| There is a pressing need
to develop treatments for ADHD in addition
to medication and behavior therapy that
have strong research support and a number
of different reasons why this is important.
Regarding medication, not all children
benefit from taking it, some experience
intolerable side effects, and many continue
to struggle even though medication may be
somewhat helpful. Behavior therapy can be
difficult for parents to consistently implement,
and does not generally reduce behavior difficulties
to normative levels. Furthermore, even though
both treatments can be extremely helpful
in managing ADHD symptoms and reducing oppositional
behavior, they do not induce lasting changes
in the child that persist after treatments
is discontinued. Finally, despite numerous
studies documenting the short- and intermediate
term benefits of these treatments, their
impact on children's long-term success remains
to be clearly documented.
Because of these limitations, there have
been numerous efforts to develop alternative
treatments for ADHD that may enhance the
benefits offered by medication and behavior
therapy. In a future issue of Attention
Research Update, I hope to provide an overview
of these efforts. Today, however, I am excited
to report results from a recently published
study on the use of computerized training
of working memory in children with ADHD
(Klingberg, et al., 2005. Computerized training
of working memory in children with ADHD
- A randomized controlled trial,. Journal
of the American Academy of Child and Adolescent
Psychiatry, 44, 177-186.) Unlike many studies
of alternative or complementary ADHD treatments,
this study includes a number of experimental
controls that allow for greater confidence
in the findings.
As noted in a recent issue of Attention
Research Update - www.helpforadd.com/2005/february.htm
- executive functioning deficits are believed
to play an important role in ADHD. Executive
functions refer to those mental operations
that help to organize and direct complex
behavior, and include such operations as
goal setting, planning, reasoning, cognitive
flexibility, and the ability to delay responding.
Working memory (WM) - the ability to hold
information in one's mind for subsequent
use - is a particularly important executive
function because it may underlie other executive
functions such as reasoning. WM deficits
in individuals with ADHD have been demonstrated
repeatedly and have been suggested to contribute
to the academic struggles that many children
with ADHD experience. Developing an intervention
to enhance WM in children with ADHD could
thus be extremely helpful.
The study reviewed below investigated whether
systematic training of WM tasks during a
5-week period could improve WM, other executive
functions, and reduce ADHD symptoms in 50
7-12 year old children - approximately 90%
male - diagnosed with ADHD. None of the
children were on medication when the study
began, or at any time during the study.
For reasons that are unclear, children with
oppositional defiant disorder or depression
in addition to ADHD were excluded, and only
those with ADHD diagnoses exclusively were
recruited into the sample.
Participants were randomly assigned to
1 of 2 conditions - a high intensity (HI)
WM training condition and a low intensity
(LI) WM training condition. The HI treatment
consisted of performing WM tasks via a computer
program developed for the study. These included
visuospatioal WM tasks - remembering the
position of objects on the screen - as well
as verbal tasks - remembering sequences
of letters, sounds, and digits. In all cases,
children responded to the WM task by clicking
on various choices with the computer mouse.
Each training session provided exposure
to 90 WM tasks and required about 45 minutes
to complete. The difficulty level of the
WM tasks was automatically adjusted to match
the WM ability of the child by modifying
the number of elements the child was required
to hold in memory on a trial-by-trial basis.
By this method, children were continually
challenged to improve their WM ability by
presenting them with more difficult tasks
after they succeeded with easier ones. In
addition to improving their working memory,
children had to attend consistently and
remain relatively inactive - remaining seated
in front of the computer - to perform well.
Thus, in addition to training memory, benefits
in attention and reductions in activity
level might be expected to occur as well.
The LI condition was identical to that
described above except that the difficulty
of the 90 WM trials remained at a low level
throughout, i.e., the number of items children
were required to recall never increased
beyond 2 to 3. Thus, these children had
the same experience as children in the high
intensity treatment group, i.e., they spent
the same amount of time engaging in computerized
WM tasks, but they were not challenged to
improve. As a result, children in this condition
were not expected to show the same improvement
in WM, other executive functions, or ADHD
symptoms as children receiving the high
intensity treatment.
