Vitamin D, Fibroblast Growth Factor 23 and Incident Cognitive Impairment: Findings from the REGARDS Study

Vitamin D status and cognitive performance in community-dwelling adults: A dose-response meta-analysis of observational studies

Low vitamin D status is linked with poorer cognition in adults while findings in relation to high levels are mixed.We performed a systematic review and meta-analyses to examine dose-response associations between 25-hydroxyvitamin D (25OHD) levelsand cognitive performance in community-dwelling adults. Thirty-eight observational studies were included in dose-response meta-analyses. Positive, nonlinear associations were identified between baseline25OHD levels and global cognition incross-sectional and longitudinal analyses, and for performance in memory and executive function in longitudinal analyses. When restricted to studies involving older adults, thepattern emerged forspecific domains in cross-sectional analyses. Poorer performance was associated with low 25OHD levels, while a sharp improvement was associated withlevels up to 60-70 nM/L. Further improvement was observed only for longitudinal global cognition. Our findings support the association between low vitamin D and poorer cognition and suggest levels of at least 60 nM/L are associated with better cognition during ageing.

Association between Vitamin D and Cognitive Deficiency in Alcohol Dependence

There are still not enough findings to elucidate how exactly alcohol use impairs cognitive abilities. Some studies have shown that there is a link between alcohol intake and vitamin D levels, but these findings are inconsistent so further research is needed. The aim of this study was to investigate the association between serum vitamin D levels and cognitive impairment in alcohol-dependent individuals. A case-control study was carried out including a total of N = 132 respondents with a medical history of alcoholism, and healthy volunteers. The Montreal Cognitive Assessment (MoCa) and Addenbrooke’s Cognitive Examination-Revised (ACE-R) screening tools were used for cognitive status assessment and serum vitamin D levels analysis (blood samples of respondents). Significant difference (p = 0.022), was found in vitamin D levels in the alcohol-dependent group with cognitive deficiency 13.7 ± 9.4 (ng/mL), alcohol-dependent group without cognitive deficiency 19.5 ± 11.2 (ng/mL) and healthy controls 19.9 ± 11.1 (ng/mL), respectively. Furthermore, vitamin D levels were significantly different across all groups based on MoCa (p = 0.016) and ACE-R (p = 0.004) scores. All three groups exhibited vitamin D deficiency. A significant correlation was found between vitamin D deficiency and cognitive impairment, but it yielded no significant difference in alcohol-dependent individuals.

Correlation between vitamin D and cognitive function in patients with traumatic brain injury in China

OBJECTIVE

This study investigated changes in vitamin D levels in traumatic brain injury (TBI) patients and the relationship between vitamin D levels and cognitive function.

METHODS

Thirty-five TBI patients in our hospital were randomly selected, and baseline data were collected. 25-Hydroxyvitamin D (25(OH)D) plasma levels were determined within a month of hospitalization, and awareness and cognitive function were assessed using the Glasgow Coma Scale (GCS) and the Mini Mental State Examination (MMSE), respectively, on the day of blood collection. The data were statistically analyzed.

RESULTS

The MMSE and GCS scores were positively correlated (p < 0.05); higher MMSE scores were associated with higher GCS scores. Moreover, the total score was positively correlated with directional ability, memory, and attention, suggesting high internal consistency of the MMSE score, but no significant correlation with other indicators was observed. 25(OH)D was positively correlated with the injury site (p < 0.05), suggesting that frontal damage has a significant impact on the plasma level of 25(OH)D.

CONCLUSION

The plasma vitamin D level in TBI patients may indicate frontal lobe damage. The overall plasma level of 25(OH)D in TBI patients was not significantly correlated with cognitive function, but the incidence of cognitive impairment was higher with 25(OH)D level between 10 and 30 ng/ml.

Serum Klotho and FGF23 Levels in Patients with Schizophrenia

Background

The aim of this study is to compare the serum levels of Klotho and fibroblast growth factor 23 in patients with schizophrenia, in whom etiopathogenesis inflammation plays an important role, with those of healthy control subjects and to investigate a possible correlation between these levels.

Methods

Forty male patients with schizophrenia and 40 healthy male control subjects who were followed up and/or treated at the High-Security Forensic Psychiatry Clinic participated in the study. Sociodemographic data form, the Positive and Negative Syndrome Scale, and the Clinical Global Impression Scale were collected from all subjects, and participants' fibroblast growth factor 23 and Klotho serum levels were measured by the enzyme-linked immunosorbent assay method.

Results

The serum levels of Klotho and fibroblast growth factor 23 were significantly higher in schizophrenia patients than in healthy controls (P  = .048 and P  = .010, respectively). A significant positive correlation was observed between serum levels of Klotho and fibroblast growth factor 23 in subjects (r = 0.816; P  < .001).

