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

Vitamin D3 Exerts a Neuroprotective Effect in Metabolic Syndrome Rats: Role of BDNF/TRKB/Akt/GS3Kβ Pathway

Metabolic syndrome (MetS) is usually associated with cognitive impairment, neuropathic pain, and reduced brain-derived neurotrophic factor (BDNF) levels. BDNF via tropomyosin receptor kinase B (TrkB) exerts neuroprotection by activating protein kinase B (Akt) to inhibit glycogen synthase kinase-3β (GSK3β). Although Vitamin D3 (VitD3) has demonstrated favorable metabolic and neuronal outcomes in MetS, the precise molecular mechanisms underlying its neuroprotective effects remain poorly elucidated. We aimed to test the hypothesis that VitD3 mitigates MetS-induced cognition deficits and neuropathic pain via modulating the BDNF/TRKB/Akt/GS3Kβ signaling pathway. MetS was induced in male rats by 10% fructose-supplemented water and 3% salt-enriched diet. After 6 weeks, normal and MetS rats received either vehicle or VitD3 (10 µg/kg/day) for an additional 6 weeks. Glycemic status, lipid profile, and behavioral changes were assessed. The advanced glycation end products (AGEs), and markers of inflammation (TNF-α and NF-κB), oxidative stress (malondialdehyde), and apoptosis (caspase3), as well as BDNF, TrkB, PI3K, Akt, GSK3β, phosphorylated tau, and amyloid beta (Aβ) were assessed in the cerebral cortex. MetS rats had deteriorated glycemic and lipid profiles, higher AGEs, reduced levels of BDNF, TrkB, PI3K, and active Akt, along with increased GSK3β levels, inflammation, oxidative stress, and apoptosis. These changes were associated with higher levels of cognitive impairment markers phosphorylated tau and Aβ, as well as behavioral changes indicative of cognitive impairment and neuropathic pain. VitD3 improved the cognitive and behavioral alterations, while mitigating the associated molecular derangements. Our results indicate that VitD3 may exert neuroprotective effects by modulating the BDNF/TrkB/PI3K/Akt/GSK3β signaling pathway.

Neuroplasticity-related effects of vitamin D relevant to its neuroprotective effects: A narrative review

The pathophysiology of a wide range of central nervous system (CNS) disorders, such as neurodegenerative and psychiatric diseases, has been associated with impairment of neurogenic and synaptogenic processes. Therefore, pharmacological and/or nutritional strategies based on the stimulation and/or restoration of these processes may have beneficial effects against diseases in which these processes are impaired. In this context, vitamin D has emerged as a promising neuroprotective compound. Due to its pleiotropic properties, it can interact with multiple molecular targets and thereby affect different cell types, including neurons and glial cells. This neurosteroid contributes to CNS homeostasis by non-genomic and genomic mechanisms through its interaction with vitamin D receptors (VDRs). Among several properties of this vitamin, its role in neuronal proliferation and differentiation as well as in synaptic plasticity has received attention. Considering this background, this narrative review aims to highlight the neuroplasticity-related mechanisms of vitamin D that may be associated with its neuroprotective effects.

Vitamin D: The crucial neuroprotective factor for nerve cells

Vitamin D is well known for its role in regulating the absorption and utilization of calcium and phosphorus as well as bone formation, and a growing number of studies have shown that vitamin D also has important roles in the nervous system, such as maintaining neurological homeostasis and protecting normal brain function, and that neurons and glial cells may be the targets of these effects. Most reviews of vitamin D's effects on the nervous system have focused on its overall effects, without distinguishing the contributors to these effects. In this review, we mainly focus on the cells of the central nervous system, summarizing the effects of vitamin D on them and the related pathways. With this review, we hope to elucidate the role of vitamin D in the nervous system at the cellular level and provide new insights into the prevention and treatment of neurodegenerative diseases in the direction of neuroprotection, myelin regeneration, and so on.

Supplementation and Mitigating Cognitive Decline in Older Adults With or Without Mild Cognitive Impairment or Dementia: A Systematic Review

This systematic literature review aims to answer the question of how micronutrients might influence the development and progression of dementia. In the present work, we focused on an overview of an updated review of relevant literature published in the last two decades. This review aims to delineate the relationship between micronutrient supplementation and cognitive decline in older subjects. In carrying out this review, we followed PRISMA, and our literature search was performed on PubMed. This systematic review includes only primary studies that have investigated the efficacy of nutritional interventions for the prevention of dementia and improvement of cognitive function in subjects aged 65 years or older with normal cognition, mild cognitive impairment (MCI), or Alzheimer's disease (AD). A gross heterogeneity of studies forbids the possibility of a direct comparison of the results. A review of the inclusion criteria and restrictions has been conducted to check the validity and reliability of the results. In this review, thirty-three primary studies were included. Results have shown that supplementation with vitamin D, probiotics, and PUFAs would most likely reduce cognitive decline, dementia, or AD compared with vitamins A, B, C, and E, which were seen to be relatively ineffective. Of note, when considering vitamin B supplementation, positive effects were only observed in non-aspirin users having high ω-3 fatty acid (ω-3 FA) plasma levels. In some cases, however, there were genotypic differences in subjects in response to vitamin B supplementation.

Vitamin D beyond the blood: Tissue distribution of vitamin D metabolites after supplementation

Vitamin D3's role in mineral homeostasis through its endocrine function, associated with the main circulating metabolite 25-hydroxyvitamin D3, is well characterized. However, the increasing recognition of vitamin D3's paracrine and autocrine functions-such as cell growth, immune function, and hormone regulation-necessitates examining vitamin D3 levels across different tissues post-supplementation. Hence, this review explores the biodistribution of vitamin D3 in blood and key tissues following oral supplementation in humans and animal models, highlighting the biologically active metabolite, 1,25-dihydroxyvitamin D3, and the primary clearance metabolite, 24,25-dihydroxyvitamin D3. While our findings indicate significant progress in understanding how circulating metabolite levels respond to supplementation, comprehensive insight into their tissue concentrations remains limited. The gap is particularly significant during pregnancy, a period of drastically increased vitamin D3 needs and metabolic alterations, where data remains sparse. Within the examined dosage ranges, both human and animal studies indicate that vitamin D3 and its metabolites are retained in tissues selectively. Notably, vitamin D3 concentrations in tissues show greater variability in response to administered doses. In contrast, its metabolites maintain a more consistent concentration range, albeit different among tissues, reflecting their tighter regulatory mechanisms following supplementation. These observations suggest that serum 25-hydroxyvitamin D3 levels may not adequately reflect vitamin D3 and its metabolite concentrations in different tissues. Therefore, future research should aim to generate robust human data on the tissue distribution of vitamin D3 and its principal metabolites post-supplementation. Relating this data to clinically appropriate exposure metrics will enhance our understanding of vitamin D3's cellular effects and guide refinement of clinical trial methodologies.

