Is vitamin D important for preserving cognition? A positive correlation of serum 25-hydroxyvitamin D concentration with cognitive function

Vitamin D as a marker of cognitive decline in elderly Indian population

Objectives:

Very few studies in India have addressed the role of vitamin D in cognitive function. The present study was conducted to assess the serum levels of 25-hydroxyvitamin D (25(OH)D) and its association with markers of cognitive impairment and homocysteine levels in the elderly Indian population.

Materials and Methods:

The study population consisted of patients with dementia (Group A, n = 32), mild cognitive impairment (MCI; Group B, n = 24), and elderly age-matched controls (Group C, n = 30). Measurement of serum levels of 25(OH)D and total homocysteine were done.

Results:

Significant decreased concentration of 25(OH)D and increased concentration of homocysteine was observed. Association of serum levels of vitamin D with markers of cognitive decline as well as serum homocysteine levels was observed in patients with dementia and MCI when compared to controls.

Conclusion:

Correlation of vitamin D with markers of cognitive decline and homocysteine opens a new door for early diagnosis of cognitive impairment.

Vitamin D cell signalling in health and disease

Vitamin D deficiency has been linked to many human diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), hypertension and cardiovascular disease. A Vitamin D phenotypic stability hypothesis, which is developed in this review, attempts to describe how this vital hormone acts to maintain healthy cellular functions. This role of Vitamin D as a guardian of phenotypic stability seems to depend on its ability to maintain the redox and Ca(2+) signalling systems. It is argued that its primary action is to maintain the expression of those signalling components responsible for stabilizing the low resting state of these two signalling pathways. This phenotypic stability role is facilitated through the ability of vitamin D to increase the expression of both Nrf2 and the anti-ageing protein Klotho, which are also major regulators of Ca(2+) and redox signalling. A decline in Vitamin D levels will lead to a decline in the stability of this regulatory signalling network and may account for why so many of the major diseases in man, which have been linked to vitamin D deficiency, are associated with a dysregulation in both ROS and Ca(2+) signalling.

A long-term fatty fish intervention improved executive function in inpatients with antisocial traits and a history of alcohol and drug abuse

The aim of the present study was to investigate the effects of fatty fish consumption on cognitive functioning in a group of inpatients characterized by antisocial behavior. Eighty-three male forensic inpatients participated in this study. Participants were randomly assigned into a Fish or a Control group (e.g., meat, chicken, pork). One decision-making task, the Iowa Gambling Task (IGT), and one planning task, the Tower of Hanoi (ToH), were administered before (pre-test) and at the end of the intervention period (post-test). For the IGT the Fish group showed improved performance from pre- to post- test. Moreover, the Fish group showed significantly better performance than the Control group on the IGT at post-test. The Fish group also demonstrated improved performance from pre- to post-test on the ToH; however, this was limited to participants with a history of substance abuse. Further, the improvement was only significant for tasks with high working memory load (5-7 move problems), and not for tasks with low working memory load (1-4 move problems). The Control group showed no improvement on any of the tasks regardless of alcohol or drug abuse history. The present study suggests that regular fatty fish consumption may improve executive functions in forensic inpatients with antisocial traits and a history of substance abuse. Thus, the current results may have important implications with regard to health care interventions.

Vitamin D status and surgical outcomes: a systematic review

The importance of vitamin D for musculoskeletal health has long been recognized, and awareness of significant extra-skeletal effects in health and disease is rapidly emerging. Although it has been possible for many decades to quantify serum markers of vitamin D deficiency, and to correct deficiency at low cost and with high safety, the influence of vitamin D status on post-surgical outcomes has only recently been identified as a research topic of interest. To the present, these data have not been the subject matter of formal review. Accordingly, we conducted a systematic review to assess the association between perioperative vitamin D status and outcomes after surgery. The databases of PubMed, Ovid MEDLINE, EMBASE, AMED, CINAHL (EBSCOHost), The Cochrane Databases of Systematic Review, and PROSPERO were searched through December, 2014 for studies relating to vitamin D and surgery. The initial search yielded 90 manuscripts. After applying exclusion criteria, 31 studies were eligible for inclusion. Fifteen studies employed prospective observational designs, 3 used prospective randomized protocols, and 13 report retrospective database interrogations. The main finding of the present review is that 26 of 31 studies (84%) report at least one statistically significant worse outcome in patients with low vitamin D status. Five of 31 studies (16%) found no association. In conclusion, this review supports the hypothesis that hypovitaminosis D is associated with adverse outcomes after diverse surgical procedures. Future studies should focus on additional surgeries and outcomes, and on the role of vitamin D supplementation in the improvement of patient safety in participants with low vitamin D status at the time of surgery.

[Anxiety/depressive disorders and vitamin D status]

OBJECTIVE

To search for the association between vitamin D status and anxiety and depression.

MATERIAL AND METHODS

Authors examined 310 residents of St. Petersburg (137 men and 173 women). Anxiety and depression were measured with the HADS.

RESULTS AND CONCLUSION

In people with vitamin D deficiency, anxiety and depression were noted in 32.5% and 11.0%, respectively. There were negative correlations between serum 25(OH)D level and anxiety (r= -0,11, p=0.03). Symptoms of depression were not correlated with vitamin D status (r= -0.08, p=0.09) but were correlated with the age (r=0.12, p=0.02). After excluding other risk factors for psychogenic disturbances (obesity, hypertension and impaired glucose metabolism) we concluded that serum 25(OH)D could be an independent risk factor for anxiety (R2=0.02, p=0.01) in the population studied.

