Vitamin D and the Brain: A Neuropsychiatric Perspective

Vitamin D Deficiency Does Not Affect Cognition and Neurogenesis in Adult C57Bl/6 Mice

Vitamin D deficiency is a global problem. Vitamin D, the vitamin D receptor, and its enzymes are found throughout neuronal, ependymal, and glial cells in the brain and are implicated in certain processes and mechanisms in the brain. To investigate the processes affected by vitamin D deficiency in adults, we studied vitamin D deficient, control, and supplemented diets over 6 weeks in male and female C57Bl/6 mice. The effect of the vitamin D diets on proliferation in the neurogenic niches, changes in glial cells, as well as on memory, locomotion, and anxiety-like behavior, was investigated. Six weeks on a deficient diet was adequate time to reach deficiency. However, vitamin D deficiency and supplementation did not affect proliferation, neurogenesis, or astrocyte changes, and this was reflected on behavioral measures. Supplementation only affected microglia in the dentate gyrus of female mice. Indicating that vitamin D deficiency and supplementation do not affect these processes over a 6-week period.

A randomized controlled trial of Vitamin D supplementation in Iranian patients with schizophrenia: Effects on serum levels of glycogen synthase kinase-3β and symptom severity

BACKGROUND

Growing evidence has shown that hypovitaminosis D is a risk factor for developing schizophrenia and comorbid conditions. Therefore, this study aimed to examine the effect of vitamin D supplementation on serum levels of vitamin D, metabolic factors related to insulin resistance (IR) and the severity of the disorder in patients with schizophrenia.

METHODS

Forty-eight chronic male patients with schizophrenia with vitamin D deficiency (≤20 ng/mL= (≤50 nmol/l) were selected and randomly assigned to vitamin D treatment and placebo groups. Subjects were supplemented for 8 weeks with vitamin D (2000 IU/day) or placebo.

RESULTS

Within-group comparison revealed that the vitamin D group had a significant reduction in waist circumference, Positive and Negative Syndrome Scale - total score (PANSS-TS), and glycogen synthase kinase 3 beta (GSK-3β) levels (P = .022, P = <.001 and P = .013, respectively). On the other hand, the placebo group showed a significant increase in the level of fasting serum insulin and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) (P = .003 and P = .003). The between-group comparison showed a significant difference in terms of PANSS-TS, GSK-3β, fasting serum insulin (FSI), and HOMA-IR (P = .022, P = .048, P = .013 and P = .014 respectively).

CONCLUSIONS

Among vitamin D deficient patients with schizophrenia, vitamin D supplementation may affect GSK-3 β, an important biomarker in schizophrenia and insulin resistance. In addition, vitamin D supplementation in such patients may reduce the disorder's symptom severity.

Maternal Plasma 25-Hydroxyvitamin D during Gestation Is Positively Associated with Neurocognitive Development in Offspring at Age 4-6 Years

BACKGROUND

Vitamin D is critical to embryonic neuronal differentiation and other developmental processes that may affect future neurocognitive function. However, observational studies have found inconsistent associations between gestational vitamin D and neurocognitive outcomes.

OBJECTIVES

We examined the association of gestational 25-hydroxyvitamin D [25(OH)D] with children's IQ at 4-6 y, and explored whether associations differed by race.

METHODS

This study used data from the CANDLE (Conditions Affecting Neurocognitive Development and Learning in Early Childhood) cohort. Between 2006 and 2011, CANDLE recruited 1503 women in their second trimester of healthy singleton pregnancies. Inclusion criteria for this analysis were gestation of ≥34 wk and availability of 25(OH)D and IQ data. Associations between second-trimester 25(OH)D plasma concentration and Stanford-Binet IQ scores in offspring at 4-6 y were examined using multivariable linear regression; interaction terms were used to explore possible effect modification by race.

