Maternal Vitamin D Levels and the Risk of Offspring Attention-Deficit/Hyperactivity Disorder

Sucksdorff M, Brown AS, Chudal R, Surcel HM, Hinkka-Yli-Salomäki S, Cheslack-Postava K, Gyllenberg D, Sourander A (2019) J Am Acad Child Adolesc Psychiatry. 60(1) 142-151.e2. doi: 10.1016/j.jaac.2019.11.021. Epub 2019 Dec 19.

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Abstract:

OBJECTIVE:

Recent evidence has highlighted the importance of vitamin D to the development of the central nervous system. Some studies have shown an association between maternal vitamin D deficiency during pregnancy and offspring Attention-deficit/hyperactivity disorder (ADHD) symptoms based on parent- or teacher ratings. There are no previous studies on early pregnancy 25-hydroxyvitamin D (25(OH)D) levels and the risk of diagnosed offspring ADHD. Our aim was to examine maternal 25(OH)D levels in early pregnancy and offspring ADHD.

METHOD:

In this nationwide population-based case-control study, 1067 ADHD cases born between 1998 and 1999 and diagnosed according to the International Classification of Diseases and 1067 matched controls, were identified from Finnish registers. Maternal 25(OH)D levels were measured using quantitative immunoassay from maternal sera, collected during the first trimester, and archived in the national biobank. Conditional logistic regression was used to examine the association between maternal 25(OH)D and offspring ADHD.

RESULTS:

There was a significant association between decreasing log-transformed maternal 25(OH)D levels and offspring ADHD both in the unadjusted analyses (OR 1.65, 95% CI 1.33-2.05, P<.001) as well as in the analyses adjusting for maternal socio-economic status and age (OR 1.45, 95% CI 1.15-1.81, P=.002). Analyses by quintiles of maternal 25(OH)D levels in the lowest versus highest quintile revealed an adjusted odds ratio for offspring ADHD of 1.53 (95% CI 1.11-2.12, P=.010).

CONCLUSION:

This study demonstrated an association between low maternal 25(OH)D during pregnancy and an elevated risk for offspring ADHD. If replicated in independent samples, this finding may have significant public health implications.

FAB RESEARCH COMMENT:

Many previous studies have linked low Vitamin D in pregnancy with the risk of ADHD (and related conditions) in the resulting children.

However, this is the first large-scale, population-based study to use a national register for formal ADHD diagnoses in the children, and then to link these with objective measures of maternal Vitamin D status taken from samples held in a national biobank.

This kind of approach is exemplary for research, as it eliminates potential confounds from so-called 'referral bias' (which can arise if the participants referred or invited to join a study may not be representative of the wider population); and also ensures that only the most definitive cases of 'ADHD' are included (rather than relying on parent and/or teacher ratings only, which may be less reliable).

Results showed that lower Vitamin D status in mothers during pregnancy was indeed linked with significantly higher risk for ADHD in their children - confirming previous similar findings from less rigoroous studies.

As the authors say: 'this finding may have significant public health implications' - but like all good researchers, they preface this with the cautionary note 'if replicated in independent samples'.

See the associated news article here:

Vitamin D deficiency during pregnancy connected to elevated risk of ADHD

For more information on the importance of Vitamin D in pregnancy and early life for children's brain development and mental health (and for their risk for allergies and immune disorders), see: