Although ADHD can create difficulties in many areas of a child's
life, the adverse impact it frequently has on academic functioning is
especially problematic. This has been documented in numerous
studies, where it has been shown that children with ADHD are less
likely to complete high school, more likely to repeat a grade, more
likely to be placed in special education classes, and less likely to
achieve to their potential.
Despite this general pattern of findings, not all children with ADHD
experience significant academic struggles. In fact, a number
manage to do reasonably well despite the disorder. What might
account for the wide range of variability in academic outcomes for
children with ADHD? Why do some achieve reasonable levels of
academic success while many others struggle mightily, regardless of how
bright they may be?
One factor that may help explain the variability in academic outcomes
in children with ADHD is the presence vs. absence of executive
functioning deficits (EFDs). Executive functions (EFs) can be
thought of as the decision-making and planning processes that help to
control and direct our behavior. For example, when a child has a
long-term assignment to complete, the executive functioning tasks
involved would include dividing the task into sub-task, making a plan
for completing those tasks, and monitoring performance along the way.
Although no single list of EFs is universally agreed upon, most experts
would agree that important EFs include such abilities as planning,
reasoning, working memory (i.e., holding information in memory for
later use), inhibiting behavior that may bring immediate rewards in
pursuit of a long-term goal, some aspects of attention, and shifting
cognitive sets, i.e., flexibility in thinking.
These EF skills are believed to be critically important for complex
human behavior because they serve to organize and guide behavior in
flexible and adaptive ways. A number of studies have demonstrated that
children with ADHD exhibit EFDs relative to children without the
disorder. In fact, current conceptualizations of ADHD emphasize
that EFDs may represent the core deficits associated with ADHD, and
that symptoms used to define the disorder - inattention and
hyperactivity-impulsivity - are the result in many instances of these
core EFDs.
Despite the important role that EFDs play in current theorizing about
ADHD, very little is known about the clinical implications of EFDs in
children and adolescents with ADHD. For example, there has been
little research on whether EFDs and core ADHD symptoms contribute
independently to academic difficulties as well as the other problems
that many children/teens with ADHD experience. In fact, one
distinct possibility is that in the absence of EFDs, children with ADHD
may not experience the severe academic struggles that are regularly
associated with the disorder.
If this were found to be true, then routinely assessing children with
ADHD for EFDs could alert parents and clinicians to when academic
problems are especially likely to develop. This knowledge could
enable them to make extra efforts to prevent this from occurring. It is
also possible that ADHD with and without EFDs is associated with
different outcomes in other important emotional and behavioral domains
and this could also have important implications for treatment planning.
This interesting issue was the focus of a study published recently in
the Journal of Consulting and
Clinical Psychology (Biederman et al., (2004). Impact of
executive function deficits and attention deficit/hyperactivity
disorder on academic outcomes in children. JCCP, 72, 757-766.
Participants in this study were children and adolescents with (n=259)
and without (n=222) ADHD. Unlike many studies in the literature,
girls and boys were represented in relatively equal numbers.
Participants ranged in age from 6-17 and received a variety of
assessment measures in the study. These included:
- psychiatric assessments to establish the ADHD diagnosis as well
as the presence of co-occurring emotional and behavioral disorders;
- psychosocial assessments to assess social difficulties at school
and in interactions with peers, siblings, and parents;
- cognitive assessments to assess IQ and academic achievement level
in reading and math; and
- neuropsychological assessments specifically intended to assess
key elements of executive functioning. The neuropsychological
battery included 6 measures to assess a range of EFs including planning
and organizational skills, reasoning, cognitive flexibility, working
memory, ability to inhibit impulsive responding, and certain components
of attention.
For each EF tested, participants were classified as having a deficit if
their performance fell in the bottom 7% for children/teens who
comprised the non-ADHD sample. Participants were then classified
as having an overall EFD if they scored in this range on 2 or more of
the EFs that were assessed. Participants who scored poorly on 1
or fewer EF measure were considered "normal" in regards to their
overall executive functioning. The rational behind this
classification procedure is that whereas impaired performance on only a
single neuropsychological test may be due to chance, two or more
impaired tests would likely be interpreted as a deficit by most
clinicians.
Participants' classification as EFD vs. non-EFD groups was combined
with their diagnostic status for ADHD to form 4 groups: control
participants without EFD (n=196); control participants with EFD (n=26);
ADHD without EFD (n=173); and ADHD with EFD (n=86). Once these
groups were identified, the researchers examined how they compared on
the academic, social, and psychiatric outcomes that were
assessed. As noted above, they were especially interested in
whether EFDs in children/teens with ADHD was reliably associated with
poorer academic, psychiatric, and social functioning.
