effect of vitamin D supplementation for improving sleep and daytime sleepiness in workers with various working conditions.

Association of asthma with low serum vitamin D and its related musculoskeletal and psychological symptoms in adults: a case-control study

There are complex potential inter-relationships between the chronic inflammation of asthma and poor control, vitamin D deficiency, musculoskeletal pain and anxiety and depression. The aim was to investigate associations between vitamin D and these possible co-morbidities. This case-controlled study involved 75 adults with asthma and 75 controls. Serum 25-hydroxyvitamin D (25(OH)D) was measured, levels of anxiety, depression, musculoskeletal pain, and asthma control were assessed. Participants with asthma had lower 25(OH)D and higher anxiety scores and higher measures of musculoskeletal pain compared to controls. Binary logistic regression showed that asthma was associated with decreased 25(OH)D (Odds ratio (OR) = 0.86), general weakness (OR = 13.29), complaint of musculoskeletal pain (OR = 13.73), and increased intensity of musculoskeletal pain (OR = 0.61) and number of painful sites (OR = 2.58). Asthma was not associated with anxiety or depression. Further studies are required to investigate if vitamin D supplementation can improve asthma symptoms and musculoskeletal pain.

Vitamin D and white matter hyperintensities: results of the population-based Heinz Nixdorf Recall Study and 1000BRAINS

BACKGROUND AND PURPOSE

Cross-sectional studies showed an inverse association between serum 25-hydroxyvitamin D (25OHD) and white matter hyperintensities (WMHs) whereas the few longitudinal studies did not. The association between baseline 25OHD and WMHs at 10-year follow-up in the Heinz Nixdorf Recall Study plus 1000BRAINS was investigated.

METHODS

Data of 505 participants (49% women, 56.2 ± 6.6 years) with 25OHD at baseline (2000-2003) and WMH volume and grade of WMHs using the Fazekas classification at 10-year follow-up were analysed. The association between deseasonalized 25OHD and the base-10 logarithm of WMH volume was evaluated by multiple linear regression, adjusted for age, sex, education, smoking, alcohol consumption, sports, diabetes mellitus, systolic blood pressure and total cholesterol. β-estimators were transformed back (10^β ). Using multiple logistic regression, odds ratios (ORs) and 95% confidence intervals (95% CI) were calculated to evaluate the association between deseasonalized 25OHD and Fazekas grades (0, absence and 1, punctate foci vs. 2, beginning and 3, large confluence).

RESULTS

Mean 25OHD was 17.0 ± 8.2 ng/ml, and mean deseasonalized 25OHD was 16.9 ± 7.5 ng/ml. Mean WMH volume was 16.6 ± 17.4 ml, range 1-132 ml. Most grade 2-3 WMHs were found to be periventricular (39% of the participants), parietal (32%) and frontal (31%) (temporal 6%, occipital 3%). The linear regression showed an inverse association between 25OHD and WMH volume. On average, a 25OHD increase of 1 ng/ml was associated with a reduced WMH volume by a factor of 0.99 (95% CI 0.98; 1.00) (fully adjusted). There was also some indication for an inverse association between 25OHD and extent of periventricular (OR 0.98 [95% CI 0.96; 1.01]), frontal (0.99 [0.97; 1.02]) and parietal (0.98 [0.95; 1.00]) WMHs according to the Fazekas classification.

CONCLUSIONS

Lower 25OHD may be a risk factor for the occurrence of WMHs.

Vitamin D status and its longitudinal association with changes in patterns of sleep among middle-aged urban adults

OBJECTIVE

We examined relationships of vitamin D status with over time changes in patterns of sleep in a longitudinal study of Whites and African-American urban middle-aged adults, while further testing effect modification by age group, sex and race and the potential roles of dietary and supplemental vitamin D.

METHODS

Data on 1,760 middle-aged participants in the Healthy Aging in Neighborhoods of Diversity Across the Life Span (HANDLS study: Age range at v₂: 33-71y, mean±SD:53.0±8.8, % women: 58.4%, % African-American:60.3%) were used, with complete baseline 25-hydroxyvitamin D [25(OH)D] serum concentration data, initial selected covariates and mediators, and initial and/or follow-up data on five sub-scales (sleep duration, daytime dysfunction, sleep disturbance, sleep latency and sleep quality) of the Pittsburgh Sleep Quality Index. Mean±SD time between initial and follow-up visits: 4.1±1.5 years. Time-interval multiple mixed-effects linear regression models were used.

