Mothers’ immune system responses could be a factor in causing autism, research from The Feinstein Institute for Medical Research in Long Island, New York suggests. The work represents the first large-scale study to examine antibodies in the mothers of children with autism. Research indicates that about one in ten mothers have antibodies that affect the brains of the gestating babies.

The study analyzed data from more than 2,700 mothers of children with autism. The results revealed that approximately 10% of mothers of children with autism have autoimmune antibodies that react with proteins found in their babies’ brains. These antibodies are deployed as an autoimmune response by the mother’s body. While they do not harm the mother’s brain, a fetus’ brain is susceptible because its blood-brain barrier is not sufficiently developed. This allows these “anti-brain” antibodies to enter the fetus’ brain, which may be a cause of autism.

The American Autoimmune Related Diseases Association, Inc. (AARDA) explains that for healthy people, the body’s immune system produces antibodies to attack foreign substances like a virus or a bacterium. However, people with autoimmunity have over-reactive immune systems that mistakenly identify the body’s own processes as threats. As a response, the immune system produces auto-antibodies that act against their own person. Since the auto-antibodies disrupt the body’s normal functions, they can lead to disease; the type of disease varies based on what the auto-antibodies attack. Approximately 50 million Americans have autoimmune disease—75% of them are women. Autoimmune disease is in the top ten leading causes of death for women under 65 years old.

Study leader, Dr. Betty Diamond, head of the Center for Autoimmune and Musculoskeletal Disorders at The Feinstein Institute commented that the study’s large sample size, “gives a clearer impression of the prevalence of these antibodies.” The AARDA commended Dr. Diamond’s work.

This research is published in the journal Molecular Psychology.

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