"Double Blind Clinical Trial of Diet for Autism"
The first randomized control study of a gluten-free,
casein-free diet for autism found
that parents in the diet group reported
their kids did significantly better.
But, that could just be the placebo effect,
where parents attribute changes to the diet,
particularly since they’re putting so much work into it
that they may be biased towards seeing evidence
of success that may not actually be there.
Ok. So, what if you don’t just rely on parental report?
What if you do a blinded study
of a gluten and casein free diet?
The parents know what the kids are eating,
but you don’t just ask the parents how the kids are doing;
you have investigators objectively assess
all the kids without knowing who was in which group,
the diet group or the control group.
And, they found a significant beneficial effect
at 8, 12, and 24 months on core autistic behaviors
with a gluten and casein free diet.
And, this was one of the largest such studies ever done,
starting out with 73 children.
But, they didn’t end up with 73,
since about a fifth dropped out, mostly from the diet group.
If a family didn’t feel their child
was making strides on the diet,
they may have been more likely to drop out of the study,
thereby skewing the analysis towards those
in which the diet appeared to work better.
And so, the remarkable results they got
in terms of improved social interaction
and fewer ADHD-type symptoms
may have ended up exaggerating the effects of the diet,
since the kids for which it didn’t help
may have gotten disproportionately weeded out.
Also, because the parents were very much aware
whether they were in the diet group versus the control group—
because they were the ones cooking the meals—
they may have changed their own behavior towards their children.
Like in that famous sugar study
where mothers were lied to and told their children
had just received a whopping dose of sugar
(even though they hadn’t).
Not only did the mothers rate their children
as significantly more hyperactive,
they inadvertently changed their own behavior.
They were videotaped, and the mothers who falsely
believed their kids just got a load of sugar
exercised more control and were more critical;
so, their expectation of an effect
may have actually ended up having an actual effect
in changing their children’s behavior.
So, in these autism studies, here
the parents are upending their family’s diet,
hoping, expecting that their child will get better,
and maybe unconsciously treating them differently,
such that they end up behaving differently
when assessed later by the blinded investigators.
That’s why we need double blind studies
where no one knows who’s in the diet group,
who’s in the control group—
not the parents, not the kids.
So, why didn’t the researchers do it?
Why didn’t they secretly sneak some gluten or casein
into their diets to see if they got worse again?
Same excuse as before; it wouldn’t be ethical.
But, that’s pre-deciding the outcome;
that’s circular logic.
We can’t test to see if it really works,
because it may really work— but we can’t test that.
Finally, however, researchers at the University of Florida
broke through the impasse by performing a double-blind study.
Now, this is not an easy thing to do.
You have to provide all the meals and snacks,
so that the families remain clueless
as to whether they were randomized
into the gluten- and casein- free diet group
or were actually in the control group getting the same foods,
but with gluten and casein slipped in.
Then, after 6 weeks, they switched the foods
so the gluten-free casein-free group started getting wheat and dairy,
and the wheat and dairy control group
were covertly switched to gluten- and casein-free.
Before they broke the codes to see who was in which group,
the parents were asked as to whether they thought
their child was on the special diet
during the first or second 6 weeks,
and… five got it right, two had ‘‘no idea’’,
and six got it wrong.
In other words, no better than a flip-of-a-coin chance.
About half pretty much thought their kids
got better on the casein and gluten;
so, no statistically significant findings,
though several parents did report an improvement in their children,
claiming marked improvements in language,
decreased hyperactivity, and decreased tantrums,
so much so that a bunch of the parents decided
to keep the children on the diet
even though the researchers just told them that it didn’t work.
Look.
You don’t want to miss anything, though.
Some of the parents claimed significant improvement;
so, what the researchers did was
to go back and examine the video tapes they made of the kids
before and after and showed them to blinded examiners.
Did their language really get better?
Apparently not.
The videotapes showed no such improvement,
so again, did not support the efficacy of a gluten-free, casein-free diet
for improving some of the core symptoms of autism,
or, at least, within 6 weeks time.
The non-double-blind studies that showed an effect
had kids on the diet for a year or two.
And so, the failure to find an effect in the double-blind study
should not necessarily be interpreted
to mean that diet doesn’t work,
given the relatively shorter duration of dietary intervention.
The same issue cropped up years later in a 2014 study in Texas.
Simple study design: put everyone on a gluten-free, casein-free diet
and then randomize parents to get baggies each week
filled with either gluten-free, casein-free brown rice flour—
thereby sticking to the diet—or,
an identical-looking powder with gluten and milk mixed in.
So, no one knew until the end
who really remained gluten and casein free, and…
no, meaningful changes were found in either diet group.
OK, but this study only lasted four weeks,
and diet proponents suggest it may take months
off gluten and casein to properly assess a response.
The problem is there hadn’t been any double-blind studies
that lasted that long…
until, now.
We’ll find out what they found, next.