Vitamin D and neurocognitive dysfunction: preventing "D"ecline?

Effects of vitamin D supplementation on neuroplasticity in older adults: a double-blinded, placebo-controlled randomised trial

Vitamin D can improve muscle function and reduce falls, but whether it can strengthen neural connections within the brain and nervous system is not known. This 10-week randomised controlled trial indicates that treatment with 2,000 IU/day vitamin D3 does not significantly alter neuroplasticity relative to placebo in older adults.

INTRODUCTION

The purpose of this study was to examine the effects of vitamin D supplementation on neuroplasticity, serum brain-derived neurotrophic factor (BDNF) and muscle strength and function in older adults.

METHODS

This was a 10-week double-blinded, placebo-controlled randomised trial in which 26 older adults with 25-hydroxyvitamin D [25OHD] concentrations 25-60 nmol/L were randomised to 2,000 IU/day vitamin D3 or matched placebo. Single- and paired-pulse transcranial magnetic stimulation applied over the motor cortex was used to assess changes in motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI), as measures of corticospinal excitability and inhibition respectively, by recording electromyography (EMG) responses to stimulation from the wrist extensors. Changes in muscle strength, stair climbing power, gait (timed-up-and-go), dynamic balance (four square step test), serum 25(OH)D and BDNF concentrations were also measured.

RESULTS

After 10 weeks, mean 25(OH)D levels increased from 46 to 81 nmol/L in the vitamin D group with no change in the placebo group. The vitamin D group experienced a significant 8-11% increase in muscle strength and a reduction in cortical excitability (MEP amplitude) and SICI relative to baseline (all P < 0.05), but these changes were not significantly different from placebo. There was no effect of vitamin D on muscle power, function or BDNF.

CONCLUSIONS

Daily supplementation with 2,000 IU vitamin D3 for 10 weeks had no significant effect on neuroplasticity compared to placebo, but the finding that vitamin D treatment alone was associated with a decrease in corticospinal excitability and intracortical inhibition warrants further investigation as this suggests that it may improve the efficacy of neural transmission within the corticospinal pathway.

Low serum levels of vitamin D are associated with post-stroke depression

BACKGROUND AND PURPOSE

Low serum levels of vitamin D have been associated with depression in non-stroke subjects. Our aim was to examine the possible association between serum vitamin D levels and the development of post-stroke depression (PSD).

METHODS

In total, 189 patients with acute ischaemic stroke were consecutively recruited. Serum levels of 25-hydroxyvitamin D [25(OH)D] were measured by competitive protein-binding assay within 24 h after admission. The 17-item Hamilton Depression Scale was used for screening for the existence of depressive symptoms at 1 month after stroke. Patients with a Hamilton Depression Scale score of ≥7 were given the Structured Clinical Interview of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, for diagnosis of PSD. Meanwhile, 100 healthy control subjects were also recruited and underwent measurement of 25(OH)D.

RESULTS

Fifty-five patients (29.1%) were diagnosed as having PSD at 1 month. Serum vitamin D levels within 24 h after admission were significantly lower in both non-PSD patients and PSD patients than in normal controls. PSD patients had significantly lower vitamin D than non-PSD patients. Serum vitamin D levels (≤37.1 and ≥64.1 nmol/l) were independently associated with the development of PSD (odds ratio 8.824, 95% confidence interval 2.011-38.720, P = 0.004, and odds ratio 0.127, 95% confidence interval 0.022-0.718, P = 0.020, respectively).

CONCLUSIONS

Serum vitamin D levels within 24 h after admission are found to be associated with PSD and may predict its development at 1 month post-stroke.

25-vitamin D, 1,25-vitamin D, parathyroid hormone, fibroblast growth factor-23 and cognitive function in men with advanced CKD: a veteran population

Abstract. Cognitive impairment is common in advanced chronic kidney disease (CKD), but little is known about its relation with abnormalities in mineral metabolism. Methods: The longitudinal association between plasma 25-hydroxyvitamin D (25(OH)D), 1,25-dihydroxyvitamin D (1,25(OH)2D), intact parathyroid hormone (iPTH), and fibroblast growth factor-23 (FGF-23) levels and cognitive function was assessed in 605 patients (67 ± 12 years) with advanced CKD not requiring dialysis (n = 247) or end-stage renal disease (ESRD; n = 358) who participated in the Homocysteine Study Cognitive Function Substudy (HOSTCOG)). Cognitive function was assessed using the Telephone Interview for Cognitive Status-modified (TICSm; mean follow-up 3.1 years) and associated with baseline mineral metabolite levels using linear regression analyses. Results: In unadjusted analyses, increasing log 1,25(OH)2D and decreasing log iPTH and FGF-23 levels were associated with worse cognitive status (p < 0.05). In fully adjusted multivariate analyses, the associations were no longer significant. Log 25(OH)D levels were not associated with cognitive function in unadjusted or adjusted analyses. Results were similar when analyzed by tertile or separately within CKD and ESRD groups. Conclusions: These results suggest that mineral metabolism dysregulation does not mediate the impairment in cognitive function common in advanced CKD.

Association Between Serum 25(OH)D Level and Nonspecific Musculoskeletal Pain in Acute Rehabilitation Unit Patients

OBJECTIVE

Nonspecific musculoskeletal pain can be difficult to manage in acute rehabilitation unit (ARU) patients. We investigated whether vitamin D status is a potential modifiable risk factor for nonspecific musculoskeletal pain in ARU patients.

MATERIALS AND METHODS

This cross-sectional study focused on 414 adults from an inpatient ARU in Mission Viejo, California, between July 2011 and June 2012. On ARU admission, all patients had serum 25-hydroxyvitamin D (25(OH)D) levels measured and were assessed for nonspecific musculoskeletal pain. We performed multivariable logistic regression to test the association of serum 25(OH)D level with nonspecific musculoskeletal pain while adjusting for clinically relevant covariates.

RESULTS

Among these 414 patients, mean (SD) 25(OH)D level was 29 (12) ng/mL, and 30% had nonspecific musculoskeletal pain. After adjustment for age, sex, race, body mass index, Functional Independence Measure score, Deyo-Charlson Comorbidity Index, fractures, steroid use, history of osteoporosis/osteomalacia, and patient type (orthopedic, cardiac, neurological, spinal cord injury, or traumatic brain injury), serum 25(OH)D level was inversely associated with nonspecific musculoskeletal pain (odds ratio [OR] per 10 ng/mL, 0.67; 95% confidence interval [CI], 0.48-0.82). When 25(OH)D level was dichotomized, patients with levels <20 ng/mL had higher odds of nonspecific musculoskeletal pain (OR, 2.33; 95% CI, 1.23-4.17) compared with patients with levels ≥20 ng/mL.

CONCLUSIONS

In adult patients, serum 25(OH)D level on admission to ARU was inversely associated with nonspecific musculoskeletal pain. These data support the need for randomized, controlled trials to test the role of vitamin D supplementation to improve nonspecific musculoskeletal pain in ARU patients.

Role of vitamin D3 in treatment of lumbar disc herniation--pain and sensory aspects: study protocol for a randomized controlled trial

BACKGROUND

Vitamin D receptors have been identified in the spinal cord, nerve roots, dorsal root ganglia and glial cells, and its genetic polymorphism association with the development of lumbar disc degeneration and herniation has been documented. Metabolic effects of active vitamin D metabolites in the nucleus pulposus and annulus fibrosus cells have been studied. Lumbar disc herniation is a process that involves immune and inflammatory cells and processes that are targets for immune regulatory actions of vitamin D as a neurosteroid hormone. In addition to vitamin D's immune modulatory properties, its receptors have been identified in skeletal muscles. It also affects sensory neurons to modulate pain. In this study, we aim to study the role of vitamin D3 in discogenic pain and related sensory deficits. Additionally, we will address how post-treatment 25-hydroxy vitamin D3 level influences pain and sensory deficits severity. The cut-off value for serum 25-hydroxy vitamin D3 that would be efficacious in improving pain and sensory deficits in lumbar disc herniation will also be studied.

