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
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.
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
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.