Gut disorders and autism: A new consensus statement

ResearchBlogging.orgOne of the key claims of the “autism biomedical” movement is that something about autism derives from or is exacerbated by the gut; i.e., that there is some sort of link between GI problems, particularly inflammatory diseases of the GI tract, and autism. Although I may not be as versed in the history of this claim as I could be, as far as I can tell, even if this idea didn’t originate with Andrew Wakefield, he certainly did a lot to popularize it. Indeed, a common misconception about his misbegotten 1998 Lancet paper that launched the anti-MMR anti-vaccine movement in the U.K. is that it claimed that there was a link between autism. In reality, its claim was that the MMR vaccine was somehow connected with what he considered to be a novel syndrome of bowel disease and autism associated with MMR vaccination that has been referred to as “autistic enterocolitis.”

Of course, Wakefield’s study showed nothing of the sort and has since been thoroughly discredited, but the idea lives on. Since then, science doesn’t support the concept that there is some sort of unique GI syndrome associated with autism (indeed, “autistic enterocolitis” is a made up syndrome–made up by Wakefield), and it has been very controversial whether autistic children suffer from more GI complaints than neurotypical children. However, in the “autism biomed” world, regardless of whether there is an increased incidence of GI problems in autistic children, the concept of “autistic enterocolitis” is a concept that’s launched a thousand quacks (at least) and continues to support a cottage industry of quackery involving supplements, special diets, and “detoxification” regimens. Indeed, Jenny McCarthy thoroughly embarrassed herself trying to explain the rationale for “biomed treatments” and gluten-free diets, so much so that the video is no longer on the Generation Rescue website after it became the subject of mockery throughout the blogosphere. Moreover, she’s made some rather amazing claims for using diet to treat her son Evan, even going so far as to assert in one interview:

You know, I could in two months turn Evan completely autistic again. I could do it completely through diet. And maybe getting some vaccine boosters. Through diet, I could load him up again with all the things that will aggravate the damage that was done. Right now, what happened now was that I healed him to the point where he got everything back to this baseline level and it stays there like this. But I mess with it at all–boom!

The idea that diet can cure or provide significant relief to autistic symptoms is a seductive one. Note how McCarthy proclaims herself in total control over her son’s autism, so much so that she believes that she could make him autistic again if she lets up for one minute with the woo. A lot of parents also think the same thing, even though a recent Cochrane review of the literature concluded:

In the first version of this review we argued that exclusion diets are not without cost in terms of inconvenience and extra financial cost and limitations on foods of choice for the affected family member and that we could not recommend their use as a standard treatment on the basis of the limited data available. The only trial identified since the first review shows no significant difference between the intervention and control group and, again, we cannot recommend these exclusion diets as standard treatment.

And a recent randomized clinical trial of a gluten-free, casein-free diet (the most common diet autism biomed adherents recommend for autism) concluded:

This study tested the efficacy of a gluten-free and casein-free (GFCF) diet in treating autism using a randomized, double blind repeated measures crossover design. The sample included 15 children aged 2-16 years with autism spectrum disorder. Data on autistic symptoms and urinary peptide levels were collected in the subjects’ homes over the 12 weeks that they were on the diet. Group data indicated no statistically significant findings even though several parents reported improvement in their children. Although preliminary, this study demonstrates how a controlled clinical trial of the GFCF diet can be conducted, and suggests directions for future research.

Moreover, such diets are not without their potential costs. First, there’s the monetary cost, but more importantly such diets may not be entirely benign. Last year, one study linked such diets with cortical bone loss in boys with autism or autism spectrum disorder (ASD). Still, parents put a lot of stock in these diets and swear by them based on anecdotal evidence. Clearly they spend a lot of money on them. Worse, the concept of autistic enterocolitis has become all wrapped up with anti-MMR hysteria, the idea being that somehow the measles virus in the MMR vaccine causes bowel inflamation that leads to some sort of immune response that leads to autism, and many of the “treatments” for this disorder involve “detoxification” to “reverse vaccine injury.” Of course, this concept would take a severe blow if it were shown that children with autism and ASDs don’t have an incidence of GI problems any higher than that of neurotypical children, and that all these special diets don’t do anything.

