The Immune System May Act as a Piece in the Autism Puzzle

By AnnElise Hatjakes, M.A.

Since the Centers for Disease Control first released figures on the prevalence of autism in 2007, diagnoses for autism spectrum disorders (ASD) have increased by 78 percent. Heightened awareness about the disorder and diagnostic changes account for much of this increase, but scientists are still searching for an answer to why so many new cases of autism spectrum disorders are being identified every year.  One theory ties this increase to inflammatory diseases, which have also increased in recent years.

An editorial in the New York Times by Moises Velasquez-Manoff asserts that “At least a subset of autism—perhaps one-third, and very likely more—looks like a type of inflammatory disease.  And it begins in the womb.”

Immunity, Inflammation and Autism:  What’s the Connection?

According to neuroimmunity expert Dr. Paul H. Patterson, the number of cases of autism related to inflammatory disease depends on the immune state that one specifies.  However, Patterson said, “It’s certainly fair to say that there’s immune dysregulation in a significant fraction of autism cases.”  He added that he would not want to put a specific number on it, though.

Both autoimmune and inflammatory diseases result from abnormal immune system reactions. Patterson and his team at Caltech have been examining how this type of immune dysregulation contributes to neurological disorders like autism and schizophrenia.  In his blog, Patterson wrote, “While there is clear evidence that inflammatory processes are involved in autism, both from post-mortem brain studies showing inflammation, from elevated cytokines in cerebral spinal fluid from living subjects, and from abnormalities in the peripheral immune system, we don’t really know if autism falls into the category of an autoimmune disorder.”

Patterson (pictured right) and his team are currently conducting  research to help concretely determine whether or not autism is an autoimmune disorder, which would help scientists to identify preventative care and treatment methods for autism.

In the article titled “An Immune Disorder at the Root of Autism,” Velasquez-Manoff explains that the increase in inflammatory diseases in general could be attributed to something called the “hygiene hypothesis.”  According to this theory, sterilizing everything in a child’s environment does not necessarily improve his or her health.

“The hygiene hypothesis suggests that we should allow our kids to get dirtier and crawl around on floors,” Patterson said.  “Also, it would suggest less frequent use of antibiotics.” Patterson said that most information he is aware of is consistent with the idea that the cleaner the environment at a very young age, the increased frequency of immune-related problems, but added that there is not currently enough clinical evidence to support this idea.

Prior to Velasquez-Manoff’s article being published, few people were aware of the connection between autism and immunity dysregulation.  Patterson explained that “getting these issues out to the public is tremendously important.  People should be aware of the impact of maternal infection.”

Autism and Immunity Research—What’s Next?

According to Patterson, one of the issues with studying autism is that this disorder is phenotypically very diverse.  “You can hardly expect that people will show up with the same immune dysregularities.”  Consequently, it’s important that researchers subdivide the population of autistic individuals they’re studying based on their dysregularities.

Antonio Persico, M.D., an associate professor at Campus Bio-Medico University in Rome, Italy, is doing just that.  Persico, who runs an outpatient autism clinic at the same institution, conducted a study wherein he subdivided autistic patients based on an extensive questionnaire.  He came up with interesting results–one subset of cases (18 percent) was immune related.

Similarly, Patterson hopes to subdivide autistic individuals into groups that share immune problems. “Then you could test therapies on these subgroups rather than the entire population,” Patterson said.  “There’s no therapy that will work on the entire diverse population.”

What Should You do if You Are Pregnant?

According to Velasquez-Manoff’s article, “A population-wide study from Denmark spanning two decades of births indicates that infection during pregnancy increases the risk of autism in the child.”  This study was corroborated by Patterson’s research, which indicates that pregnant mice who were given a viral mimic that triggered an immune response in the mother had offspring that exhibited autism-like behaviors.

If autism does in fact begin in the womb because of immune dysregulation, you may be wondering what you can do to prevent it.  Patterson offered some pragmatic advice to women who are pregnant like staying away from others who are sick.  Velasquez-Manoff suggests that pregnant women take a probiotic since “many of which have anti-inflammatory properties…”.  Patterson said that the use of probiotics to prevent immune disorders is a hypothesis.  However, he explained that people need their microbiome (the makeup of microorganisms in the body) to keep their immune system healthy.

“I’m sure that is relevant to humans, but you need the appropriate microbiome, not just any old bacteria,” Patterson said.  “Probiotic therapy is something that a lot of people are interested in, ourselves included.”

Autism and Gastroenterology

In 2006, Professor Glenn Gibson at the University of Reading in the United Kingdom performed a study in order to see if probiotics could be used as a treatment for children who have been diagnosed with autism.  His study included 40 autistic children aged between four and eight.  Half were given the bacterium Lactobacillus plantarum and half were given a placebo.  Parents were told to keep a journal of their child’s behavior, and the parents of children taking the probiotics noticed a marked improvement.

However, many children dropped out of the study before Gibson could perform the rest of the crossover study because, “Some of the parents worked out that their child was on the [probiotic] and didn’t want to move on to the placebo because they were seeing some positive results.”  So, the study was deemed statistically insignificant with results that were inconclusive.

Compared to typical children, children with autism often have more gastrointestinal problems.  In a study published in 2011 by James B. Adams, Ph.D., researchers assessed the gastrointestinal flora and gastrointestinal status of 58 children with autism spectrum disorders.  They found that gastrointestinal symptoms were strongly correlated with the severity of autism.  According to the study’s conclusion published in the journal, BMC Gastroenterology, “The strong correlation of gastrointestinal symptoms with autism severity indicates that children with more severe autism are likely to have more severe gastrointestinal symptoms and vice versa.  It is possible that autism symptoms are exacerbated or even partially due to the underlying gastrointestinal problems.”