METHODS/DESIGN

We will conduct a randomized, placebo-controlled, double-blind clinical trial. Our study population will include 380 cases with one-level and unilateral lumbar disc herniation with duration of discogenic pain less than 8 weeks. Individuals who do not have any contraindications, will be divided into three groups based on serum 25-hydroxy vitamin D3 level, and each group will be randomized to receive either a single-dose 300,000-IU intramuscular injection of vitamin D3 or placebo. All patients will be under conservative treatment. Pre-treatment and post-treatment assessments will be performed with the McGill Pain Questionnaire and a visual analogue scale. For the 15-day duration of this study, questionnaires will be filled out during telephone interviews every 3 days (a total of five times). The initial and final interviews will be scheduled at our clinic. After 15 days, serum 25-hydroxy vitamin D3 levels will be measured for those who have received vitamin D3 (190 individuals).

TRIAL REGISTRATION

Iranian Registry for Clinical Trials ID: IRCT2014050317534N1 (trial registration: 5 June 2014).

Association between serum 25-hydroxyvitamin D levels measured 24 hours after delivery and postpartum depression

OBJECTIVE

To assess the possible relationship between serum levels of 25[OH]D (25-hydroxyvitamin D) collected 24 hours after delivery and postpartum depression in a Chinese cohort sample.

DESIGN

Cohort study.

SETTING

One city hospital in Beijing, China.

POPULATION

Women delivering a full-term, singleton, live-born infant at one city hospital in Beijing between August 2013 and November 2013.

METHODS

Women were enrolled immediately postpartum. A blood sample was obtained 24-48 hours after childbirth to test serum levels of 25[OH]D. Participation consisted of a visit to an obstetric unit 3 months after delivery.

MAIN OUTCOME MEASURE

At 3 months' postpartum, women were screened for depression using the Edinburgh Postnatal Depression Scale (EPDS). The primary outcome measure was a prespecified EPDS score of ≥12.

RESULTS

During the study period, 323 women were admitted. In all, 248 agreed to enrol and 213 completed 3 months' follow-up (21 were lost to follow-up and 14 withdrew). Of the 213 women who were included, 26 (12.2%) were considered to meet criteria for postpartum depression. Serum 25[OH]D levels in women with no postpartum depression were significantly higher than those in women with postpartum depression (P < 0.0001). Based on the receiver operating characteristic curve, the optimal cutoff value for serum 25[OH]D level as an indicator for screening for postpartum depression was estimated to be 10.2 ng/ml, with an area under the curve of 0.801 (95%CI 0.704-0.896). In multivariate analysis, there was an increased risk of postpartum depression associated with 25[OH]D levels ≤10.2 ng/ml (OR 7.17, 95%CI 3.81-12.94; P < 0.0001) after adjusting for possible confounders.

CONCLUSION

Our study demonstrated that lower serum 25[OH]D levels were associated with postpartum depression. This association was independent of other possible variables.

Vitamin D: a critical and essential micronutrient for human health

Vitamin D is a micronutrient that is needed for optimal health throughout the whole life. Vitamin D₃ (cholecalciferol) can be either synthesized in the human skin upon exposure to the UV light of the sun, or it is obtained from the diet. If the photoconversion in the skin due to reduced sun exposure (e.g., in wintertime) is insufficient, intake of adequate vitamin D from the diet is essential to health. Severe vitamin D deficiency can lead to a multitude of avoidable illnesses; among them are well-known bone diseases like osteoporosis, a number of autoimmune diseases, many different cancers, and some cardiovascular diseases like hypertension are being discussed. Vitamin D is found naturally in only very few foods. Foods containing vitamin D include some fatty fish, fish liver oils, and eggs from hens that have been fed vitamin D and some fortified foods in countries with respective regulations. Based on geographic location or food availability adequate vitamin D intake might not be sufficient on a global scale. The International Osteoporosis Foundation (IOF) has collected the 25-hydroxy-vitamin D plasma levels in populations of different countries using published data and developed a global vitamin D map. This map illustrates the parts of the world, where vitamin D did not reach adequate 25-hydroxyvitamin D plasma levels: 6.7% of the papers report 25-hydroxyvitamin D plasma levels below 25 nmol/L, which indicates vitamin D deficiency, 37.3% are below 50 nmol/Land only 11.9% found 25-hydroxyvitamin D plasma levels above 75 nmol/L target as suggested by vitamin D experts. The vitamin D map is adding further evidence to the vitamin D insufficiency pandemic debate, which is also an issue in the developed world. Besides malnutrition, a condition where the diet does not match to provide the adequate levels of nutrients including micronutrients for growth and maintenance, we obviously have a situation where enough nutrients were consumed, but lacked to reach sufficient vitamin D micronutrient levels. The latter situation is known as hidden hunger. The inadequate vitamin D status impacts on health care costs, which in turn could result in significant savings, if corrected. Since little is known about the effects on the molecular level that accompany the pandemic like epigenetic imprinting, the insufficiency-triggered gene regulations or the genetic background influence on the body to maintain metabolic resilience, future research will be needed. The nutrition community is highly interested in the molecular mechanism that underlies the vitamin D insufficiency caused effect. In recent years, novel large scale technologies have become available that allow the simultaneous acquisition of transcriptome, epigenome, proteome, or metabolome data in cells of organs. These important methods are now used for nutritional approaches summarized in emerging scientific fields of nutrigenomics, nutrigenetics, or nutriepigenetics. It is believed that with the help of these novel concepts further understanding can be generated to develop future sustainable nutrition solutions to safeguard nutrition security.

Vitamin D and subclinical cerebrovascular disease: the Atherosclerosis Risk in Communities brain magnetic resonance imaging study

IMPORTANCE

Vitamin D deficiency has been associated with hypertension, diabetes mellitus, and incident stroke. Little is known about the association between vitamin D and subclinical cerebrovascular disease.

OBJECTIVE

To examine the relationship of 25-hydroxyvitamin D (25[OH]D) levels with cerebrovascular abnormalities as assessed on brain magnetic resonance imaging (MRI) among participants of the Atherosclerosis Risk in Communities (ARIC) Brain MRI study.

DESIGN, SETTING, AND PARTICIPANTS

Participants were white and black adults aged 55 to 72 years with no history of clinical stroke who underwent a cerebral MRI at ARIC visit 3 (n = 1622) and a second cerebral MRI approximately 10 years later (n = 888).

EXPOSURES

The 25(OH)D level was measured by mass spectrometry at visit 3, with levels adjusted for calendar month and categorized using race-specific quartiles.

MAIN OUTCOMES AND MEASURES

The cross-sectional and prospective associations of 25(OH)D levels with white matter hyperintensities (WMHs) and MRI-defined infarcts were investigated using multivariable regression models.

RESULTS

The mean age of the participants was 62 years, 59.6% were women, and 48.6% were black. Lower 25(OH)D levels were not significantly associated with WMH score of severity, prevalent high-grade WMH score (≥3), or prevalent infarcts in cross-sectional, multivariable-adjusted models (all P > .05). Similarly, no significant prospective associations were found for lower 25(OH)D levels with change in WMH volume, incident high WMH score (≥3), or incident infarcts on the follow-up MRI, which occurred approximately 10 years later.

CONCLUSIONS AND RELEVANCE

A single measure of 25(OH)D was not cross-sectionally associated with WMH grade or prevalent subclinical infarcts and was not prospectively associated with WMH progression or subclinical brain infarcts seen on serial cerebral MRIs obtained approximately 10 years apart. These findings do not support optimizing vitamin D levels for brain health.

[Role of vitamin D in the physiopathology of neurodegenerative diseases]

The involvement of vitamin D in brain function has been discovered in the past 25 years by epidemiological and fundamental studies. Research on neurodegenerative diseases and their animal or cellular models unveiled converging lines of evidence indicating that hypovitaminosis D is not just an effect of the progression of neurodegenerative diseases, but truly an aggravating co-factor, sometimes very closely related to their physiopathology. Vitamin D is a steroid hormone capable of regulating the expression of hundreds of genes through both genetic and epigenetic mechanisms. This reflects the highly pleiotropic nature of its action in its conventional bone and phosphocalcic metabolism targets. Its role in the central nervous system and neurodegenerative diseases makes no exception to this rule. Here we focus on the identified role and mechanisms of vitamin D in multiple sclerosis, Alzheimer's disease and Parkinson's disease. The important prevalence of hypovitaminosis D under our latitudes in general and in at-risk groups in particular, its easy evaluation and correction, and the results of early clinical studies, suggest that vitamin D supplementation could usefully complement our therapeutic armory to fight these diseases.

