Midlife dietary vitamin D intake and subsequent performance in different cognitive domains

Dementia, osteoporosis and fragility fractures: Intricate epidemiological relationships, plausible biological connections, and twisted clinical practices

Dementia, osteoporosis, and fragility fractures are chronic diseases, often co-existing in older adults. These conditions pose severe morbidity, long-term disability, and mortality, with relevant socioeconomic implications. While in the research arena, the discussion remains on whether dementia is the cause or the consequence of fragility fractures, healthcare professionals need a better understanding of the interplay between such conditions from epidemiological and physiological standpoints. With this review, we summarized the available literature surrounding the relationship between cognitive impairment, dementia, and both low bone mineral density (BMD) and fragility fractures. Given the strength of the bi-directional associations and their impact on the quality of life, we shed light on the biological connections between brain and bone systems, presenting the main mediators, including gut microbioma, and pathological pathways leading to the dysregulation of bone and brain metabolism. Ultimately, we synthesized the evidence about the impact of available pharmacological treatments for the prevention of fragility fractures on cognitive functions and individuals' outcomes when dementia coexists. Vice versa, the effects of symptomatic treatments for dementia on the risk of falls and fragility fractures are explored. Combining evidence alongside clinical practice, we discuss challenges and opportunities related to the management of older adults affected by cognitive impairment or dementia and at high risk for fragility fracture prevention, which leads to not only an improvement in patient health-related outcomes and survival but also a reduction in healthcare cost and socio-economic burden.

Vitamin D Intake and Brain Cortical Thickness in Community-Dwelling Overweight Older Adults: A Cross-Sectional Study

BACKGROUND

Vitamin D is critical to brain health and a promising candidate to prevent cognitive decline and onset of Alzheimer disease (AD), although the underlying brain mechanisms are unclear.

OBJECTIVES

This study aimed to determine the association between vitamin D intake and brain cortical thickness in older adults.

METHODS

This was a cross-sectional investigation of 263 cognitively unimpaired participants, aged 65 y and older, participating in the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) trial (an ongoing study testing the effects of a 3-y diet intervention on cognitive decline). Vitamin D intake, from diet and supplements, was ascertained from an FFQ. Linear regression analysis, adjusted for age, sex, race, education, income, cognitive and physical activities, and cardiovascular disease risk factors, was used to determine the association between vitamin D intake and cortical thickness of the whole brain, lobes, and AD signature.

RESULTS

Total vitamin D intake was associated with cortical thickness of the temporal lobe and AD signature. Compared with individuals in the lowest quartile of total vitamin D intake [median: 140 international units (IU)/d], those in the highest quartile (median: 1439 IU/d) had a 0.038-mm (95% CI: 0.006, 0.069 mm) thicker temporal lobe and 0.041-mm (95% CI: 0.012, 0.070 mm) thicker AD signature. Most vitamin D intake was from supplements, and supplemental intake was also associated with cortical thickness. Compared with those who used no supplement, individuals taking 800-1000 IU/d and >1000 IU/d of supplemental vitamin D had a 0.039-mm (95% CI: 0.013, 0.066 mm) and 0.047-mm (95% CI: 0.013, 0.081 mm) thicker temporal lobe and a 0.037-mm (95% CI: 0.013, 0.061 mm) and 0.046-mm (95% CI: 0.015, 0.077 mm) thicker AD signature, respectively. Dietary vitamin D was not related to brain cortical thickness in our sample.

CONCLUSIONS

In cognitively unimpaired older adults, total and supplemental vitamin D intakes were associated with cortical thickness in regions vulnerable to AD.This trial was registered at clinicaltrials.gov as NCT02817074.

