Healthy Skepticism Library item: 7037

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Publication type: news

O'Meara KP.
In ADHD Studies, Pictures May Lie
Insight Magazine 2003 Aug 11

Abstract:

It has been two decades since researchers first began to explore the use of brain imaging for the purpose of diagnosing attention-deficit/hyperactivity disorder (ADHD), the alleged mental disorder affecting an estimated 5 million children.
And two decades later, despite widely accepted beliefs, there still are no confirming data to support the use of any brain-imaging modalities in the diagnosis of ADHD.

A recent review by Jonathan Leo, professor of anatomy at the Western University of Health Sciences in Pomona, Calif., and professor David Cohen of the School of Social Work at Florida International University in Miami, dispels the myth of brain imaging as a way to diagnose ADHD. And it finds that the majority of studies dating back to 1978 failed, unaccountably, to consider a major variable – the use of psychotropic drugs by participants in the studies.

Leo and Cohen’s review, entitled “Broken Brains or Flawed Studies? A Critical Review of ADHD Neuroimaging Research,” was published last month in the Journal of Mind and Behavior and looked at 33 of the most recent studies using computerized topography, magnetic resonance imaging (MRI), single photon emission computerized topography or positron emission topography on ADHD-diagnosed subjects. The researchers were stunned: According to Leo, “Dr. Cohen and I pulled the studies that had been done on brain imaging and ADHD and what jumped out at us was that every single study used medicated kids, subjects who had been on stimulants or some other drugs that we don’t know because that information wasn’t made part of the study.”

Leo explains, “The general public sees a picture of a brain, and one brain looks a little brighter than the ‘normal’
brain, but how do you know if you’re not looking at something like ‘this is your brain’ and ‘this is your brain on drugs’? We found that most subjects with ADD [attention-deficit disorder] or ADHD had prior medication use, often for several months or years. So the major conclusion of our review of these studies is to ask ourselves what are these researchers doing? You have to wonder if they’re really doing research or trying to come up with a marketing slogan.”

Cohen tells Insight that “there were a number of problems with these studies, but the fact that the kids were either on drugs or stopped taking them within days of the study was not an outstanding issue when we first got into the studies.
In other words, this wasn’t something that we were looking for.” He notes, “Only in about one or two of the studies is mention even made about medications and that’s as far as it went – a mention. But this is a major variable and it’s important because drugs influence the brain. That’s why we give drugs in the first place. It’s not an abstract issue, and we do cite a number of studies on animals and kids that show that stimulant drugs cause very persistent changes in the brain.”

Cohen explains, “You want to be able to rule out these changes, so you would want to use kids that aren’t on drugs or just recently taken off of them when you’re scanning them. At the very least what you want to do is report the medication status. What we found was that only 19 of the 33 studies reported the medication status, some of the 19 reported in an unclear manner and a single study made something out of the fact that most subjects were on medications.”

According to the researchers, 93 percent of the subjects in the ADHD diagnosed group were either on drugs, just off drugs or had been medicated for years. This is a major confound, but it wasn’t a major issue among the researchers reviewing the ADHD studies. Perhaps the most troubling issue came when professors Leo and Cohen reviewed the widely touted 2001 study conducted by some of the most renowned scientists of the National Institute of Mental Health (NIMH), entitled Developmental Trajectories of Brain Volume Abnormalities in Children and Adolescents with Attention- Deficit/Hyperactivity Disorder.

Although 14 scientists contributed to the study, it is generally referred to as the “Castellanos study” after the lead scientist, child psychiatrist F. Xavier Castellanos. Ten years in the making and unknown millions spent, Castellanos and his team conducted 544 MRI scans of 291 subjects – 152 ADHD-diagnosed patients and 139 control subjects (normal). The Castellanos results were that “on initial scan, patients with ADHD had significantly smaller brain volumes in all regions, even after adjustment for significant covariates.”