Vitamin D status and Parkinson's disease: a systematic review and meta-analysis

To estimate the associations between vitamin D status and Parkinson's disease (PD). We searched electronic databases of the human literature in PubMed, EMBASE and the Cochrane Library up to February, 2014 using the following keywords: 'vitamin D' or '25(OH)D' and 'status' or 'deficiency' or 'insufficiency' and 'Parkinson's disease'. A systematic review and meta-analysis were conducted on observational studies that reported the association between blood vitamin D levels and PD. Seven studies met the inclusion criteria. 1,008 patients and 4,536 controls were included. Results of our meta-analysis show that PD patients had lower mean levels of 25-hydroxyvitamin D [25(OH)D] than healthy controls [weighted mean difference (MD), -16.9, 95 % confidence interval (CI)], -33.5 to -0.2). Patients with vitamin D insufficiency [25(OH)D level <75 nmol/l] had an increased risk of PD (OR 1.5, 95 % CI 1.1-2.0). Patients with vitamin D deficiency [25(OH)D level <50 nmol/l] experienced a twofold increased risk of PD (OR 2.2, 95 % CI 1.5-3.4). Low vitamin D levels are associated with an increased risk of PD.

Metabolic syndrome: an important risk factor for Parkinson's disease

Metabolic syndrome is becoming commoner due to a rise in obesity rates among adults. Generally speaking, a person with metabolic syndrome is twice as likely to develop cardiovascular disease and five times as likely to develop diabetes as someone without metabolic syndrome. Increasing oxidative stress in metabolic syndrome and Parkinson's disease is mentioned in the comprehensive articles; however, the system review about clear relation between metabolic syndrome and Parkinson's disease is deficient. In this review, we will focus on the analysis that the metabolic syndrome may be a risk factor for Parkinson's disease and the preventions that reduce the incident of Parkinson's disease by regulating the oxidative stress.

Effect of vitamin D therapy in addition to amitriptyline on migraine attacks in pediatric patients

The purpose of this study was to investigate the effect of supplementary vitamin D therapy in addition to amitriptyline on the frequency of migraine attacks in pediatric migraine patients. Fifty-three children 8-16 years of age and diagnosed with migraine following the International Headache Society 2005 definition, which includes childhood criteria, were enrolled. Patients were classified into four groups on the basis of their 25-hydroxyvitamin D [25(OH)D] levels. Group 1 had normal 25(OH)D levels and received amitriptyline therapy alone; group 2 had normal 25(OH)D levels and received vitamin D supplementation (400 IU/day) plus amitriptyline; group 3 had mildly deficient 25(OH)D levels and received amitriptyline plus vitamin D (800 IU/day); and group 4 had severely deficient 25(OH)D levels and was given amitriptyline plus vitamin D (5000 IU/day). All groups were monitored for 6 months, and the number of migraine attacks before and during treatment was determined. Calcium, phosphorus alkaline phosphatase, parathormone, and 25(OH)D levels were also determined before and during treatment. Results were compared between the groups. Data obtained from the groups were analyzed using one-way analysis of variance. The number of pretreatment attacks in groups 1 to 4 was 7±0.12, 6.8±0.2, 7.3±0.4, and 7.2±0.3 for 6 months, respectively (all P>0.05). The number of attacks during treatment was 3±0.25, 1.76±0.37 (P<0.05), 2.14±0.29 (P<0.05), and 1.15±0.15 (P<0.05), respectively. No statistically significant differences in calcium, phosphorus, alkaline phosphatase, or parathormone levels were observed (P>0.05). Vitamin D given in addition to anti-migraine treatment reduced the number of migraine attacks.

Cellular and molecular mechanisms of immunomodulation in the brain through environmental enrichment

Recent studies on environmental enrichment (EE) have shown cytokines, cellular immune components [e.g., T lymphocytes, natural killer (NK) cells], and glial cells in causal relationship to EE in bringing out changes to neurobiology and behavior. The purpose of this review is to evaluate these neuroimmune mechanisms associated with neurobiological and behavioral changes in response to different EE methods. We systematically reviewed common research databases. After applying all inclusion and exclusion criteria, 328 articles remained for this review. Physical exercise (PE), a form of EE, elicits anti-inflammatory and neuromodulatory effects through interaction with several immune pathways including interleukin (IL)-6 secretion from muscle fibers, reduced expression of Toll-like receptors on monocytes and macrophages, reduced secretion of adipokines, modulation of hippocampal T cells, priming of microglia, and upregulation of mitogen-activated protein kinase phosphatase-1 in central nervous system. In contrast, immunomodulatory roles of other enrichment methods are not studied extensively. Nonetheless, studies showing reduction in the expression of IL-1β and tumor necrosis factor-α in response to enrichment with novel objects and accessories suggest anti-inflammatory effects of novel environment. Likewise, social enrichment, though considered a necessity for healthy behavior, results in immunosuppression in socially defeated animals. This has been attributed to reduction in T lymphocytes, NK cells and IL-10 in subordinate animals. EE through sensory stimuli has been investigated to a lesser extent and the effect on immune factors has not been evaluated yet. Discovery of this multidimensional relationship between immune system, brain functioning, and EE has paved a way toward formulating environ-immuno therapies for treating psychiatric illnesses with minimal use of pharmacotherapy. While the immunomodulatory role of PE has been evaluated extensively, more research is required to investigate neuroimmune changes associated with other enrichment methods.

Plasma vitamin D levels and cognitive function in aging women: the nurses' health study

BACKGROUND

Vitamin D may play a role in preserving cognitive function. However, there is a paucity of prospective studies on the relationship between vitamin D and cognition with aging. The aim of this study was to examine the association between plasma levels of vitamin D and subsequent cognitive function.

METHODS

This is a prospective study including 1,185 women aged 60-70 years from the Nurses' Health Study, who had plasma 25-hydroxy-vitamin D levels measured in 1989-1990 and completed an initial Telephone Interview of Cognitive Status approximately 9 years later. Subsequently, three follow-up cognitive assessments were conducted at 1.5-2.0 years intervals. We used multivariable-adjusted linear regression to model initial cognitive function, and mixed linear regression to model change in cognitive function over time.

RESULTS

Lower vitamin D levels were associated with significantly worse cognitive function 9 years later. For example, the mean global composite score averaging all the cognitive tests was 0.20 lower (95% Confidence Interval (CI):-0.33,-0.08; p-trend=0.009) in women in the lowest quintile (median=14.1 ng/mL) compared with women in the highest quintile of vitamin D (median=38.4 ng/mL). The observed differences were equivalent to the effect estimates we found for women who were approximately 4-6 years apart in age. However, vitamin D levels were not significantly associated with subsequent cognitive decline during 6 years of follow-up.

CONCLUSIONS

Higher levels of plasma vitamin D in women aged 60-70 years were associated with better cognitive function about a decade later but were not associated with cognitive decline during 6 years of follow-up.

Relationship between 25-hydroxyvitamin D and cognitive function in older adults: the Health, Aging and Body Composition Study

OBJECTIVES

To examine the relationship between 25-hydroxyvitamin D (25(OH)D) levels and cognitive performance over time in older adults in the Health, Aging and Body Composition (Health ABC) Study.

DESIGN

Prospective cohort study.

SETTING

Community-dwelling participants in Pittsburgh, Pennsylvania, and Memphis, Tennessee.

PARTICIPANTS

Well-functioning adults aged 70 to 79 at baseline with serum 25(OH)D measured at the 12-month follow-up visit and cognitive function measured at baseline and 4-year follow-up visit (N = 2,777).

MEASUREMENTS

Vitamin D status was categorized as 25(OH)D levels of less than 20.0 ng/mL, 20.0 to 29.9 ng/mL, or 30.0 ng/mL or greater. Cognition was measured using the modified Mini-Mental State Examination (3MS) and Digit Symbol Substitution Test (DSST). Linear regression models adjusting for multiple covariates, including age, education, sex, race, site, season, physical activity, and comorbidities, were used in the analysis.