A follow-up study with a double-blinded, randomized controlled vitamin D supplementation trial in patients with major depressive episode (DepFuD): A study protocol and baseline characteristics

Promising initial studies on vitamin D (VD) supplementation as an adjunct treatment for major depressive disorder (MDD) require rigorously designed randomized controlled trials (RCTs). We aim to investigate the effects of augmenting standard MDD treatment with VD supplementation and examine factors influencing the treatment outcome. This article describes the study design, measures, and baseline characteristics. This multicenter RCT compares the efficacy of a six-month VD intervention at 100 micrograms/day versus 10 micrograms/day (μg/day) (4000 IU (international units)/day vs. 400 IU/day) added to a standard treatment in outpatients aged 20-61 years with MDD. The primary outcome is change in the Montgomery-Åsberg Depression Rating Scale (MADRS) score. Secondary outcomes are other indicators of mental health and functionality (BDI, SOC, 15-D, PSS10, LS-4, LOT-R, YSQ-S2-extended, CORE-OM, TAS-20, BRCS, TADS, SCL-90, DIAD, GAF), and circulating biomarkers. Intervention assessments are conducted at baseline, 3, and 6 months, and follow-ups at 18 months and 6 years post-baseline. The baseline sample had 319 subjects (74% women; median age 31 (inter-quartile range (IQR) 15), mean MADRS score 21.38 (SD 6.04)), with 281 assigned to the RCT. At present, the study continues as a follow-up study. DepFuD project will provide extensive information regarding the potential benefits of VD and enables to identify various biopsychosocial depression-associated risk factors.

The impact of mold exposure on anxiety symptoms in the older adults: A moderated mediation model based on CLHLS

BACKGROUND

Mold exposure is a common environmental issue that can adversely affect health, particularly among older adults. The impact of mold exposure on anxiety symptoms in this population has not been extensively studied.

OBJECTIVE

This study aims to examine the relationship between mold exposure and anxiety symptoms in older adults, considering the mediating role of cognitive function and the moderating effects of open window ventilation and multivitamin supplementation.

METHODS

Data from the eighth wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS) was utilized, including 11,021 participants aged 65 and older. Logistic regression models and moderated mediation analysis were employed to explore these relationships.

RESULTS

Mold exposure was significantly associated with increased anxiety symptoms (OR=1.831, 95 % CI=1.588-2.110). Cognitive impairment partially mediated this relationship. Open window ventilation (B=-0.040, P<0.001) and multivitamin supplementation (B=-0.197, P<0.001) served as protective factors. Subgroup analysis indicated higher vulnerability among females (OR=1.72, P<0.001), those aged 65-79 (OR=1.86, P<0.001), urban residents (OR=2.50, P<0.001), individuals not living with family members (OR=1.89, P<0.001), those with higher education (OR=2.01, P<0.001), married individuals (OR=1.80, P<0.001), and those in very good health (OR=2.11, P=0.026).

CONCLUSION

Mold exposure contributes to anxiety symptoms in older adults, with cognitive decline playing a mediating role. Effective interventions, including improved ventilation and multivitamin supplementation, can mitigate these effects. These findings highlight the need for targeted public health strategies to enhance the well-being of older adults.

Correlation of Co-Morbidities with Symptom Severity of Children with Autism Spectrum Disorder: A Cross-Sectional Survey

This study aims to identify potential correlations of the severity of symptoms of children with autism spectrum disorder (ASD) with serum nutritional levels, body composition indicators, diet partiality, and sleep disturbances. The cohort of this cross-sectional study included 120 children with ASD and 110 typically developing (TD) children to assess symptoms of ASD, and to measure serum levels of vitamins and minerals and the body composition values. Diet partiality and sleep disturbances were assessed by administering questionnaires. The serum levels of folic acid, copper, and vitamin B were lower in children with ASD than in TD children, while magnesium and homocysteine were higher (p < 0.05). Children with ASD had greater chest circumference, abdominal skinfold thickness, and body mass index (BMI) than TD children (p < 0.05), and higher prevalences of diet partiality and sleep disturbances (p < 0.001). Lower vitamin A levels and higher vitamin D levels were related to social impairment in children with ASD. Moreover, there were significantly positive correlations of BMI, chest circumference, diet partiality, and sleep disturbances with severity of ASD symptoms (p < 0.05). Collectively, rational nutritional supplementation, dietary management, and behavioral interventions are essential for children with ASD.

Association between vitamin D metabolism gene polymorphisms and schizophrenia

Schizophrenia (SZ) is a multifactorial and neurodegenerative disorder that results from the interaction between genetic and environmental factors. Notably, hundreds of single nucleotide polymorphisms (SNPs) are associated with the susceptibility to SZ. Vitamin D (VD) plays an essential role in regulating several genes important for maintaining brain function and health. To the best of the authors' knowledge, no studies have yet been conducted on the association between the VD pathway and patients with SZ. Therefore, the present study aimed to assess the potential association between eight SNPs in genes related to the VD pathway, including CYP2R1, CYP27B1, CYP24A1 and VDR among patients with SZ. A case-control study was conducted, involving a total of 400 blood samples drawn from 200 patients and 200 healthy controls. Genomic DNA was extracted and variants were genotyped using the tetra-amplification refractory mutation system-polymerase chain reaction method. The present study revealed statistically significant differences between patients with SZ and controls regarding the genotypes and allele distributions of three SNPs [CYP2R1 (rs10741657), CYP27B1 (rs10877012) and CYP24A1 (rs6013897) (P<0.0001)]. The AA genotype of rs10741657 was identified to be associated with SZ (P<0.0001) and the frequency of the A allele was higher in patients with SZ (P<0.0001) compared with the control group. Similarly, the TT genotype of rs10877012 was revealed to be associated with SZ (P<0.0001) and the T allele was more frequent in patients with SZ (P<0.0001) than in the control group. Moreover, the AA genotype of rs6013897 was revealed to be associated with SZ (P<0.0001), although no significant difference was detected between the two groups regarding the A allele (P=0.055). VDR (rs2228570, rs1544410, rs731236 and rs7975232) and CYP27B1 (rs4646536) gene polymorphisms did not exhibit a significant association with SZ. While the studied SNPs revealed promising discriminatory capacity between patients with SZ and controls, the rs10741657 SNP exhibited the most optimal area under the curve value at 0.615. A logistic model was applied considering only the significant SNPs and VD levels, which revealed that rs6013897 (T/A) and VD may have protective effects (0.267, P<0.001; 0.888, P<0.001, respectively). Moreover, a low serum VD level was highly prevalent in patients with SZ compared with the controls. Based on this finding, an association between serum 25(OH)D and SZ could be demonstrated. The present study revealed that CYP2R1 (rs10741657), CYP27B1 (rs10877012) and CYP24A1 (rs6013897) gene SNPs may be associated with SZ susceptibility.

Amitriptyline and cholecalciferol amend hippocampal histological structure and myelination during stress in Wistar rats via regulating miR200/BMP4/Olig-2 signaling

Chronic stress is a universal condition commonly associated with many psychiatric diseases. An extensive body of evidence discussed hippocampal affection upon chronic stress exposure, however, the underlying molecular pathways still need to be identified. We investigated the impact of chronic stress on miR200/BMP/Olig-2 signaling and hippocampal myelination. We also compared the effects of chronic administration of amitriptyline and cholecalciferol on chronically stressed hippocampi. Both amitriptyline and cholecalciferol significantly decreased serum cortisol levels, reduced immobility time in the forced swim test, increased the number of crossed squares in open field test, decreased the hippocampal expression of bone morphogenetic protein 4 (BMP4) and its messenger RNA (mRNA) levels, reduced miR200 expression as compared to untreated chronically stressed rats. Also, both drugs amended the hippocampal neuronal damage, enhanced the surviving cell count, and increased the pyramidal layer thickness of Cornu Ammonis subregion 1 (CA1) and granule cell layer of the dentate gyrus. Cholecalciferol was more effective in increasing the area percentage of myelin basic protein (MBP) and Olig-2 positive cells count in hippocampi of chronic stress-exposed rats than amitriptyline, thus enhancing myelination. We also found a negative correlation between the expression of BMP4, its mRNA, miR200, and the immunoexpression of MBP and Olig-2 proteins. This work underscores the amelioration of the stress-induced behavioral changes, inhibition of miR200/BMP4 signaling, and enhancement of hippocampal myelination following chronic administration of either amitriptyline or cholecalciferol, though cholecalciferol seemed more effective in brain remyelination.