Vitamin D levels and cognition in elderly adults in China

OBJECTIVES

To evaluate the association between vitamin D level and cognitive impairment in individuals aged 60 and older.

DESIGN

Cross-sectional cohort study.

SETTING

Chinese Longitudinal Healthy Longevity Survey, a community-based cohort study in areas in China where the density of centenarians is exceptionally high.

PARTICIPANTS

Individuals with mean age of 84.9 ± 12.7 (N = 2,004).

MEASUREMENTS

Participants' cognitive state was evaluated using the Mini-Mental State Examination (MMSE). Vitamin D was measured in plasma using an enzyme-linked immunoassay.

RESULTS

The cross-sectional association between quartiles of plasma vitamin D level and cognitive impairment (MMSE score <18) was modeled using logistic regressions. Plasma vitamin D levels were lower in individuals with cognitive impairment (31.9 ± 15.3 nmol/L) than in those without (45.6 ± 19.6 nmol/L). There was a reverse association between plasma vitamin D and cognitive impairment. After adjusting for age, sex, chronic conditions, smoking and drinking habits, outdoor activities, depression, and activity of daily living limitations, the association remained significant. The multivariable-adjusted odds ratio for lowest versus highest vitamin D levels was 2.15 (95% confidence interval (CI) = 1.05-4.41) for cognitive impairment, and the multivariable odds ratio associated with a 1-standard deviation decrement in plasma vitamin D was 1.32 (95% CI = 1.00-1.74) for cognitive impairment.

CONCLUSION

Low plasma vitamin D levels were associated with greater odds of cognitive impairment. Further prospective studies in Asian populations are needed to examine the causal direction of this association.

Vitamin D prevents cognitive decline and enhances hippocampal synaptic function in aging rats

Vitamin D is an important calcium-regulating hormone with diverse functions in numerous tissues, including the brain. Increasing evidence suggests that vitamin D may play a role in maintaining cognitive function and that vitamin D deficiency may accelerate age-related cognitive decline. Using aging rodents, we attempted to model the range of human serum vitamin D levels, from deficient to sufficient, to test whether vitamin D could preserve or improve cognitive function with aging. For 5-6 mo, middle-aged F344 rats were fed diets containing low, medium (typical amount), or high (100, 1,000, or 10,000 international units/kg diet, respectively) vitamin D3, and hippocampal-dependent learning and memory were then tested in the Morris water maze. Rats on high vitamin D achieved the highest blood levels (in the sufficient range) and significantly outperformed low and medium groups on maze reversal, a particularly challenging task that detects more subtle changes in memory. In addition to calcium-related processes, hippocampal gene expression microarrays identified pathways pertaining to synaptic transmission, cell communication, and G protein function as being up-regulated with high vitamin D. Basal synaptic transmission also was enhanced, corroborating observed effects on gene expression and learning and memory. Our studies demonstrate a causal relationship between vitamin D status and cognitive function, and they suggest that vitamin D-mediated changes in hippocampal gene expression may improve the likelihood of successful brain aging.

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.

Association of serum 25-hydroxyvitamin D with symptoms of depression after 6 months in stroke patients

Our aim was to determine whether there was a relationship between 25-hydroxyvitamin D (25[OH] D) and post-stroke depression (PSD). Two hundred and forty-four ischemic stroke patients admitted to the hospital within the first 24 h after stroke onset were consecutively recruited and followed up for 6 months. Clinical information was collected. Serum 25[OH] D levels were measured at baseline. Based on the symptoms, diagnoses of depression were made in accordance with DSM-IV criteria for depression at 6-month after stroke. At 6-month, 91 patients (37.3 %) showed depression and in 60 patients (24.6 %) this depression was classified as major. There was a significant difference in median serum 25[OH] D levels between PSD patients and no depression cases [8.3 (IQR, 6.8-9.5) vs. 15.6 (IQR, 13.2-20.3) ng/ml, respectively; P < 0.001]. Serum 25[OH] D levels ≤ 11.2 ng/ml were independently associated with PSD [odds ratio 10.32, 95 % confidence interval 4.97-28.63; P < 0.001], after adjusting for possible confounders. Serum 25[OH] D levels reduced at admission was found to be associated with PSD. Additional research is needed on vitamin D supplementation to improve the outcome of patients with PSD.

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.

Vitamin D in relation to cognitive impairment, cerebrospinal fluid biomarkers, and brain volumes

BACKGROUND

Low vitamin D status is associated with poorer cognitive function in older adults, but little is known about the potential impact on cerebrospinal fluid (CSF) biomarkers and brain volumes. The objective of this study was to examine the relations between plasma 25-hydroxyvitamin D (25(OH)D) and cognitive impairment, CSF biomarkers of Alzheimer's disease (AD), and structural brain tissue volumes.

METHODS

A total of 75 patients (29 with subjective cognitive impairment, 28 with mild cognitive impairment, 18 with AD) referred to the Memory Clinic at Karolinska University Hospital, Huddinge, Sweden were recruited. Plasma 25(OH)D, CSF levels of amyloid β (Aβ(1-42)), total-tau, and phosphorylated tau, and brain tissue volumes have been measured.