RESULTS

Upon multiple testing adjustment, among Whites, initial 25(OH)D was associated with better sleep duration [25(OH)D × TIME γ±SE: -0.027±0.011, P=0.017] and sleep quality [25(OH)D × TIME γ±SE: -0.026±0.010, P=0.008] over time, with heterogeneity by race found for both relationships (P<0.05 for 25(OH)D × TIME × Race in the un-stratified model). These relationships remained unaltered after further adjustment for dietary and supplemental vitamin D, indicating that this association may be largely explained by sunlight exposure.

LIMITATIONS

Limitations included small sample size, selection bias, residual confounding and lack of objective sleep measures. Conclusions Vitamin D status, possibly through mechanisms involving sunlight exposure, was linked to a potential improvement in sleep duration and quality among White urban adults.

Vitamin D Signaling in Gastro-Rheumatology: From Immuno-Modulation to Potential Clinical Applications

In the last decades, the comprehension of the pathophysiology of bone metabolism and its interconnections with multiple homeostatic processes has been consistently expanded. The branch of osteoimmunology specifically investigating the link between bone and immune system has been developed. Among molecular mediators potentially relevant in this field, vitamin D has been recently pointed out, and abnormalities of the vitamin D axis have been described in both in vitro and in vivo models of inflammatory bowel diseases (IBD) and arthritis. Furthermore, vitamin D deficiency has been reported in patients affected by IBD and chronic inflammatory arthritis, thus suggesting the intriguing possibility of impacting the disease activity by the administration vitamin D supplements. In the present review, the complex interwoven link between vitamin D signaling, gut barrier integrity, microbiota composition, and the immune system was examined. Potential clinical application exploiting vitamin D pathway in the context of IBD and arthritis is presented and critically discussed. A more detailed comprehension of the vitamin D effects and interactions at molecular level would allow one to achieve a novel therapeutic approach in gastro-rheumatologic inflammatory diseases through the design of specific trials and the optimization of treatment protocols.

Vitamin D: Brain and Behavior

It has been 20 years since we first proposed vitamin D as a "possible" neurosteroid.( 1 ) Our work over the last two decades, particularly results from our cellular and animal models, has confirmed the numerous ways in which vitamin D differentiates the developing brain. As a result, vitamin D can now confidently take its place among all other steroids known to regulate brain development.( 2 ) Others have concentrated on the possible neuroprotective functions of vitamin D in adult brains. Here these data are integrated, and possible mechanisms outlined for the various roles vitamin D appears to play in both developing and mature brains and how such actions shape behavior. There is now also good evidence linking gestational and/or neonatal vitamin D deficiency with an increased risk of neurodevelopmental disorders, such as schizophrenia and autism, and adult vitamin D deficiency with certain degenerative conditions. In this mini-review, the focus is on what we have learned over these past 20 years regarding the genomic and nongenomic actions of vitamin D in shaping brain development, neurophysiology, and behavior in animal models. © 2020 The Author. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Vitamin D and sleep duration: Is there a bidirectional relationship?

Vitamin D contributes to numerous physiological processes within the body but primarily calcium and bone homeostasis. Emerging evidence highlights a novel role for vitamin D in maintaining and regulating optimal sleep. Sleep is a known regulator of bone health, highlighting the interconnectedness between vitamin D concentrations, sleep duration and bone metabolism. It is possible that the relationship between sleep length and vitamin D is bidirectional, with vitamin D playing a role in sleep health and conversely, sleep affecting vitamin D levels. Nevertheless, limited information on the direction of the interaction is available, and much remains to be learned concerning the complex relationship between insufficient sleep duration and vitamin D deficiency. Given the potential to implement interventions to improve sleep and vitamin D supplementation, understanding this relationship further could represent a novel way to support and improve health.

Implications of Vitamin D in Multiple Sclerosis and Other Neurodegenerative Processes: Bibliometric Analysis and Systematic Review