RESULTS

Sixty-eight percent of participants had 25(OH)D levels of less than 30.0 ng/mL. Lower 25(OH)D levels were associated with lower baseline cognitive scores on the 3MS (adjusted mean 89.9, 95% confidence interval (CI) = 89.4-90.4 for <20.0 ng/mL; adjusted mean 90.8, 95% CI = 90.4-91.3 for 20.0-29.9 ng/mL; adjusted mean 90.6, 95% CI = 90.2-91.1 for ≥ 30.0 ng/mL; P trend = .02) and the DSST (adjusted mean 35.2, 95% CI = 34.5-36.0 for <20.0 ng/mL; adjusted mean 35.9, 95% CI = 35.2-36.6 for 20.0-29.9 ng/mL; adjusted mean 37.0, 95% CI = 36.3-37.8 for ≥ 30.0 ng/mL; P trend = .01). Participants with low 25(OH)D levels had greater declines in 3MS scores over 4 years than those with higher levels (least square mean change -1.0, 95% CI = -1.5 to -0.6 for <20.0 ng/mL; least square mean change -0.8, 95% CI = -1.2 to -0.3 for 20.0-29.9 ng/mL; least square mean change -0.2, 95% CI = -0.7 to 0.2 for ≥30.0 ng/mL; P = .05). There was no significant difference in DSST decline according to 25(OH)D level.

CONCLUSION

Low 25(OH)D levels were associated with worse global cognitive function and greater decline over time according to the 3MS. Intervention trials are needed to determine whether vitamin D supplementation can reduce cognitive decline.

Decrease in age-related tau hyperphosphorylation and cognitive improvement following vitamin D supplementation are associated with modulation of brain energy metabolism and redox state

In the present study we examined whether vitamin D supplementation can reduce age-related tau hyperphosphorylation and cognitive impairment by enhancing brain energy homeostasis and protein phosphatase 2A (PP2A) activity, and modulating the redox state. Male F344 rats aged 20 months (aged) and 6 months (young) were randomly assigned to either vitamin D supplementation or no supplementation (control). Rats were housed in pairs and the supplementation group (n=10 young and n=10 aged) received subcutaneous injections of vitamin D (1, α25-dihydroxyvitamin D3) for 21 days. Control animals (n=10 young and n=10 aged) received equal volume of normal saline and behavioral testing in the water maze started on day 14 after the initiation of vitamin D supplementation. Tau phosphorylation, markers of brain energy metabolism (ADP/ATP ratio and adenosine monophosphate-activated protein kinase) and redox state (levels of reactive oxygen species, activity of superoxide dismutase, and glutathione levels) as well as PP2A activity were measured in hippocampal tissues. Our results extended previous findings that: (1) tau phosphorylation significantly increased during aging; (2) markers of brain energy metabolism and redox state are significantly decreased in aging; and (3) aged rats demonstrated significant learning and memory impairment. More importantly, we found that age-related changes in brain energy metabolism, redox state, and cognitive function were attenuated by vitamin D supplementation. No significant differences were seen in tau hyperphosphorylation, markers of energy metabolism and redox state in the young animal groups. Our data suggest that vitamin D ameliorated the age-related tau hyperphosphorylation and cognitive decline by enhancing brain energy metabolism, redox state, and PP2A activity making it a potentially useful therapeutic option to alleviate the effects of aging.

Changes in the expression of the vitamin D receptor and LVSCC‑A1C in the rat hippocampus submitted to single prolonged stress

Vitamin D signaling not only controls calcium (Ca2+) and phosphorus uptake and transport, but also correlates with neurocognitive decline and neurodegenerative diseases. Almost all actions of Vitamin D are mediated by the transcription factor, vitamin D receptor (VDR), which has been widely identified in the central nervous system. Although previous studies have substantially advanced the understanding of the action of VDR in the brain, much remains unknown concerning how VDR relates to stress. Multiple lines of evidence indicate that the downregulation of L-type voltage-sensitive Ca2+-channels α-1C (LVSCC-A1C) by vitamin D in hippocampal neurons is able to reduce the influx and excitotoxic effects of Ca2+ to neurons. Along these lines, the purpose of the present study was to analyze the relative expression of VDR in the hippocampus of rats exposed to single prolonged stress (SPS) as a putative animal model for human post-traumatic stress disorder (PTSD). Furthermore, changes in the levels of expression of LVSCC-A1C and Ca2+ (neurotransmitter content) were examined during the onset periods of PTSD. The results revealed an increase in the expression of VDR at 1, 3 and 7 days post-stress compared with the control group. The intracellular free Ca2+ levels in the hippocampus increased 1 day after SPS exposure, and then decreased gradually to the normal level at 14 days, consistent with the expression pattern of LVSCC-A1C. These results indicated that VDR may be involved in the pathogenesis of SPS rats, thereby providing an alternative preparation to search for optimal therapeutic strategies for PTSD.

Hypovitaminosis D in Delirium: a Retrospective Cross-sectional Study

Background

As vitamin D may have a neuroprotective effect, the authors studied the association of biomarkers of vitamin D status and delirium to see if low vitamin D status was common in delirium cases.

Methods

Biochemical measures of vitamin D (25-hydroxyvitamin D [25-OHD]) and calcium metabolism were used in this retrospective cross-sectional analysis of adult in-patients with delirium, admitted at three Canadian academic hospitals from January 2011 to July 2012. Primary outcome was to determine estimates of the prevalence of hypovitaminosis D in this group in whom vitamin D was checked.

Results

Seventy-one (5.8%) out of 1,232 delirium inpatients had their vitamin D measured. Thirty-nine (55%) showed vitamin D insufficiency (25-OHD of 25-75 nmol/L) and 8 (11%) showed vitamin D deficiency (25-OHD < 25 nmol/L). Mean serum 25-OHD levels were lower in males (57.1±7.7 nmol/L) than in females (78.2±6.1 nmol/L), p = .01, even when controlled for age and season. Men were younger than the women (74.4±2.3 vs. 82.4±1.7, p = .005). Mean age was 78.7±1.5 years, and 33 (47%) were male.

Conclusions

Although vitamin D is rarely checked during delirium workup and/or management, high rates of hypovitaminosis D were found to be common in the delirium in-patients in whom it was checked. Larger studies would be needed to estimate the prevalence of hypovitaminosis D in delirium and whether hypovitaminosis D plays a role in the pathogenesis of delirium.

Prevalence of vitamin D deficiency and association with functional status in newly admitted male veteran nursing home residents

OBJECTIVES

To provide the first report on prevalence of vitamin D deficiency in newly admitted nursing home (NH) residents and associations with functional disabilities and chronic diseases.

DESIGN

Retrospective chart review.

SETTING

Nursing home (NH).

PARTICIPANTS

Male veterans newly admitted to a NH for rehabilitation, skilled-nursing care, intermediate care, or respite care between January 2011 and June 2012.

MEASUREMENTS

Total serum 25-hydroxyvitamin D (25(OH)D) levels were measured on admission. Vitamin D supplement users and those without 25(OH)D measurement within 7 days of admission were excluded, leaving an analytical sample of 104 residents. Vitamin D deficiency was defined as 25(OH)D less than 20 ng/mL. Data were collected on age, ethnicity, season, body mass index (BMI), functional disability in activities of daily living (ADLs) (mobility, bathing, dressing, toileting, continence, and feeding), and prevalent chronic diseases.

RESULTS

Prevalence of vitamin D deficiency was 49.0%. In multivariate logistic regression models adjusted for age, ethnicity, and BMI, vitamin D deficiency was significantly associated with number of ADL disabilities (odds ratio (OR) = 1.4 for each 1-point increase in ADL disability score, P = .03) and prevalent diabetes mellitus (OR = 3.0, P = .03). In regression models using each ADL disability as a separate variable, only disability in feeding (OR = 4.7, P = .05) and diabetes mellitus (OR = 2.9, P = .04) remained significant.

CONCLUSION

Almost half the individuals entering the NH and not taking vitamin D supplements had vitamin D deficiency. Greater number of ADL disabilities, disability in feeding, and prevalent diabetes mellitus were independently associated with vitamin D deficiency.