RESULTS

After adjustment for several potential confounders, the odds ratios (95% confidence interval) for cognitive impairment were as follows: 0.969 (0.948-0.990) per increase of 1 nmol/L of 25(OH)D and 4.19 (1.30-13.52) for 24(OH)D values less than 50 nmol/L compared with values greater than or equal to 50 nmol/L. Adjusting for CSF Aβ(1-42) attenuated the 25(OH)D-cognition link. In a multiple linear regression analysis, higher 25(OH)D levels were related to higher concentrations of CSF Aβ(1-42) and greater brain volumes (eg, white matter, structures belonging to medial temporal lobe). The associations between 25(OH)D and tau variables were not significant.

CONCLUSIONS

This study suggests that vitamin D may be associated with cognitive status, CSF Aβ(1-42) levels, and brain tissue volumes.

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.

Dietary vitamin D deficiency in rats from middle to old age leads to elevated tyrosine nitration and proteomics changes in levels of key proteins in brain: implications for low vitamin D-dependent age-related cognitive decline

In addition to the well-known effects of vitamin D (VitD) in maintaining bone health, there is increasing appreciation that this vitamin may serve important roles in other organs and tissues, including the brain. Given that VitD deficiency is especially widespread among the elderly, it is important to understand how the range of serum VitD levels that mimic those found in humans (from low to high) affects the brain during aging from middle age to old age. To address this issue, 27 male F344 rats were split into three groups and fed isocaloric diets containing low (100 IU/kg food), control (1000 IU/kg food), or high (10,000 IU/kg food) VitD beginning at middle age (12 months) and continued for a period of 4-5 months. We compared the effects of these dietary VitD manipulations on oxidative and nitrosative stress measures in posterior brain cortices. The low-VitD group showed global elevation of 3-nitrotyrosine compared to control and high-VitD-treated groups. Further investigation showed that this elevation may involve dysregulation of the nuclear factor κ-light-chain enhancer of activated B cells (NF-κB) pathway and NF-κB-mediated transcription of inducible nitric oxide synthase (iNOS) as indicated by translocation of NF-κB to the nucleus and elevation of iNOS levels. Proteomics techniques were used to provide insight into potential mechanisms underlying these effects. Several brain proteins were found at significantly elevated levels in the low-VitD group compared to the control and high-VitD groups. Three of these proteins, 6-phosphofructokinase, triose phosphate isomerase, and pyruvate kinase, are involved directly in glycolysis. Two others, peroxiredoxin-3 and DJ-1/PARK7, have peroxidase activity and are found in mitochondria. Peptidyl-prolyl cis-trans isomerase A (cyclophilin A) has been shown to have multiple roles, including protein folding, regulation of protein kinases and phosphatases, immunoregulation, cell signaling, and redox status. Together, these results suggest that dietary VitD deficiency contributes to significant nitrosative stress in brain and may promote cognitive decline in middle-aged and elderly adults.

Vitamin D2-enriched button mushroom (Agaricus bisporus) improves memory in both wild type and APPswe/PS1dE9 transgenic mice

Vitamin D deficiency is widespread, affecting over 30% of adult Australians, and increasing up to 80% for at-risk groups including the elderly (age>65). The role for Vitamin D in development of the central nervous system is supported by the association between Vitamin D deficiency and incidence of neurological and psychiatric disorders including Alzheimer's disease (AD). A reported positive relationship between Vitamin D status and cognitive performance suggests that restoring Vitamin D status might provide a cognitive benefit to those with Vitamin D deficiency. Mushrooms are a rich source of ergosterol, which can be converted to Vitamin D2 by treatment with UV light, presenting a new and convenient dietary source of Vitamin D2. We hypothesised that Vitamin D2-enriched mushrooms (VDM) could prevent the cognitive and pathological abnormalities associated with dementia. Two month old wild type (B6C3) and AD transgenic (APPSwe/PS1dE9) mice were fed a diet either deficient in Vitamin D2 or a diet which was supplemented with VDM, containing 1±0.2 µg/kg (∼54 IU/kg) vitamin D2, for 7 months. Effects of the dietary intervention on memory were assessed pre- and post-feeding. Brain sections were evaluated for amyloid β (Aβ) plaque loads and inflammation biomarkers using immuno-histochemical methods. Plasma vitamin D metabolites, Aβ40, Aβ42, calcium, protein and cholesterol were measured using biochemical assays. Compared with mice on the control diet, VDM-fed wild type and AD transgenic mice displayed improved learning and memory, had significantly reduced amyloid plaque load and glial fibrillary acidic protein, and elevated interleukin-10 in the brain. The results suggest that VDM might provide a dietary source of Vitamin D2 and other bioactives for preventing memory-impairment in dementia. This study supports the need for a randomised clinical trial to determine whether or not VDM consumption can benefit cognitive performance in the wider population.

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.

Psychometric properties and measurement equivalence of the English and Chinese versions of the functional assessment of cancer therapy-cognitive in Asian patients with breast cancer

OBJECTIVE

This study was designed to examine the psychometric properties and measurement equivalence of the English and Chinese versions of the Functional Assessment of Cancer Therapy-Cognitive Function (Version 3) (FACT-Cog) in multiethnic Asian patients with breast cancer.

