Although it is established that the incidence of epilepsy is higher among individuals with autoimmune disorders — particularly those that directly affect the brain — a Danish study published in Neurology has specifically linked epilepsy risk among children to whether their mothers have rheumatoid arthritis (RA).
Earlier research, including a 2014 study by scientists at Boston Children’s Hospital, has linked epilepsy and autoimmune disorders. That prompted Ane Lilleøre Rom, PhD, of the Department of Obstetrics and Research Unit Women’s and Children’s Health, the Juliane Marie Centre, Copenhagen University Hospital, Rigshospitalet, and colleagues to explore the topic further.
They classified some 2 million Danish children born between Jan. 1, 1977, and Dec. 31, 2008, based on whether they were exposed to maternal or paternal RA, or not exposed to RA at all. They then tracked the incidence of epilepsy among the children for an average of 16 years.
Children exposed to maternal RA had an overall 26 percent higher risk of early- and late-childhood epilepsy than those who were not exposed, whereas paternal RA had no effect. Further, children whose mothers had clinical RA, meaning they had the condition at the time they gave birth, had a higher risk of early-childhood epilepsy than those whose mothers had preclinical RA, or RA that was diagnosed after childbirth.
Rom cautions that the total number of affected children is comparatively small and says the study’s key benefit is that it provides a tool for better understanding some of the mechanisms behind epilepsy.
“Though children exposed to maternal clinical RA were up to 90 percent more likely [than children who were not exposed] to develop epilepsy, ... this in absolute numbers translates to 3 percent of the children,” she explains. “Thus, 97 percent of the children born to mothers with clinical RA will not develop epilepsy.”
Rom is looking into whether other maternal autoimmune diseases increase the risk of epilepsy in children. Her research suggests additional avenues of investigation as well.
“The fact that paternal RA did not influence the risk of childhood epilepsy makes it more likely that there is a fetal environmental exposure resulting in an increased risk of epilepsy, rather than a heritable factor,” Russell C. Dale, MRCP, PhD, and J. Nicholas Brenton, MD, write in an editorial accompanying the Neurology study. “While therapies to treat maternal RA could conceivably be an alternative exposure factor that increases epilepsy risk, the fact that mothers with preclinical RA ... had offspring with an increased risk of epilepsy makes this less plausible.”