In recent years, numerous investigations focused on the pleiotropic actions of vitamin D have been carried out. These actions include the participation of this molecule in neurophysiological and neuropathological processes. As a consequence, abundant scientific literature on the role of this vitamin in neurodegenerative entities has emerged, even concerning clinical studies. To identify the level of scientific evidence concerning the relation between vitamin D and neurodegenerative diseases, from a quantitative and qualitative perspective. To describe, by means of a bibliometric analysis, the scientific production and its evolution through time in quantitative terms, regarding the implications of vitamin D in neurodegeneration. To analyse and present the degree of evidence in the aforementioned field of study, a systematic review of the literature focused on the most prevalent neurodegenerative diseases was carried out. We retrieved 848 articles in the bibliometric analysis, the majority of which were dated between the years 2010-2017. The most studied metabolite was the 25(OH)D3 and the most cited disease was multiple sclerosis. In the systematic review, we found studies about Alzheimer's and Parkinson's diseases and again, about multiple sclerosis prominently (in number and quality), with 12 randomised double-blind clinical trials. The research about vitamin D and its relations with neurodegenerative diseases shows a growing evolution over the last decade. More studies are needed to find correlations between the clinical severity of these diseases and the specific status of vitamin D and the genotypes related with them, which seems to be a future trend.

Bile Acid Signaling in Neurodegenerative and Neurological Disorders

Bile acids are commonly known as digestive agents for lipids. The mechanisms of bile acids in the gastrointestinal track during normal physiological conditions as well as hepatic and cholestatic diseases have been well studied. Bile acids additionally serve as ligands for signaling molecules such as nuclear receptor Farnesoid X receptor and membrane-bound receptors, Takeda G-protein-coupled bile acid receptor and sphingosine-1-phosphate receptor 2. Recent studies have shown that bile acid signaling may also have a prevalent role in the central nervous system. Some bile acids, such as tauroursodeoxycholic acid and ursodeoxycholic acid, have shown neuroprotective potential in experimental animal models and clinical studies of many neurological conditions. Alterations in bile acid metabolism have been discovered as potential biomarkers for prognosis tools as well as the expression of various bile acid receptors in multiple neurological ailments. This review explores the findings of recent studies highlighting bile acid-mediated therapies and bile acid-mediated signaling and the roles they play in neurodegenerative and neurological diseases.

Vitamin D and Its Potential Interplay With Pain Signaling Pathways

About 50 million of the U.S. adult population suffer from chronic pain. It is a complex disease in its own right for which currently available analgesics have been deemed woefully inadequate since ~20% of the sufferers derive no benefit. Vitamin D, known for its role in calcium homeostasis and bone metabolism, is thought to be of clinical benefit in treating chronic pain without the side-effects of currently available analgesics. A strong correlation between hypovitaminosis D and incidence of bone pain is known. However, the potential underlying mechanisms by which vitamin D might exert its analgesic effects are poorly understood. In this review, we discuss pathways involved in pain sensing and processing primarily at the level of dorsal root ganglion (DRG) neurons and the potential interplay between vitamin D, its receptor (VDR) and known specific pain signaling pathways including nerve growth factor (NGF), glial-derived neurotrophic factor (GDNF), epidermal growth factor receptor (EGFR), and opioid receptors. We also discuss how vitamin D/VDR might influence immune cells and pain sensitization as well as review the increasingly important topic of vitamin D toxicity. Further in vitro and in vivo experimental studies will be required to study these potential interactions specifically in pain models. Such studies could highlight the potential usefulness of vitamin D either alone or in combination with existing analgesics to better treat chronic pain.

Vitamin D Supplementation Rescues Aberrant NF-κB Pathway Activation and Partially Ameliorates Rett Syndrome Phenotypes in Mecp2 Mutant Mice

Rett syndrome (RTT) is a severe, progressive X-linked neurodevelopmental disorder caused by mutations in the transcriptional regulator MECP2 We previously identified aberrant NF-κB pathway upregulation in brains of Mecp2-null mice and demonstrated that genetically attenuating NF-κB rescues some characteristic neuronal RTT phenotypes. These results raised the intriguing question of whether NF-κB pathway inhibitors might provide a therapeutic avenue in RTT. Here, we investigate whether the known NF-κB pathway inhibitor vitamin D ameliorates neuronal phenotypes in Mecp2-mutant mice. Vitamin D deficiency is prevalent among RTT patients, and we find that Mecp2-null mice similarly have significantly reduced 25(OH)D serum levels compared with wild-type littermates. We identify that vitamin D rescues aberrant NF-κB pathway activation and reduced neurite outgrowth of Mecp2 knock-down cortical neurons in vitro Further, dietary supplementation with vitamin D in early symptomatic male Mecp2 hemizygous null and female Mecp2 heterozygous mice ameliorates reduced neocortical dendritic morphology and soma size phenotypes and modestly improves reduced lifespan of Mecp2-nulls. These results elucidate fundamental neurobiology of RTT and provide foundation that NF-κB pathway inhibition might be a therapeutic target for RTT.