The association between vitamin D and cognition: a systematic review

Vitamin D insufficiency and deficiency are a major health care problem. The association between vitamin D levels and cognitive function is still under debate. We conducted a systematic review to assess the association between levels of vitamin D and cognition. Therefore, the databases of Embase and Pubmed were searched through June 2012 for observational studies relating vitamin D levels to cognition. Our initial search yielded 2182 articles. After applying exclusion criteria, there were 28 studies eligible for inclusion: 25 cross-sectional and 6 prospective studies (3 studies show cross-sectional as well as prospective data). The main finding of the 25 cross-sectional studies was a statistically significant worse outcome on one or more cognitive function tests or a higher frequency of dementia with lower vitamin D levels or intake in 18 out of 25 (72%) studies, whereas 7 (28%) studies failed to show an association. Four out of 6 (66.7%) prospective studies showed a higher risk of cognitive decline after a follow-up period of 4-7 years in participants with lower vitamin D levels at baseline. In conclusion, this review supports the hypothesis that hypovitaminosis D is associated with worse outcome on one or more cognitive function tests or a higher frequency of dementia in cross-sectional as well as prospective studies. Further studies should focus on the role of vitamin D supplementation in the prevention of cognitive decline in participants with low vitamin D levels.

Progesterone and vitamin D: Improvement after traumatic brain injury in middle-aged rats

Progesterone (PROG) and vitamin D hormone (VDH) have both shown promise in treating traumatic brain injury (TBI). Both modulate apoptosis, inflammation, oxidative stress, and excitotoxicity. We investigated whether 21 days of VDH deficiency would alter cognitive behavior after TBI and whether combined PROG and VDH would improve behavioral and morphological outcomes more than either hormone alone in VDH-deficient middle-aged rats given bilateral contusions of the medial frontal cortex. PROG (16 mg/kg) and VDH (5 μg/kg) were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG were injected subcutaneously over 7 days post-injury. VDH deficiency itself did not significantly reduce baseline behavioral functions or aggravate impaired cognitive outcomes. Combination therapy showed moderate improvement in preserving spatial and reference memory but was not significantly better than PROG monotherapy. However, combination therapy significantly reduced neuronal loss and the proliferation of reactive astrocytes, and showed better efficacy compared to VDH or PROG alone in preventing MAP-2 degradation. VDH+PROG combination therapy may attenuate some of the potential long-term, subtle, pathophysiological consequences of brain injury in older subjects.

Dementia and hip fractures: development of a pathogenic framework for understanding and studying risk

Dementia and hip fractures are 2 conditions that are seen primarily in older adults, and both are associated with substantial morbidity and mortality. An individual with dementia is up to 3 times more likely than a cognitively intact older adult to sustain a hip fracture. This may occur via several mechanisms, including (1) risk factors that are common to both outcomes; (2) the presence of dementia increasing hip fracture incidence via intermediate risk factors, such as falls, osteoporosis, and vitamin D; and (3) treatment of dementia causing side effects that increase hip fracture risk. We describe a model that applies these 3 mechanisms to explain the relationship between dementia and hip fractures. Comprehensive understanding of these pathways and their relative influence on the outcome of hip fracture will guide the development of effective interventions and potentially improve prevention efforts.

Cholecalciferol attenuates perseverative behavior associated with developmental alcohol exposure in rats in a dose-dependent manner

Alcohol is a known teratogen that is estimated to affect 2-5% of the births in the U.S. Prenatal alcohol exposure can produce physical features such as facial dysmorphology, physiological alterations such as cell loss in the central nervous system (CNS), and behavioral changes that include hyperactivity, cognitive deficits, and motor dysfunction. The range of effects associated with prenatal alcohol exposure is referred to as fetal alcohol spectrum disorders (FASD). Despite preventative measures, some women continue to drink while pregnant. Therefore, identifying interventions that reduce the severity of FASD is critical. This study investigated one such potential intervention, vitamin D3, a nutrient that exerts neuroprotective properties. The present study determined whether cholecalciferol, a common vitamin D3 nutritional supplement, could serve as a means of mitigating alcohol-related learning deficits. Using a rat model of FASD, cholecalciferol was given before, during, and after 3rd trimester equivalent alcohol exposure. Three weeks after cholecalciferol treatment, subjects were tested on a serial spatial discrimination reversal learning task. Animals exposed to ethanol committed significantly more errors compared to controls. Cholecalciferol treatment reduced perseverative behavior that is associated with developmental alcohol exposure in a dose-dependent manner. These data have important implications for the treatment of FASD and suggest that cholecalciferol may reduce some aspects of FASD. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Vitamin D deficiency impairs spatial learning in adult rats

BACKGROUND

Through its membrane and intracellular receptors, vitamin D regulates many vital functions in the body including its well known actions on musculoskeletal system. Growing body of evidences demonstrate that vitamin D undergoes some of behavioral aspects of neurocognition. The present study was designed to evaluate the effect of food regimens without vitamin D or with a supplement of 1,25(OH)2D3 on spatial performance of adult rats.

METHODS

The animals were trained in the Morris water maze to find a hidden platform. The time spent and the distance traveled to find the platform, speed of navigation and the percentage of unsuccessful trials were considered for assessment of the task learning.

RESULTS

Our findings indicated that the vitamin D-deprived rats had a significant lower performance compared to both the controls and the animals receiving 1,25(OH)2D3 supplementation. Concerning the unsuccessful trials, lack of vitamin D resulted in the highest failures in the maze navigation. The regimen with additional 1,25(OH)2D3 did not considerably influence learning of the maze task.

CONCLUSION

We concluded that while vitamin D deficiency deteriorates the spatial task learning, the 1,25(OH)2D3 supplementation did not effectively underlie the maze performance.

Vitamin D: do we get enough? A discussion between vitamin D experts in order to make a step towards the harmonisation of dietary reference intakes for vitamin D across Europe

On September 29, 2011, acknowledged experts in the field of vitamin D, mainly European, were brought together in order to discuss the recent scientific advances in relation to vitamin D: the current requirements and associations with various health outcomes. In this article, the discussions resulting from the meeting are summarized.

INTRODUCTION

Several groups at risk for developing vitamin D insufficiency have been identified. Accordingly, reviews indicate that a significant percentage of the population worldwide have serum 25-hydroxyvitamin D levels below 50 nmol/l. In addition to the role of vitamin D in bone health, recent studies suggest that it may play a pivotal role in other systems, e.g., the cardiovascular system, pancreas, muscle, immune system and brain. Most evidence, however, is obtained from observational studies and yet inconclusive.

METHODS

To exchange and broaden knowledge on the requirements for vitamin D and its effect on various health outcomes, a workshop entitled "Vitamin D Expert Meeting: Do we get enough?", was organized.

RESULTS

Despite low vitamin D levels worldwide, consensus on the definition of deficiency is not yet reached. In order to define cut-off points for vitamin D whilst taking into account extraskeletal health effects, randomized controlled trials in these fields are warranted. The experts do emphasize that there is evidence to suggest an important role for vitamin D in the maintenance of optimal bone health at all ages and that vitamin D supplementation, in most studies co-administered with calcium, reduces fracture risk in the senior population.

CONCLUSION

To reach a serum 25-hydroxyvitamin D level of 50 nmol/l older adults aged ≥65 years are therefore recommended to meet a mean daily vitamin D intake of 20 μg (800 IU), which is best achieved with a supplement.

The new metabolic treatments for sarcopenia

In terms of managing sarcopenia, many studies have shown that physical activity (in particular resistance exercise) and specific nutrition interventions such as protein and amino acids supplementation can improve muscle mass and strength in older adults. Moreover, several drugs have been suggested to have an impact on muscle outcomes, with various levels of scientific evidence. In the present paper we have reviewed the evidence regarding the effect of some new metabolic agents (vitamin D, leucine, β-hydroxy β-methylbutyrate, citrulline malate, ornithine, isoflavones) on sarcopenia and muscular outcomes in older adults. For each metabolic agent, we have also discussed the biological plausibility of the described effect.

