Neurological disorders remain an area of research where scientists have just begun to scratch the surface to better understand how these debilitating diseases progress. Looking at previous clues from epidemiologic data led a team of researchers from Aarhus University, Denmark and the University of Queensland (UQ), Australia to confirm the hypothesis that prenatal vitamin D deficiency may increase the risk of schizophrenia later in life. Findings from the new study—published today in Scientific Reports through an article titled “The association between neonatal vitamin D status and risk of schizophrenia”—could prevent some cases of the disease, and shows that neonatal vitamin D deficiency could possibly account for about 8% of all schizophrenia cases in Denmark.
“Schizophrenia is a group of poorly understood brain disorders characterized by symptoms such as hallucinations, delusions, and cognitive impairment,” explains senior study investigator John McGrath, M.D., Ph.D., a professor at UQ and Aarhus University. “As the developing fetus is totally reliant on mother’s vitamin D stores, our findings suggest that ensuring pregnant women have adequate levels of vitamin D may result in the prevention of some schizophrenia cases, in a manner comparable to the role folate supplementation has played in the prevention of spina bifida.”
The current study, which was based on 2602 individuals, confirmed a previous study led by Dr. McGrath that also found an association between neonatal vitamin D deficiency and an increased risk of schizophrenia. The team made the discovery by analyzing vitamin D concentration in blood samples taken from Danish newborns between 1981 and 2000 who went on to develop schizophrenia as young adults.
“The concentration of 25 hydroxyvitamin D (25OHD) was assessed from neonatal dried blood samples. Incidence rate ratios (IRR) were calculated when examined for quintiles of 25OHD concentration,” the authors write. “In addition, we examined statistical models that combined 25OHD concentration and the schizophrenia polygenic risk score (PRS) in a sample that combined the new sample with a previous study (total n = 3464; samples assayed and genotyped between 2008-2013). Compared to the reference (fourth) quintile, those in the lowest quintile (<20.4 nmol/L) had a significantly increased risk of schizophrenia (IRR = 1.44, 95% CI: 1.12–1.85). None of the other quintile comparisons were significantly different. There was no significant interaction between 25OHD and the PRS.”
The research team noted that schizophrenia is associated with many different risk factors, both genetic and environmental, but their research suggests that neonatal vitamin D deficiency could possibly account for about eight percent of schizophrenia cases in Denmark.
“Much of the attention in schizophrenia research has been focused on modifiable factors early in life with the goal of reducing the burden of this disease,” Dr. McGrath states. “Previous research identified an increased risk of schizophrenia associated with being born in winter or spring and living in a high-latitude country, such as Denmark.
Interestingly, Dr. McGrath noted that although Australia had more bright sunshine compared to Denmark, vitamin D deficiency could still be found in pregnant women in Australia because of their lifestyle and sun-safe behavior.
“The next step is to conduct randomized clinical trials of vitamin D supplements in pregnant women who are vitamin D deficient, in order to examine the impact on child brain development and risk of neurodevelopmental disorders such as autism and schizophrenia,” Dr. McGrath concludes.