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. 

Many facets of rheumatoid arthritis remain a mystery.
One of these unknowns is whether mothers with rheumatoid arthritis (RA) will pass the condition along to their children.
A new study published in the journal Neurology shows that while a genetic lineage of RA may not yet be certain, there may be a link between moms with RA and kids with epilepsy.
The study’s researchers concluded that children born to mothers with RA were 26 percent more likely to have epilepsy than children who had moms without the condition.
It was also noted that kids of fathers with RA did not appear to be at greater risk for developing epilepsy.

An increased risk

The study was supported by the U.S. National Institutes of Health, Danish Council for Independent Research, and Augustinus Foundation.

It focused on nearly 2 million children born between 1977 and 2008. The children were followed for an average of 16 years.
During that time, 31,491 of these children developed epilepsy, and 13,556 of these children had mothers who had RA. That group included mothers who had the condition when the child was born as well as those who were diagnosed with RA after their child’s birth.
The researchers said the children whose mothers had RA at the time of birth were up to 90 percent more likely to develop epilepsy than children whose mothers were never diagnosed with the disease.
Researchers noted that RA isn’t the only autoimmune disease that links offspring to epilepsy. Children who are born to mothers with multiple sclerosis are also at an increased risk for epileptic disorders.
Researchers pointed out that multiple sclerosis and epilepsy are both diseases that affect the brain while RA isn’t.

Looking for explanations

Why RA can increase the risk of epilepsy in children isn’t known yet.
In a press release, Dr. Ane Lilleore Rom, of Copenhagen University Hospital in Denmark, who was a lead author of the study, stated, “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,” she added, “but it could involve the production of maternal antibodies that could affect the unborn child.”
Later in the published statement, Rom added that “it is new knowledge that also offspring of mothers with rheumatoid arthritis seem to have an increased risk of developing epilepsy.”
According to the latest statistics, 1 in 26 Americans will develop epilepsy in their lifetime. In two-thirds of these people, the cause is unknown.

More than 1.3 million adults live with RA — a disease for which the cause is also unknown. It is noted that in both epilepsy and RA, that causative factors can include family history, genetics, environmental factors, trauma, and lifestyle.
It is worth noting that other research has been done linking epilepsy to other autoimmune disorders in adults — including RA.