Role of Vitamin D in Preventing and Treating Selected Extraskeletal Diseases-An Umbrella Review

Evidence is accumulating that vitamin D may have beneficial effects on respiratory tract, autoimmune, neuro-degenerative, and mental diseases. The present umbrella review of systematic reviews (SRs) of cohort studies and randomised controlled trials (RCTs), plus single Mendelian randomisation studies aims to update current knowledge on the potential role of vitamin D in preventing and treating these extraskeletal diseases. Altogether, 73 SRs were identified. Observational data on primary prevention suggest an inverse association between vitamin D status and the risk of acute respiratory tract infections (ARI), dementia and cognitive decline, and depression, whereas studies regarding asthma, multiple sclerosis (MS), and type 1 diabetes mellitus (T1DM) are scarce. SRs of RCTs support observational data only for the risk of ARI. No respective RCTs are available for the prevention of chronic obstructive pulmonary disease (COPD), MS, and T1DM. SRs of RCTs indicate beneficial therapeutic effects in vitamin D-deficient patients with asthma and COPD, while effects on major depression and T1DM need to be further elucidated. Mendelian randomisation studies do not consistently support the results of SRs. Since several limitations of the included SRs and existing RCTs do not permit definitive conclusions regarding vitamin D and the selected diseases, further high-quality RCTs are warranted.

The Influence of Vitamin D on Neurodegeneration and Neurological Disorders: A Rationale for its Physio-pathological Actions

Vitamin D is a steroid hormone implicated in the regulation of neuronal integrity and many brain functions. Its influence, as a nutrient and a hormone, on the physiopathology of the most common neurodegenerative diseases is continuously emphasized by new studies. This review addresses what is currently known about the action of vitamin D on the nervous system and neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Parkinson's disease and Amyotrophic Lateral Sclerosis. Further vitamin D research is necessary to understand how the action of this "neuroactive" steroid can help to optimize the prevention and treatment of several neurological diseases.

Association of polymorphisms in the vitamin D receptor gene with susceptibility to and severity of hand, foot, and mouth disease caused by coxsackievirus A16

Coxsackievirus A16 (CA16) remains the most common causative agent of hand, foot, and mouth disease (HFMD), and is related to high incidence and critical complications. Vitamin D receptor (VDR) activity might affect the outcome of CA16 infection. Our case-control research aims to evaluate the relationship between VDR polymorphisms in the gene encoding and susceptibility to and severity of HFMD due to CA16. Three single-nucleotide polymorphisms (SNPs) of VDR gene were selected according to functional prediction and linkage disequilibrium, and were examined utilizing the SNPscan method to identify possible associations with HFMD caused by CA16. A significant relationship was found in the HFMD cases of polymorphism rs11574129 (GA vs GG: odds ratio (OR) = 0.068, 95% confidence interval (CI) = 0.007-0.693, P = .023; GA + AA vs GG: OR = 0.322, 95%CI = 0.106-0.984, P = .047), and vitamin D levels in genotype AA were significantly higher than those in genotype GG (P < .05). These results suggest that VDR rs11574129 may influence genetic susceptibility to CA16-associated HFMD.

Maternal blood folate status during early pregnancy and occurrence of autism spectrum disorder in offspring: a study of 62 serum biomarkers

BACKGROUND

Autism spectrum disorder (ASD) evolves from an interplay between genetic and environmental factors during prenatal development. Since identifying maternal biomarkers associated with ASD risk in offspring during early pregnancy might result in new strategies for intervention, we investigated maternal metabolic biomarkers in relation to occurrence of ASD in offspring using both univariate logistic regression and multivariate network analysis.

METHODS

Serum samples from 100 women with an offspring diagnosed with ASD and 100 matched control women with typically developing offspring were collected at week 14 of pregnancy. Concentrations of 62 metabolic biomarkers were determined, including amino acids, vitamins (A, B, D, E, and K), and biomarkers related to folate (vitamin B₉) metabolism, lifestyle factors, as well as C-reactive protein (CRP), the kynurenine-tryptophan ratio (KTR), and neopterin as markers of inflammation and immune activation.

RESULTS

We found weak evidence for a positive association between higher maternal serum concentrations of folate and increased occurrence of ASD (OR per 1 SD increase: 1.70, 95% CI 1.22-2.37, FDR adjusted P = 0.07). Multivariate network analysis confirmed expected internal biochemical relations between the biomarkers. Neither inflammation markers nor vitamin D₃ levels, all hypothesized to be involved in ASD etiology, displayed associations with ASD occurrence in the offspring.