Tremendous Fidelity of Vitamin D3 in Age-related Neurological Disorders

Vitamin D3 (VD) is a secosteroid hormone and shows a pleiotropic effect in brain-related disorders where it regulates redox imbalance, inflammation, apoptosis, energy production, and growth factor synthesis. Vitamin D3's active metabolic form, 1,25-dihydroxy Vitamin D3 (1,25(OH)2D3 or calcitriol), is a known regulator of several genes involved in neuroplasticity, neuroprotection, neurotropism, and neuroinflammation. Multiple studies suggest that VD deficiency can be proposed as a risk factor for the development of several age-related neurological disorders. The evidence for low serum levels of 25-hydroxy Vitamin D3 (25(OH)D3 or calcidiol), the major circulating form of VD, is associated with an increased risk of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), dementia, and cognitive impairment. Despite decades of evidence on low VD association with neurological disorders, the precise molecular mechanism behind its beneficial effect remains controversial. Here, we will be delving into the neurobiological importance of VD and discuss its benefits in different neuropsychiatric disorders. The focus will be on AD, PD, and HD as they share some common clinical, pathological, and epidemiological features. The central focus will be on the different attributes of VD in the aspect of its anti-oxidative, anti-inflammatory, anti-apoptotic, anti-cholinesterase activity, and psychotropic effect in different neurodegenerative diseases.

Vitamin D prophylaxis in persons with epilepsy?

Limited guidelines exist regarding osteoporosis prevention in the general population. Despite being a subject of controversy, the majority of research suggests that decreased vitamin D levels correlate with increased bone turnover, that is, an important risk factor for osteoporosis development. In most guidelines, daily vitamin D supplementation is recommended. In persons with epilepsy (PWE), the situation is more complex, as other factors can increase the chance of being vitamin D deficient. Currently, there are no internationally accepted guidelines regarding monitoring bone health in PWE. Our aim was to review the existing evidence in PWE on: (1) risk factors for vitamin D deficiency, (2) the identification of higher risk groups, and (3) the optimal ways to monitor bone health. Our narrative review shows that: (1) anti-seizure medication (ASM) use, especially enzyme-inducing ASM (EIASM) and valproic acid, is identified as an important risk factor for impaired bone health (e.g., increased risk for osteoporosis/fractures and/or vitamin D deficiency); (2) higher risk groups within the PWE population are present: intellectual or physical disability, institutionalized patients, puberty, early onset epilepsy and developmental epileptic encephalopathies, postmenopausal women, and use of multiple ASM/concomitant drugs (e.g. corticosteroids); and (3) a monitoring scheme can be suggested including laboratory tests, bone density measurements, managing of risk factors, and/or vitamin D supplementation. Overall, regular vitamin D measurement in PWE is a cost-effective and practical method for monitoring vitamin D deficiency, whereas in high-risk patients the combination of vitamin D measurement and bone densitometry is recommended. There is not enough evidence to advocate continuous vitamin D supplementation in all PWE. Children with epilepsy should receive the recommended daily intake of vitamin D for age and additional monitoring and supplementation if at higher risk of deficiency. There is a need for prospective trials exploring the potential benefit of vitamin D supplementation in PWE.

Vitamin D Relieves Epilepsy Symptoms and Neuroinflammation in Juvenile Mice by Activating the mTOR Signaling Pathway via RAF1: Insights from Network Pharmacology and Molecular Docking Studies

Epilepsy is a common neurological disorder, and the exploration of potential therapeutic drugs for its treatment is still ongoing. Vitamin D has emerged as a promising treatment due to its potential neuroprotective effects and anti-epileptic properties. This study aimed to investigate the effects of vitamin D on epilepsy and neuroinflammation in juvenile mice using network pharmacology and molecular docking, with a focus on the mammalian target of rapamycin (mTOR) signaling pathway. Experimental mouse models of epilepsy were established through intraperitoneal injection of pilocarpine, and in vitro injury models of hippocampal neurons were induced by glutamate (Glu) stimulation. The anti-epileptic effects of vitamin D were evaluated both in vivo and in vitro. Network pharmacology and molecular docking analysis were used to identify potential targets and regulatory pathways of vitamin D in epilepsy. The involvement of the mTOR signaling pathway in the regulation of mouse epilepsy by vitamin D was validated using rapamycin (RAPA). The levels of inflammatory cytokines (TNF-α, IL-1β, and IL-6) were assessed by enzyme-linked immunosorbent assay (ELISA). Gene and protein expressions were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, respectively. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling (TUNEL) staining was used to analyze the apoptosis of hippocampal neurons. In in vivo experiments, vitamin D reduced the Racine scores of epileptic mice, prolonged the latency of epilepsy, and inhibited the production of TNF-α, IL-1β, and IL-6 in the hippocampus. Furthermore, network pharmacology analysis identified RAF1 as a potential target of vitamin D in epilepsy, which was further confirmed by molecular docking analysis. Additionally, the mTOR signaling pathway was found to be involved in the regulation of mouse epilepsy by vitamin D. In in vitro experiments, Glu stimulation upregulated the expressions of RAF1 and LC3II/LC3I, inhibited mTOR phosphorylation, and induced neuronal apoptosis. Mechanistically, vitamin D activated the mTOR signaling pathway and alleviated mouse epilepsy via RAF1, while the use of the pathway inhibitor RAPA reversed this effect. Vitamin D alleviated epilepsy symptoms and neuroinflammation in juvenile mice by activating the mTOR signaling pathway via RAF1. These findings provided new insights into the molecular mechanisms underlying the anti-epileptic effects of vitamin D and further supported its use as an adjunctive therapy for existing anti-epileptic drugs.

Vitamin-D as a multifunctional molecule for overall well-being: An integrative review

Vitamin D is amongst the most important biomolecules to regularize and help in sustainable health, however, based on the studies, deficiency of this multifunctional vitamin is common. Vitamin D, besides playing a role in the form of vitamins, also acts as a multifunctional hormone (steroid). Vitamin D is synthesized inside the body through various steps starting from ultraviolet radiation exposure and comes from limited food sources, however, vitamin D-fortified food products are still among the major sources of vitamin D. Current review, focused on how vitamin D acts as a multifunctional molecule by effecting different functions in the body in normal or specific conditions and how it is important in fortification and how it can be managed from the available literature till date. During the Covid pandemic, people were aware of vitamin D and took supplementation, fortified foods, and sat under sunlight. As COVID prevalence decreases, people start forgetting about vitamin D. Vitamin D is very crucial for overall well-being as it has protective effects against a broad range of diseases as it can reduce inflammation, cancer cell growth and helps in controlling infection, increase metabolism, muscle, and bone strength, neurotransmitter expression, etc. Therefore, the present review is to provoke the population, and fulfillment of the vitamin D recommended dietary allowance daily must be confirmed.

The therapeutic potential of 1, 25-dihydroxy vitamin D3 on cisplatin-affected neurological functions is associated with the regulation of oxidative stress and inflammatory markers as well as levels of MMP2/9

Calcitriol as a biologically active form of vitamin D3 has beneficial effects on all body systems. This vitamin has a potent neuroprotective effect via several independent mechanisms against brain insults induced by anticancer drugs. The present study was designed to examine the neuroprotective effects of calcitriol against neurotoxicity induced by cisplatin. Induction of neurotoxicity was done with cisplatin administration (5 mg/kg/week) for 5 successive weeks in male Wistar rats. The neuroprotective influence of calcitriol supplementation (100ng/kg/day for 5 weeks) was assessed through behavioral, electrophysiological, and molecular experiments. Cisplatin administration impaired spatial learning and memory and decreased prefrontal brain-derived neurotrophic factor (BDNF). Peripheral sensory neuropathy was induced through cisplatin administration. Cisplatin also reduced the amplitudes of the compound action potential of sensory nerves in electrophysiological studies. Cisplatin treatment elevated MDA levels and reduced anti-oxidant (SOD and GPx) enzymes. Pro-inflammatory cytokines (IL-1β and TNF-α) and metalloproteinase-2 and 9 (MMP-2/9) were augmented through treatment with cisplatin. Learning and memory impairments along with BDNF changes caused by cisplatin were amended with calcitriol supplementation. Reduced sensory nerve conduction velocity in the cisplatin-treated group was improved by calcitriol. Calcitriol partially improved redox imbalance and diminished the pro-inflammatory cytokines and MMP-2/9 levels. Our findings showed that calcitriol supplementation can relieve cisplatin-induced peripheral neurotoxicity. Calcitriol can be regarded as a promising new neuroprotective agent.

The metabolic role of vitamin D in children's neurodevelopment: a network study

Neurodevelopmental disorders are rapidly increasing in prevalence and have been linked to various environmental risk factors. Mounting evidence suggests a potential role of vitamin D in child neurodevelopment, though the causal mechanisms remain largely unknown. Here, we investigate how vitamin D deficiency affects children's communication development, particularly in relation to Autism Spectrum Disorder (ASD). We do so by developing an integrative network approach that combines metabolomic profiles, clinical traits, and neurodevelopmental data from a pediatric cohort. Our results show that low levels of vitamin D are associated with changes in the metabolic networks of tryptophan, linoleic, and fatty acid metabolism. These changes correlate with distinct ASD-related phenotypes, including delayed communication skills and respiratory dysfunctions. Additionally, our analysis suggests the kynurenine and serotonin sub-pathways may mediate the effect of vitamin D on early life communication development. Altogether, our findings provide metabolome-wide insights into the potential of vitamin D as a therapeutic option for ASD and other communication disorders.

Putative Pharmacological Depression and Anxiety-Related Targets of Calcitriol Explored by Network Pharmacology and Molecular Docking

Depression and anxiety disorders, prevalent neuropsychiatric conditions that frequently coexist, limit psychosocial functioning and, consequently, the individual's quality of life. Since the pharmacological treatment of these disorders has several limitations, the search for effective and secure antidepressant and anxiolytic compounds is welcome. Vitamin D has been shown to exhibit neuroprotective, antidepressant, and anxiolytic properties. Therefore, this study aimed to explore new molecular targets of calcitriol, the active form of vitamin D, through integrated bioinformatic analysis. Calcitriol targets were predicted in SwissTargetPrediction server (2019 version). The disease targets were collected by the GeneCards database searching the keywords "depression" and "anxiety". Gene ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) were used to analyze the intersections of targets. Network analyses were carried out using GeneMania server (2023 version) and Cytoscape (V. 3.9.1.) software. Molecular docking predicted the main targets of the network and Ligplot predicted the main intermolecular interactions. Our study showed that calcitriol may interact with multiple targets. The main targets found are the vitamin D receptor (VDR), histamine H3 receptor (H3R), endocannabinoid receptors 1 and 2 (CB1 and CB2), nuclear receptor NR1H3, patched-1 (PTCH1) protein, opioid receptor NOP, and phosphodiesterase enzymes PDE3A and PDE5A. Considering the role of these targets in the pathophysiology of depression and anxiety, our findings suggest novel putative mechanisms of action of vitamin D as well as new promising molecular targets whose role in these disorders deserves further investigation.

The Effect of Genetic Variations in the Vitamin D Receptor Gene on the Course of Depressive Symptoms

BACKGROUND

Evidence on the association between single nucleotide polymorphisms (SNPs) in the vitamin D receptor (VDR) and depressive symptoms is inconclusive.

OBJECTIVES

The primary aim of the study was to investigate the association between SNPs in the VDR gene and depressive symptoms.

METHODS

In a sample of older adults from the Longitudinal Ageing Study Amsterdam (n = 922), depressive symptoms were assessed using the Centre for Epidemiological Studies Depression scale (CES-D scale) at baseline and after 3, 6, and 10 y of follow-up. Blood samples for SNP and serum 25-hydroxyvitamin D3 (25(OH)D3) determination were obtained at baseline. The association between 13 SNPs in the VDR gene and the course of depressive symptoms were evaluated using linear mixed models. The interaction between SNPs and serum 25(OH)D3 in relation to depressive symptoms was evaluated using multiple linear regression.

RESULTS

No SNPs were associated with the course of depressive symptoms. Significant interactions between serum 25(OH)D3 and SNPs in the VDR gene were found. Stratified analysis revealed that within the GG genotype strata, 10 nmol/L higher serum 25(OH)D3 was associated with 0.27 (95% CI: -0.50, -0.04) and 0.23 (95% CI: -0.48, 0.02) lower scores on the CES-D scale for Cdx-2 and 1b-G-886A, respectively. This association was not found in persons having the GA or AA genotype.

CONCLUSIONS

No SNPs are associated with the course of depressive symptoms. Stratified analysis shows that the effect of serum 25(OH)D3 concentrations on depressive symptoms is different among genotypes of Cdx-2 and 1b-G-886A. Future research should elucidate on the function of Cdx-2 and 1b-G-886A to describe their effect.

Association of cord blood vitamin D with child neurodevelopment at 7 years of age

AIM

The role of fetal vitamin D [25-hydroxyvitamin D (25(OH)D)], one of the nuclear steroid transcription regulators, and brain development is unclear. We previously found a weak but persistent association between cord blood 25(OH)D and child language abilities at 18 months and 4 years of age, but no association with cognition or behaviour. The aim of this study was to investigate the association between cord blood 25(OH)D and a range of neurodevelopmental outcomes in these same children at 7 years of age.

METHODS

Cord blood samples from 250 Australian mother-child pairs were analysed for 25(OH)D by mass spectroscopy. Children underwent tests of cognition, language, academic abilities and executive functions with a trained assessor at 7 years of age. Caregivers completed questionnaires to rate their child's behaviour and executive functioning in the home environment. Associations between standardised 25(OH)D and outcomes were assessed using regression models, taking into account possible social and demographic confounders.