The celebrated doctor further concluded that “developmental trajectories for all structures, except caudate, remain roughly parallel for patients and controls during childhood and adolescence, suggesting that genetic and/or early environmental influences on brain development in ADHD are fixed, not progressive and unrelated to stimulant treatment.”
In other words, kids diagnosed with ADHD had smaller brains than those kids in the “normal” control group, and brain size isn’t due to drug use.

Leo and Cohen are not only disturbed by the conclusion, but surprised that the Castellanos study received such strong public attention given that even the NIMH doctor was not using matched groups. According to Cohen, “Castellanos essentially is the first-ever study using un-medicated kids. So we say finally here comes a study from a very experienced researcher – who has done four or five of these brain-imaging studies – and what do we get? The control group is completely inappropriate for these ADHD-diagnosed kids. Castellanos picked a control group of kids that are more than two years older than the unmedicated ADHD kids and he finds that the unmedicated ADHD kids have smaller brains? That’s obvious because the control group is two years older and significantly heavier and taller.”

Cohen says, “What is surprising is that the Castellanos review is saying that a major difference with ADHD and normal kids is brain size. But brain size is typically correlated with head size, and I really doubt that with all these kids on Ritalin it all boils down to head size. That’s a stretch. But another way of looking at it is that for 30 years researchers have had trouble getting appropriate subjects for these studies. So with the NIMH review it finally has a group of non-medicated ADHD kids but now the problem is getting a control group – undiagnosed kids?”

Castellanos, now with the Child Studies Center of New York University, tells Insight that he accounted for the age difference in subgroups and “the control group is age-matched for the ADHD group as a whole and unmedicated children with ADHD were significantly younger. That’s because by the time kids get older they’ve been medicated. It is very difficult to find kids that are unmedicated. This is the nature of the condition. It is very difficult to find very hyperactive children who have not been medicated who are older. We included all of the children in one analyses and in another analyses we limited ourselves to age-matched subgroups.”

Leo argues that NIMH “still can do a legitimate study and take their unmedicated ADHD kids and compare them to a normal control group – same age, size, etc. But they haven’t done it and the question is why? In a landmark 10-year study the NIMH didn’t use a normal control group – what’s the hang up?”

Cohen agrees. “The study that needs to be done is so simple: Just compare ADHD-diagnosed kids who haven’t been medicated with a similar age group of ‘normal’ kids who haven’t been diagnosed. It’s the only study that needs to be done, and there isn’t a single study that compares these two groups of kids. In essence what you’ve got here is a large body of studies that cannot support the notion that there is some brain pathology specific to ADHD because of the confound of prior or current medication used during the studies. And until they do the appropriate study, this won’t change.”

Finally, says Leo, “Given all the problems with the ADHD imaging research, parents who are contemplating medicating their children should not be told that this research suggests that there is a biological basis for ADHD.”

Because the Leo-Cohen review is newly published, no critiques have been posted to date about the validity of the review.
NIMH has not responded to Insight’s questions about the Castellanos review nor the cost of the 10-year study.

This, by the way, is the concluding statement of Jonathan Leo’s and David Cohen’s paper “Broken Brains or Flawed
Studies?”:

“… after twenty-five years, and thirty-five studies, there is not a single straightforward experiment comparing typical unmedicated children with an ADHD diagnosis to typical controls. We are perplexed.”

It seems, then, that the proponents of biopsychiatry who claim ‘ADHD’ to be a ‘neurological disorder’ or ‘brain disease’
have had their opportunities to resolve the debate over the validity of their dubious ‘diagnosis’ once and for all, but they have failed to take advantage of those opportunities – in Professor Cohen’s words, “The study that needs to be done is so simple: Just compare ADHD-diagnosed kids who haven’t been medicated with a similar age group of ‘normal’ kids who haven’t been diagnosed.”

Then we’d know for sure, wouldn’t we?

Could it be that the reason the proponents of biopsychiatry will not make that obvious and simple comparison is that they DARE NOT RISK IT?