CONCLUSIONS

Our findings suggest that high maternal serum folate status during early pregnancy may be associated with the occurrence of ASD in offspring. No inference about physiological mechanisms behind this observation can be made at the present time because blood folate levels may have complex relations with nutritional intake, the cellular folate status and status of other B-vitamins. Therefore, further investigations, which may clarify the potential role and mechanisms of maternal blood folate status in ASD risk and the interplay with other potential risk factors, in larger materials are warranted.

Genetic, environmental and biomarker considerations delineating the regulatory effects of vitamin D on central nervous system function

Studies show that vitamin D (vit-D) (25(OH)D), the bioactive metabolite (1,25(OH)2D3) and vit-D receptors (vit-D receptor; protein disulphide isomerase, family A member 3) are expressed throughout the brain, particularly in regions pivotal to learning and memory. This has led to the paradigm that avoiding vit-D deficiency is important to preserve cognitive function. However, presently, it is not clear if the common clinical measure of serum 25(OH)D serves as a robust surrogate marker for central nervous system (CNS) homeostasis or function. Indeed, recent studies report CNS biosynthesis of endogenous 25(OH)D, the CNS expression of the CYP group of enzymes which catalyse conversion to 1,25(OH)2D3 and thereafter, deactivation. Moreover, in the periphery, there is significant ethnic/genetic heterogeneity in vit-D conversion to 1,25(OH)2D3 and there is a paucity of studies which have actually investigated vit-D kinetics across the cerebrovasculature. Compared with peripheral organs, the CNS also has differential expression of receptors that trigger cellular response to 1,25(OH)2D3 metabolites. To holistically consider the putative association of peripheral (blood) abundance of 25(OH)D on cognitive function, herein, we have reviewed population and genetic studies, pre-clinical and clinical intervention studies and moreover have considered potential confounders of vit-D analysis.

Serum vitamin D levels in acute stroke patients

Background

Vitamin D deficiency has been proposed as a risk factors of cerebrovascular stroke.

Objectives

The aim of this study was firstly, to assess the serum level of vitamin D in cerebral stroke patients and secondly, to examine if its deficiency was associated with stroke severity and outcome.

Methods

We utilized a case-control study design and recruited 138 acute stroke patients and 138 age- and sex-matched controls from subjects attending outpatient clinic for other reasons. All participants were subjected to full general and neurological examination. Brain imaging CT and/or MRI was performed. Blood samples were collected for measurement of serum level of vitamin D (ng/ml) by ELISA, alkaline phosphatase, serum calcium, and phosphorous. The stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS) and stroke outcome was assessed by modified Rankin Scale (mRS).

Results

Stroke patients had significant lower levels of vitamin D compared with the control group. Vitamin D deficiency remained significantly associated with the NIHSS stroke severity score and the mRS 3-month stroke outcome after controlling for other significant factors such as age, dyslipidemia, and infarction size using multivariable logistic regression analysis.

Conclusion

Our results demonstrated that stroke patients suffer from vitamin D deficiency, which was associated with both stroke severity and poor outcome. Vitamin D supplementation could exert a therapeutic role in the management of cerebral stroke.

Small talk: microbial metabolites involved in the signaling from microbiota to brain

The wealth of biotransformational capabilities encoded in the microbiome expose the host to an array of bioactive xenobiotic products. Several of these metabolites participate in the communication between the gastrointestinal tract and the central nervous system and have potential to modulate central physiological and pathological processes. This biochemical interplay can occur through various direct and indirect mechanisms. These include binding to host receptors in the brain, stimulation of the vagus nerve in the gut, alteration of central neurotransmission, and modulation of neuroinflammation. Here, the potential for short chain fatty acids, bile acids, neurotransmitters and other bioactive products of the microbiome to participate in the gut-brain axis will be reviewed.

