Subtypes in ADHD: A Newsmaker Interview With Mary Solanto, PhD
Robert Kennedy and Robert Glassman
Oct. 17, 2003 — Editor's Note: Attention deficit-hyperactivity disorder
(ADHD) has become an important area in child and adolescent psychiatry. Much of the
new research has delved into the various diagnostic subtypes, response to
treatment, and cognitive styles of both children and adults diagnosed with ADHD.
To discuss this new research, Medscape spoke with Mary Solanto, PhD, an
associate professor of psychiatry in the Division of Child and Adolescent
Psychiatry at Mt. Sinai School of Medicine and director of ADHD Clinic at Mt. Sinai
Medical Center in New York City.
Medscape caught up with Dr. Solanto at the annual meeting of the American
Academy of Child & Adolescent Psychiatry in Miami Beach, Florida.
Medscape: You presented a poster here in Miami on ADHD subtypes. Can you tell
us about it?Dr. Solanto: We are doing a lot of research trying to understand
what may be critical differences between the two most recognized types of
ADHD. There are kids who are predominantly inattentive, who've only been
recognized recently in the DSM-IV, and then there is the more commonly recognized child
with ADHD that is also hyperactive and impulsive. There seem to be many
differences in the behavioral functioning of these children and possibly in the
kinds of deficits they're likely to experience. We're evaluating these children
on a whole array of neuropsychological measures. What we reported on were some
differences on the WISC [Weschler Intelligence Scale for Children] and we
looked at whether there were differences on measures of processing speed, which is
how quickly a child can respond to a task and complete it, as well as
measures of distractibility.
Parents and teachers often report that kids with this inattentive type are
very sluggish, they're very slow to accomplish many things, homework among them.
And other kids often observe that they are very slow to respond
interpersonally. You ask them a question and you don't even know if they heard you, and
they are looking around and daydreaming. [Their peers] may not have patience for
that kind of behavior. These kids can suffer socially as well.
What we showed on the WISC was that there was a much higher proportion of
kids with this inattentive type who did very poorly on the processing speed
index. They were more likely to have a big discrepancy between their verbal
functioning and their processing speed. They were also more likely to have a big
discrepancy between their verbal functioning and their freedom from
distractibility index on that test. That seems to verify the kinds of behaviors that we
observed interpersonally with these kids, and it also provided a way for them to
be assessed in a more formal manner to differentiate which type of ADHD they
Medscape: Has anyone else done similar studies? Dr. Solanto: There have been
some reports in the literature of longer reaction times of these kids in
laboratory tasks. There was also one other study that suggested a difference in
processing speed. This is the first time where it has been demonstrated on
commonly used tests that are used in psychological evaluations. What we want to do
now is see if we can understand more about why processing is slower for these
kids. Is it occurring on the input side, in terms of their ability to orient to
a stimulus and process that stimulus, or is it occurring on the output side
where they are processing the task and then deciding or executing a particular
response? Other tests in the battery will hopefully shed more light on what is
causing the longer reaction time. Another possibility is that they take
longer to retrieve information and to call up the appropriate information for the
task at hand. We'll also be looking at that as a potential mediator.
Future studies will look at whether these children respond differently to
stimulant medication than children with a combined type or perhaps they may
require a different dosage. We are also collecting fMRI studies to look at whether
different portions of the brain are activated in children with the two
subtypes, particularly when they are doing a task that requires inhibitory control.
We have data that will hopefully help to elaborate differences between the
subtypes and ultimately construct treatments that are more targeted for their
Medscape: Is this a particular age group or is it the spectrum of children
and adolescents? Dr. Solanto: That's an interesting issue. Studies show that the
age of onset or at least the age at which children with the inattentive
subtype are recognized is much later. They often do not come to clinical attention
till ages 9 to 11, and it may be hard to document that there were symptoms
before that. It has been proposed that the criterion for onset should be higher
for the inattentive. Why this should be the case isn't entirely clear. It could
be that demands on attention don't increase so that these children don't look
impaired in the classroom until they get to be 9 years old because they are
not behaviorally disruptive, they don't have other problems. Their problems are
primarily on structured tasks that require concentration and focus. It is
possible that this is a subtype that does not have an onset until later. In the
study, the children were matched for age, so that wouldn't account for
differences. The age range for both subtypes was 7-12 years old.
Medscape: Could you tell us about your ADHD clinic and some of the things you
do in the program? Dr. Solanto: We see the whole range of ADHD at the program
at Mt. Sinai. Children, adolescents, and increasingly, more adults, who
sometimes recognize in themselves the symptoms that their children have, because as
you know ADHD is highly heritable. Often they can see they have experienced
difficulties similar to [those of] their child and sometimes, with a little
encouragement, they will come forth for an evaluation for themselves.
In the clinic, we provide follow-up treatment in the way of medication [and]
individual behavior therapy, which is done by coaching parents and teachers in
how best to respond and how to manage these behaviors.
We also have a group that teaches adults time management and organizational
skills that they may have not developed because of the impairments associated
with ADHD, which is very hard to acquire later on without specific coaching.
Not even medication will fully address that. It may help them learn these new
strategies, but it is something they have to work at and have help with. The
groups have done pretty well, they seem to have a positive impact. Next we will
evaluate the whole process in a more rigorous fashion.
Medscape: Adult ADHA seems to have a new focus, in the literature and even in
the press. People are making it seem like it is a new diagnosis, which it
isn't. Can you address that? Dr. Solanto: The follow-up studies have shown as
many as half of kids with ADHD will continue to have many symptoms in adulthood,
if not the full-fledged disorder. We knew these people were out there, they
had to be given the results of these longitudinal studies. They might not be
recognized by mental health professionals because they often have many other
symptoms and problems that by time they reach adulthood take precedence. Many are
depressed or have problems with anxiety, and often those are the conditions
and the problems that are recognized if they go for consultation, and unless one
takes a very careful history beginning at childhood, one may overlook the
fact that there were certain ADHD symptoms that are present very early on and
have continued into adulthood. So it's good that there is now much more publicity
about it, there are some books that are very helpful to adults in helping
recognize problems they may have had. There are actually very few specialized
centers, even in Manhattan, that do evaluations and treatment of adults with
Medscape: I notice that the researchers in the field of ADHD are a small
group and there seems to be a great deal of collaboration. Do you work with other
researchers in other areas in New York as well as in the rest of the country?
Dr. Solanto: It's really important to exchange ideas and share findings and
instruments that are used for diagnosis, as well as strategies for intervention.
We're working with adults to develop organizational skills. For example,
Howard Abacoff, at New York University, has developed a superb program to teach
children how to better organize themselves and has gotten really excellent
results. There is an exchange of ideas and approaches that benefits everyone
involved, and it is great to do that at a meeting like this, especially one that is
provided in such a gorgeous environment.
Reviewed by Gary D. Vogin, MD
Robert Kennedy is site editor of Medscape Psychiatry; Robert Glassman is a
freelance editor for Medscape.
Conference CoverageChild and Adolescent Psychiatry Annual Meeting
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