Conclusion

Our study is the first to show significantly higher combined serum levels of fibroblast growth factor 23 and Klotho in patients with schizophrenia. The Klotho/fibroblast growth factor 23 pathway may play a role in the pathogenesis of schizophrenia. The involvement of Klotho and fibroblast growth factor 23 in inflammatory processes has the potential to provide alternative approaches to elucidate the etiopathogenesis and treatment of schizophrenia.

Biomarkers as MEDiators of racial disparities in risk factors (BioMedioR): Rationale, study design, and statistical considerations

PURPOSE

Relative to White adults, Black adults have a substantially higher prevalence of hypertension and diabetes, both key risk factors for stroke, cardiovascular disease, cognitive impairment, and dementia. Blood biomarkers have shown promise in identifying contributors to racial disparities in many chronic diseases.

METHODS

We outline the study design and related statistical considerations for a nested cohort study, the Biomarker Mediators of Racial Disparities in Risk Factors (BioMedioR) study, within the 30,239-person biracial REasons for Geographic And Racial Differences in Stroke (REGARDS) study (2003-present). Selected biomarkers will be assessed for contributions to racial disparities in risk factor development over median 9.4 years of follow-up, with initial focus on hypertension, and diabetes. Here we outline study design decisions and statistical considerations for the sampling of 4,400 BioMedioR participants.

RESULTS

The population for biomarker assessment was selected using a random sample study design balanced across race and sex to provide the optimal opportunity to describe association of biomarkers with the development of hypertension and diabetes. Descriptive characteristics of the BioMedioR sample and analytic plans are provided for this nested cohort study.

CONCLUSIONS

This nested biomarker study will examine pathways with the target to help explain racial differences in hypertension and diabetes incidence.

Impact of 25-Hydroxy Vitamin D on White Matter Hyperintensity in Elderly Patients: A Systematic Review and Meta-Analysis

Some studies show that low serum vitamin D levels are associated with white matter hyperintensity (WMH), while other studies report no association. This meta-analysis aimed to investigate the presence of an association between serum 25-hydroxy vitamin D [25(OH)D] levels and WMH. PubMed, Embase, the Cochrane Library, CNKI, WANFANG, and VIP were searched for available papers published up to December 2020. The outcomes were the odds ratios (ORs) with 95% confidence intervals (CIs) for the association between different vitamin D statuses and WMH. All meta-analyses were performed using a random-effects model. Five studies (4393 patients) were included. Compared with sufficient 25(OH)D levels, 25(OH)D deficiency was not associated with WMH (OR = 1.67, 95%CI: 0.92–3.04; I² = 70.2%, P_{heterogeneity} = 0.009), nor was 25(OH)D insufficiency (OR = 1.21, 95%CI: 0.89–1.65; I² = 48.1%, P_{heterogeneity} = 0.103). A decrease of 25 nmol/L in 25(OH)D levels was associated with WMH (OR = 1.83, 95%CI: 1.34-2.49; I² = 0%, P_{heterogeneity}= 0.512). The sensitivity analyses showed that the results were robust. 25(OH)D deficiency and insufficiency are not associated with WMH. A decrease of 25 nmol/L in 25(OH)D levels was associated with WMH, but this result will have to be confirmed. Prospective trials, both cross-sectional and longitudinal, are necessary to examine the association between 25(OH)D levels and WMH.

Fibroblast growth factor 23 and cognitive impairment: The health, aging, and body composition study

BACKGROUND

Concentrations of fibroblast growth factor 23 (FGF-23), a hormone that regulates phosphorus and vitamin D metabolism, increase as kidney function declines. Excess fibroblast growth factor 23 may impact brain function through promotion of vascular disease or through direct effects on neuronal tissue.

METHODS

In the Healthy Aging and Body Composition Study, a longitudinal observational cohort of well-functioning older adults, intact serum FGF-23 was assayed in 2,738 individuals. Cognitive function was assessed at baseline and longitudinally at years 3, 5, and 8 by administration of the Modified Mini Mental State Examination (3MSE), a test of global cognitive function, and the Digit Symbol Substitution Test (DSST), a test primarily of executive function. The associations between FGF-23 and baseline cognitive function and incident cognitive impairment were evaluated using logistic and Poisson regression respectively, and were adjusted for demographics, baseline estimated glomerular filtration rate (eGFR), urine albumin/creatinine ratio, comorbidity, and other measures of mineral metabolism including soluble klotho.