Vitamin D, arterial hypertension & cerebrovascular disease

Vitamin D is mainly derived from endogenous ultraviolet-B induced vitamin D synthesis in the skin, and the current high prevalence of vitamin D deficiency can, therefore, largely be attributed to lifestyle related low sunlight exposure. Regulation of bone and mineral metabolism is a classic vitamin D effect, but the identification of the vitamin D receptor (VDR) in almost all human cells suggests a role for vitamin D also in extra-skeletal diseases. Experimental studies demonstrated several antihypertensive and vascular protective effects of vitamin D, such as suppression of the renin angiotensin aldosterone system, beneficial modulation of classic cardiovascular risk factors, and anti-atherosclerotic properties including improvements of endothelial function. Additional neuroprotective actions of vitamin D have also been reported. In line with this, epidemiological studies have largely shown that vitamin D deficiency is an independent risk factor for arterial hypertension and strokes. Data from randomized controlled trials (RCTs) are, however, limited and less promising, with currently no confirmation that vitamin D reduces stroke incidence. Whereas some RCTs suggest that vitamin D supplementation might modestly reduce blood pressure, this has not been consistently observed in all studies. It is, therefore, premature to recommend vitamin D supplementation for the prevention and treatment of arterial hypertension and stroke. Nevertheless, the fact that patients with arterial hypertension and cerebrovascular disease are at a relatively high risk of vitamin D deficiency, and therewith associated musculoskeletal diseases can serve as a rationale for the evaluation, prevention and treatment of vitamin D deficiency in these patients.

Therapeutic effects of vitamin D as adjunctive therapy to fluoxetine in patients with major depressive disorder

OBJECTIVE

To compare the therapeutic effects of vitamin D3 plus fluoxetine and fluoxetine alone in patients with major depressive disorder.

METHODS

In the present double-blind, randomized, placebo-controlled trial, 42 patients with a diagnosis of major depressive disorder based on DSM-IV criteria were randomly assigned into two groups to receive daily either 1500 IU vitamin D3 plus 20 mg fluoxetine or fluoxetine alone for 8 weeks. Depression severity was assessed at 2-week intervals using the 24-item Hamilton Depression Rating Scale (HDRS) as a primary outcome measure and the 21-item Beck Depression Inventory (BDI) as a secondary outcome measure. Serum 25(OH) vitamin D was measured at baseline and after intervention.

RESULTS

Forty patients completed the trial. A two-way repeated-measures analysis of variance showed that depression severity based on HDRS and BDI decreased significantly after intervention, with a significant difference between the two groups. The vitamin D + fluoxetine combination was significantly better than fluoxetine alone from the fourth week of treatment.

CONCLUSIONS

In the present 8-week trial, the vitamin D + fluoxetine combination was superior to fluoxetine alone in controlling depressive symptoms.

Is high dose vitamin D harmful?

With the potential to minimize the risk of many chronic diseases and the apparent biochemical safety of ingesting doses of oral vitamin D several-fold higher than the current recommended intakes, recent research has focussed on supplementing individuals with intermittent, high-dose vitamin D. However, two recent randomized controlled trials (RCTs) both using annual high-dose vitamin D reported an increase, rather than a decrease, in the primary outcome of fractures. This review summarises the results from studies that have used intermittent, high doses of vitamin D, with particular attention to those finding evidence of adverse effects. Results from observational, population-based studies with evidence of a U- or J-shaped curve are also presented as these findings suggest an increased risk in those with the highest serum 25D levels. Speculative mechanisms are discussed and biochemical results from studies using high-dose vitamin D are also presented. Emerging evidence from both observational studies and RCTs suggests there should be a degree of caution about recommending high serum 25D concentrations for the entire population. Furthermore, benefit of the higher doses commonly used in clinical practice on falls risk reduction needs to be demonstrated. The safety of loading doses of vitamin D should be demonstrated before these regimens become recommended as routine clinical practice. The current dilemma of defining vitamin D insufficiency and identifying safe and efficacious repletion regimens needs to be resolved.

High vitamin D status in younger individuals is associated with low circulating thyrotropin

BACKGROUND

Vitamin D is an immunomodulator and may affect autoimmune thyroid diseases. Vitamin D has also been shown to influence thyrocytes directly by attenuating thyrotropin (TSH)-stimulated iodide uptake and cell growth. However, it is unclear how vitamin D status is related to TSH at the population level. The goal of the present study was to investigate the relationship between vitamin D status and TSH levels according to thyroid autoantibodies in a population-based health survey in Thailand.

METHODS

A total of 2582 adults, aged 15-98 years, were randomly selected according to the geographical region from the Thailand 4th National Health Examination Survey sample. By study design, the sexes were equally represented. Serum levels of 25-hydroxyvitamin D [25(OH)D], TSH, the thyroid peroxidase antibody (TPOAb), and the thyroglobulin antibody (TgAb) were measured in all subjects.

RESULTS

The mean age was 55.0±0.4 (SE) years. In subjects positive for serum TgAb, serum TSH levels were higher, whereas total serum 25(OH)D levels were lower. In addition, the prevalence of vitamin D insufficiency in TgAb-positive subjects was significantly higher than that observed in TPOAb- and TgAb-negative subjects, whether based on cutoff values of 20 or 30 ng/mL: 8.3% vs. 5.6%, p<0.05; or 47.6% vs. 42.0%, p<0.05, respectively. However, vitamin D status was not associated with positive TPOAb and/or TgAb after controlling for sex and age. To explore the probable interaction between vitamin D status and age on serum TSH, analyses were performed according to age tertiles; it was found that higher 25(OH)D levels were independently associated with lower TSH, but only in subjects in the lowest age tertile.

CONCLUSIONS

This population-based study showed that high vitamin D status in younger individuals is associated with low circulating TSH.

The transcriptomic response of mixed neuron-glial cell cultures to 1,25-dihydroxyvitamin d3 includes genes limiting the progression of neurodegenerative diseases

Seasonal or chronic vitamin D deficiency and/or insufficiency is highly prevalent in the human population. Receptors for 1,25-dihydroxyvitamin D3, the hormonal metabolite of vitamin D, are found throughout the brain. To provide further information on the role of this hormone on brain function, we analyzed the transcriptomic profiles of mixed neuron-glial cell cultures in response to 1,25-dihydroxyvitamin D3. 1,25-dihydroxyvitamin D3 treatment increases the mRNA levels of 27 genes by at least 1.9 fold. Among them, 17 genes were related to neurodegenerative and psychiatric diseases, or brain morphogenesis. Notably, 10 of these genes encode proteins potentially limiting the progression of Alzheimer's disease. These data provide support for a role of 1,25-dihydroxyvitamin D3 in brain disease prevention. The possible consequences of circannual or chronic vitamin D insufficiencies on a tissue with a low regenerative potential such as the brain should be considered.

Vitamin D inquiry in hippocampal neurons: consequences of vitamin D-VDR pathway disruption on calcium channel and the vitamin D requirement

Vitamin D receptor (VDR) and the enzymes involved in bioactivation of vitamin D, shown to be expressed in the central nervous system, particularly in areas affected by neurodegenerative disorders, especially in hippocampus. We showed that amyloid beta (Aβ) pathology includes VDR protein depletion and vitamin D-VDR pathway disruption either induced by Aβ or by VDR siRNA have very similar effects on cortical neurons. The goal of this study is to show the presence of 25 hydroxy vitamin D3-24 hydroxylase (24OHase) which is essential for vitamin D catabolism in hippocampal and cortical neurons. Additional goal is to compare the expression pattern of VDR and 24OHase both in hippocampal and in cortical neurons and to investigate the effects of VDR suppression in hippocampal neurons in order to see whether similar mechanisms work in hippocampus and cerebral cortex. Primary neuronal cultures were prepared from Sprague-dawley rat embryos. qRT-PCR was performed to determine VDR, 24OHase, and LVSCC-A1C mRNA expression levels. Cytotoxicity levels were determined by ELISA. Our findings illustrate that 24OHase mRNA was present both in hippocampal and in cortical neurons. VDR and 24OHase mRNA were higher in hippocampal neurons than the cortical ones. LVSCC-A1C mRNA levels increased in hippocampal neurons when VDR is down-regulated. Our results indicate that hippocampal neurons response to VDR suppression similar as cortical neurons, regarding calcium channel regulation. Higher gene expression of 24OHase and VDR might indicate "higher requirement of vitamin D" in hippocampus and potential consequences of vitamin D deficiency in cognitive decline, neurodegeneration, and Alzheimer's disease.

Vitamin D, cognition, and dementia: a systematic review and meta-analysis

OBJECTIVE

To examine the association between cognitive function and dementia with vitamin D concentration in adults.