RESULTS

Standardised 25(OH)D in cord blood was not associated with any test or parent-rated scores. Nor was there any association with the risk of having a poor test or parent-rated score. Likewise, cord blood 25(OH)D categorised as <25, 25-50 and >50 nmol/L was not associated with test scores or parent-rated scores.

CONCLUSIONS

There was no evidence that cord blood vitamin D concentration or deficiency was associated with cognition, language, academic abilities, executive functioning or behaviour at 7 years of age.

Vitamin D and human health: evidence from Mendelian randomization studies

We summarized the current evidence on vitamin D and major health outcomes from Mendelian randomization (MR) studies. PubMed and Embase were searched for original MR studies on vitamin D in relation to any health outcome from inception to September 1, 2022. Nonlinear MR findings were excluded due to concerns about the validity of the statistical methods used. A meta-analysis was preformed to synthesize study-specific estimates after excluding overlapping samples, where applicable. The methodological quality of the included studies was evaluated according to the STROBE-MR checklist. A total of 133 MR publications were eligible for inclusion in the analyses. The causal association between vitamin D status and 275 individual outcomes was examined. Linear MR analyses showed genetically high 25-hydroxyvitamin D (25(OH)D) concentrations were associated with reduced risk of multiple sclerosis incidence and relapse, non-infectious uveitis and scleritis, psoriasis, femur fracture, leg fracture, amyotrophic lateral sclerosis, anorexia nervosa, delirium, heart failure, ovarian cancer, non-alcoholic fatty liver disease, dyslipidemia, and bacterial pneumonia, but increased risk of Behçet's disease, Graves' disease, kidney stone disease, fracture of radium/ulna, basal cell carcinoma, and overall cataracts. Stratified analyses showed that the inverse association between genetically predisposed 25(OH)D concentrations and multiple sclerosis risk was significant and consistent regardless of the genetic instruments GIs selected. However, the associations with most of the other outcomes were only pronounced when using genetic variants not limited to those in the vitamin D pathway as GIs. The methodological quality of the included MR studies was substantially heterogeneous. Current evidence from linear MR studies strongly supports a causal role of vitamin D in the development of multiple sclerosis. Suggestive support for a number of other health conditions could help prioritize conditions where vitamin D may be beneficial or harmful.

Induction of autism-related behavior in male mice by early-life vitamin D deficiency: association with disruption of the gut microbial composition and homeostasis

Vitamin D deficiency (VDD) during early life emerges as a potential risk factor for autism spectrum disorder (ASD). Individuals with autism commonly exhibit lower vitamin D (VD) levels compared to the general population, and VD deficiency is prevalent during pregnancy and lactation. Moreover, gastrointestinal comorbidity, prevalent in ASD patients, correlates closely with disruptions in the gut microbiota and altered intestinal permeability. Therefore, it is fascinating and significant to explore the effects of maternal VD deficiency during pregnancy and lactation on the maturation of the gut microbiota of the offspring and its relevance to autism spectrum disorders. In this study, we established maternal pregnancy and lactation VD-deficient mouse models, employed shotgun macrogenomic sequencing to unveil alterations in the gut microbiome of offspring mice, and observed autism-related behaviours. Furthermore, fecal microbial transplantation (FMT) reversed repetitive and anxious behaviours and alleviated social deficits in offspring mice by modulating the gut microbiota and increasing short-chain fatty acid levels in the cecum, along with influencing the concentrations of claudin-1 and occludin in the colon. Our findings confirm that VDD during pregnancy and lactation is a risk factor for autism in the offspring, with disturbances in the structure and function of the offspring's gut microbiota contributing at least part of the effect. The study emphasises the importance of nutrition and gut health early in life. Simultaneously, this study further demonstrates the effect of VDD on ASD and provides potential ideas for early prevention and intervention of ASD.

Vitamin D and ischemic stroke - Association, mechanisms, and therapeutics

Confronting the rising tide of ischemic stroke and its associated mortality and morbidity with ageing, prevention and acute management of ischemic stroke is of paramount importance. Mounting observational studies have established a non-linear association of vitamin D status with cardiovascular diseases, including ischemic stroke. Paradoxically, current clinical trials fail to demonstrate the cardiovascular benefits of vitamin D supplementation. We aim to update recent clinical and experimental findings on the role of vitamin D in the disease course of ischemic stroke, from its onset, progression, recovery, to recurrence, and the established and alternative possible pathophysiological mechanisms. This review justifies the necessities to address stroke etiological subtypes and focus on vitamin D-deficient subjects for investigating the potential of vitamin D supplementation as a preventive and therapeutic approach for ischemic stroke. Well-powered clinical trials are warranted to determine the efficacy, safety, timing, target individuals, optimal dosages, and target 25OHD concentrations of vitamin D supplementation in the prevention and treatment of ischemic stroke.

The role and impact of abnormal vitamin levels in autism spectrum disorders

The prevalence of autism spectrum disorder (ASD), a neurodevelopmental disorder with a predominance of social behavioral disorders, has increased dramatically in various countries in recent decades. The interplay between genetic and environmental factors is believed to underlie ASD pathogenesis. Recent analyses have shown that abnormal vitamin levels in early life are associated with an increased risk of autism. As essential substances for growth and development, vitamins have been shown to have significant benefits for the nervous and immune systems. However, it is unknown whether certain vitamin types influence the emergence or manifestation of ASD symptoms. Several studies have focused on vitamin levels in children with autism, and neurotypical children have provided different insights into the types of vitamins and their intake. Here, we review the mechanisms and significance of several vitamins (A, B, C, D, E, and K) that are closely associated with the development of ASD in order to prevent, mitigate, and treat ASD. Efforts have been made to discover and develop new indicators for nutritional assessment of children with ASD to play a greater role in the early detection of ASD and therapeutic remission after diagnosis.

Vitamin D profile in autism spectrum disorder children and its relation to the disease severity

Background

The study aimed to investigate whether vitamin D deficiency is a common finding in autism spectrum disorder (ASD) children and whether such deficiency is related to ASD severity and language age or not.

Methods

A cross-sectional observational study was conducted on ASD children aged 2-6 years. The participants were 80 Egyptian children with ASD. All participants were assessed using DSM-V, the Childhood Autism Rating Scale (CARS), language assessment, and assessment of serum vitamin D using ADVIA Centaur Vit D assay.

Results

About 63.8% of ASD children have vitamin D insufficiency, 28.8 % have vitamin D deficiency, and 7.4% have normal serum levels. No correlation was found between serum vitamin D and language age (r = -0.085, P = 0.451), DSM 5 severity levels (r = 0.015,P= 0.894), and CARS scores (r= 0.075, P= 0.511).

Conclusion

ASD children have lower serum vitamin D levels, which may be one of the environmental factors contributing to ASD development in genetically susceptible individuals, and its correction may be helpful as adjuvant therapy for ASD.

Association of time spent outdoors with the risk of Parkinson's disease: a prospective cohort study of 329,359 participants

BACKGROUND

Studies on the association between time spent outdoors and the development of Parkinson's disease (PD) are lacking, and whether this relationship differs in different subgroups (age, sex) remains unclear.