METHODS

This prospective study involved patients with breast cancer from the National Cancer Centre Singapore. The concurrent validity of the FACT-Cog was assessed according to its strength of correlation with the validated European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 cognitive functioning scale, and its association with fatigue, global health status, and anxiety. The known-group validity was assessed on the basis of receipt of chemotherapy. Factor analysis was conducted to ascertain the one-factor structure of each cognitive domain. The reliability was evaluated by using Cronbach's alpha and intraclass correlation coefficient within the cognitive domains. Multiple regression analyses were performed to compare the total scores between the two language versions, adjusting for covariates.

RESULTS

A total of 185 English-speaking and 143 Chinese-speaking patients were recruited. Both the English and Chinese FACT-Cog total scores correlated strongly with the European Organization for Research and Treatment of Cancer Quality of Life Core Questionnaire 30 cognitive functioning scale scores (r = 0.725 and 0.646), whereas correlations with fatigue, anxiety, and global health status were weak to moderate (|r| = 0.376-0.589). Regarding the known-group validity, more severe perceived cognitive disturbance was observed among patients receiving chemotherapy than among those who were not for both versions (P = .010 and .008, respectively). Internal consistencies within the cognitive domains were high (Cronbach's α 0.707-0.929), and test-retest reliability was satisfactory for both versions (intraclass correlation coefficient 0.762 and 0.697). The measurement equivalence between the English and Chinese versions was established for all domains except the multitasking domain.

CONCLUSION

The English and Chinese versions of the FACT-Cog are valid, reliable, and equivalent for clinical and research use.

Effects of vitamin C and vitamin D administration on mood and distress in acutely hospitalized patients

BACKGROUND

Hypovitaminosis C and D are highly prevalent in acute-care hospitals. Malnutrition with regard to these vitamins has been linked to mood disturbance and cognitive dysfunction.

OBJECTIVE

The objective was to determine whether vitamin C or D supplementation improves mood state or reduces psychological distress in acutely hospitalized patients with a high prevalence of hypovitaminosis C and D.

DESIGN

A randomized, double-blind, active-control clinical trial compared the effects of vitamin C (500 mg twice daily) with those of high-dose vitamin D (5000 IU/d) on mood (Profile of Mood States) and psychological distress (Distress Thermometer).

RESULTS

Vitamin C provided for a mean of 8.2 d increased plasma vitamin C concentrations to normal (P < 0.0001) and was associated with a 71% reduction in mood disturbance (P = 0.0002) and a 51% reduction in psychological distress (P = 0.0002). High-dose vitamin D provided for a mean of 8.1 d increased plasma 25-hydroxyvitamin D [25(OH)D] concentrations (P < 0.0001), but not into the normal range, and had insignificant effects on mood (P = 0.067) and distress (P = 0.45). The changes in mood and distress in the vitamin C group were greater than those in the vitamin D group (P = 0.045 for mood; P = 0.009 for distress).

CONCLUSIONS

Short-term therapy with vitamin C improves mood and reduces psychological distress in acutely hospitalized patients with a high prevalence of hypovitaminosis C and D. No conclusion is possible regarding the effects of vitamin D because the dose and duration of therapy were insufficient to raise 25(OH)D concentrations into the normal range. This trial was registered at clinicaltrials.gov as NCT01630720.

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.

The effect of 2 different single injections of high dose of vitamin D on improving the depression in depressed patients with vitamin D deficiency: a randomized clinical trial

The correlation between vitamin D deficiency and depression has recently been put forward and resulted in controversial findings. The present study was conducted to find out the effect of 2 single injections of 150,000 and 300,000 IU of vitamin D on improving the depression in depressed patients with vitamin D deficiency.This clinical trial study was carried out during 2011-2012 in Yazd, Islamic Republic of Iran. A total of 120 patients who had a Beck Depression Inventory II score of 17+ and were affected with vitamin D deficiency were randomly assigned to 3 groups of 40. They included G300, G150, and NTG. G300 and G150 received an intramuscular single dose of 300,000 and 150,000 IU of vitamin D, respectively, and the NTG group received nothing. After 3 months of intervention, the depression state, serum vitamin D, calcium, phosphorus, and parathormone were measured.The median of serum vitamin D after intervention were 60.2, 54.6, and 28.2 nmol/L (P < 0.001) for the G300, G150, and NTG, respectively. Percentages of vitamin D deficiency after intervention were 18, 20, and 91.2 for the groups, respectively. The serum calcium mean showed a statistically significant increase in just the 2 test groups receiving vitamin D. There was only significant difference in mean of Beck Depression Inventory II test score between G300 and NTG (P = 0.003).The results of the study revealed that first, the correction of vitamin D deficiency improved the depression state, and second, a single injection dose of 300,000 IU of vitamin D was safe and more effective than a 150,000-IU dose.

Vitamin D, effects on brain development, adult brain function and the links between low levels of vitamin D and neuropsychiatric disease

Increasingly vitamin D deficiency is being associated with a number of psychiatric conditions. In particular for disorders with a developmental basis, such as autistic spectrum disorder and schizophrenia the neurobiological plausibility of this association is strengthened by the preclinical data indicating vitamin D deficiency in early life affects neuronal differentiation, axonal connectivity, dopamine ontogeny and brain structure and function. More recently epidemiological associations have been made between low vitamin D and psychiatric disorders not typically associated with abnormalities in brain development such as depression and Alzheimer's disease. Once again the preclinical findings revealing that vitamin D can regulate catecholamine levels and protect against specific Alzheimer-like pathology increase the plausibility of this link. In this review we have attempted to integrate this clinical epidemiology with potential vitamin D-mediated basic mechanisms. Throughout the review we have highlighted areas where we think future research should focus.