METHODS

Five databases were searched for English-language studies up to August 2010, and included all study designs with a comparative group. Cognitive function or impairment was defined by tests of global or domain-specific cognitive performance and dementia was diagnosed according to recognized criteria. A vitamin D measurement was required. Two authors independently extracted data and assessed study quality using predefined criteria. The Q statistic and I² methods were used to test for heterogeneity. We conducted meta-analyses using random effects models for the weighted mean difference (WMD) and Hedge's g.

RESULTS

Thirty-seven studies were included; 8 contained data allowing mean Mini-Mental State Examination (MMSE) scores to be compared between participants with vitamin D <50 nmol/L to those with values ≥50 nmol/L. There was significant heterogeneity among the studies that compared the WMD for MMSE but an overall positive effect for the higher vitamin D group (1.2, 95% confidence interval [CI] 0.5 to 1.9; I² = 0.65; p = 0.002). The small positive effect persisted despite several sensitivity analyses. Six studies presented data comparing Alzheimer disease (AD) to controls but 2 utilized a method withdrawn from commercial use. For the remaining 4 studies the AD group had a lower vitamin D concentration compared to the control group (WMD = -6.2 nmol/L, 95% CI -10.6 to -1.8) with no heterogeneity (I² < 0.01; p = 0.53).

CONCLUSION

These results suggest that lower vitamin D concentrations are associated with poorer cognitive function and a higher risk of AD. Further studies are required to determine the significance and potential public health benefit of this association.

Vitamin D, race, and experimental pain sensitivity in older adults with knee osteoarthritis

OBJECTIVE

Low circulating serum levels of 25-hydroxyvitamin D (referred to hereafter as vitamin D) have been correlated with many health conditions, including chronic pain. Recent clinical practice guidelines define vitamin D levels <20 ng/ml as deficient and levels of 21-29 ng/ml as insufficient. Vitamin D insufficiency, including the most severe levels of deficiency, is more prevalent in black Americans. Ethnic and race group differences have been reported in both clinical and experimental pain, with black Americans reporting increased pain. The purpose of this study was to examine whether variations in vitamin D levels contribute to race differences in knee osteoarthritis pain.

METHODS

The sample consisted of 94 participants (74% women), including 45 blacks and 49 whites with symptomatic knee osteoarthritis. Their average age was 55.8 years (range 45-71 years). Participants completed a questionnaire on knee osteoarthritis symptoms and underwent quantitative sensory testing, including measures of sensitivity to heat-induced and mechanically induced pain.

RESULTS

Blacks had significantly lower levels of vitamin D compared to whites, demonstrated greater clinical pain, and showed greater sensitivity to heat-induced and mechanically induced pain. Low levels of vitamin D predicted increased experimental pain sensitivity, but did not predict self-reported clinical pain. Group differences in vitamin D levels significantly predicted group differences in heat pain and pressure pain thresholds at the index knee and ipsilateral forearm.

CONCLUSION

These data demonstrate that race differences in experimental pain are mediated by differences in the vitamin D level. Vitamin D deficiency may be a risk factor for increased knee osteoarthritis pain in black Americans.

Vitamin D mitigates age-related cognitive decline through the modulation of pro-inflammatory state and decrease in amyloid burden

Background

Increasing evidence shows an association between the use of vitamin D and improvement in age-related cognitive decline. In this study, we investigated the possible mechanisms involved in the neuroprotective effects of vitamin D on age-related brain changes and cognitive function.

Methods

Male F344 rats aged 20 months (old) and 6 months (young) were used and randomly assigned to either vitamin D supplementation or no supplementation (control). A total of n = 39 rats were used in the study. Rats were individually housed and the supplementation group received a subcutaneous injection of vitamin D (1, α25-dihydroxyvitamin D3) 42 I.U./Kg for 21 days. Control animals received equal volume of normal saline. Behavioral testing in water maze and spontaneous object recognition tasks started on day 14. Levels of interleukin (IL)-1β and IL-10 were quantified to assess inflammatory state. Also, beta amyloid (Aβ) clearance and Aβ load were measured.

Results

Our results show that: (1) aged rats demonstrated significant learning and memory impairment overall compared to younger animals. However, the age-related decline in learning and memory was ameliorated by the supplementation of vitamin D. No vitamin D effect on learning and memory was seen in the young animals; 2) the pro-inflammatory cytokine IL-1β is significantly increased while the anti-inflammatory cytokine IL-10 is significantly decreased in the aged rats compared to the young animals; but this age-related change in inflammatory state was mitigated by vitamin D supplementation. No effects of vitamin D were seen on the IL-1β and IL-10 expression in the young rats; (3) vitamin D increased Aβ clearance and decreased amyloid burden in the aged rats while no significant difference was seen between the young animal groups.

Conclusions

Our data suggest that vitamin D supplementation modulated age-related increase in pro-inflammatory state and amyloid burden. It is possible that these effects of vitamin D mediated the decrease memory impairment seen in the aged rats making it a useful therapeutic option to alleviate the effects of aging on cognitive function.

Nervous system autoantibodies and vitamin D receptor gene polymorphisms in hemodialysis patients

Cognitive deficits are prevalent in hemodialysis (HD) patients. Vitamin D deficiency and vitamin D receptor (VDR) gene single nucleotide polymorphism (SNPs) have been linked to both neurodegeneration (ND) and neuroprotection, respectively. Autoantibodies (Ab) to myelin basic protein (MBP), glial fibrillary acidic protein (GFAP), and neurofilament (NF) triplet proteins arise secondary to nervous system (NS) damage providing a means to assess neurological injury. Characterization of Ab biomarkers of NS damage in HD patients, their association with VDR SNPs, and nutritional vitamin D (NVD) therapy was performed. VDR genotypes, cytokines, and Ab biomarkers to NS proteins in HD subjects receiving ergocalciferol (n = 40) were compared with nonusers (n = 71). Interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and immunoglobulin G (IgG) titers against NFs, GFAP, and MBP were measured by immunoassay. Subjects were genotyped for VDR SNPs BsmI (rs1544410) and FokI (rs2228570). Subjects (age 63.3 ± 16.1 years, 66% male) who were C allele carriers of BsmI had higher values of NF-68 antibody titers (p = 0.027). Ergocalciferol users (n = 40) compared with nonusers (n = 71) had lower Ab titers to NS proteins; however, only anti-NF-160 and anti-MBP titers were significantly (p < 0.05) higher. IgG against NS proteins in HD patients suggests neuronal and glial insult and a relationship with VDR alleles. NVD may provide some neuroprotection, indicated by anti-NF-160 and anti-MBP, which was markedly lowered in ergocalciferol patients. This preliminary study suggests that Ab detection may be useful in monitoring ND and the potential of NVD for neuroprotection in HD patients.

A 21st century evaluation of the safety of oral vitamin D

The safety of daily consumption of vitamin D was examined. A detailed literature search was conducted using the search term vitamin D; primary and secondary sources of original data and meta-analyses and systematic reviews were evaluated and summarized. A large body of scientific evidence demonstrates that long-term daily intakes of 600 to 800 IU of vitamin D are insufficient to achieve and sustain vitamin D adequacy (serum 25-hydroxyergocalciferol + 25-hydroxycholecalciferol concentration >75 nmol/L). Maximization of the physiologic benefits of vitamin D to the musculoskeletal system, the central and peripheral nervous systems, the heart and central and peripheral cardiovascular systems, the respiratory system, the skin, the eyes, dentition, glucoregulation, immunoregulation, and disease resistance requires daily vitamin D intakes of at least 1500 IU. Because long-term daily intakes up to and including 10 000 IU of vitamin D do not produce signs or symptoms of vitamin D toxicity and are safe for the entire general population of otherwise healthy adults, even daily vitamin D intakes of 2000 IU allow for the often-cited and excessively conservative five-fold safety factor. In conclusion, long-term daily intakes of up to and including 10 000 IU of vitamin D maximize physiologic benefits and are safe.

Could nutrition prevent the onset of dementia? Current evidence from epidemiological and intervention studies

SUMMARY Cardiovascular and metabolic risk factors for cognitive decline and dementia, such as hypertension, diabetes, metabolic syndrome and obesity, may be modified by diet. Moreover, several classes of nutrients, including long-chain ω-3 polyunsaturated fatty acids, antioxidants (i.e., vitamins C and E, carotenoids and polyphenols) and vitamins B and D can lower inflammation and oxidative stress associated with neurodegeneration, in addition to specific neuroprotective effects. However, most randomized clinical trials of supplementation with high doses of single nutrients have been disappointing. Healthy dietary patterns, such as the Mediterranean diet, combine several classes of nutrients that could work in synergy to slow down cognitive decline. Healthy dietary habits at midlife could contribute to decrease the risk of late-life dementia.

