Children with autism are six to eight times more likely to suffer gastrointestinal upsets than children who are developing typically, say researchers from the University of California-Davis' MIND Institute.
And they say gastrointestinal (GI) upsets, including constipation, diarrhea and food sensitivity, are themselves related to behavioral problems, such as irritability, repetitive behavior and social withdrawal.
As many as 1 in 88 American children are diagnosed with an autism spectrum disorder, which includes autism, Asperger's and atypical autism, according to the Centers for Disease Control and Prevention (CDC). The organization says that boys are more likely affected than girls - 1 in 54 for boys, compared with 1 in 252 for girls.
Virginia Chaldez, lead author of the study, which was published in the Journal of Autism and Developmental Disorders, says:
"Parents of children with autism have long said that their kids endure more GI problems, but little has been known about the true prevalence of these complications or their underlying causes."
Tummy ache and bad behavior
Autism is characterized by social withdrawal and a reluctance to engage with people. Researchers are now linking symptoms to GI symptoms, including tummy upsets.
The research is the largest and most ethnically diverse study comparing tummy troubles in autistic children with developmental delay and typical development. It is also the first to explore the relationship between stomach upsets and problem behaviors.
But at the moment, the researchers are not sure which is the chicken and which the egg. As Chaldez explains:
"The GI problems they experience may be bidirectional. GI problems may create behavior problems, and those behavior problems may create or exacerbate GI problems. One way to try to tease this out would be to begin investigating the effects of various treatments and their effects on both GI symptoms and problem behaviors."
For the study, the parents of almost 1,000 children aged between 24 and 60 months who were enrolled in the Childhood Autism Risks from Genetics and the Environment (CHARGE) study in North Carolina completed two questionnaires.
The first questionnaire detailed GI health history (GIH) and covered stomach pain, diarrhea, constipation and difficulty swallowing. The second questionnaire, an abherent behavior checklist (ABC), detailed incidences of irritability, social withdrawal/lethargy, repetitive behavior, hyperactivity and inappropriate speech.
According to the researchers, approximately half the study population was white, with one-third Hispanic and the remainder from other ethnic or racial backgrounds.
GI testing for autistic kids
The researchers found that parents of autistic children were six to eight times more likely to report food sensitivities, bloating, constipation and diarrhea than the parents of children developing typically. It was also noted that children with developmental delays suffered five times as much constipation and were far more likely to report problems with swallowing.
It stands to reason that if you are suffering chronic GI symptoms, with the associated pain and discomfort, you are less likely to want to engage socially. This behavior is exacerbated in children lacking communication and social skills. And as the researchers point out, hyperactivity and repetitive behavior may be coping mechanisms for physical discomfort.
They claim that children with autism may benefit from a full GI evaluation, particularly if they lack verbal skills. For these children, it is possible that treatments that alleviate tummy troubles may lead to an improvement in problem behaviors.
Irva Hertz-Picciotto, principal investigator for the CHARGE Study and a researcher affiliated with the MIND Institute, says:
"After years of parents raising concerns about such symptoms, the huge differences we see between parental reports on children with autism spectrum disorder versus those on children with typical development puts to rest the idea that gastrointestinal problems among children with autism spectrum disorder are just an accumulation of case reports. Our data clearly show that gastrointestinal problems are very common in children with autism."
The researchers hope that a better understanding of the impact of GI problems will lead to more effective autism treatments that not only decrease GI upsets, but antisocial behaviors as well.
The relationship between autism and celiac disease has also been posed, but Medical News Today reported in September 2013 that Swedish researchers could not establish a link.