Vitamin D deficiency, cognitive impairment and dementia: a systematic review and meta-analysis

BACKGROUND

Recent preventive strategies for patients with cognitive impairment include the identification of modifiable somatic risk factors like vitamin D deficiency.

METHODS

A systematic literature research and meta-analysis were conducted to assess the association of cognitive impairment and vitamin D deficiency.

RESULTS

Data from cross-sectional and longitudinal studies suggest an association between cognitive impairment and vitamin D deficiency. Meta-analysis of 5 cross-sectional and 2 longitudinal studies comprising 7,688 participants showed an increased risk of cognitive impairment in those with low vitamin D compared with normal vitamin D (OR 2.39, 95% CI 1.91-3.00; p < 0.0001).

CONCLUSIONS

Methodological limitations of these studies comprise heterogeneity of study populations, different forms of cognitive assessment, the problem of reverse causality, different definitions of vitamin D deficiency and inconsistent control for confounders. As the value of vitamin D substitution in cognitive impairment remains doubtful, a long-time major placebo-controlled randomized trial of vitamin D supplementation in participants with mild cognitive impairment (MCI) should be started.

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.

Circulating 25-hydroxyvitamin D3 in pregnancy and infant neuropsychological development

OBJECTIVE

To investigate whether circulating 25-hydroxyvitamin D(3) [25(OH)D(3)] concentration in pregnancy is associated with neuropsychological development in infants.

METHODS

The Spanish population-based cohort study INfancia y Medio Ambiente Project recruited pregnant women during the first trimester of pregnancy between November 2003 and February 2008. Completed data on 1820 mother-infant pairs were used. Maternal plasma 25(OH)D(3) concentration was measured by high-performance liquid chromatography in pregnancy (mean 13.5 ± 2.1 weeks of gestation). Offspring mental and psychomotor scores were assessed by trained psychologists at age 14 months (range, 11-23) by using the Bayley Scales of Infant Development. β-Coefficients with 95% confidence intervals (CIs) of mental and psychomotor scores associated with continuous or categorical concentrations of maternal plasma 25(OH)D(3) were calculated by using linear regression analysis.

RESULTS

The median plasma value of 25(OH)D(3) in pregnancy was 29.6 ng/mL (interquartile range, 21.8-37.3). A positive linear relationship was found between circulating concentrations of maternal 25(OH)D(3) concentrations in pregnancy and mental and psychomotor scores in the offspring. After adjustment for potential confounders, infants of mothers with 25(OH)D(3) concentrations in pregnancy >30 ng/mL showed higher mental score (β = 2.60; 95% CI 0.63-4.56) and higher psychomotor score (β = 2.32; 95% CI 0.36-4.28) in comparison with those of mothers with 25(OH)D(3) concentrations <20 ng/mL.

CONCLUSIONS

Higher circulating concentration of maternal 25(OH)D(3) in pregnancy was associated with improved mental and psychomotor development in infants.

Dysregulation of neural calcium signaling in Alzheimer disease, bipolar disorder and schizophrenia

Neurons have highly developed Ca(2+) signaling systems responsible for regulating a large number of neural functions such as the control of brain rhythms, information processing and the changes in synaptic plasticity that underpin learning and memory. The tonic excitatory drive, which is activated by the ascending arousal system, is particularly important for processes such as sensory perception, cognition and consciousness. The Ca(2+) signaling pathway is a key component of this arousal system that regulates the neuronal excitability responsible for controlling the neural brain rhythms required for information processing and cognition. Dysregulation of the Ca(2+) signaling pathway responsible for many of these neuronal processes has been implicated in the development of some of the major neural diseases in man such as Alzheimer disease, bipolar disorder and schizophrenia. Various treatments, which are known to act by reducing the activity of Ca(2+) signaling, have proved successful in alleviating the symptoms of some of these neural diseases.

Cancer-related stress and complementary and alternative medicine: a review

A cancer diagnosis elicits strong psychophysiological reactions that characterize stress. Stress is experienced by all patients but is usually not discussed during patient-healthcare professional interaction; thus underdiagnosed, very few are referred to support services. The prevalence of CAM use in patients with history of cancer is growing. The purpose of the paper is to review the aspects of cancer-related stress and interventions of commonly used complementary and alternative techniques/products for amelioration of cancer-related stress. Feasibility of intervention of several CAM techniques and products commonly used by cancer patients and survivors has been established in some cancer populations. Efficacy of some CAM techniques and products in reducing stress has been documented as well as stress-related symptoms in patients with cancer such as mindfulness-based stress reduction, yoga, Tai Chi Chuan, acupuncture, energy-based techniques, and physical activity. Much of the research limitations include small study samples and variety of intervention length and content. Efficacy and safety of many CAM techniques and some herbs and vitamin B and D supplements need to be confirmed in further studies using scientific methodology. Several complementary and alternative medicine therapies could be integrated into standard cancer care to ameliorate cancer-related stress.

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.

