DENVER – Maternal autoimmune disease might be a risk factor for the development of obsessive-compulsive disorder or tics or both in children.
Autoimmune disorders were present in 17.8% of the biological mothers of 107 children, average age 9.2 years, with a primary diagnosis of a tic disorder, OCD, or both. This is a substantially higher figure than the 5% prevalence of autoimmune disease typically cited in the general population of women, Dr. Tanya K. Murphy noted at the annual meeting of the American Neuropsychiatric Association.
Moreover, the prevalence of autoimmune disease was greater among the mothers of children considered to be likely cases of Pediatric Autoimmune Neuropsychiatric Disorders Associated With Streptococcus (PANDAS) than in the mothers of children who were considered unlikely to have PANDAS, according to Dr. Murphy, director of the Rothman Center for Pediatric Neuropsychiatry at the University of South Florida, St. Petersburg.
The hallmark of PANDAS is sudden and dramatic onset and fluctuating course of tics, OCD, or both in association with group A beta-hemolytic streptococcal infection. Forty children were deemed likely to have PANDAS. The prevalence of autoimmune disorders among their mothers was 25%, nearly twice the 13.4% figure among the mothers of children who had a tic disorder, OCD, or both and were unlikely to have PANDAS.
The most common maternal autoimmune diseases in this study were Hashimoto’s thyroiditis, with a prevalence of 11.9%; SLE, 3%; rheumatic fever, 3%; rheumatoid arthritis, 2%; and Graves’ disease, 2%.
The mechanism underlying the observed association between maternal autoimmune disease and pediatric neuropsychiatric disorders remains unknown. One hypothesis is that prenatal exposure to maternal immune activation and inflammatory cytokines could produce significant effects upon CNS development and behavior.
The PANDAS link suggests a genetic susceptibility to autoimmunity involving transmission of immune vulnerability and resistance genes. Group A strep is a potent inducer of inflammatory cytokines. One popular theory is that PANDAS arises because of molecular mimicry, with antibodies that are intended to attack group A strep targeting brain proteins instead.
It’s likely that innate immunity plays a role in PANDAS as well. In a second study Dr. Murphy presented at the meeting, she showed for the first time that elevated levels of soluble cluster of differentiation 14 (sCD14) are present at the same time as acute flares of neuropsychiatric symptoms in children with PANDAS. High levels of sCD14 are indicative of macrophage activation, a key component of innate immunity.
The work on maternal autoimmune disease could eventually open the door to new immunologic-based therapies for neuropsychiatric symptoms such as tics and OCD in young children. For example, in animal models of familial autoimmunity, interleukin-6 blockade diminishes pathologic behaviors in the treated offspring, the neuropsychiatrist noted.
Dr. Murphy’s studies are funded by the National Institutes of Health. She declared having no financial conflicts.