Given the controversy and the number of autistic children being “treated” with such diets, an expert panel was convened recently to review the scientific evidence about GI symptoms, autism, and ASDs. Despite the hijacking of a legitimate scientific question by the anti-vaccine autism biomed movement, it’s important to know if there really is an association between ASDs and GI complaints or not, and in fact there has been a fair amount of research on this question. This research is what the expert panel reviewed, and the result were two articles, one providing consensus recommendations for how to diagnose and treat children with autism or ASD who present with bowel complaints, and the other being a consensus report on the evaluation, diagnosis, and treatment of GI disorders in children with ASDs. The consensus recommendations basically involve the relatively uncontroversial adaptation of standard of care guidelines for various pediatric GI complaints to children with ASDs. It is the consensus statement that is likely to cause controversy.

For example:

The existence of a gastrointestinal disturbance specific to persons with ASDs (eg, “autistic enterocolitis”) has not been established.

And:

In summary, published reports have not established the presence of a unique gastrointestinal pathophysiology specific to ASDs.

The above statements may seem wishy-washy, but in “consensus statement speak” this is about as strong as language gets. It’s a ringing denunciation of the concept of “autistic enterocolitis” as there is. Even more ringing a rebuke to Wakefield is a quote by Dr. Timothy Bule, the study’s lead author, in which he pointed out (quite correctly, from my observation) that researchers and doctors have avoided discussing and studying digestive issues in autism because of their connection with Wakefield’s utterly discredited research, the anti-MMR fear mongering promoted by the anti-vaccine movement, and the gross quackery associated with them. Scientists are understandably reluctant to get involved with a field so steeped in pseudoscience and quackery, lest their reputations suffer as a result or they become subjects of campaigns of demonization and harassment if they don’t find the reults that the anti-vaccine biomed movement wants.

Here’s another one of the conclusions of the consensus panel:

Available research data do not support the use of a casein-free diet, a gluten-free diet, or combined gluten-free, casein-free (GFCF) diet as a primary treatment for individuals with ASDs.

Few studies have examined the effects of a casein-free diet, a gluten-free diet, or combined GFCF diet on the behavior of individuals with ASDs. To our knowledge, only 1 double-blind placebo-controlled study has been published to date.46

In this double-blind crossover trial of GFCF or typical diet in 15 children with ASDs, there were no differences in measures of severity of ASD symptoms, communication, social responsiveness, and urinary peptide levels after 12 weeks.46 Nevertheless, after being informed of the results, 9 parents wanted to continue the diet and reported positive subjective clinical changes while their child was on the GFCF diet. Study limitations included the small sample size and heterogeneity, concerns about compliance and possible dietary infractions by study subjects, and lack of a direct observational outcome measure.

In other words, the quality of evidence available is not very high, with only one randomized, double-blind study, but what evidence is out there does not support the efficacy of these diets for relieving or decreasing autistic symptoms.

Finally, the panel didn’t take a firm stand on whether children with ASDs have a higher rate of GI complaints:

The prevalence of gastrointestinal abnormalities in individuals with ASDs is incompletely understood.

The reported prevalence of gastrointestinal symptoms in children with ASDs has ranged from 9% to 70% or higher (Table 4). 13,16-25 Prospective descriptive reports from autism clinics have described significant gastrointestinal symptoms in at least 70% of patients,22 data that might reflect a referral bias. In contrast, secondary analysis of a UK database indicated that the prevalence of gastrointestinal symptoms was no different in children with ASDs compared with children without ASDs (9%) at the time of their initial ASD diagnosis.

The panel suggested that multicenter prospective studies are needed using validated instruments and accepted outcome measures in people diagnosed with ASD using established and accepted methods and using appropriate control groups. It’s hard not to agree that more research isn’t needed in this particular area, but it’s important to make sure that the research is highly rigorous and not of the quality performed by someone like, say, Wakefield. There indeed may be something to the contention that autistic children with gut issues may not be able to communicate their distress and instead act out or increase repetitive behaviors.

