Children whose mothers have rheumatoid arthritis (RA) – an autoimmune disease where the immune system attacks the joints – have an increased risk of developing childhood epilepsy, according to a study published in the scientific journal Neurology. The risk is not increased if it is the child’s father who has RA, which suggests that it may be changes in the environment inside the uterus that play a role rather than genetics.The first author of the study, Dr Ane Lilleore Rom, at Copenhagen University Hospital, said in a press release: “These results suggest that changes in the environment for the fetus may play a role in the development of epilepsy. We don’t know yet how this may work, but it could involve the production of maternal antibodies that could affect the unborn child.”The team performed a nationwide study that included almost two million children born in Denmark between 1977 and 2008. They followed the children for an average of 16 years and identified those who developed epilepsy and those whose parents had RA.The researchers then divided the children with epilepsy into four groups: those who developed the condition in early childhood (between 29 days and four years of age), those who developed it in late childhood (between 5 and 15 years of age), those who developed it in adolescence/adulthood (aged 15 years and above), and those who developed it at any age until the end of the follow-up period, which was 31 December 2010.In total 31,491 (1.6%) of the children followed developed epilepsy and 13,556 (0.7%) had a mother with RA. This included women with clinical RA (already diagnosed) and those with ‘preclinical’ RA (diagnosed after the birth). The results showed that children born to a mother with RA had a 34% and 27% increased chance of developing early and late childhood epilepsy, respectively, than children born to women without RA. The risk of developing epilepsy in adolescence or adulthood was not influenced by exposure to maternal RA. Looking at children exposed to RA in the womb (clinical RA), the researchers found that they had up to 90% more risk of developing epilepsy in early childhood than children whose mothers did not have RA. In cases where a mother had pre-clinical RA, the child was shown to have a 26% greater chance than an unexposed child of developing epilepsy in early childhood.*Paternal RA was not associated with a higher risk of epilepsy in the children at any age.According to Dr Rom, the increased epilepsy risk posed by preclinical RA suggests an important role for RA itself (rather than RA treatments) in epilepsy development. However, she notes that the specific influence of RA treatments requires further investigation.Over all, these results suggest that changes in the environment of the foetus caused by RA may play a role in the development of epilepsy. More work is needed to clarify the effect that RA has on the developing nervous system and the mechanism that associates it with epilepsy.*The actual figures are low: 3% of children whose mothers had clinical RA and 2% of children whose mothers had preclinical RA at the time of birth developed epilepsy. Click here for more articles about conditions related to epilepsy.Authors: Dr Özge Özkaya and Delphine van der Pauw