Maternal Vitamin D Deficiency Increases Risk of ADHD in Offspring

Andre Sourander, MD, PhD

Vitamin D deficiency during pregnancy was associated with an increased risk of ADHD in offspring, according to recent study findings.

Andre Sourander, MD, PhD, and a team of investigators included more than 1000 children born between 1998-1999 who were diagnosed with ADHD in Finland to learn the relationship between maternal vitamin D deficiency and the chronic disease.

The team found a significant association between decreasing log-transformed maternal 25(OH)D levels and offspring ADHD.

The findings may have public health implications for vitamin D supplementation and lifestyle changes during pregnancy to ensure optimal levels, the investigators reported.

Sourander, a professor of child psychiatry at the University of Turku in Finland, and colleagues included 1067 children diagnosed with ADHD and a control group. Data were derived from 3 registers in Finland: the Care Register for Health Care (CRHC), the Finnish Medical Birth Register, and the Finnish Central Population Register. Information included public and private inpatient diagnoses and comprehensive data on all newborns during the neonatal period up to 7 days of age.

Childhood ADHD cases were identified from the CRHC by using personal identification code. Patients in the control group were singleton offspring born in Finland without a diagnosis of ADHD.

The investigators matched each control to a case subject on sex, date, and place of birth.

Sourander and the team collected information in the number of previous births; maternal socioeconomic status; maternal age; self-reported smoking during pregnancy; gestational age; and weight for gestational age. The team also had information on maternal and paternal psychiatric diagnoses, ADHD diagnoses, and maternal diagnoses of substance use disorder.

First, the investigators examined the association of ADHD and maternal vitamin D defined as a continuous variable. Then, they examined the vitamin D categorized into quintiles. What’s more, the team looked at vitamin D as a three-class categorical variable based on clinical categories: deficient (25(OH)D <30 nmol/L), insufficient (25(OH)D 30-49.9 nmol/L), and sufficient maternal vitamin D levels (25(OH)D >50 nmol/L).

Children were 7.3 years old (mean age) at the time of their ADHD diagnosis. Median maternal vitamin D level among cases was 29.2 nmol/L (range: 8.9-115.6 nmol/L; Q1 = 21.5 nmol/L; Q3 = 41.7 nmol/L) and 32.2 nmol/L (range: 7.5-132.5 nmol/L; Q1 = 23.2 nmol/L; Q3 = 45.4 nmol/L) among controls.

Maternal age; socioeconomic status; self-reported smoking; psychopathology; substance abuse; ADHD diagnosis; immigrant status; number of previous births; and cotinine levels, along with paternal psychopathology and ADHD diagnosis and offspring gestational age and weight for gestational age were associated with offspring ADHD (P <.01).

Socioeconomic status, maternal age, and season of blood collection were associated with maternal 25(OH)D level (P <.01). Maternal age and socioeconomic status were associated with both offspring ADHD and maternal vitamin D level.

There was a significant link between decreasing log-transformed 25(OH)D levels and increasing risk of offspring in ADHD in the unadjusted (OR, 1.65; 95% CI, 1.33-2.05; P <.001) and adjusted analyses (OR, 1.45; 95% CI, 1.15-1.81; P = .002).

The findings were the strongest to link developmental vitamin D deficiency and offspring ADHD, the investigators reported. What’s more, the findings suggested that insufficient in utero vitamin D could adversely influence fetal programming and expose offspring to a suboptimal environment, resulting in possible ADHD.

The study, “Maternal Vitamin D Levels and the Risk of Offspring Attention-Deficit/Hyperactivity Disorder,” was published online in the Journal of the American Academy of Child & Adolescent Psychiatry.