Vitamin D and osteoporosis-related fracture

The age-related decline in mass and quality of bone (osteoporosis) and muscle (sarcopenia) leads to an exponential increased risk for osteoporosis-related fracture with advancing age in older adults. As vitamin D inadequacy plausibly causally contributes to these declines, optimization of vitamin D status might reduce the deterioration of bone and muscle function with age. Putative mechanisms by which vitamin D inadequacy may increase fracture risk include both direct and indirect effects on bone and muscle. However, controversy currently clouds the role(s) of vitamin D in osteoporosis-related fracture, the amount of vitamin D required and the optimal 25-hydroxyvitamin D level. This review provides an overview of current knowledge and suggests a clinical approach to vitamin D status in older adults with, or at risk for, osteoporosis-related fracture. These recommendations are likely to evolve as additional data becomes available.

Vitamin D receptor and Alzheimer's disease: a genetic and functional study

Genetic studies on late-onset Alzheimer's disease (AD) have repeatedly mapped susceptibility loci onto chromosome 12q13, encompassing the vitamin D receptor (VDR) gene. Epidemiology studies have indicated vitamin D insufficiency as a risk factor for AD. Given that VDR is the major mediator for vitamin D's actions, we sought to clarify the role of VDR in late-onset AD. We conducted an association study in 492 late-onset AD cases and 496 controls with 80 tagging single nucleotide polymorphisms (SNPs). The strongest association was found at a promoter SNP rs11568820 (P = 9.1 × 10(-6), odds ratio (OR) = 1.69), which resides within the transcription factor Cdx-2 binding site and the SNP has been also known as CDX2. The risk-allele at rs11568820 is associated with lower VDR promoter activity (p < 10(-11)). The overexpression of VDR or vitamin D treatment suppressed amyloid precursor protein (APP) transcription in neuroblastoma cells (p < 0.001). We provide both statistical evidence and functional data suggesting VDR confers genetic risk for AD. Our findings are consistent with epidemiology studies suggesting that vitamin D insufficiency increases the risk of developing AD.

Vitamin D receptor and megalin gene polymorphisms and their associations with longitudinal cognitive change in US adults

BACKGROUND

Vitamin D receptor (VDR) and the megalin gene polymorphism's link with longitudinal cognitive change remains unclear.

OBJECTIVE

The associations of single nucleotide polymorphisms (SNPs) for VDR [rs11568820 (CdX-2:T/C), rs1544410 (BsmI:G/A), rs7975232 (ApaI:A/C), rs731236 (TaqI:G/A)], and Megalin (rs3755166:G/A; rs2075252:C/T; rs4668123:C/T) genes with longitudinal cognitive performance changes were examined.

DESIGN

Data from 702 non-Hispanic white participants in the Baltimore Longitudinal Study of Aging were used. Longitudinal annual rates of cognitive change (LARCCs) between age 50 y and the individual mean follow-up age were predicted with linear mixed models by using all cognitive score time points (prediction I) or time points before dementia onset (prediction II). Latent class, haplotype, and ordinary least squares (OLS) regression analyses were conducted.

RESULTS

Among key findings, in OLS models with SNP latent classes as predictors for LARCCs, Megalin(2) [rs3755166(-)/rs2075252(TT)/rs4668123(T-)] compared with Megalin(1) [rs3755166(-)/rs2075252(CC)/rs4668123(-)] was associated with greater decline among men for verbal memory (prediction II). Significant sex differences were also found for SNP haplotype (SNPHAP). In women, VDR(1) [BsmI(G-)/ApaI(C-)/TaqI(A-); baT] was linked to a greater decline in category fluency (prediction I: β = -0.031, P = 0.012). The Megalin(1) SNPHAP (GCC) was related to greater decline among women for verbal memory, immediate recall [California Verbal Learning Test (CVLT), List A; prediction II: β = -0.043, P = 0.006) but to slower decline among men for delayed recall (CVLT-DR: β > 0, P < 0.0125; both predictions). In women, the Megalin(2) SNPHAP (ACC) was associated with slower decline in category fluency (prediction II: β = +0.026, P = 0.005). Another finding was that Megalin SNP rs3755166:G/A was associated with greater decline in global cognition in both sexes combined and in verbal memory in men.

CONCLUSION

Sex-specific VDR and Megalin gene variations can modify age-related cognitive decline among US adults.

Evaluation of selected cognitive functions before and after surgery for primary hyperparathyroidism

BACKGROUND AND AIMS

Cognitive functions have been reported to be impaired in patient with primary hyperparathyroidism (pHPT). The aim of this psychological study was to evaluate cognitive disturbances in pHPT in relation to serum calcium levels before and after surgery.

PATIENTS AND METHODS

A prospective, case-control study with 1-year follow-up of 35 pHPT patients versus 35 matched controls was undertaken. All patients were tested before surgery and at 12-18 months following surgery with a battery of selected cognitive function psychological tools: Benton Visual Retention Test (BVRT), Wisconsin Card Sorting Test (WCST), Memory Verbal Learning Test (DCS), The Rey's Auditory Verbal Learning Test (RAVLT), Trail Making Test A & B, Verbal Fluency Test, and Beck Depression Inventory. In addition to psychological testing, serum calcium, parathyroid hormone and phosphate levels were evaluated.

RESULTS

The following cognitive functions of pHPT patients versus controls were deteriorated before surgery: impaired concentration, decreased nonverbal learning process, difficulties in using direct memory, verbal fluency and visual constructive abilities. However, no correlation was found between serum calcium levels and the results of neuropsychological tests. In longitudinal comparison of pHPT patients before and 1 year after surgery, there was a significant improvement in visual memory, visual-constructive abilities and direct memory.

