In addition to genotype, prenatal factors such as vitamin D deficiency during pregnancy, can influence the development of ADHD, according to Minna Sucksdorff, MD, from the University of Turku in Finland. The Turku team, in collaboration with Columbia University in New York, published a study (“Maternal Vitamin D Levels and the Risk of Offspring Attention-Deficit/Hyperactivity Disorder”), in Journal of the American Academy of Child and Adolescent Psychiatry, which reportedly is the first population-level research to demonstrate an association between low maternal vitamin D levels in early to mid-pregnancy and an elevated risk for diagnosed attention-deficit/hyperactivity disorder ADHD in the offspring.
The study included 1,067 children born between 1998 and 1999 diagnosed with ADHD in Finland and the same number of matched controls. The data was collected before the current national recommendation in Finland for the intake of vitamin D during pregnancy, which is 10 micrograms per day throughout the year.
“Recent evidence has highlighted the importance of vitamin D in 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,” write the investigators.
“In this nationwide population-based case-control study, 1,067 ADHD cases (born between 1998 and 1999 and diagnosed according to the International Classification of Diseases) and 1,067 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.
“There was a significant association between decreasing log-transformed maternal 25(OH)D levels and offspring ADHD both in the unadjusted analyses (odds ratio 1.65; 95% CI 1.33–2.05; p < .001) and in the analyses adjusting for maternal socioeconomic status and age (odds ratio 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).”
“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.”
The primary investigator, Andre Sourander, MD, PhD, says that, despite the recommendations, vitamin D deficiency is still a global problem. In Finland, for example, mothers’ vitamin D intake among several immigrant groups is not at a sufficient level.
“This research offers strong evidence that a low level of vitamin D during pregnancy is related to attention deficiency in offspring. As ADHD is one of the most common chronic diseases in children, the research results have a great significance for public health,” notes Sourander.
The study is part of a larger research project that aims to discover the connections between the mother’s health during pregnancy and ADHD in offspring. The goal is to produce information for developing preventative treatments and measures for identifying children with ADHD risk. The researchers used the Finnish Maternity Cohort (FMC) consisting of approximately 2 million serum specimens collected during the first and early second trimester of pregnancy.