Oddly enough, Generation Rescue through its anti-vaccine crank blog Age of Autism promoted surprisingly benign characterizations of the new consensus statement by groups normally associated with anti-vaccine quackery, such as the Autism Research Institute (home of DAN! quackery) and the National Autism Association. Of course, these commentaries were clearly self-serving in that they all utterly ignored the report’s dismissal of Andrew Wakefield’s findings, strongly downplayed the statements not recommending the use of gluten-free casein-free diets, given that such diets are the mainstays of DAN! doctors. On the other hand, it’s not too hard to see why they would like the recognition that autistic children can have bowel problems, and that autistic children with bowel symptoms should be treated and researched. Clearly these statements appealed to these groups, for obvious reasons. Of course, it’s highly ironic that these groups would be so pleased. As Kev said, TACA and other autism groups probably could have had a report like this several years ago if they hadn’t been so vociferously promoting Andrew Wakefield’s quackery for so long. Andrew Wakefield did autistic children a grave disservice by tainting the whole field of research into bowel issues in autistic children with the stench of his bad science, conflicts of interest, and even possible scientific fraud.

Not surprisingly, not everyone in the autism biomed movement is down with the new recommendations. Indeed, Jenny McCarthy, ever the dimmest of dim bulbs in the anti-vaccine movement and always willing to shoot off her mouth to reveal her ignorance, doesn’t like these at all. For some reason, ABC News thought it would be a good idea to interview her about the consensus statement, which strikes me as being about as useful as interviewing Deepak Chopra about quantum physics, only without the entertainment value. In any case, basically, she spewed the same old anecdote, most likely full of confirmation bias, just like the one I linked to above, saying:

We’re the ones seeing the real results, and until doctors start listening to our anectodal evidence, which is “this is working,” it’s going to take so many more years for these kids to get better.

I love it when Jenny says, “Until they [scientists and doctors] listen to our anecdotal evidence…” Jenny’s apparently too self-absorbed and dim to realize that scientists and doctors have listened to her anecdotal evidence and that of parents. That’s the reason they’ve bothered to do controlled studies to determine if there is anything to these anecdotes. It’s one reason why a consensus conference was put together to come up with an expert consensus on these issues. That’s one reason why they looked at the available science behind the issue. That’s why they went to all the work to write that consensus statement.

The stupid, truly it burns, and ABC News should be ashamed of itself for interviewing a crank like Jenny McCarthy about actual science.

From my perspective, it’s a very good thing that these consensus reports were released. The reason is simple. Besides providing evidence-based guidelines for treating bowel issues in autistic children, these reports begin the process of taking back these issues from quacks like DAN! doctors and Andrew Wakefield and bringing them back into the realm of science- and evidence-based medicine.

It’s about time.

REFERENCES:

  1. Buie, T., Campbell, D., Fuchs, G., Furuta, G., Levy, J., VandeWater, J., Whitaker, A., Atkins, D., Bauman, M., Beaudet, A., Carr, E., Gershon, M., Hyman, S., Jirapinyo, P., Jyonouchi, H., Kooros, K., Kushak, R., Levitt, P., Levy, S., Lewis, J., Murray, K., Natowicz, M., Sabra, A., Wershil, B., Weston, S., Zeltzer, L., & Winter, H. (2010). Evaluation, Diagnosis, and Treatment of Gastrointestinal Disorders in Individuals With ASDs: A Consensus Report PEDIATRICS, 125 (Supplement) DOI: 10.1542/peds.2009-1878C
  2. Buie, T., Fuchs, G., Furuta, G., Kooros, K., Levy, J., Lewis, J., Wershil, B., & Winter, H. (2010). Recommendations for Evaluation and Treatment of Common Gastrointestinal Problems in Children With ASDs PEDIATRICS, 125 (Supplement) DOI: 10.1542/peds.2009-1878D