The Effect of Vitamin D Supplementation on Attention-Deficit/Hyperactivity Disorder: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective: A systematic review and meta-analysis of randomized controlled trials (RCTs) were conducted to assess the benefits and harms of vitamin D supplementation for attention-deficit/hyperactivity disorder (ADHD) patients. Methods: We followed the standard methodological procedures of the Cochrane Handbook for Systematic Reviews of Intervention. PubMed, Embase, the Cochrane Central Register of Controlled Trials, Science and Conference Proceedings Citation Index-Social Science and Humanities (Web of Science), ClincalTrials.gov, and World Health Organization's International Clinical Trials Registry Platform were searched for RCTs in January 2019. Independently, two authors (J.G., T.X.) extracted data, assessed the risk of bias, combined the data, and graded evidence quality using the Grading of Recommendations Assessment, Development, and Evaluation approach. Our primary outcomes were assessed through rating scales of ADHD severity. Secondary outcomes measured were the possible adverse effects of vitamin D supplementation and vitamin D status after supplementation for ADHD. Results: We included four RCTs with 256 children addressing vitamin D supplementation as adjunctive therapy to methylphenidate on ADHD symptoms. Vitamin D supplementation demonstrated a small but statistically significant improvement in ADHD total scores, inattention scores, hyperactivity scores, and behavior scores. The improvement was likely limited due to the low to very low quality of evidence in the literature. There was no statistically significant improvement in oppositional scores. Reported adverse events in the vitamin D group were mild and not significantly different from the control group. Vitamin D supplementation increased serum vitamin D levels and the ratio of patients with sufficient vitamin D levels. Conclusions: Vitamin D supplementation as adjunctive therapy to methylphenidate appeared to reduce ADHD symptoms without serious adverse events, associated with improved vitamin D status. However, considering the generally low strength of evidence, well-designed RCTs are needed to determine the efficacy and safety of vitamin D supplementation for both children and adults with ADHD, especially in the setting of a combination of vitamin D and other ADHD treatments.

Effect of sun exposure on cognitive function among elderly individuals in Northeast China

Background

Previous findings on the relationship between serum 25-hydroxyvitamin D [25(OH)D] level and cognitive impairment have been inconsistent. One reason is that serum 25(OH)D has a relatively short half-life, but the development of cognitive impairment is a long-term process. Skin exposure to solar ultraviolet radiation is the primary source of vitamin D synthesis. For this study, we hypothesized that people with different sun exposure behaviors would have different cognitive functions.

Methods

This study included 1,192 rural-dwelling elders in People’s Republic of China whose sun exposure behaviors, including the duration of outdoor activities, use of sun protection, and time of day participants engaged in outdoor activities, were collected. Their global cognitive function was assessed by Mini-Mental State Examination (MMSE). Partitioning cluster analysis was used to classify participants into groups based on their sun exposure behaviors. Ordinal logistic regression analysis was used to examine the association between sun exposure and cognitive function.

Results

The participants were divided into high-, medium-, and low-sun-exposure groups by cluster analysis. The participants in the high-sun-exposure group had the longest sun exposure time, reported the least sun-protective behaviors, and usually spent time outdoors in the morning (8:00–11:00) and afternoon (13:00–16:00). The participants in the low-sun-exposure group had the shortest sun exposure time, had the most positive sun-protective behaviors, and mainly spent time outdoors in the early morning (6:00–8:00) and late afternoon (16:00–18:00). After adjusting for potential confounders, participants with habitually high sun exposure were more likely to have higher MMSE score (25.4) than those with habitually low sun exposure (MMSE score =24.4).

Conclusion

Long-term high sun exposure is positively related with better cognitive functioning.

Vitamin D Status and Intakes and Their Association With Cognitive Trajectory in a Longitudinal Study of Urban Adults

CONTEXT

Serum 25-hydroxyvitamin D [25(OH)D], and dietary and supplemental vitamin D may influence cognitive outcomes.

OBJECTIVES

Sex-, age-, and race-specific associations of vitamin D status and intake with longitudinal change in various cognitive domains were examined in a large sample of ethnically and socioeconomically diverse US urban adults.

DESIGN

Two prospective waves of data from the Healthy Aging in Neighborhoods of Diversity across the Life Span study were used.

PARTICIPANTS

Adults in Baltimore, Maryland, aged 30 to 64 years at baseline (n = 1231 to 1803), were followed for a mean (± standard deviation) of 4.64 ± 0.93 years. Visit 1 occurred between 2004 and 2009; visit 2, between 2009 and 2013; there were 1.5 to 2.0 visits per participant.

MAIN OUTCOME AND EXPOSURE MEASURES

Cognitive performance was assessed using 11 test scores covering domains of global cognition, attention, learning/memory, executive function, visuospatial/visuoconstruction ability, psychomotor speed, and language/verbal. Serum 25(OH)D, vitamin D intake, and use of supplements containing vitamin D were the key exposures.

RESULTS

A consistent relationship was found between vitamin D status (overall) and supplemental intake (older women and black adults), with a slower rate of decline in the domain of verbal fluency. Higher dietary intake of vitamin D was linked to slower rate of decline in verbal memory among younger women, and a slower rate of decline in visual memory/visuoconstructive abilities among white adults. All other associations were inconsistent.