RESULTS

The mean (SD) age was 74(3) years, with 51% female, and 39% black. The median (25th, 75th) FGF-23 concentration was 47 pg/mL (37, 60). Three hundred ninety-two individuals had prevalent cognitive impairment by the 3MSE and 461 by the DSST. There was no observed association between FGF-23 and baseline cognitive function for either cognitive test. There were 277 persons with incident cognitive impairment by 3MSE, and 333 persons with incident cognitive impairment by DSST. In fully adjusted models, each two-fold higher concentration of baseline FGF-23 was not associated with incident cognitive impairment by the 3MSE (IRR = 1.02[0.88, 1.19] fully adjusted model) or by the DSST (IRR = 0.98 [0.84, 1.15]. We saw no difference when analyses were stratified by eGFR greater than or less than 60 ml/min/1.73m2.

CONCLUSION

Intact FGF-23 was not associated with baseline cognitive function or incident cognitive impairment in this cohort well-functioning older adults.

Association Between Chronic Kidney Disease-Mineral Bone Disease (CKD-MBD) and Cognition in Children: Chronic Kidney Disease in Children (CKiD) Study

Rationale & Objective

Chronic kidney disease (CKD) in children is associated with cognitive dysfunction that affects school performance and quality of life. The relationship between CKD-mineral and bone disorder and cognitive function in children is unknown.

Study Design

Observational study.

Participants

702 children enrolled in the Chronic Kidney Disease in Children (CKiD) Study.

Predictors

Plasma fibroblast growth factor 23 (FGF-23), parathyroid hormone (PTH), calcium, phosphorus, 25 hydroxyvitamin D (25[OH]D), and 1,25 dihydroxyvitamin D (1,25[OH]₂D).

Outcomes

Neurocognitive tests of intelligence, academic achievement, and executive functions.

Analytical Approach

Linear regression models to analyze the cross-sectional associations between log₂FGF-23, 25(OH)D, 1,25(OH)₂D, PTH, calcium, and phosphorus z scores and the cognitive test scores of interest after adjustment for demographics, blood pressure, proteinuria, and kidney function.

Results

At baseline, median age was 12 (95% CI, 8.3, 15.2) years and estimated glomerular filtration rate was 54 (40.5, 67.8) mL/min/1.73 m². In fully adjusted analyses, 25(OH)D, 1,25(OH)₂D, PTH, calcium, and phosphorus z scores did not associate with cognitive test scores. In fully adjusted analyses, log₂FGF-23 was associated with abnormal test scores for attention regulation (P < 0.05); specifically, Conners' Continuous Performance Test II Errors of Omission (β = 2.3 [1.0, 3.6]), Variability (β=1.4 [0.4, -2.4]), and Hit Reaction Time (β = 1.3 [0.2, 2.4]). Children in the highest FGF-23 tertile group had 7% and 9% greater cognitive risk for Hit Reaction Time and Errors of Omission compared with those in the lowest tertile, respectively. In fully adjusted analyses, higher FGF-23 tertile was associated with increased cognitive risk (P < 0.05) for Errors of Omission (β = 0.4 [0.1, 0.7]) and Hit Reaction Time (β = 0.4 [0.1, 0.7]).

Limitations

The study does not assess the cumulative effects of FGF-23 excess on cognitive function over time. Within-population stratified analyses were not performed due to limited sample size.

Conclusions

In children with CKD, higher plasma FGF-23 level is associated with lower performance in targeted tests of executive function, specifically attention regulation, independent of glomerular filtration rate.

Association of 25-hydroxyvitamin D with incident coronary heart disease in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study

BACKGROUND

Low circulating 25-hydroxyvitamin D (25[OH]D) has been associated with increased risk of coronary heart disease (CHD), but whether this association differs by race is unclear.

METHODS

We examined the association of 25[OH]D with incident CHD in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a prospective cohort study of black and white adults ≥45 years of age enrolled between 2003 and 2007 with follow-up through December 31, 2011. Using a case-cohort design, we measured 25[OH]D in 829 participants who developed incident CHD (cases) and in 813 participants without CHD randomly selected from the REGARDS cohort (comparison subcohort). Cox proportional hazards models were used to examine associations of 25[OH]D with incident CHD adjusting for established CHD risk factors in the study sample overall and stratified by race.

RESULTS

In the fully adjusted model, lower quintiles of 25[OH]D were associated with a greater risk of incident CHD (25[OH]D > 33.6 ng/mL reference; 25[OH]D > 27.1-33.6 ng/mL, hazard ratio [HR] 2.79, 95% CI 1.64-4.76; 25[OH]D > 22.4-27.1 ng/mL, HR 2.77, 95% CI 1.57-4.89; 25[OH]D > 16.5-22.4 ng/mL, HR 5.52, 95% CI 3.21-9.50; 25[OH]D ≤ 16.5 ng/mL, HR 7.46, 95% CI 4.19-13.25). The results were similar when 25[OH]D was examined on a continuous scale (HR per 10-ng/mL decrement in 25[OH]D 2.04, 95% CI 1.65-2.52). The results did not statistically differ by race whether 25[OH]D was examined as a categorical or continuous variable (P_interaction > .10).