During the 5-weeks of training, children
needed to complete a minimum of 20 training
sessions that were completed at home or
wherever else children had access to a computer.
(Note: Parents had been given a CD with
the training software and simply had to
install it on a computer their child had
access to.) Training session results were
uploaded by the researchers via the Internet
so that they could maintain a database of
each child's performance. Parents were contacted
by phone on a weekly basis to inquire about
any technical difficulties and provide feedback
about how many training sessions the child
had completed that week. This was intended
to insure that all children completed the
required number of sessions.
A number of different measures were collected
so that the impact of the computerized training
of WM could be evaluated. These included
several measures of WM, a measure of response
inhibition, i.e., the ability to delay responding,
and a measure of non-verbal reasoning ability.
In addition, ratings of ADHD symptoms were
obtained from parents and teachers. These
measures were collected before treatment
began, immediately following treatment,
and 3 months after treatment ended. This
enabled the researchers to determine whether
children receiving high intensity treatment
showed greater improvement immediately following
the intervention, and whether these benefits
remained evident 3 months later, even though
no further training had occurred.
Before summarizing the results, it is important
to highlight several important design features
that make this study exceptionally strong.
First, children were assigned at random
to the HI or LI conditions. There is thus
no reason to expect that pre-existing differences
between children in the 2 groups could explain
any treatment differences that emerged.
Second, parents, children, nor and teachers
were not aware of which condition children
had been assigned to. Parents and children
were simply told that the child would be
taking part in 1 of 2 different treatments,
and that 1 of these treatments was expected
to be more helpful than the other. It would
not have been evident to parents or children,
however, whether the child was in the condition
that was expected to be more or less helpful.
In addition, psychologists who performed
the neuropsychological assessments were
"blind" to the child's condition.
Thus, the outcome measures collected can
be considered "unbiased" because
no one responsible for providing or obtaining
the data really knew whether the child would
be expected to show improvement.
Finally, the experience of children in
the HI and LI conditions was highly similar.
They spent the same amount of time in training
and completed training exercises that were
similar in form. The only difference was
in the difficulty level of the training
tasks that were presented to them.
Collectively, these design elements help
rule out the possibility that any treatment
differences could be attributed to pre-existing
differences between the groups, biased reports
from raters, or non-specific differences
in children's experience during the study.
Instead, any such differences that emerged
are likely to reflect the actual WM training
that children in the high intensity condition
received.
RESULTS
To examine intervention effects, researchers
compared results for the HI and LI groups
immediately following the intervention and
3 months after treatment ended. In all analyses,
baseline assessments were included as controls,
which further assures that treatment differences
could not be explained by pre-existing group
differences. Results from this study were
as follows: (Note - Participants included
children with the combined and inattentive
subtypes of ADHD. The results reported below
apply to each subtype and no subtype differences
in treatment response were observed.)To
examine intervention effects, researchers
compared results for the HI and LI groups
immediately following the intervention and
3 months after treatment ended. In all analyses,
baseline assessments were included as controls,
which further assures that treatment differences
could not be explained by pre-existing group
differences. Results from this study were
as follows: (Note - Participants included
children with the combined and inattentive
subtypes of ADHD. The results reported below
apply to each subtype and no subtype differences
in treatment response were observed.)
1) Immediately following the treatment,
children in the HI group showed significantly
better WM than children in the LI group.
The gains made by children in the HI group
were comparable to gains associated with
medication treatment that had been demonstrated
in prior studies. These benefits remained
evident at the 3-month follow up and showed
no decline in magnitude.
2) The HI group performed better on all
other executive functioning assessments
- non-verbal reasoning and response inhibition
- at post treatment than the LI group, although
the magnitude of the difference was not
as great as for WM. The better performance
was still evident at the 3-month follow
up.
3) Parent ratings of inattentive and hyperactive-impulsive
symptoms were lower at post-intervention
and at the 3-month follow up for children
in the HI group. The reductions in parent
ratings of attention difficulties were substantial
while reductions in ratings of hyperactive-impulsive
symptoms were more moderate. Parent ratings
of oppositional behavior were also significantly
lower in the HI group at both time points.
4) Group differences in ADHD symptoms ratings
completed by children's teachers were not
significant.
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