Vitamin D considerations for childhood disorders of learning, behavior and development

Evidence continues to accumulate regarding the important role of vitamin D in brain development and immune regulation. As such vitamin D is considered a neurosteroid. The authors of a paper published recently in the journal Psychoneuroendocrinology state:

"There is now clear evidence that vitamin D is involved in brain development."

The specific focus of their study is schizophrenia as a developmental disorder. This is of interest to all parents and clinicians because the same mechanisms may be involved for neurodevelopmental disorders on a lower end of the spectrum of intensity including problems of learning and behavior.

"The origins of schizophrenia are considered developmental. We hypothesised that developmental vitamin D (DVD) deficiency may be the plausible neurobiological explanation for several important epidemiological correlates of schizophrenia..."

The authors developed an animal model to study the effects of vitamin D deficiency on brain development that included removing vitamin D from the diet during gestation while being sure to maintain normal calcium levels. The effects were dramatic:

"The brains of offspring from DVD-deficient dams are characterised by (1) a mild distortion in brain shape, (2) increased lateral ventricle volumes, (3) reduced differentiation and (4) diminished expression of neurotrophic factors. As adults, the alterations in ventricular volume persist and alterations in brain gene and protein expression emerge. Adult DVD-deficient rats also display behavioural sensitivity to agents that induce psychosis (the NMDA antagonist MK-801) and have impairments in attentional processing."

The summarize their findings by stating:

"Our conclusions from these data are that vitamin D is a plausible biological risk factor for neuropsychiatric disorders and that vitamin D acts as a neurosteroid with direct effects on brain development."

The authors of a paper published in the FASEB Journal (The Journal of the Federation of American Societies for Experimental Biology) report their review of the scientific evidence for the link between vitamin D and brain dysfunction. The examination included:

"1) biological functions of vitamin D relevant to cognition and behavior; 2) studies in humans and rodents that directly examine effects of vitamin D inadequacy on cognition or behavior; and 3) immunomodulatory activity of vitamin D relative to the proinflammatory cytokine theory of cognitive/behavioral dysfunction."

The data over a wide range of topics was mixed, but the overall weight of evidence significant:

"We conclude there is ample biological evidence to suggest an important role for vitamin D in brain development and function...While mechanistic and biological evidence strongly suggests that calcitriol is involved in brain development and critical brain functions, it has proved more difficult experimentally to demonstrate obvious effects of vitamin D inadequacy on cognitive or behavioral endpoints...Despite residual uncertainty, we believe the evidence overall suggests that supplementation to ensure adequacy is prudent..."

Consider also a paper published a few months ago in Acta Neurologica Scandinavica that further examines the role of vitamin D in the central nervous system:

"Epidemiological and experimental evidence suggest that vitamin D deficiency is a risk factor for multiple sclerosis and other autoimmune diseases...Hypovitaminosis D is also associated with several other neurological diseases that is less likely mediated by dysregulated immune responses, including Parkinson’s disease and Alzheimer’s disease, schizophrenia and affective disorders, suggesting a more diverse role for vitamin D in the maintenance of brain health."

Moreover...

"...both the vitamin D receptor and the enzymes necessary to synthesize bioactive 1,25-dihydroxyvitamin D are expressed in the brain, and hypovitaminosis D is associated with abnormal development and function of the brain."

They offer insight into why studying the effects of vitamin D in the brain may not be as simple as presumed—specifically the difference between the levels in peripheral blood and intrathecal levels (in the cerebrospinal fluid around the spinal cord and brain):

"We here review current knowledge on the intrathecal vitamin D homeostasis in heath and disease, highlighting the need to assess vitamin D in the intrathecal compartment."

What other evidence is there for a link between low levels of vitamin D and psychiatric diagnoses? A recent paper published in The Journal of Steroid Biochemistry and Molecular Biology examines the association between low vitamin D and psychiatric diagnoses in a group of Swedish patients. For 117 subjects serum 25-hydroxy-vitamin D (25-OHD) and plasma intact parathyroid hormone (iPTH) was collected, together with demographic data and psychiatric diagnoses.

"Their median 25-OHD was considerably lower than published reports on Swedish healthy populations. Only 14.5% had recommended levels...Patients with ADHD had unexpectedly low iPTH levels...having a diagnosis of autism spectrum disorder or schizophrenia predicted low 25-OHD levels. Hence, the diagnoses that have been hypothetically linked to developmental (prenatal) vitamin D deficiency, schizophrenia and autism, had the lowest 25-OHD levels in this adult sample, supporting the notion that vitamin D deficiency may not only be a predisposing developmental factor but also relate to the adult patients’ psychiatric state."

And their data yielded another very relevant observation:

"This is further supported by the considerable psychiatric improvement that coincided with vitamin D treatment in some of the patients whose deficiency was treated."

But how prevalent is vitamin D deficiency among American children? A paper published in the journal Pediatrics last year should serve as a reminder to both parents and doctors. The authors set out to...

"...determine the prevalence of 25-hydroxyvitamin D (25[OH]D) deficiency and associations between 25(OH)D deficiency and cardiovascular risk factors in children and adolescents."

What did the data show? Even using a low reference range thatand is presently considered too low by most labs and has been updated:

"Overall, 9% of the pediatric population, representing 7.6 million US children and adolescents, were 25(OH)D deficient and 61%, representing 50.8 million US children and adolescents, were 25(OH)D insufficient."

Even by outdated standards that amounts to 70% of the pediatric population in the US. Hence their conclusion:

"25(OH)D deficiency is common in the general US pediatric population and is associated with adverse cardiovascular risks."

We can see from the above that the risks include brain health and development as well. How do you find out if your child's (and your) vitamin D level is sufficient? Since individual genetic and circumstantial needs can vary so greatly, taking out the guesswork with a serum 25(OH)D (25-hydroxy vitamin D) test is best.