RESULTS

Mean ± SD 25(OH)D concentration among 1019 eligible dyads was 21.6 ± 8.4 ng/mL, measured at a mean ± SD gestational age of 23.0 ± 3.0 wk. Vitamin D deficiency [25(OH)D < 20 ng/mL] was observed in 45.6%. Maternal 25(OH)D differed by race with a mean ± SD of 19.8 ± 7.2 ng/mL in Blacks sand 25.9 ± 9.3 ng/mL in Whites ( P  < 0.001). In adjusted models a 10-ng/mL increase in 25(OH)D was associated with a 1.17-point higher Full Scale IQ (95% CI: 0.27, 2.06 points), a 1.17-point higher Verbal IQ (95% CI: 0.19, 2.15 points), and a 1.03-point higher Nonverbal IQ (95% CI: 0.10, 1.95 points). We observed no evidence of effect modification by race.

CONCLUSIONS

Second-trimester maternal 25(OH)D was positively associated with IQ at 4-6 y, suggesting that gestational vitamin D status may be an important predictor of neurocognitive development. These findings may help inform prenatal nutrition recommendations and may be especially relevant for Black and other dark-skinned women at high risk of vitamin D deficiency.

Associations between vitamin D status in pregnancy and offspring neurodevelopment: a systematic literature review

CONTEXT

Vitamin D plays an important role in the development of the brain, which is one of the earliest fetal organs to develop. Results from epidemiological studies investigating associations between maternal levels of vitamin D during pregnancy and offspring neurodevelopment are mixed and inconclusive.

OBJECTIVE

This systematic review of studies that examined vitamin D levels in pregnancy and offspring neurodevelopment used 3 specific domains-timing of exposure during pregnancy trimesters, neurodevelopmental outcomes, and offspring age at assessment of outcomes-to determine whether vitamin D status in pregnancy is associated with offspring neurodevelopment.

DATA SOURCES

A search of the Embase, PsychInfo, Scopus, and The Cochrane Library databases in September 2017 and February 2018 identified 844 articles, of which 46 were retrieved for full-text assessment.

STUDY SELECTION

Eligibility criteria were used to select studies. All authors examined the studies, and consensus was reached through discussion. Results were divided according to the 3 domains.

DATA EXTRACTION

Authors examined the studies independently, and data from eligible studies were extracted using a modified version of the Cochrane data collection form. Using the modified Downs and Black checklist, 2 authors assessed the quality of the studies independently and were blinded to each other's assessment. Consensus was reached upon discussion and with the involvement of the third author.

RESULTS

Fifteen observational studies were included. Vitamin D in pregnancy was associated with offspring language and motor skills in young children. Associations persisted into adolescence, and results were not dependent on the timing of vitamin D exposure during pregnancy. No supplementation studies were identified.

CONCLUSIONS

There is some evidence that low vitamin D status in pregnancy is associated with offspring language and motor development, particularly in young children.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number CRD42017078312.

Low serum 25-hydroxyvitamin D concentrations in chronic insomnia patients and the association with poor treatment outcome at 2months

BACKGROUND

The association between low 25-hydroxyvitamin D [25(OH)D] and sleep disorder has been reported. We investigated whether serum concentrations of 25(OH)D are altered in chronic insomnia patients. The relationship between serum concentrations of 25(OH)D and the treatment outcome in patients at 2months was also investigated.

METHODS

In total, 181 chronic insomnia patients were consecutively recruited. All patients received pharmacotherapy for the treatment of chronic insomnia. Serum 25(OH)D concentrations were quantified by a competitive electrochemiluminescence protein binding assay. Treatment outcomes were defined as "response" versus "non-response", according to the change of the Pittsburgh Sleep Quality Index (PSQI). We also recruited 100 healthy subjects as a control group.

