And the latest cause of autism is ...
A highly publicized claim that Mr. Clean may cause autism is as ridiculous as I've just made it sound. It also is the latest in disappointing journalism on the roots of a complex disease.
By Michael Yudell
Autism, the lifelong neurodevelopmental disorder marked by a range of social and communication impairments, has seen its share of reckless claims about causes and cures.
From the belief that the emotional coldness of the so-called refrigerator mother caused her child's autism to the fabricated science that vaccines were a trigger, such misbegotten ideas have, at best, offered only temporary hope to affected families, and, at worst, done incalculable harm to the public's health. Because scientists still know so little about autism's causes – almost certainly a complex combination of multiple factors – it should come as no surprise that claims based loosely or not at all on science continue to attract public attention.
At quick glance, a recent opinion article in the New York Times by writer Moises Velasquez-Manoff, claiming that "perhaps one-third, and very likely more" of autism cases look like a brain-damaging inflammatory disease caused by a parasite deficiency that "begins in the womb," offers interesting insight into the science of autism causation. Researchers around the world are hard at work trying to decipher the puzzle that is autism, and Velasquez-Manoff draws attention to some of their work.
But upon closer inspection the article's claims about the causes of autism and its possible treatments and cures are not an accurate reflection of the best state of the science, may generate widespread misinformation among a public impatient for answers, and should caution us about how to present ideas about a disorder that has witnessed the communication of so much bad information. (For me, this is more than just another blog post. The history of autism, and the impact of poor communication about the disorder to the public, is one of my research interests and the subject of a book that is in the works. A paper I led examining the challenges of communicating autism risk was just published online ahead of print in the journal Autism.)
If the commentary had simply claimed that research is examining the possibility that autism is a brain-damaging inflammatory disease and that it might be caused by a changing microbial environment to which humans are poorly adapted, there would be little controversy here. There is research around the world examining these very issues. But Velasquez-Manoff, a journalist who has a new book out this week titled An Epidemic of Absence: A New Way of Understanding Allergies and Autoimmune Diseases, makes claims that are inaccurate and in some cases simply untrue, leaving readers of one of the most distinguished opinion sections in the world with a false impression of autism causation and a possible cure.
The piece makes four interrelated claims:
First, it maintains that "at least a subset of autism—perhaps one-third, and very likely more—looks like a type of inflammatory disease." While it is true that scientists are increasingly researching the relationship between autism and inflammation, there is no consensus that a subset of autism is an inflammatory disease, certainly not one that accounts for one-third or more of cases. Instead, scientific articles on inflammation, immune function, and autism are more circumspect, referring, for example, to "accumulating evidence" of a relationship between these factors or suggesting "that localized brain inflammation and autoimmune disorder may be involved" in causing autism.
Second, Velasquez-Manoff asserts that the identification of brain cells "enlarged from chronic activation" means "there is finally a therapeutic target for a disorder defined by behavioral criteria." Sure, scientists are identifying genes that are associated with these inflammation-caused brain differences. But autism is a complicated and heterogeneous disorder, and it remains unclear whether autism-associated brain inflammation is itself a cause of the disorder or, rather, is caused by the disorder. This type of hope-raising exaggerates the chances for curing this still poorly understood condition; indeed, the idea of a "cure" is controversial in itself among some in the autism community. To be clear, a drug developed to target this brain change in autistic individuals may or may not have any effect on autism.
Third, the true culprit in all the immune dysfunction and inflammation at work in autism, according to this thesis, is that humans in the developed world, where sanitation and hygiene have altered our relationship to microbes and parasites, are now "prone to inflammatory disorders." Here Velasquez-Manoff is relying on the highly charged and very controversial idea in science known as the "hygiene hypothesis." It posits that various conditions, in this case autism, are thriving in our environment of dramatically decreased exposure to microbes and parasites. Velasquez-Manoff also suggests that "in environments that resemble the world of yore, the immune system is much less prone to diseases of dysregulation" (that is, diseases caused by a malfunctioning immune system).
Yet even those scientists investigating the hygiene hypothesis speak of it as, well, a hypothesis. That means we are still testing the idea and trying to figure out if, in fact, it is a viable explanation for disorders ranging from asthma, to eczema, and allergies. There is not yet and may never be either an explanation for autism that makes sense in the context of the hygiene hypothesis, or it may turn out that the hygiene hypothesis itself is bunk. Time will tell. At this point certainly, this is not yet a model to explain autism in the way Velasquez-Manoff believes.
For this hypothesis to make sense, there should be little to no autism in parts of the world without the level of sanitation and hygiene we see in autism-rich environments. Velasquez-Manoff claims to have that evidence, and that, "in a Cambodian population rife with parasites and acute infections, autism was nearly nonexistent." But neither the original article nor a list of sources that was belatedly published online provide a citation for this claim, so it cannot be verified. Moreover, research suggests that autism prevalence is similar worldwide (it varies considerably from survey to survey, but apparently not by geographic, ethnic, cultural, or socioeconomic factors).
Finally, and most controversially, Velasquez-Manoff claims that if you "fix the maternal dysregulation" that causes inflammation, "you've most likely prevented autism." This is an outrageous claim with absolutely no scientific support beyond some preliminary studies and an early (phase 1) research trial to which he refers. Keyword searches of autism paired with microbes, parasite(s), inflammation, and/or intestinal at clinicaltrials.gov, which is a reasonably comprehensive registry and results database of qualified research worldwide, reveals not even a handful of studies under way testing this claim.
I am also concerned, although I doubt this was his intention, that given the history of blaming mothers for autism, these latest claims have the potential to to make moms both guilt-ridden and blameworthy if they don't do their best to fix their allegedly dysregulated immune systems. As science blogger Emily Willingham has written in a pointed critique of Velasquez-Manoff's article, "anyone without a deeper understanding of immunology or autism could come away from reading this piece thinking that autistic children or pregnant women should immediately be exposed to parasitic worms and rolled around in dung as a cure."
Because there is still so much uncertainty around the disorder, claims made in places like the New York Times opinion pages can hold considerable sway and potentially cause confusion and frustration for parents and their children on the autism spectrum. You'd think that the Times would have done a better job researching Velasquez-Manoff's assertions before publishing a piece like this.
If someone wants to share ideas about what might cause autism or how it might be treated, that's great. But to frame preliminary ideas as the state of the field is both belittling to the scientists whose work it is to actually decipher this puzzling disorder and potentially harmful to the families who live with autism every day.
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