Researchers Study the Most Dysfunctional
ADDers,
Resulting in Biased Views
When reading about ADD be cautious about statistics and
sweeping statements made by researchers. The reason is simple: Researchers are
basing their theories not on a representative group of people meeting the DSM IV criteria,
but on only those people who are the most dysfunctional. Such people are naturally
more likely to end up in jail, more likely to have a lower IQ (smarter ADDers are often
able to compensate for their problem traits), and more likely to have learning
disabilities.
Here is an example of how this type of bias can radically
change the way a condition is viewed. Until 1999, researchers believed that between
5 and 15% of the population suffered from mitral valve prolapse, a condition in which a
heart valve does not work properly. Scientists and physician warned that the
condition could lead to heart failure, stroke, reduced blood flow and infection within the
heart. However, when researchers recently studied several thousand people at random
from the general population using state-of-the art equipment, they found that only 2% had
a mitral valve prolapse. Further, they found that these people did not experience
the complications that scientists and physicians claimed they would. They also found
that mitral valve prolapse was not more common in women, which earlier studies had
suggested. Mitral valve prolapse diagnoses increased sharply in the 1970's and
1980's with advanced in technology. Patients sometimes complained of shortness of
breath, chest pain, and palpitations, symptoms which may be also caused by anxiety and
fatigue.
Why was the conventional wisdom on mitral valve prolapse so
off target? Researchers gave several reasons:
1. Earlier research was done in university hospitals where
the worst cases were referred.
2. The enthusiasm factor. Dr. Benjamin at Boston
University Medical Center explained it this way. "Whenever a condition is first
appreciated in medicine, first discovered, there is an enthusiasm about it and a tendency
to embrace it. And the condition suddenly becomes the cause of all evil. It
becomes a fad diagnosis, like attention deficit disorder or chronic fatigue syndrome.
Researchers are not being intellectually dishonest, just overenthusiastic."
3. There was no good baseline data for what a
"normal" mitral valve was. Note that, in the case of ADD, there is very
little information on what constitutes a "normal" brain. In fact, very few
brain of normal people have been studied. Even so, scientists are increasingly
finding that brains differ significantly from person to person. Over and over
scientists have discovered that differences assumed to be brain defects were in fact quite
normal. Parts of Einstein's brain were smaller than average while other parts were
larger than average. Did Einstein have a brain defect because part of his brain was
smaller than average, leading to verbal difficulties (his mother feared he might actually
be retarded)?
You've probably heard that ADDers have a trademark PET scan
(a type of brain scan) which shows less activity in the forebrain while the ADDer is asked
to do something really boring, like count numbers. Let's assume for a moment that
the PET scan can indeed predict those people who meet the DSM IV criteria for ADD (a big
assumption). What would happen if researchers took thousands of people at
random and gave them the PET scan? My guess is they would find lots and lots of
ADDers who are quite successful, kids who are behaving OK, and a lower incidence of
learning disabilities than predicted by earlier studies. The researchers would then
have to go back to the drawing board and try and figure out why some ADD kids are fine and
others have serious problems.
Sources:
"Heart Valve Defect Found to Be Rarer And Not as
Serious," New York Times 7/1/99.
"So, Is This Why Einstein Was So Brilliant?" New
York Times, June 18, 1999.