RESULTS

Fifty-four out of 181 (29.8%) patients met the criteria for non-response. Chronic insomnia patients had significantly lower 25(OH)D concentrations compared with healthy controls (23.01±9.18 vs 27.17±6.41ng/ml, P<0.001). Non-response patients also had significantly lower 25(OH)D concentrations than those with response. Vitamin D deficiency(25(OH)D concentrations<20ng/ml) was independently associated with a higher probability of treatment non-response at 2months (odds ratio 11.636, 95% confidence interval 3.966-34.142, P<0.001).

CONCLUSIONS

Measurement of serum 25(OH)D concentrations are probably useful for judging treatment outcomes of pharmacotherapy in chronic insomnia patients.

Clinical symptoms of psychotic episodes and 25-hydroxy vitamin D serum levels in black first-generation immigrants

OBJECTIVE

Dark-skinned immigrants have a higher risk for schizophrenia and other psychoses than other immigrants. The first British studies reported that first-generation immigrants (FGIs) from the Caribbean presented atypical psychoses. This study examines the characteristics of psychotic episodes in black FGIs to Canada.

METHOD

The charts of 18 FGIs from Africa and Haiti, extracted from a series of 20 black patients consecutively admitted to Psychiatry, were retrospectively reviewed regarding clinical features, diagnoses and vitamin D levels.

RESULTS

Young FGIs presented acute psychotic episodes with abrupt onset, florid positive symptoms, few negative symptoms and good evolution. The onset was more insidious in older FGIs. Overall, catatonia was very frequent (28%), and mood symptoms still more frequent (44%). No cognitive decline was observed during follow-up. Serum levels of 25-hydroxy vitamin D were in the insufficiency range. Supplementation at 1000 IU/day did not restore normal levels.

CONCLUSION

The clinical features of psychotic episodes in black FGIs are similar to those reported in dark-skinned FGIs to other countries. They are also observed in other immigrants and in non-immigrants. These atypical psychoses are possibly related to a recent vitamin D deficit. This hypothesis should be tested by clinical trials of sufficient vitamin D supplementation.

Prevalence of autism according to maternal immigrant status and ethnic origin

OBJECTIVE

To examine the rates of autism separately according to maternal immigrant status and ethnic origin in respect to the vitamin D insufficiency hypothesis.

METHOD

Articles were identified by electronic searches. Studies were selected when they analysed autism rates according to maternal immigrant status and/or ethnic origin using multivariate techniques.

RESULTS

This review gave further support to the association between maternal immigrant status and an increased risk of autism. The relationship with ethnic origin was more complex. Although the crude rates did not differ, multivariate analyses taking into account confounding factors found that black ethnicity was associated with an increased risk for autism. The risk was highly significant when considering the strict definition of autistic disorders as opposed to the large definition of other pervasive developmental disorders. The risk was also very significant for autism associated with mental retardation.

CONCLUSION

These results are consistent with the maternal vitamin D insufficiency hypothesis. Neurobiological studies are warranted to document the effect of maternal vitamin D insufficiency during pregnancy on the foetal brain and the window of vulnerability. This review stresses the importance of monitoring vitamin D levels in pregnant women, especially those who are immigrant, dark-skinned or veiled, and the urgency of randomized controlled trials.

Ethnic origin and increased risk for schizophrenia in immigrants to countries of recent and longstanding immigration

OBJECTIVES

Compare the risk for schizophrenia in immigrants to countries of recent and longstanding immigration. Compare prevalence and incidence rates in black subjects under different conditions.

METHOD

An electronic literature search was complemented by review articles and cross-references. Studies reporting standard diagnosis and incidence or prevalence rates were included.

RESULTS

Immigrants had an increased risk for schizophrenia in countries of longstanding immigration, but with lower risk ratios than in those of recent immigration. The risk was higher in black immigrants and the black population living in the United States. But incidence and prevalence rates in Africa and the Caribbean were similar to those of international studies.

CONCLUSION

Comparing the most recent generation of immigrants with descendants of previous ones may account for the lower risk ratios observed in countries of longstanding vs. recent immigration. Two neurobiological hypotheses are proposed to explain the epidemiological findings in black populations and in immigrants.