Low Vitamin D Levels At Birth Linked to Schizophrenia in Adulthood

Welcome to Impact Factor, your weekly commentary
on the most interesting new medical studies. This week – a study appearing in Nature
Scientific Reports strongly suggests a link between Vitamin D levels at birth, and the
subsequent risk of schizophrenia. European countries with their decades-long
data collection on the entire population make great settings for epidemiologic research
as well as dystopian science fiction novels. Since 1981, Denmark has been collecting dried
blood spots on all newborns in the country. These biosamples, frozen in time, were then
linked to adult patients who had developed schizophrenia. The simple question – would Vitamin D levels
at birth be related to schizophrenia later in life. It’s not totally crazy. The same group had shown in an earlier study
that abnormal Vitamin D levels at birth – either too low or too high – were associated with
subsequent schizophrenia. This larger study attempted to reproduce those
findings. In any case, they identified 1,301 individuals
with schizophrenia and an equal number of age- and sex-matched controls. They then rehydrated those old dried blood
spots and measured Vitamin D levels. The figure tells the main story – 26% of
the individuals with schizophrenia were born with very low Vitamin D levels, only 20% of
the controls were. Even after adjustment for family history of
mental illness, age, sex, urbanization at birth, maternal and paternal age, gestational
age and birth weight, the finding persisted – low vitamin D: more schizophrenia. Is vitamin D to schizophrenia what folic acid
is to neural tube defects? The authors suggest as much, writing:
“These findings raise the tantalizing prospect that optimization of maternal vitamin D status
may result in the primary prevention of schizophrenia in a manner comparable to the role of folate
supplementation in the prevention of spina bifida.” OK – No. Let’s have some perspective. Folate supplementation decreased the rate
of neural tube defects by 72% in a large, randomized study. By the authors own calculation, only 8% of
cases of schizophrenia can be attributed to low neonatal Vitamin D levels, even assuming
low Vitamin D is causal. And, that’s the elephant in the room. Is it causal? Remember, Vitamin D is the lifestyle biomarker. Higher levels are associated with all sorts
of healthy behaviors, like being active, getting outside, eating a varied diet. Because of that, observational studies have
suggested that Vitamin D might protect against colon cancer, dementia, heart disease, and
virtually any other ill you can think of. But here’s the catch. Interventional studies, where individuals
are actually randomized to Vitamin D supplementation have almost all been underwhelming. That suggests that much of the signal we see
in studies like this are not due to Vitamin D per se, but the things that vitamin D levels
stand in for. The authors have called for a randomized trial
to figure out the Vitamin D – Schizophrenia link once and for all. These data support such a trial. But let’s not get our hopes too high. Not to be a downer, I’m just, you know,
reality testing.

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3 thoughts on “Low Vitamin D Levels At Birth Linked to Schizophrenia in Adulthood

  1. As a medical student these quick videos are great to catch up on new developments in the field, thanks again for all your work!

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