CONCLUSIONS

Vitamin D status and intakes were inversely related to domain-specific cognitive decline in US urban adults.

Strategies for dementia prevention: latest evidence and implications

Dementia is a common and debilitating syndrome with enormous impact on individuals and societies. Preventing disease onset or progression would translate to public health and societal benefits. In this review, we discuss the latest evidence on interventions that may show promise for the prevention of cognitive decline. We appraise existing evidence primarily drawn from randomized controlled trials, systematic reviews, and meta-analyses, but also highlight observational studies in humans and relevant work in model organisms. Overall, there is currently limited evidence to support a cause-effect relationship between any preventive strategy and the development or progression of dementia. However, studies to date suggest that a multifactorial intervention comprising regular exercise and healthy diet, along with the amelioration of vascular risk factors, psychosocial stress, and major depressive episodes may be most promising for the prevention of cognitive decline. We discuss the challenges, future directions, and implications of this line of research.

Vitamin D is not associated with incident dementia or cognitive impairment: an 18-y follow-up study in community-living old men

Background: Vitamin D has been implicated as being important for maintaining cognitive function in old age. Results from longitudinal studies examining the association of vitamin D with incident dementia and cognitive impairment have been inconsistent.Objective: We investigated the relation between vitamin D, assessed in 3 different ways, and the risk of dementia.Design: We measured plasma 25-hydroxyvitamin D [25(OH)D] with the use of high-performance liquid chromatography-mass spectrometry, assessed dietary vitamin D intake with the use of 7-d dietary records, and created a vitamin D-synthesis genetic risk score (GRS) at baseline (1991-1995) in a cohort of 1182 Swedish men (mean age: 71 y). In a maximum of 18 y (median: 12 y) of follow-up, 116 men developed Alzheimer disease, 64 men developed vascular dementia, and 250 men developed all-cause dementia. An additional 80 men declined in cognitive function as assessed with the use of the Mini-Mental State Examination. Adjusted HRs and ORs were calculated with the use of Cox and logistic regressions.Results: The mean ± SD plasma 25(OH)D concentration was 68.7 ± 19.1 nmol/L. Plasma 25(OH)D, dietary vitamin D intake, and vitamin D-synthesis GRS were not associated with any cognitive outcomes (crude and adjusted HRs and ORs were ∼1.0 for all continuous exposures). The adjusted HR for all-cause dementia was 0.88 (95% CI: 0.59, 1.31) in men with plasma 25(OH)D concentrations ≤50 compared with >75 nmol/L. The adjusted HR for all-cause dementia was 0.92 (95% CI: 0.63, 1.32) for the lowest compared with highest tertiles of vitamin D intake. The adjusted HR for the continuous GRS for all-cause dementia was 1.04 (95% CI: 0.91, 1.19).Conclusion: In this cohort study, we show that there is no association between baseline vitamin D status and long-term risk of dementia or cognitive impairment over an 18-y period of time.

Integration of VDR genome wide binding and GWAS genetic variation data reveals co-occurrence of VDR and NF-κB binding that is linked to immune phenotypes

Background

The nuclear hormone receptor superfamily acts as a genomic sensor of diverse signals. Their actions are often intertwined with other transcription factors. Nuclear hormone receptors are targets for many therapeutic drugs, and include the vitamin D receptor (VDR). VDR signaling is pleotropic, being implicated in calcaemic function, antibacterial actions, growth control, immunomodulation and anti-cancer actions. Specifically, we hypothesized that the biologically significant relationships between the VDR transcriptome and phenotype-associated biology could be discovered by integrating the known VDR transcription factor binding sites and all published trait- and disease-associated SNPs. By integrating VDR genome-wide binding data (ChIP-seq) with the National Human Genome Research Institute (NHGRI) GWAS catalog of SNPs we would see where and which target gene interactions and pathways are impacted by inherited genetic variation in VDR binding sites, indicating which of VDR’s multiple functions are most biologically significant.