Association of serum 25-hydroxyvitamin D₃ and D₂ with academic performance in childhood: findings from a prospective birth cohort

Background

Higher total serum 25-hydroxyvitamin D (25(OH)D) concentrations have been associated with better cognitive function mainly in cross-sectional studies in adults. It is unknown if the associations of different forms of 25(OH)D (25(OH)D₃ and 25(OH)D₂) are similar.

Methods

Prospective cohort study (n=3171) with serum 25(OH)D₃ and 25(OH)D₂ concentrations measured at mean age of 9.8 years and academic performance at age 13–14 years (total scores in English, mathematics and science) and 15–16 years (performance in General Certificates of Education examinations).

Results

Serum 25(OH)D₃ concentrations were not associated with any educational outcomes. Higher 25(OH)D₂ concentrations were associated with worse performance in English at age 13–14 years (adjusted SD change per doubling in 25(OH)D₂ (95% CI) −0.05 (−0.08 to −0.01)) and with worse academic performance at age 15–16 years (adjusted OR for obtaining ≥5 A*–C grades (95% CI) 0.91 (0.82 to 1.00)).

Conclusion

The null findings with 25(OH)D₃ are in line with two previous cross-sectional studies in children. It is possible that the positive association of 25(OH)D with cognitive function seen in adults does not emerge until later in life or that the results from previous cross-sectional adult studies are due to reverse causality. The unexpected inverse association of 25(OH)D₂ with academic performance requires replication in further studies. Taken together, our findings do not support suggestions that children should have controlled exposure to sunlight, or vitamin D supplements, in order to increase academic performance.

25-Hydroxyvitamin D deficiency is associated with fatal stroke among whites but not blacks: The NHANES-III linked mortality files

OBJECTIVE

Deficient 25-hydroxyvitamin D (25[OH]D) levels are associated with cardiovascular disease (CVD) events and mortality. 25(OH)D deficiency and stroke are more prevalent in blacks. We examined whether low 25(OH)D contributes to the excess risk of fatal stroke in blacks compared with whites.

METHODS

The Third National Health and Nutrition Examination Survey, a probability sample of U.S. civilians, measured 25(OH)D levels and CVD risk factors from 1988 through 1994. Vital status through December 2006 was obtained by a linkage with the National Death Index. In white and black adults without CVD reported at baseline (n = 7981), Cox regression models were fit to estimate hazard ratios (HR) for fatal stroke by 25(OH)D status and race.

RESULTS

During a median of 14.1 y, there were 116 and 60 fatal strokes in whites and blacks, respectively. The risk of fatal stroke was greater in blacks compared with whites in models adjusted for socioeconomic status and CVD risk factors (HR 1.60, 95% confidence interval 1.01-2.53). Mean baseline 25(OH)D levels were significantly lower in blacks compared with whites (19.4 versus 30.8 ng/mL, respectively). In multivariable-adjusted models, deficient 25(OH)D levels lower than 15 ng/mL were associated with fatal stroke in whites (HR 2.13, 1.01-4.50) but not blacks (HR 0.93, 0.49-1.80).

CONCLUSIONS

Vitamin D deficiency was associated with an increased risk of stroke death in whites but not in blacks. Although blacks had a higher rate of fatal stroke compared with whites, the low 25(OH)D levels in blacks were unrelated to stroke incidence. Therefore 25(OH)D levels did not explain this excess risk.

Progesterone and low-dose vitamin D hormone treatment enhances sparing of memory following traumatic brain injury

Progesterone (PROG) has been shown to protect the brain from traumatic injury and is now in Phase III clinical trials. Our work shows that PROG's beneficial effects can be reduced in vitamin D hormone (VDH)-deficient subjects. VDH can modulate neuronal apoptosis, trophic factors, inflammation, oxidative stress, excitotoxicity, and myelin and axon repair. We investigated whether VDH combined with PROG could improve behavioral outcomes more than PROG alone in VDH-sufficient rats given bilateral contusions of the medial frontal cortex. PROG and different doses of VDH (1 μg/kg, VDH1; 2.5 μg/kg, VDH2; 5 μg/kg, VDH3) were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG were given subcutaneously over 8 days with tapering over the last 2 days. Neurobehavioral tests, necrotic cavity, neuronal death and activation of astrocytes were evaluated 21 days post-injury. We found that PROG and PROG + VDH preserve spatial memory processing. VDH1 + PROG improved performance in acquisition more effectively than PROG alone, indicating that the low VDH dose is optimal for combination therapy. There were no significant differences in necrotic cavity size among the groups. The density of positive staining for reactive astrocytes (glial fibrillary acidic protein (GFAP)) increased and the cell bodies and processes of GFAP-positive cells were enlarged in the PROG + VDH1 group. Our data indicate that the combination of PROG and VDH is more effective than PROG alone in preserving spatial and reference memory, and that PROG plus low-dose VDH can activateGFAP reactions up to 21 days after injury. This effect may be one of the mechanisms underlying PROG's neuroprotective effects in combination with VDH.

Association between serum 25(OH) vitamin D and the risk of cognitive decline in older women

BACKGROUND

Results of prospective studies examining the association between 25 hydroxyvitamin D (25[OH]D) levels and cognitive decline have been inconsistent. We tested the hypothesis that lower 25(OH)D levels are associated with a greater likelihood of cognitive impairment and risk of cognitive decline.

METHODS

The study is a cross-sectional and longitudinal analysis of a prospective cohort of 6,257 community-dwelling elderly women followed for 4 years. Global cognitive function was measured by the Modified Mini-Mental State Examination and executive function was measured by Trail Making Test Part B (Trails B). Cognitive impairment at baseline was defined as a score >1.5 SD below the sample mean; cognitive decline was defined as decline from baseline to follow-up >1 SD from mean change in score.

RESULTS

Women with very low vitamin D levels had an increased odds of global cognitive impairment at baseline: odds ratio (95% confidence interval), 1.60 (1.05-2.42) for women with 25(OH)D <10 ng/mL (25 nmol/L) compared with those with 25(OH)D levels ≥30 ng/mL (75 nmol/L). Compared with women with baseline 25(OH)D level ≥30 ng/mL (75 nmol/L), women with lower levels had an increased risk of global cognitive decline: odds ratio (95% confidence interval), 1.58(1.12-2.22) for women with levels <10 ng/mL (25 nmol/L), and 1.31 (1.04-1.64) for those with levels 10-19.9 ng/mL (25-49 nmol/L). Levels of 25(OH)D were not associated with executive cognitive function.

CONCLUSIONS

Low 25(OH)D levels among older women were associated with a higher odds of global cognitive impairment and a higher risk of global cognitive decline.

Prenatal exposure to mercury and infant neurodevelopment in a multicenter cohort in Spain: study of potential modifiers

Vulnerability of the central nervous system to mercury is increased during early development. This study aimed to evaluate whether cord blood total mercury levels may have a negative effect on both mental and psychomotor development in a maternal-birth cohort from moderate-high fish consumption areas. Study subjects were 1,683 child participants in the INMA (Environment and Childhood) Project from 4 areas of Spain between 2003 and 2010. Cord blood total mercury levels were analyzed by atomic absorption spectrometry. Infant neurodevelopment was assessed around age 14 months by the Bayley Scales of Infant Development. Sociodemographic, lifestyle, and dietary information was obtained by questionnaire during pregnancy. The geometric mean of total mercury levels was 8.4 μg/L (95% confidence interval (CI): 8.1, 8.7). In multivariate analysis, a doubling in total mercury levels did not show an association with mental (β = 0.1, 95% CI: -0.68, 0.88) or psychomotor (β = -0.05, 95% CI: -0.79, 0.68) developmental delay; however, stratified findings by sex suggest a negative association between prenatal exposure to total mercury and psychomotor development among female infants (β = -1.09, 95% CI: -2.21, 0.03), although follow-up is required to confirm these results.