"Are Autism Diet Benefits Just a Placebo Effect?"
The first randomized controlled trial to put
a gluten-free, casein-free diet to the test for children with autism
reported significant improvements in attention problems,
less aloofness, fewer needs for routines and rituals,
and improved response to learning after a year on the diet,
whereas there was no significant difference
reported before and after in the control group.
Same with improvements in social and emotional factors:
significantly fewer problems with relationships with their peers,
less anxiety, more empathy, and more acceptance of physical contact,
but again, no significant changes reported in the control group.
Significantly fewer communication problems, too,
more facial expressions, better eye contact, more responsive,
and fewer things like meaningless word repetition in the diet group,
whereas no significant changes in the control group.
And in terms of cognitive factors and movement, after a year on the diet,
there was significant improvements in the ability
to judge dangerous situations, and expanded personal interests,
and lower likelihood of being inordinately restless or passive.
Now, the problem with this study
is that they relied mostly on parental report.
They asked parents questions like these before and after
the year-long trial to see if they detected any differences.
Why is that a problem?
I mean who better knows the day-to-day functioning
of children than their parents?
Yeah, they could have had some impartial observer come in
before and after to make assessments, you know,
blind to which group the children were in,
but those would just be like snapshots in time.
Who better than the parents to know what was going on with their children?
The problem is the placebo effect.
I mean here the parents are investing a great deal
of time and effort to maintain these strict diets.
I mean, there's wheat and dairy in so many products
that it's a big shift for most families,
and so they have this hopeful expectation of an effect.
So while the families in the control group did nothing special that year
and reported no significant changes before and after,
the families in the diet group put all this work in,
and so when asked if their kids appeared better,
their opinions may have been impacted by their expectations of benefit.
In other words, "placebo effects may have been at play."
Oh, come on, though, are parents that gullible?
Well, "the power of suggestion on the part of parents
can be very strong in situations affecting their children's behavior."
For example, there was this famous study in which all the children
were given a drink with artificial sweetener, but half of the parents
were told that the drink was sweetened with a boatload of sugar.
And the parents who thought their children had received the sugar drink
rated their own children's behavior as significantly worse.
So in these autism studies, it's possible that parents
were unconsciously looking for positive changes in behavior
and ignoring or explaining away negative changes.
So ideally what we need are double-blind studies,
where kids are given foods made to look and taste the same,
but one food has gluten and casein and the other doesn't.
The kids don't know which is which,
the parents don't know which is which.
Even the researchers, at first, don't know which is which,
until they break the code at the end.
In this way, the behaviors recorded after the food challenges
couldn't be impacted by preconceived ideas or biases.
OK, so why didn't this study do that?
"With regard to design," the researchers conceded,
"it might be argued that a double-blind study might have been ideal."
With all children on the diet, gluten and casein could have been
secretly administered, for example, in capsules
with wheat flour or powdered milk during specific altering periods.
Then parents and caretakers would have been blind
to who was still on the diet and who was, unbeknownst to them,
actually off the diet, secretly getting gluten and casein.
Then we could eliminate the placebo effect,
eliminate that expectation bias.
So why didn't they do it?
The researchers refused to do it because they were so convinced
that gluten and casein were harmful that from an ethical standpoint
they just couldn't bring themselves to give these kids gluten or casein.
The kids in the diet group seemed to be doing so much better,
and they had seen cases in which kids appeared to relapse
when those proteins were reintroduced back into their diet,
and so they just couldn't bring themselves to slip them any on the sly.
I understand that, but if they really were so certain
that gluten and casein were bad,
then by designing a less-than-ideal study,
they were potentially dooming scores of other children
by failing to provide the strongest possible evidence.
Thankfully, 4 years later, other researchers stepped in
and published the first double-blind clinical trial of diet and autism.
We'll find out what they found next.