Mothers with chronic inflammatory and autoimmune diseases, such as multiple sclerosis, have a higher risk of having children with attention-deficit/hyperactivity disorder (ADHD), according to a Norwegian study.
The findings were reported in a study titled “Attention-Deficit/Hyperactivity Disorder in Offspring of Mothers With Inflammatory and Immune System Diseases” in the journal Biological Psychiatry.
ADHD, which is two to three times more frequent in boys than girls, stems from deficient development of the nervous system. One hypothesis is that maternal inflammation generates a harmful inflammatory response in the fetus’s central nervous system.
In the study, researchers investigated whether mothers with chronic inflammatory diseases are at higher risk of having children with ADHD.
The study covered millions of Norwegian children born between 1967 and 2008. Researchers defined ADHD patients as the 47,944 who received ADHD medication between 2004 and 2012. The remaining 2,274,713 individuals were the control group in the study.
Researchers confirmed previous studies’ findings that there were more boys in the ADHD group — 65.7% — than the control group — 50.9%. Also, parents of children with ADHD were younger and had less education than parents of those who were not medicated for ADHD.
The team found that within the ADHD children’s group, the frequency of mothers with inflammatory chronic diseases was higher. These diseases included multiple sclerosis, rheumatoid arthritis, type 1 diabetes, asthma, and hypothyroidism.
Maternal multiple sclerosis was associated with 80% higher odds of ADHD in children. In contrast, there was no association between maternal chronic hypertension, type 2 diabetes, and hyperthyroidism and ADHD in children.
Researchers suggested that abnormal exposure of the fetus to immune molecules produced by the mother may affect fetal brain development. “Subsequently, this exaggerated inflammatory response could harm the developing brain. Inflammatory mechanisms are believed to play a role in the pathogenesis of psychiatric disorders such as schizophrenia and autism, and similar mechanisms may be relevant for the development of ADHD,” the authors wrote.
Other explanations for the association between maternal chronic inflammatory diseases and children with ADHD include maternal medication used during pregnancy and genetic factors. Further insight into the factors that impact the development of the fetus’s nervous system is important for the prevention and treatment of ADHD, the researchers wrote.