Serum Vitamin D is Differentially Associated with Socioemotional Adjustment in Early School-Aged Ugandan Children According to Perinatal HIV Status and In Utero/Peripartum Antiretroviral Exposure History

An impact of vitamin D in neurocognitive function has been theorized but it remains unknown whether vitamin-D insufficiency (VDI) is associated with worse socio-emotional adjustment (SEA) in vulnerable early school-aged children. This study examines the thesis that deficits in SEA are related to VDI using longitudinal data from 254 children that are perinatally HIV-infected (PHIV), exposed-uninfected (HEU), or unexposed-uninfected (HUU). In utero/peripartum antiretroviral (IPA) exposure was established per medical record documentation of biological mother’s ART regimen in pregnancy. Four caregiver-reported age- and sex-standardized measures of SEA were obtained at months 0, 6, and 12 for dependent children aged 6–10 years: externalizing problems (EPC), internalizing problems (IPC), behavioral symptoms index (BSI), and adaptive skills index (ASI). VDI was highly prevalent (74%, n = 188), and its association with change in SEA measures over 12 months varied by HIV-status (VDI*HIV, all p-values < 0.03). There was further variation in relationship of vitamin-D to SEA by IPA among PHIV (for ASI, BSI, and EPC, vitamin-D*IPA, p-value ≤ 0.01) and HEU (for BSI and EPC, vitamin-D*IPA, p-value ≤ 0.04). Among HUU, BSI (β = −0.32, 95% CI: −0.50, −0.13), IPC (β = −0.28, 95% CI: −0.47, −0.09), and EPC (β = −0.20, 95% CI: −0.37, −0.02) all declined moderately per quartile increment in VD. Among PHIV, on the one hand higher vitamin D predicted ASI gains (moderate vs. low VD, β = 0.52, p = 0.002), but this protective association was absent for BSI, EPC, and IPC (β = 0.36–0.77, p < 0.05). In absence of IPA-exposure, increasing vitamin-D predicted declines in BSI and EPC (moderate vs. low Vitamin D, β = −0.56 to −0.71, p ≤ 0.02) among HEU. However, given IPA exposure among HEU, higher VDI predicted moderate elevation in BSI (β = 0.39, 95% CI: 0.00, 0.78) and IPC (β = 0.48, 95% CI: 0.05, 0.92). Interaction between VD and IPA exposure for SEA outcomes among HEU and PHIV children warrants further investigation. The vitamin-D associated SEA improvement among HUU and HEU without IPA exposure suggests vitamin-D supplementation may remediate behavioral and adaptive deficits in this groups.

Modulating Effects of Cholecalciferol Treatment on Estrogen Deficiency-Induced Anxiety-Like Behavior of Adult Female Rats

BACKGROUND

Vitamin D can be one of the candidate substances that are used as additional supplementation in the treatment of anxiety-related disorders in women with estrogen imbalance.

MATERIALS AND METHODS

The aim of the present study was to examine the effects of chronic cholecalciferol administration (1.0, 2.5 or 5.0 mg/kg/day, s.c.) on the anxiety-like behavior and monoamines levels in the rat hippocampus following ovariectomy in female rats. Cholecalciferol was given to ovariectomized (OVX) rats and OVX rats treated with 17β-estradiol (17β-E2, 0.5 μg/rat, s.c.). The anxiety-like behavior was assessed in the elevated plus maze (EPM) and the light-dark tests (LDT), locomotor and grooming activities were assessed in the open-field test (OFT).

RESULTS

Cholecalciferol in high doses alone or in combination with 17β-E2-induced anxiolytic-like effects in OVX and OVX rats treated with 17β-E2 as evidenced in the EPM and LDT tests, and increased grooming activity in the OFT test. We found that DA and 5-HT levels increased while 5-HT turnover in the hippocampus decreased in these groups of OVX rats.

CONCLUSION

Our results indicate that cholecalciferol in high doses has a marked anxiolytic-like effect due to an increase in the monoamines levels in the experimental rat model of estrogen deficiency.

Cholecalciferol (Vitamin D3) Reduces Rat Neuropathic Pain by Modulating Opioid Signaling

The impact of vitamin D on sensory function, including pain processing, has been receiving increasing attention. Indeed, vitamin D deficiency is associated with various chronic pain conditions, and several lines of evidence indicate that vitamin D supplementation may trigger pain relief. However, the underlying mechanisms of action remain poorly understood. We used inflammatory and non-inflammatory rat models of chronic pain to evaluate the benefits of vitamin D₃ (cholecalciferol) on pain symptoms. We found that cholecalciferol supplementation improved mechanical nociceptive thresholds in monoarthritic animals and reduced mechanical hyperalgesia and cold allodynia in a model of mononeuropathy. Transcriptomic analysis of cerebrum, dorsal root ganglia, and spinal cord tissues indicate that cholecalciferol supplementation induces a massive gene dysregulation which, in the cerebrum, is associated with opioid signaling (23 genes), nociception (14), and allodynia (8), and, in the dorsal root ganglia, with axonal guidance (37 genes) and nociception (17). Among the identified cerebral dysregulated nociception-, allodynia-, and opioid-associated genes, 21 can be associated with vitamin D metabolism. However, it appears that their expression is modulated by intermediate regulators such as diverse protein kinases and not, as expected, by the vitamin D receptor. Overall, several genes-Oxt, Pdyn, Penk, Pomc, Pth, Tac1, and Tgfb1-encoding for peptides/hormones stand out as top candidates to explain the therapeutic benefit of vitamin D₃ supplementation. Further studies are now warranted to detail the precise mechanisms of action but also the most favorable doses and time windows for pain relief.

