New research suggests that low levels of vitamin D in utero may be associated with increased risk of schizophrenia later in life. Schizophrenia is a debilitating mental illness that affects 2.4 million Americans. Decades of research have identified numerous risk factors for the condition, one of which is the observation that those born in the winter or spring have a small but significantly increased risk of developing schizophrenia.
Because sun exposure stimulates production of vitamin D in our bodies, deficiencies are more common during the winter and early spring. These convergent clues led researchers to develop the hypothesis that vitamin D deficiency during critical periods of development may be a risk factor for developing schizophrenia later in life.
This new study, featured in the Archives of General Psychiatry, aimed to examine the association of neonatal vitamin D status and incidence of schizophrenia. A total of 424 Danish individuals with schizophrenia and 424 controls (matched for sex and date of birth) were drawn from a large population-based cohort in Denmark. Neonatal blood samples were collected in 1981, and for each schizophrenia case identified through 2005, researchers analyzed the subject’s blood for vitamin D levels, and performed the same analysis among the blood samples of controls. They then grouped all subjects into five equally-sized groups based on their blood levels of vitamin D.
Researchers found that neonates with levels of vitamin D in the three groups with the lowest Vitamin D levels had a significantly increased risk of developing schizophrenia later in life. For these individuals, the risk of developing schizophrenia were double compared to those individuals in the fourth-highest Vitamin D level group. Unexpectedly, researchers also found that those with the highest levels of vitamin D (the fifth group) also had an increased risk compared to those falling within the fourth-highest group. Several variables, such as maternal, paternal and sibling history of mental illness were accounted for in evaluating these risk levels.
These findings imply that the nature of the relationship between neonatal vitamin D levels and schizophrenia may be non-linear; meaning, schizophrenia was associated with both low levels of vitamin D and high levels of vitamin D. At first glance, a relationship like this can be rather confusing, and more research is needed to clarify exactly what the optimal level of neonatal vitamin D is in utero. As we’ve seen in other studies, different health outcomes may be associated with different levels of vitamin D.
The results of this study should be interpreted with caution, but when reading a study like this one, it’s important to take a step back and consider the public health implications. If future research shows this “non-linear” relationship between vitamin D status and schizophrenia, then interventions and dosage recommendations will have to be tailored more specifically for pregnant women. Authors of the study note that there are several limitations to this study, but that does not negate the fact that they found an association. Currently there is no cure for schizophrenia, so preventative medicine is the most effective intervention.
The latest population-wide data confirms that there are widespread deficiencies amond people of all age groups and races, and low levels of vitamin D have increasingly been associated with various health complications, including neuropsychiatric conditions.
Vitamin D has been getting a lot of press lately, and pregnant are not, it may be time to get more of the sunshine vitamin.