RESULTS
The researchers first tested whether EFDs were more common in children
and teens with ADHD than in control participants. Thirty-three
percent of participants with ADHD had EFDs compared to only 12% of
control participants; this difference was statistically significant.
Next, they examined whether particular clinical aspects of ADHD were
associated with EFDs. Participants with ADHD and EFDs did not
differ from those with ADHD but without EFDs in their age of onset of
ADHD or the number of hyperactive-impulsive symptoms. They did,
however, have slightly more inattentive symptoms, but the average
difference was not large (i.e., less than 1 symptom).
EFDs and Academic
Functioning
As expected, children with ADHD showed poorer academic performance in a
variety of areas compared to control children; this was true regardless
of whether or not control children had EFDs. Of greater interest,
however, is that within the group of participants with ADHD, the
presence of EFDs was strongly and consistently associated with poorer
academic performance.
Compared to participants with ADHD and no EFD, those with ADHD + EFD
were more likely to have repeated a grade (42% vs. 19%), to be
diagnosed with a learning disability (44% vs. 20%), to have lower IQ
scores (98 vs. 109), and to have lower achievement in math (85 vs. 99)
and reading (92 vs. 106). (Note that for IQ and the achievement
scores, the average score is 100.) The differences found for
grade retention, learning disability, and achievement in reading and
math were evident even after controlling for IQ, SES, and medication
status, which suggests that EFDs were the critical variable accounting
for the differential performance. Among children without ADHD,
those without EFDs tended to perform better, but the differences were
not as pronounced and were generally not significant.
EFDs and Other
Outcomes
In regards to the other areas assessed, the association between EFDs,
ADHD, and negative outcomes was different. Specifically, although
participants with ADHD had more negative outcomes than control
participants in virtually all areas, the presence EFDs within the ADHD
group did not appear to make a difference. Thus, both groups of
participants with ADHD - i.e., those with EFDs and those without - had
similar rates of mood disorders (34% vs. 37%), anxiety disorders (32%
vs. 40%), disruptive behavior disorders (53% vs. 55%), substance use
(10% vs. 9%), and smoking (13% vs. 13%). Except for substance use,
these rates were all substantially higher than those reported for
control participants, and in no instance did they differ significantly
from one another. In regards to the overall measure of social
functioning, participants in the 2 ADHD groups were again equivalent
and had significantly more difficulties than control participants.
SUMMARY and IMPLICATIONS
Results from this study suggest that EFDs are significantly more common
in children/teens with ADHD than in those without the disorder, and
that among individuals with ADHD, EFDs increase the risk for grade
retention, learning disability, and lower academic achievement.
Furthermore, the greater academic difficulties experienced by children
with ADHD who also have EFDs cannot be explained by differences
in IQ, SES, medication status, or in the greater severity of core ADHD
symptoms. Thus, it appears that EFDs may make an independent
contribution to academic problems above and beyond those related to the
core symptoms of ADHD alone.
In regards to other psychiatric outcomes and overall social
functioning, however, there was no indication that EFDs add to the
difficulties that are associated with ADHD alone. The authors
note that this does not necessarily mean that EFDs do not add to the
risk posed by ADHD in regards to these other negative outcomes.
Instead, it is possible that when EFDs are present along with ADHD, it
may take longer for this additional risk to become evident, whereas for
academic difficulties, the negative impact occurs earlier in
development. This, of course, is a hypothesis that would require
additional study in order to test.
These findings have potentially important clinical implications in that
only about 1/3 of participants with ADHD also had EFDs as defined by
the researchers. If these findings were replicated, it would
provide a strong indication that routinely screening children newly
diagnosed with ADHD for EFDs could be an important addition to ADHD
evaluations protocols. To my knowledge, such screening is not
typically done, particularly when the diagnosis is being made by
primary care physicians who are not generally trained to administer and
interpret neuropsychological tests.
The benefit of this screening is that by identifying those children
with ADHD who also showed EFDs, more intensive efforts to prevent the
development of academic struggles could be initiated. As the
authors note, because it is not clear how EFDs respond to standard
pharmacological treatment for ADHD, children with ADHD and EFDs may
require additional academic intervention to prevent academic failure;
they may also required a different type of intervention that is
specifically designed to address their executive functioning
deficits. Developing and evaluating such intervention efforts
remains an important topic for subsequent research in this interesting
and important area.