CONCLUSIONS

pHPT patients have significantly decreased concentration level, nonverbal learning process, access to verbal resources and constructional and visual memory ability. Thus, neuropsychological testing may be useful in the decision making for early surgery in patients with mild asymptomatic disease in order to avoid further deterioration of cognitive functions.

Effects of vitamin D supplementation on cognitive and emotional functioning in young adults--a randomised controlled trial

Background

Epidemiological research links vitamin D status to various brain-related outcomes. However, few trials examine whether supplementation can improve such outcomes and none have examined effects on cognition. This study examined whether Vitamin D supplementation led to improvements in diverse measures of cognitive and emotional functioning, and hypothesised that supplementation would lead to improvements in these outcomes compared to placebo.

Methods/Principal Findings

Healthy young adults were recruited to a parallel-arm, double-blind trial conducted at The University of Queensland. Participants were randomly allocated to receive Vitamin D (one capsule daily, containing 5000 IU cholecalciferol) or identical placebo capsule for six weeks. All participants and outcome assessors were blinded to group assignment. Primary outcome measures assessed at baseline and 6 weeks were working memory, response inhibition and cognitive flexibility. Secondary outcomes were: hallucination-proneness, psychotic-like experiences, and ratings of depression, anxiety and anger. 128 participants were recruited, randomised and included in primary analyses (vitamin D n = 63; placebo n = 65). Despite significant increases in vitamin D status in the active group, no significant changes were observed in working memory (F = 1.09; p = 0.30), response inhibition (F = 0.82; p = 0.37), cognitive flexibility (F = 1.37; p = 0.24) or secondary outcomes. No serious adverse effects were reported.

Conclusions

Our findings indicate that vitamin D supplementation does not influence cognitive or emotional functioning in healthy young adults. Future controlled trials in targeted populations of interest are required to determine whether supplementation can improve functioning in these domains.

Australian and New Zealand Clinical Trials Registry; ACTRN12610000318088.

Vitamin D and Executive Function: A Preliminary Report

The aim of this study was to investigate the relationship between vitamin D levels and cognition, both executive and nonexecutive functions, in men incarcerated in a Norwegian prison. Participants were divided into high vitamin D and low vitamin D groups based on established criteria (high level ≥ 50 nmol/L; low level < 50 nmol/L). The mean vitamin D concentration was 69 ( SD = 12) and 38 ( SD = 9) nmol/L in the high-level group ( n = 14) and the low level group ( n = 11), respectively. Results revealed that the high vitamin D group had significantly more correct responses than the low vitamin D group on the executive function task. There was no difference between the groups on the nonexecutive function task. The reaction time data indicated that the high levels of correct responses in the high vitamin D group on the executive function tasks were not due to a speed-accuracy trade-off.

Vitamin D deficiency and connective tissue disease

Recently, the evidence linking vitamin D status as a potential environmental factor affecting autoimmune disease prevalence continues to accumulate. Beyond that the traditional known metabolic activities, vitamin D has been shown to modulate the immune system and has anti-inflammatory properties. The immune-regulatory role of vitamin D affects both the innate and adaptive immune responses contributing to the immune-tolerance of self-structures. Vitamin D deficiency skews the immunologic response towards loss of tolerance. Serum levels of vitamin D have been found to be significantly lower in several autoimmune or immune-mediated diseases than in the healthy population. Experimental animal models and clinical studies show that 1,25-dihydroxyvitamin D3 or vitamin D receptor (VDR) agonists can either prevent or suppress symptoms of type 1 diabetes, experimental autoimmune encephalomyelitis, rheumatoid arthritis, systemic lupus erthyematosus and inflammatory bowel disease. The heading aims at reviewing the complex immune-regulatory role of vitamin D from the cellular and humoral level through animal models of autoimmune rheumatic diseases and representing the known contribution of vitamin D in the pathogenesis of connective tissue diseases. Increased vitamin D intakes might reduce the incidence and severity of autoimmune disorders besides reducing the rate of osteoporotic bone fracture.

Possible role of serum 25-hydroxyvitamin D in black-white health disparities in the United States

Significant health disparities exist between African Americans (AAs) and White Americans (WAs). The all-cause mortality rate for AAs in 2006 was 26% higher than for non-Hispanic WAs. Explanations for the disparities usually include socioeconomic status, lifestyle behaviors, social environment, and access to preventive health care services. However, several studies indicate that these factors do not account for the observed disparities. Many studies report that vitamin D has important health benefits through paracrine and autocrine mechanisms and that higher serum 25-hydroxyvitamin D (25[OH]D) levels are associated with better health outcomes. AAs have a population mean serum 25(OH)D level of 16 ng/mL, whereas WAs have a level of 26 ng/mL. From preliminary meta-analyses of serum 25(OH)D level-disease outcome from observational studies, differences in serum 25(OH)D level for AAs and WAs can explain many of the health disparities. The ratios of mortality rates for AAs to WAs for female breast cancer, colorectal cancer, cardiovascular disease, and all-cause mortality rate in 2006 were 1.34, 1.43, 1.29, and 1.26, respectively. The 25(OH)D level-disease outcome ratios for 16 ng/mL versus 26 ng/mL for the same diseases were 1.26, 1.44, 1.27, and 1.26, respectively. The close agreement between these 2 sets of numbers suggests that low serum 25(OH)D level is an important health risk for AAs. Given the widespread vitamin D deficiency in the AA population and the potential widespread health benefits that accompany adequate replacement, we believe that addressing this issue may be the single most important public health measure that can be undertaken.