Results

To examine how genetic variation impacts VDR function we overlapped 23,409 VDR genomic binding peaks from six VDR ChIP-seq datasets with 191,482 SNPs, derived from GWAS-significant SNPs (Lead SNPs) and their correlated variants (r² > 0.8) from HapMap3 and the 1000 genomes project. In total, 574 SNPs (71 Lead and 503 SNPs in linkage disequilibrium with Lead SNPs) were present at VDR binding loci and associated with 211 phenotypes. For each phenotype a hypergeometric test was used to determine if SNPs were enriched at VDR binding sites. Bonferroni correction for multiple testing across the 211 phenotypes yielded 42 SNPs that were either disease- or phenotype-associated with seven predominately immune related including self-reported allergy; esophageal cancer was the only cancer phenotype. Motif analyses revealed that only two of these 42 SNPs reside within a canonical VDR binding site (DR3 motif), and that 1/3 of the 42 SNPs significantly impacted binding and gene regulation by other transcription factors, including NF-κB. This suggests a plausible link for the potential cross-talk between VDR and NF-κB.

Conclusions

These analyses showed that VDR peaks are enriched for SNPs associated with immune phenotypes suggesting that VDR immunomodulatory functions are amongst its most important actions. The enrichment of genetic variation in non-DR3 motifs suggests a significant role for the VDR to bind in multimeric complexes containing other transcription factors that are the primary DNA binding component. Our work provides a framework for the combination of ChIP-seq and GWAS findings to provide insight into the underlying phenotype-associated biology of a given transcription factor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3481-4) contains supplementary material, which is available to authorized users.

Long-term association between the dietary inflammatory index and cognitive functioning: findings from the SU.VI.MAX study

PURPOSE

Inflammation is a ubiquitous underlying mechanism of the links between diet and cognitive functioning. No study has yet evaluated the overall inflammatory potential of the diet, using the dietary inflammatory index (DII), in relation to cognitive functioning. In a French cohort of middle-aged adults, we evaluated the association between the DII, assessed in midlife, and cognitive performance evaluated 13 years later.

METHODS

The DII is a literature-derived dietary index developed to determine the inflammatory potential of diet. The DII was estimated at baseline (1994-1996) among 3080 subjects of the SU.VI.MAX (supplementation with antioxidant vitamins and minerals) cohort. Cognitive performance was assessed in 2007-2009 via a battery of standardized neuropsychological tests. Principal component analysis was performed to extract a summary score of cognitive performance. Multivariable-adjusted linear regression analyses were performed to provide regression coefficients and 95 % confidence intervals (95 % CI).

RESULTS

In a multivariate model, a strong inverse association was observed between a higher DII (reflecting a more inflammatory diet) and overall cognitive functioning (mean difference Q4 vs. Q1 = -1.76; 95 % CI = -2.81, -0.72, P for trend =0.002). With regard to specific cognitive domains, similar associations were observed with scores reflecting verbal memory, but not executive functioning.

CONCLUSION

This study suggests that a pro-inflammatory diet at midlife might be associated with subsequent lower cognitive functioning. A diet exhibiting anti-inflammatory properties may help to maintain cognitive health during aging.

CLINICAL TRIAL REGISTRATION

Clinicaltrials.gov (number NCT00272428).

Vitamin D Status Is an Independent Risk Factor for Global Cognitive Impairment in Peritoneal Dialysis Patients

Objective

Vitamin D (VD) deficiency is an independent risk factor for cognitive impairment (CI) in the general population, but VD status in peritoneal dialysis (PD) patients has not been investigated. In this study, we aimed to investigate the relationship between serum VD levels and global and specific cognitive functions in PD patients.

Design and Setting

Cross-sectional study, simultaneously conducted at two PD centers.

Patients

Clinically stable patients (n = 273) undergoing PD for at least 3 months were enrolled over a period of one year.

Main outcome Measures

Demographic and comorbidity data were recorded, and routine biochemical parameters and serum 25-hydroxyvitamin D (25(OH) D) levels of overnight fasted patients were determined. Global cognitive function was assessed by the Modified Mini-Mental State Examination (3MS) score; executive function, by the trail making tests (Trails A and B); and immediate memory, delayed memory, and language ability by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) sub-tests.

Results

In the univariate analysis, serum 25(OH) D levels significantly correlated with 3MS scores (r = -0.139; P = 0.02), and Trail A (r = -0.188; P = 0.002) and B (r = -0.154; P = 0.01) completion times. In the multivariate analysis, 25(OH) D was found to be independently associated with global CI, but not with executive dysfunction. Serum 25(OH) D could not predict scores of immediate/delayed memory and language ability.

Conclusions

VD deficiency is highly prevalent in PD patients and is an independent risk factor for global CI in this patient cohort.