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 - http://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
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
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.
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
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.
SUMMARY AND IMPLICATIONS
Results from this study provide
strong evidence that approximately 20 hours of computerized WM training over
a 5-week period produced gains in this important executive function and in
other executive functions that were not the specific focus of training.
These benefits were evident immediately following training and remained evident
3 months later, even though no further training had occurred. In addition,
there were significant reductions in children's ADHD symptoms according
to parents, although no comparable benefits were evident in teachers' ratings.
The gains in WM and the reductions in attention difficulties reported by
parents were large, and comparable in magnitude to effects obtained by medication.
The strong design of this study, which
included random assignment and "blind" raters, provides a basis for attributing
these gains to the WM training itself rather than to other confounding factors.
As such, this would appear to be a very promising intervention for children
with ADHD. It is especially noteworthy that benefits persisted for
3 months after treatment ended. This suggests that, unlike medication
and behavior therapy, gains associated with computerized WM training may
be more enduring. How long these gains might last is unclear, however,
as is the need for continued training in order to sustain these gains over
a longer period.
Despite the exciting nature of these findings,
the authors themselves highlight several limitations to their study that
will be important to address in future research.
First, despite the exciting nature of the
findings, replication with a larger sample that includes more females will
Second, because children with co-occurring
oppositional defiant disorder and/or depression were excluded, the extent
to which the results would generalize to children with ADHD and these other
conditions is not known. Because many children with ADHD also have these
other conditions, it will be especially important to learn whether this intervention
is helpful to these children as well.
Third, the absence of teacher reported
gains is concerning. Although the authors suggest that ratings from
parents are more reliable because they were consistent with the executive
functioning results, the basis for this suggestion is unclear. Because a
goal of ADHD treatment is improving children's functioning at school, demonstrating
that this treatment produces this effect remains critically important.
This would include assessment of "real-world" academic functioning, which
was not part of the current study.
In summary, this study provides preliminary
evidence that computerized training of WM may be an effective intervention
for children with ADHD. It is important to recognize, however, that
additional research will be required in order to conclusively document the
benefits of this intervention as well as to understand its limitations.
Lets hope that such research is currently underway and will become available
Information presented in Attention Research
Update is for informational purposes only, and is not a substitute for professional
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