Vitamin D, neurocognitive functioning and immunocompetence

PURPOSE OF REVIEW

Vitamin D deficiency is recognized as one of the most common medical conditions in children and adults. The major causes are inadequate sun exposure and inadequate intakes of dietary and supplemental vitamin D. Vitamin D deficiency and insufficiency defined as a 25-hydroxyvitamin D level less than 20 and 21-29 ng/ml, respectively, have been linked to increased risk for a variety of medical conditions including cancer, heart disease, type II diabetes, infectious diseases, autoimmune diseases, metabolic bone diseases and neurological disorders.

RECENT FINDINGS

The skeletal muscle and brain have a vitamin D receptor and the central nervous system has a capacity to activate vitamin D. Low vitamin D status has been linked to poor performance in neurocognitive testing in elderly. Vitamin D deficiency has been associated with muscle weakness, depression, schizophrenia, Alzheimer's disease, multiple sclerosis and a lower motor neuron-induced muscle atrophy.

SUMMARY

Correcting vitamin D deficiency and preventing vitamin D deficiency in children and adults should be a high priority for healthcare professionals to reduce risk for a wide variety of neurological disorders. Children and adults should take at least 400 international unit IU and 2000 IU vitamin D/day, respectively, to prevent vitamin D deficiency and insufficiency.

The association of circulating 25-hydroxyvitamin D and calcium with cognitive performance in adolescents: cross-sectional study using data from the third National Health and Nutrition Examination Survey

Studies in middle- and older-aged adults have shown positive associations between serum levels of 25-hydroxyvitamin D [25(OH)D] and cognitive function. Higher serum calcium levels have been associated with greater cognitive decline in older adults. There have been relatively few studies of the associations of 25(OH)D and calcium with cognitive function in adolescents. We investigated the cross sectional association between circulating levels of 25(OH)D and pH-normalised calcium with different domains of cognitive function (block design and digit span components from Wechsler Intelligence Scale for Children-revised and reading and mathematics subtests of Wide-range Achievement Test-revised) in adolescents (age 12-16.9 years) of the third National Health and Nutrition Examination Survey (NHANES III). Serum 25(OH)D was positively associated with performance in all four cognitive tests (e.g. 1 standard deviation (SD) change in digit span score per 1SD in 25(OH)D was 0.10 [95% confidence interval 0.03, 0.16]), but the association was attenuated to the null after adjusting for ethnicity/race and language used in test (1SD change in digit span per 1SD in 25(OH)D after adjusting for self-reported race/ethnicity and language used in test was 0.01[-0.06, 0.09]). pH-normalised calcium levels were not associated with any of the cognitive domains and adjustment for serum calcium levels did not alter the association between 25(OH)D and cognitive function. Thus, we found no evidence that the serum levels of 25(OH)D or calcium were associated with cognitive function in adolescents. A positive association of 25(OH)D with cognitive function was completely explained by confounding due to race/ethnicity.

The association of serum ionized calcium and vitamin D with adult cognitive performance

BACKGROUND

High serum calcium levels have been associated with cognitive decline in older adults. These associations have not been studied in younger adults. The possible association of vitamin D with cognitive function, independent of calcium, is unknown.

METHODS

A cross-sectional study of associations of serum ionized calcium and 25-hydroxyvitamin D levels with cognitive function in younger adults (20-59 years) and older adults (60-90 years) was conducted using data from the US third National Health and Nutrition Examination Survey (NHANES III).

RESULTS

Neither serum ionized calcium nor 25-hydroxyvitamin D was associated with cognitive function in either age group. For example, the confounder-adjusted mean difference in reaction time in young adults was 0.00 (95% confidence interval = -0.07 to 0.06) per 1 SD calcium.

CONCLUSION

Our results do not support an important role for calcium or vitamin D in cognitive performance in adults.

Predictors of clock drawing test (CDT) performance in elderly patients attending an internal medicine outpatient clinic: a pilot study on sun exposure and physical activity

Influence of sun exposure and physical activity on cognition has not been evaluated simultaneously. We aimed to evaluate predictors of clock drawing test (CDT) performance on n=125 patients attending an internal medicine outpatient clinic. Interview data was gathered on sociodemographic, health-related and lifestyle factors referring to the last year. Factors associated with obtaining a score >0 and a full score (10/10) were analyzed by univariate (UVA) and multivariate (MVA) logistic regression analyses. Mean age of the participants was 72 ± 5, 58% were women and 17% were illiterate. Mean CDT score was 4.70 ± 2.27, 61.6% scored >0 and 21.6% scored 10/10. Both duration of walking and summer sun exposure predicted a CDT score >0 in UVA. However only summer sun exposure was an independent predictor (odds ratio=OR=1.73, 95% confidence interval=CI=1.16-2.57). Other factors independently associated with obtaining a score >0 were education level (OR=2.70, 95%CI=1.77-4.12) and cerebrovascular disease (CVD) history (OR=0.08, 95%CI=0.008-0.78). Factors independently associated with obtaining a full score were weight (OR=1.05, 95%CI=1.00-1.10), education level (OR=2.04, 95%CI=1.38-3.00) and visiting the clinic alone (OR=3.92, 95%CI=1.354-11.39). Our study shows that CDT can be utilized to unravel the lifestyle factors associated with cognitive function. To our knowledge, this is the first study to suggest an association between sun exposure and cognition.