Congenital laryngomalacia: Is it an inflammatory disease? The role of vitamin D

OBJECTIVES/HYPOTHESIS

Laryngomalacia is the most common cause of stridor in infants. The exact pathophysiology is still not well understood. Our objective was to investigate whether laryngomalacia is an inflammatory disease, focusing on the possible role of vitamin D.

STUDY DESIGN

Case-control study.

METHODS

Sixty Egyptian infants and 60 mothers were included in this study. They were divided into four equal groups (n = 30 for each): infants with laryngomalacia (LM-infants), control infants (C-infants), mothers of the infants with laryngomalacia (LM-mothers), and mothers of the control infants (C-mothers). Laryngoscopy was performed and serum 25-hydroxyvitamin D (25[OH]-vitamin-D) and interleukin 6 (IL-6) were estimated.

RESULTS

Significant increase of serum IL-6 associated with a significant decrease in serum 25(OH)-vitamin D was observed in the LM-infants compared to the C-infants (P < .001 for both). LM-mothers had significantly lower 25(OH)-vitamin D status compared to C-mothers (P < .001).

CONCLUSIONS

Deficiency of 25(OH)-vitamin D in LM-infants may result in dysregulation of the immune responses with elevation of a proinflammatory cytokine (IL-6). Laryngomalacia could be an inflammatory disease due to 25(OH)-vitamin D deficiency as evidenced by the high level of IL-6. This finding may open the door to the appropriate prevention, diagnosis, and treatment, especially for moderate to severe laryngomalacia.

LEVEL OF EVIDENCE

3b Laryngoscope, 130:448-453, 2020.

Vitamin D3 treatment differentially affects anxiety-like behavior in the old ovariectomized female rats and old ovariectomized female rats treated with low dose of 17β-estradiol

BACKGROUND

Estrogen deficiency effects on affective-related behavior are restricted to certain periods of age after ovary removal. Among other nutraceuticals, one of such «natural» substances for treatment of affective-related diseases could be vitamin D₃. It is a great interest to evaluate the effects of repeated cholecalciferol administration on anxiety-related behavior in the old female rats with long-term estrogen deficiency. The present study was performed to determine the behavioral effects of cholecalciferol treatment at different doses as an adjunctive therapy alone or in a combination with low dose of 17β-estradiol on anxiety-like behavior of the old (16-18 months) female rats at 12 weeks after ovariectomy.

METHODS

Vitamin D₃ supplementation individually (as cholecalciferol at doses of 1.0, 2.5 or 5.0 mg/kg/day, s.c.) or in co-administration with of 17β-estradiol (17β-E₂, 0.5 μg/rat, s.c.) were given to the old ovariectomized (OVX) rats at 12 weeks after ovariectomy. Anxiety-related state was tested in the elevated plus maze (EPM) and light-dark test (LDT), as well behavioral reactivity was registered in the open field test (OFT). Moreover, 25-hydroxyvitamin D₃ levels in the blood serum of these OVX rats treated with Vitamin D₃ or Vitamin D₃ plus 17β-E₂ were measured.

RESULTS

The results of the present study indicated that Vitamin D₃ supplementation at dose of 1.0 mg/kg/day decreased manifestations of anxiety-like profile in the old OVX rats. Treatment with Vitamin D₃ (1.0 mg/kg/day) plus 17β-E₂ in resulted in more profound anxiolytic-like effects the old OVX rats than effects of both drugs administered alone. Moreover, treatment with cholecalciferol (1.0 mg/kg/day, s.c.) in the old ovariectomized rats after ovariectomy at 12 weeks produced elevated estradiol and 25-OH-VD₃ levels for these rats as compared to the old OVX females treated with oil solvent.

CONCLUSIONS

Using the preclinical study, chronic cholecalciferol, 17β-E₂ and their combination treatment were shown to be effective for anxiety-like treatment in the old subjects with long-term estrogen deficiency.