OBJECTIVE

We here examined the association between time spent outdoors and the incidence of PD in different seasons.

METHODS

This study included 329,359 participants from the UK Biobank. Data regarding hours spent outdoors during a typical day were obtained through questionnaires. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) for the association between exposure to outdoors duration and PD incidence. Restricted cubic spline was used to explore the potential nonlinear relationship between time spent outdoors and PD risk. To explore the potential mechanisms of time spent outdoors effecting the risk of PD incidence, their association with serum vitamin D was further analysed separately.

RESULTS

During a median follow-up of 13.57 years, 2,238 participants developed PD. In summer, time spent outdoors > 5.0 h/day was associated with a reduced PD risk compared with ≤ 2.0 h/day (HR = 0.84, 95% CI, 0.74-0.95). In winter too, time spent outdoors > 2.0 h/day was also associated with a reduced PD risk compared with ≤ 1.0 h/day (HR = 0.85, 95% CI, 0.76-0.94). For annual average time spent outdoors, participants who went outdoors for more than 3.5 h/day had a reduced PD risk than those who went outdoors for ≤ 1.5 h/day (HR = 0.85, 95% CI, 0.75-0.96). Additionally, sex and age differences were observed in the association between time spent outdoors and the PD risk. Moreover, Time spent outdoors was observed to be positively associated with serum vitamin D levels. Compared with serum vitamin D-deficient participants, the risk of PD was reduced by 15% in the sufficient participants.

CONCLUSION

In the total population, higher time spent outdoors was linked to a reduced PD risk. However, this association may vary among different age or sex groups.

Vitamin D deficiency associated with neurodevelopmental problems in 2-year-old Japanese boys

AIM

While associations between vitamin D deficiency and neurodevelopmental disorders have been found, large studies on child vitamin D, neurodevelopment, and sex differences among the general population are lacking. This study aimed to investigate the association between child serum 25-hydroxyvitamin D (25(OH)D)) levels and neurodevelopmental problems (NDPs).

METHODS

Serum 25(OH)D and NDPs were measured at age two among the subcohort study of the Japan Environment and Children's Study. NDPs were assessed with the Kyoto Scale of Psychological Development 2001 (Kyoto scale). Adjusted odds ratios (aORs) for the Kyoto-scale developmental quotient scores <70 were calculated, for postural-motor, cognitive-adaptive, and language-social domains and overall scores, adjusted for test month, latitude, small for gestational age, maternal age, and daycare attendance.

RESULTS

Among 2363 boys and 2290 girls, boys had higher 25(OH)D levels, but scored lower in the Kyoto scale. For boys in the vitamin D deficiency (<20 ng/mL) group, aORs of scoring the Kyoto-scale DQs <70 were 2.33 (p = 0.006) for overall DQs, 1.91 (p = 0.037) for cognitive-adaptive, and 1.69 (p = 0.024) for language-social domains. For girls, results were inconclusive.

CONCLUSION

Only boys showed a clear and cross-modal association between vitamin D deficiency and NDPs.

Advances in the Treatment of Autism Spectrum Disorder: Current and Promising Strategies

Autism spectrum disorder (ASD) is an umbrella term for developmental disorders characterized by social and communication impairments, language difficulties, restricted interests, and repetitive behaviors. Current management approaches for ASD aim to resolve its clinical manifestations based on the type and severity of the disability. Although some medications like risperidone show potential in regulating ASD-associated symptoms, a comprehensive treatment strategy for ASD is yet to be discovered. To date, identifying appropriate therapeutic targets and treatment strategies remains challenging due to the complex pathogenesis associated with ASD. Therefore, a comprehensive approach must be tailored to target the numerous pathogenetic pathways of ASD. From currently viable and basic treatment strategies, this review explores the entire field of advancements in ASD management up to cutting-edge modern scientific research. A novel systematic and personalized treatment approach is suggested, combining the available medications and targeting each symptom accordingly. Herein, summarize and categorize the most appropriate ways of modern ASD management into three distinct categories: current, promising, and prospective strategies.

The roles of serum vitamin D and tobacco smoke exposure in insomnia: a cross-sectional study of adults in the United States

Aim

Tobacco smoke exposure and vitamin D (VD) status were both associated with insomnia. However, the combined effect of smoking and VD on insomnia has not been discussed. This study aimed to explore the role of VD in the association between tobacco smoke exposure and insomnia.

Methods

Data on adults were extracted from the National Health and Nutrition Examination Surveys (NHANES) database in 2005-2008 for this cross-sectional study. Weighted univariate and multivariate logistic regression analyses were used to explore the associations between serum cotinine, serum VD, and insomnia. A surface diagram was drawn to reflect the effect of VD on the association between serum cotinine and insomnia. In addition, the potential regulating effect of VD in subgroups of smoking status was also performed. The evaluation index was odds ratios (ORs) with 95% confidence intervals (CIs).

Results

Among the eligible participants, 1,766 had insomnia. After adjusting for covariates, we found that elevated serum cotinine levels were associated with higher odds of insomnia [OR = 1.55, 95% CI: (1.22, 1.97)]. However, the relationship between serum VD level and insomnia was not significant (P = 0.553). Higher serum cotinine levels were also associated with higher odds of insomnia [OR = 1.52, 95% CI: (1.17, 1.98)] when serum VD level was <75 nmol/L; however, this relationship became non-significant when serum VD concentration was elevated (P = 0.088). Additionally, the potential regulating effect of VD was also found in adults who were not smoking.

Conclusion

VD may play a potential regulative role in the association between tobacco smoke exposure and insomnia. Further studies are needed to clarify the causal relationships between VD, tobacco smoke exposure, and insomnia.

Association between Vitamin D and Short-Term Functional Outcomes in Acute Ischemic Stroke

Vitamin D (Vit D) affects musculoskeletal performance and central nervous system neuroprotection. We aimed to investigate the association between serum Vit D levels and short-term functional outcomes in patients with acute ischemic stroke. This study involved patients with acute ischemic stroke confirmed on brain MRI. The National Institutes of Health Stroke Scale (NIHSS) was used to assess initial stroke severity upon admission. We evaluated the functional outcomes using the Berg Balance Scale (BBS), Manual Function Test (MFT), Korean Mini-Mental State Examination (K-MMSE), Korean version of the modified Barthel Index (K-MBI) within three weeks from the onset of stroke, and modified Rankin Scale (mRS) score at discharge. Overall, 192 patients were finally included and divided into three groups: Vit D sufficient (n = 28), insufficient (n = 49), and deficient (n = 115). Multivariate analysis showed that the Vit D deficient group presented with a higher risk of initially severe stroke (p = 0.025) and poor functional outcomes on the BBS (p = 0.048), MFT (p = 0.017), K-MMSE (p = 0.001), K-MBI (p = 0.003), and mRS (p = 0.032) compared to the Vit D sufficient group. Vit D deficiency may be associated with severe initial stroke and poor short-term post-stroke functional outcomes.

