Considering Combined Disorders: ADHD and Reading
Disability
by Richard Rubin, MD
Clinical Associate Professor, University of Vermont
College of Medicine
Practicing clinicians and researchers are
recognizing that over 70% of people with ADHD have
additional disorders that influence treatment
planning and outcomes. Of children with ADHD, it is
estimated that 15-30% will also have a Reading
Disability, possibly defined as Dyslexia. Brain
dysfunction, in addition to environmental
circumstances, is currently viewed as a major cause,
based on family inheritance and brain scanning
findings. However, very little research has been
done on ADHD medication outcomes in the presence of
combined Reading Disability/Dyslexia. Short term
studies of stimulants show ADHD core symptom
improvements, but not specific effects on Reading
Disorder characteristics.
I presented a New Research Poster (E48) of the
first study done with the ADHD medicine atomoxetine
(Strattera) on combined ADHD and Reading Disorders
at the October 2006 Annual Meeting of the American
Academy of Child and Adolescent Psychiatry. This
study had two objectives: 1) To assess influence of
the Reading Disorder comorbidity on ADHD treatment
response, both efficacy and tolerability (side
effects); 2) To examine possible effects of
atomoxetine on Reading Disorders. These questions
are relevant because atomoxetine works by increasing
the brain neurotransmitter norepinephrine, different
from stimulants’ action primarily on dopamine. The
study is properly viewed as a pilot exploration,
comparing a group of youths 10-16 with combined ADHD
plus Reading Disorder to a group with ADHD alone. It
was conducted at eight university and community
practice research sites around the US.
The 36 participants with ADHD and Reading
Disorder (ADHD+RD) and 20 with ADHD alone were
treated open label with approved doses of
atomoxetine for 16 weeks. Control for educational
program effects was not done, and participants had a
diverse range of services. The ADHD core symptoms
were measured every two weeks with the standardized
ADHD Rating Scale. Both groups improved with good
clinical and statistical significance: the ADHD+RD
by an average of 17 points, and the ADHD alone by
about 19 points. Impairments such as social skills
and self-esteem also improved substantially in both
groups as assessed by parents on the Life
Participation Scale. There were no significant
differences in medicine side effects between the two
groups.
Reading Disorder was defined for this study as
at least a 22 point deficit between the best
aptitude score on the Kaufman Brief Intelligence
Test and the initial Reading Composite score on the
Kaufman Test of Educational Achievement. After the 4
months on atomoxetine, the ADHD+RD group improved
their Reading Composite score by an average of 24
months, and the ADHD alone group by 17 months.
The Working Memory Test Battery for Children
(WMTB-C) was also applied to assess function changes
and areas of the brain affected. The ADHD+RD group
had more prominent score increase in both left
(phonological) and right (visuo-spatial) cortex
areas, while the ADHD alone group improved most in
the frontal (central executive) area. This suggests
that the brain regions related to the therapeutic
benefit of atomoxetine may be different in people
with ADHD+RD versus ADHD without combined Reading
Disorder. As a preliminary pilot study, these
results support beneficial ADHD outcomes with
ADHD+RD youth. They are encouraging for further
research, but should not be construed as conclusive
evidence for treatment of Learning Disabilities with
atomoxetine at this time.
Dr. Rubin practices Child and Adult Psychiatry,
directs The Clinical Study Center in Burlington
Vermont, and serves as Clinical Associate Professor
at the University of Vermont College of Medicine.