Vitamin D levels in children and adolescents with attention-deficit hyperactivity disorder (ADHD): a meta-analysis

The aim of this article was to assess the differences in serum 25(OH)D levels between children and adolescents with attention-deficit/hyperactivity disorder (ADHD) and healthy controls. We used the PubMed (1966-2017), Scopus (2004-2017), ClinicalTrials.gov (2008-2017), Cochrane Central Register of Controlled Trials CENTRAL (2000-2017), and Google Scholar (2004-2017) databases. Statistical meta-analysis was performed with RevMan 5.3. Εight studies were finally included in the present meta-analysis with a total number of 11,324 children. Among them, 2655 were diagnosed with ADHD, while the remaining 8669 were recruited as healthy controls. All eight trials reported significantly lower serum concentrations of 25(OH)D in patients diagnosed with ADHD compared to healthy controls. The pooled data showed that there was a significant difference between the ADHD group and the control group (SMD = - 0.73, 95% CI [- 1.00, - 0.46]). The systematic review and meta-analysis of observational studies demonstrated an inverse association between serum 25(OH)D and young patients with ADHD. Large cohort studies are required to investigate whether vitamin D-deficient infants are more likely to develop ADHD in the future. Also, whether children with ADHD should be supplemented with higher doses of vitamin D3 remains to be confirmed through long-term controlled clinical trials.

Vitamin D3 deficiency in puberty rats causes presynaptic malfunctioning through alterations in exocytotic release and uptake of glutamate/GABA and expression of EAAC-1/GAT-3 transporters

Recent experimental and epidemiologic investigations have revealed that the central nervous system is a target for vitamin D3 action and also linked vitamin D3 deficiency to Alzheimer's and Parkinson's disease, autism and dementia. Abnormal homeostasis of glutamate and GABA and signaling disbalance are implicated in the pathogenesis of major neurological diseases. Here, key transport characteristics of glutamate and GABA were analysed in presynaptic nerve terminals (synaptosomes) isolated from the cortex of vitamin D3 deficient (VDD) rats. Puberty rats were kept at the VDD diet up to adulthood. VDD caused: (i) a decrease in the initial rates of L-[¹⁴C]glutamate and [³H]GABA uptake by plasma membrane transporters of nerve terminals; (ii) a decrease in exocytotic release of L-[¹⁴C]glutamate and [³H]GABA; (iii) changes in expression of glutamate (EAAC-1) and GABA (GAT-3) transporters. Whereas, the synaptosomal ambient levels and Ca²⁺-independent transporter-mediated release of L-[¹⁴C]glutamate and [³H]GABA were not significantly altered in VDD. Vitamin D3 is a potent neurosteroid and its nutritional deficiency can provoke development of neurological consequences changing glutamate/GABA transporter expressions and excitation/inhibition balance. Also, changes in glutamate transport can underlie lower resistance to hypoxia/ischemia, larger infarct volumes and worsened outcomes in ischemic stroke patients with VDD.

The Association between Vitamin D Deficiency and Sleep Disorders: A Systematic Review and Meta-Analysis

Epidemiology studies have investigated the association between vitamin D and the risk of sleep disorders, but the results remain controversial. Therefore, we conducted this meta-analysis with the goal of clarifying the association between vitamin D and sleep disorders risk. All relevant studies were searched using PubMed, EMBASE, and Web of Science from inception to January 2018. Pooled odds ratios (ORs) and 95% confidence interval (CIs) were calculated using a fixed-effect model A total of nine studies (6 cross-sectional, 2 case-control, and 1 cohort studies) involving 9397 participants were included. By comparing the lowest verse highest levels of serum vitamin D, we found that participants with vitamin D deficiency (VDD) had a significantly increased risk of sleep disorders (OR: 1.50, 95% CI: 1.31, 1.72). Subgroup analysis showed that VDD also was associated with poor sleep quality (OR: 1.59, 95% CI: 1.23, 2.05), short sleep duration (OR: 1.74, 95% CI: 1.30, 2.32), and sleepiness (OR: 1.36, 95% CI: 1.12, 1.65). Subgroup analyses further indicated that serum 25(OH)D <20 ng/mL could significantly increase the risk of unhealthy sleep. This meta-analysis suggest that vitamin D deficiency is associated with a higher risk of sleep disorders. More high-quality cohort studies and randomized controlled trials (RCTs) are needed to verify this association.