CONCLUSIONS

Lower plasma 25(OH)D concentrations were associated with higher risk of incident CHD. In contrast to prior studies, these associations did not differ by race.

Quality assessment of systematic reviews of vitamin D, cognition and dementia

BACKGROUND

There is conflicting evidence regarding the association of vitamin D with cognition performance and dementia.AimsWe aimed to summarise the evidence on the association of vitamin D with cognitive performance, dementia and Alzheimer disease through a qualitative assessment of available systematic reviews and meta-analyses.

METHOD

We conducted an overview of the systematic reviews of all study types with or without meta-analyses on vitamin D and either Alzheimer disease, dementia or cognitive performance up to June 2017.

RESULTS

Eleven systematic reviews were identified, nine of which were meta-analyses with substantial heterogeneity, differing statistical methods, variable methodological quality and quality of data abstraction. A Measurement Tool to Assess Systematic Reviews checklist scores ranged from 4 to 10 out of 11, with seven reviews of 'moderate' and four of 'high' methodological quality. Out of six meta-analyses on the association between low serum concentration of 25-hydroxyvitamin D and risk of dementia, five showed a positive association. Results of meta-analyses on the association between low serum concentration of 25-hydroxyvitamin D and memory function tests showed conflicting results.

CONCLUSIONS

This systematic evaluation of available systematic reviews provided a clearer understanding of the potential link between low serum vitamin D concentrations and dementia. This evaluation also showed that the quality of the available evidence is not optimal because of both the low methodological quality of the reviews and low quality of the original studies. Interpretation of these systematic reviews should therefore be made with care.Declaration of interestNone.

High Prevalence of Insufficient Vitamin D Intake and Serum 25-Hydroxyvitamin D in Chinese School-Age Children: A Cross-Sectional Study

Despite the importance of vitamin D in early stages of life, data are lacking on the levels of vitamin D intake and serum 25-hydroxyvitamin D (25-(OH)D) among Chinese school-age children. The aims of this study were to investigate the vitamin D intake and serum 25-(OH)D concentration of children aged 7 to 12 years in China, and to measure the associations between vitamin D status and children's growth and development parameters. We obtained data on vitamin D intake, serum 25-(OH)D concentration, and anthropometric measurements from a cross-sectional study on school-aged children in China. Multiple linear regression and multivariable logistic regression analyses assessed the associations mentioned above. A total of 563 children (9.5 ± 1.6 years) from six areas of China were included. Among them, 86.1% had a vitamin D intake below the recommended nutrient intake (10 μg/day), and 54.7% had vitamin D deficiency (serum 25-(OH)D <15 ng/mL). We also found that high vitamin D intake was inversely associated with the risk of vitamin D deficiency (OR = 0.836, 95% confidence interval: 0.713, 0.980), and serum 25-(OH)D concentration was positively associated with the intelligence score and body mass index-for-age Z-score (BAZ) (p < 0.05). Insufficient vitamin D intake and serum 25-(OH)D are prevalent among Chinese school-aged children. A negative association was observed between vitamin D intake and the risk of vitamin D deficiency. Moreover, vitamin D status was positively associated with intelligence and BAZ, which await confirmation in future studies.

Cerebrospinal fluid FGF23 levels correlate with a measure of impulsivity

Fibroblast growth factor 23 (FGF23) is a bone-derived protein produced mainly by osteocytes and osteoblasts and at low levels in specific parts of the brain. It has been shown to associate with mood regulation. Lithium treatment gives rise to significant elevations of serum FGF23 levels in depressive patients. High peripheral blood FGF23 levels correlated with poor cognitive performance in hemodialysis patients. However, no direct evidence demonstrates a relationship between FGF23 and mood regulation. In this study, we aimed to measure the concentration of cerebrospinal fluid (CSF) FGF23 and to explore its relationship with a cluster of emotional characteristics. We measured CSF FGF23 levels in 96 male Chinese subjects. All subjects completed the Chinese version of the Barratt Impulsiveness Scale (BIS 11), the Beck Depression Inventory (BDI) and the Self-Rating Anxiety Scale (SAS). CSF FGF23 levels ranged from 12.8 to 99.3 pg/mL. Negative correlations were found between CSF FGF23 concentrations and BIS non-planning, BIS cognition and BIS total score (all p < 0.05). Nevertheless, except for the BIS cognition scores, these correlations became insignificant after Bonferroni correction. No correlations were found between CSF FGF23 concentrations and BDI or SAS scores. These findings suggest that CSF FGF23 levels correlate with a measure of impulsivity.