Interplay of Vitamin D, Unfolded Protein Response, and Iron Metabolism in Neuroblastoma Cells: A Therapeutic Approach in Neurodegenerative Conditions

Vitamin D3 (VD) is crucial for various cell functions, including gene regulation, antioxidant defense, and neural health. Neurodegenerative conditions are closely linked to the unfolded protein response (UPR), a mechanism reacting to endoplasmic reticulum (ER) stress. Iron metabolism is intricately associated with UPR and neurodegeneration. This study used SH-SY5Y neuroblastoma cells to investigate the relationship between UPR, iron metabolism, and VD. Different sequences of treatments (pre- and post-treatments) were applied using VD and thapsigargin (Tg), and various methods were used for evaluation, including real-time qPCR, Western blotting, ELISA, and iron content analysis. The findings indicate that VD affects UPR pathways, cytokine release, and iron-related genes, potentially offering anti-inflammatory benefits. It also influences iron transporters and storage proteins, helping to maintain cellular iron balance. Furthermore, pro-inflammatory cytokines like interleukin-6 (IL-6) and tumor necrosis factor alpha (TNFα) were impacting UPR activation in cells. VD also influenced fractalkine (CX3CL1) gene expression and secretion, suggesting its potential as a therapeutic agent for addressing neuroinflammation and iron dysregulation. This research provides insights into the intricate connections among VD, UPR, and iron metabolism in SH-SY5Y neuroblastoma cells, with implications for future investigations and potential therapeutic approaches in neurodegenerative diseases characterized by UPR dysregulation and iron accumulation.

Vitamin D Status in Bipolar Disorder

Vitamin D status may impact acute affective symptomatology and the severity of symptoms in patients with bipolar disorder (BD). Therefore, this cross-sectional study analyzed 25(OH)D, 24,25(OH)2D, and the vitamin D metabolite ratio (VMR) in BD and correlated the results with clinical affective symptomatology and functionality. The inactive precursor 25(OH)D, and its principal catabolite 24,25(OH)2D, were measured simultaneously with a validated liquid chromatography-tandem mass spectrometry method in 170 BD outpatients and 138 healthy controls. VMR was calculated as follows: VMR = 100×(24,25(OH)2D/25(OH)D). The psychometric assessment comprised: Beck Depression Inventory-II, Hamilton Depression Rating Scale, Young Mania Rating Scale, Global Assessment of Functioning, and number of suicide attempts. We did not find a significant difference between patients and controls in the concentrations of 25(OH)D and 24,25(OH)2D. Additionally, the VMR was comparable in both groups. The calculations for the clinical parameters showed a negative correlation between the Young Mania Rating Scale and 24,25(OH)2D (r = -0.154, p = 0.040), as well as the Young Mania Rating Scale and the VMR (r = -0.238, p = 0.015). Based on the small effect size and the predominantly euthymic sample, further exploration in individuals with manic symptoms would be needed to confirm this association. In addition, long-term clinical markers and an assessment in different phases of the disease may provide additional insights.

Neuroprotective strategies for neonatal hypoxic-ischemic brain damage: Current status and challenges

Neonatal hypoxic-ischemic brain damage (HIBD) is a prominent contributor to both immediate mortality and long-term impairment in newborns. The elusive nature of the underlying mechanisms responsible for neonatal HIBD presents a significant obstacle in the effective clinical application of numerous pharmaceutical interventions. This comprehensive review aims to concentrate on the potential neuroprotective agents that have demonstrated efficacy in addressing various pathogenic factors associated with neonatal HIBD, encompassing oxidative stress, calcium overload, mitochondrial dysfunction, endoplasmic reticulum stress, inflammatory response, and apoptosis. In this review, we conducted an analysis of the precise molecular pathways by which these drugs elicit neuroprotective effects in animal models of neonatal hypoxic-ischemic brain injury (HIBD). Our objective was to provide a comprehensive overview of potential neuroprotective agents for the treatment of neonatal HIBD in animal experiments, with the ultimate goal of enhancing the feasibility of clinical translation and establishing a solid theoretical foundation for the clinical management of neonatal HIBD.

Serum Vitamin D3 Concentration, Sleep, and Cognitive Impairment among Older Adults in China

BACKGROUND

Cognitive decline in older adults has become one of the critical challenges to global health. This study aims to examine both cross-sectional and longitudinal associations of levels of serum 25-hydroxyvitamin D3 (25(OH)D3) (briefed as VD3) concentration and sleep quality/duration, especially their interactions, with risk of cognitive impairment among older adults in China.

METHODS

We utilized a special subsample of adults aged 65-105 years (individuals = 3412, observations = 4816) from eight provinces in China derived from the 2011/2012 and 2014 waves of the Chinese Longitudinal Healthy Longevity Survey. Cognitive impairment was measured by the Mini-Mental State Examination scale. Sleep quality was classified as good versus fair/poor, and sleep duration was classified into short (<7 h), normal (≥7 but <9 h), and long (≥9 h). The VD3 concentration was divided into three levels: deficiency (VD3 < 25 nmol/L), insufficiency (25 nmol/L ≤ VD3 < 50 nmol/L), and sufficiency (VD3 ≥ 50 nmol/L). A wide set of covariates that include demographics, socioeconomic status, family support, health practice, and health conditions was adjusted for robust findings. Multilevel random intercept logit regression models were used to examine the cross-sectional associations between VD3, sleep, and cognitive impairment, whereas logit regression models were applied to investigate the longitudinal associations.

RESULTS

In the cross-sectional analyses, when all covariates were adjusted, VD3 sufficiency was significantly associated with a 33% lower risk of cognitive impairment compared with VD3 deficiency; good sleep quality was associated with 34% lower odds of cognitive impairment compared with fair/poor sleep quality; sleep hours were not associated with cognitive impairment, although a long sleep duration (≥9 h) was associated with 30% higher odds of being cognitively impaired when baseline health was not controlled. Interaction analyses reveal that VD3 sufficiency could help to additionally reduce the risk of cognitive impairment for good sleep quality and normal sleep hours. In the longitudinal analyses, the association of VD3 sufficiency remains significant, whereas sleep quality and sleep duration were not significant associates.

CONCLUSIONS

Good sleep quality, normal sleep hours, and VD3 sufficiency are positively associated with good cognitive function. VD3 sufficiency could enhance the associations between sleep and cognitive impairment.

The Influence of Vitamin D Status on Cognitive Ability in Patients with Bipolar Disorder and Healthy Controls

Recent evidence on the association between vitamin D and cognition in mentally healthy individuals is inconsistent. Furthermore, the link between vitamin D and cognitive ability in individuals with bipolar disorder has not been studied yet. Thus, we aimed to investigate the association between 25-hydroxyvitamin D (25(OH)D), 24,25 dihydroxyvitamin D (24,25(OH)2D, the vitamin D metabolite ratio (VMR) and cognition in a cohort of euthymic patients with bipolar disorder. Vitamin D metabolites were measured simultaneously by liquid-chromatography tandem mass-spectrometry in serum samples from 86 outpatients with bipolar disorder and 93 healthy controls. Neither the inactive precursor 25(OH)D, nor the primary vitamin D catabolite 24,25(OH)2D, or the vitamin D metabolite ratio were significantly associated with the domains "attention", "memory", or "executive function" in individuals with bipolar disorder and healthy controls. Further, no vitamin D deficiency effect or interaction group × vitamin D deficiency was found in the cognitive domain scores. In summary, the present study does not support vitamin D metabolism as a modulating factor of cognitive function in euthymic BD patients. Considering the current study's cross-sectional design, future research should expand these results in a longitudinal setting and include additional aspects of mental health, such as manic or depressive symptoms, long-term illness course and psychopharmacological treatment.

The Synaptic and Circuit Functions of Vitamin D in Neurodevelopment Disorders

Vitamin D deficiency/insufficiency is a public health issue around the world. According to epidemiological studies, low vitamin D levels have been associated with an increased risk of some neurodevelopmental disorders, including autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). Animal models reveal that vitamin D has a variety of impacts on the synapses and circuits in the brain. A lack of vitamin D affects the expression of synaptic proteins, as well as the synthesis and metabolism of various neurotransmitters. Depending on where vitamin D receptors (VDRs) are expressed, vitamin D may also regulate certain neuronal circuits through the endocannabinoid signaling, mTOR pathway and oxytocin signaling. While inconsistently, some data suggest that vitamin D supplementation may be able to reduce the core symptoms of ASD and ADHD. This review emphasizes vitamin D's role in the synaptic and circuit mechanisms of neurodevelopmental disorders including ASD and ADHD. Future application of vitamin D in these disorders will depend on both basic research and clinical studies, in order to make the transition from the bench to the bedside.

Towards Novel Potential Molecular Targets for Antidepressant and Antipsychotic Pharmacotherapies

Depression and schizophrenia are two highly prevalent and severely debilitating neuropsychiatric disorders. Both conventional antidepressant and antipsychotic pharmacotherapies are often inefficient clinically, causing multiple side effects and serious patient compliance problems. Collectively, this calls for the development of novel drug targets for treating depressed and schizophrenic patients. Here, we discuss recent translational advances, research tools and approaches, aiming to facilitate innovative drug discovery in this field. Providing a comprehensive overview of current antidepressants and antipsychotic drugs, we also outline potential novel molecular targets for treating depression and schizophrenia. We also critically evaluate multiple translational challenges and summarize various open questions, in order to foster further integrative cross-discipline research into antidepressant and antipsychotic drug development.

Vitamin D and Bone fragility in Individuals with Osteogenesis Imperfecta: A Scoping Review

Vitamin D affects several body functions, and thus general health, due to its pleiotropic activity. It plays a key role in bone metabolism, and its deficiency impacts bone development, leading to bone fragility. In osteogenesis imperfecta (OI), a group of hereditary connective tissue disorders characterized by bone fragility, additional factors, such as vitamin D deficiency, can affect the expression of the phenotype and aggravate the disorder. The aim of this scoping review was to assess the incidence of vitamin D deficit in OI patients and the association between vitamin D status and supplementation in individuals affected by OI. We searched the PubMed Central and Embase databases and included studies published between January/2000 and October/2022 evaluating vitamin D measurement and status (normal, insufficiency, deficiency) and supplementation for OI. A total of 263 articles were identified, of which 45 were screened by title and abstract, and 10 were included after a full-text review. The review showed that low levels of vitamin D was a frequent finding in OI patients. Vitamin D supplementation was mainly indicated along with drug therapy and calcium intake. Even if widely used in clinical practice, vitamin D supplementation for OI individuals still needs a better characterization and harmonized frame for its use in the clinical setting, as well as further studies focusing on its effect on bone fragility.

The Role of Vitamin D in Health and Disease: A Narrative Review on the Mechanisms Linking Vitamin D with Disease and the Effects of Supplementation

Vitamin D insufficiency or deficiency (VDD) is a very prevalent condition in the general population. Vitamin D is necessary for optimal bone mineralization, but apart from the bone effects, preclinical and observational studies have suggested that vitamin D may have pleiotropic actions, whereas VDD has been linked to several diseases and higher all-cause mortality. Thus, supplementing vitamin D has been considered a safe and inexpensive approach to generate better health outcomes-and especially so in frail populations. Whereas it is generally accepted that prescribing of vitamin D in VDD subjects has demonstrable health benefits, most randomized clinical trials, although with design constraints, assessing the effects of vitamin D supplementation on a variety of diseases have failed to demonstrate any positive effects of vitamin D supplementation. In this narrative review, we first describe mechanisms through which vitamin D may exert an important role in the pathophysiology of the discussed disorder, and then provide studies that have addressed the impact of VDD and of vitamin D supplementation on each disorder, focusing especially on randomized clinical trials and meta-analyses. Despite there already being vast literature on the pleiotropic actions of vitamin D, future research approaches that consider and circumvent the inherent difficulties in studying the effects of vitamin D supplementation on health outcomes are needed to assess the potential beneficial effects of vitamin D. The evaluation of the whole vitamin D endocrine system, rather than only of 25-hydroxyvitamin D levels before and after treatment, use of adequate and physiologic vitamin D dosing, grouping based on the achieved vitamin D levels rather than the amount of vitamin D supplementation subjects may receive, and sufficiently long follow-up are some of the aspects that need to be carefully considered in future studies.

Vitamin D in Depression: A Potential Bioactive Agent to Reduce Suicide and Suicide Attempt Risk

Suicide is one of the leading causes of death worldwide. According to the World Health Organization (WHO), every year, more than 700 thousand people die from this cause. Therefore, suicide is a public health issue. The complex interaction between different factors causes suicide; however, depression is one of the most frequent factors in people who have attempted suicide. Several studies have reported that vitamin D deficiency may be a relevant risk factor for depression, and vitamin D supplementation has shown promising effects in the adjunctive treatment of this mood disorder. Among the beneficial mechanisms of vitamin D, it has been proposed that it may enhance serotonin synthesis and modulate proinflammatory cytokines since low serotonin levels and systemic inflammation have been associated with depression and suicide. The present narrative review shows the potential pathogenic role of vitamin D deficiency in depression and suicide and the potential benefits of vitamin D supplementation to reduce their risk.

Causal association between vitamin D and diabetic neuropathy: a Mendelian randomization analysis

OBJECTIVES

Vitamin D has been linked to diabetic neuropathy (DN) in previous epidemiological observational studies, however, their findings are inconsistent. The causal relationship between vitamin D and DN remains unknown. In this study we aim to investigate the causal association of serum 25-hydroxyvitamin D (25OHD) and DN.

METHODS

Based on summary statistics from publicly available genome-wide association studies (GWAS) database, we detected the genetic correlation between serum 25OHD levels and DN by a two-sample Mendelian randomization (MR) analysis. The inverse-variance weighted (IVW) method was used as the primary analysis, weighted median and MR-Egger were applied as complementary methods for MR estimates. In addition, we took sensitivity analyses including Cochran's Q test, MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) and leave-one-out analysis to ensure that we obtained stable and reliable results.

RESULTS

Our MR study showed no significant genetic association between serum 25OHD levels and DN (OR = 1.13, 95% CI = 0.81-1.57, P = 0.46). Furthermore, in the reverse direction analysis, we did not find a significant causal effect of DN and serum 25OHD levels (OR = 0.99, 95% CI = 0.98-1.00, P = 0.09). Results of MR-Egger, Weighted Median were consistent with those of the IVW method. The sensitivity analysis suggesting that no significant heterogeneity and genetic pleiotropy was observed.

CONCLUSIONS

Our results provided no evidence to support the causal association of serum 25OHD levels with DN.

A Pleiotropic Nuclear Hormone Labelled Hundred Years Ago Vitamin D

This year we are celebrating 100 years of the naming of vitamin D, but the molecule is, in fact, more than one billion years old [...].