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ADHD seems to be more
prevalent in boys than girls for the
hyperactive-impulsive subtype and for the combined
subtype. The gender difference is less in the
inattentive subtype. Dr. Joseph Biederman and his
colleagues compared boys and girls with ADHD to
boys and girls without ADHD. They found that girls
with ADHD were more likely than boys to have
predominantly inattentive subtype of ADHD. When
compared to boys with ADHD, girls with ADHD were
less likely to have a learning disability and less
likely to experience problems in school or outside
of school . Girls with ADHD were also less likely
to have depression, conduct disorder, or
oppositional defiant disorder. In light of these
data, the investigators suggested that there might
be a gender bias in terms of referring children for
assessment or treatment, with girls being less
likely to be referred.
In an analysis of other
studies on ADHD, Gershon (2002) looked at gender
differences in ADHD. Gershon's analysis indicated
that when compared to ADHD boys, ADHD girls had
lower ratings on hyperactivity, inattention,
impulsivity, and externalizing problems, and had
greater intellectual impairment and more
internalizing problems than boys with ADHD.
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Over the years, I have
occasionally encountered references to a possible
connection between ADHD and visual problems that
might be related to reading disabilities. Although
a search of Medline did not turn up too many
articles, I thought I would share a few
of the reports with site visitors.
The first question, of
course, is whether there is any demonstration that
children with ADHD are different from the non-ADHD
population in terms of visually related processes.
Farrar et al. (2001) compared children who had been
diagnosed with ADHD and who were under
pharmacological treatment for ADHD to age- and
gender-matched controls on parental and
self-reports of visual symptoms and quality of life
issues. The ADHD reportedly experienced more
symptoms of visual system dysfunction than their
age-matched control peers: 14 of the 33 symptoms on
the survey were found to be significantly more
severe in the ADHD group than in the control group.
Thus, even with pharmacological treatment, there
was some indication that children with ADHD may
have more visual (and quality of life) symptoms
than non-ADHD children.
But what specific kinds of
problems might relate to reading disabilities?
Several studies have indicated that children with
ADHD have significantly more deficits in saccadic
control. They have more difficulty in inhibiting
movements and display greater variability. The
implications are that children with ADHD who have
such visual deficits may have more trouble
sustaining their visual attention on targeted
stimuli (such as reading material) and in
suppressing unwanted visual activity away from the
targeted material. Approximately one half of
children with dyslexia display abnormalities in
saccadic control.
Although a full discussion of
this complex research area is beyond the scope of
this web site, it is helpful for educators to be
aware that some of the visual attention and reading
problems observed in a child with ADHD may be
linked to an oculomotor disturbance. Thus,
even when visual acuity is normal, I have, on
occasion, referred some children or teens with
ADHD for optometric or ophthalmological
examination to determine if oculomotor problems
were contributing to learning disabilities.
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Up to 85% of children with
ADHD may continue to have problems in adolescence.
Peer problems that are noted in childhood may
persist, and if the ADHD symptoms also persist into
adolescence, the peer impact is even more
significant. Adolescents who have a history of ADHD
in their childhood may be more likely to have fewer
friends, experience greater peer rejection, and
have friends who are less involved in conventional
activities.
A number of studies have
attempted to look at the long-term outcomes for
children with ADHD. Although there is some
variability in the results, it appears that ADHD
symptoms remain problematic in two thirds to three
quarters of these children in early and middle
adolescence, with relative academic and social
deficits noted. Antisocial behaviors (and in more
severe cases: conduct disorder) may be observed in
adolescents with persistent ADHD, and many of these
same difficulties persist into late
adolescence.
Adolescents with persisting
ADHD tend to exhibit lower grades, fail more
courses, have worse performance on standardized
tests, have fewer friends, and are rated less
adequate in psychosocial adjustment. About 40%
continue to experience ADHD symptoms to a
clinically significant degree, and 25% - 33% of
these adolescents have a diagnosed antisocial
disorder. This subgroup - ADHD + antisocial
disorder - experiences significant problems, and up
to 2/3 of them are arrested.
The estimates of the percent
of children with ADHD who continue to have problems
in adulthood vary widely, but anywhere between 1/3
and 2/3 of the children are likely to continue to
have problems in adulthood.
By their mid-twenties, when
compared to non-ADHD peers, those with ADHD have
completed less schooling, tend to hold
lower-ranking occupations, and continue to suffer
from poor self-esteem and social skills deficits.
In addition, they are more likely to exhibit an
antisocial personality and (perhaps) a substance
use disorder in adulthood. For example, Fischer,
Barkley, et al. (2002) compared young adults who
had been diagnosed with ADHD as children to
community controls (CC). They found that the ADHD
group had significantly higher rates of non-drug
psychiatric disorders, were more likely to have
ADHD as young adults than the CC group, and had
significantly higher rates of major depressive
disorder and personality disorders (histrionic,
antisocial, passive-aggressive, and borderline
personality disorders). Consistent with findings of
other researchers, their data indicated that
conduct problems in adolescence contributed
significantly to the risk of personality disorders,
two of which significantly increased the risk for
major depression.
In the discussion above,
general patterns were described without respect to
subtype of ADHD. Do different subtypes have
different outcomes as adults? Murphy et al. (2002)
addressed that question by comparing adults with
ADHD-combined type (ADHD-C) to adults with
ADHD-inattentive type (ADHD-I) and community
controls (CC). Both ADHD groups had completed less
formal education than the CC group, were less
likely to have graduated from college, and were
more likely to have received special educational
placement in high school. Both groups also reported
more alcohol dependence/abuse, more dysthymia, more
cannabis dependence/abuse, and more learning
disorders, as well as greater psychological
distress. Elsewhere on this site, in the article,
"ADHD
and Safety," site
visitors can also learn about the increased rate of
accidents (pedestrian and vehicular) and the
increased risk of more serious injuries in both
children and adults with ADHD.
But how did the two ADHD
groups fare when compared to each other? For the
measures employed, the two groups differed in only
a few respects: The ADHD-C were more likely to have
oppositional behaviors, interpersonal hostility,
paranoia, and some history of attempted suicide.
They were also more likely to have been arrested
than the ADHD-I group. Their findings suggest that
the impulsivity of the Combined subtype predicts a
poorer outcome as an adult, particularly if there
are also conduct problems in childhood. But a more
recent study suggests that those with more severe
problems of inattention during childhood may be
significantly more likely to report frequent
episodes of drunkenness, higher alcohol problem
scores, and a greater likelihood of substance abuse
as teenagers and that impulsivity-hyperactivity was
not associated with teenage substance
abuse.
The research described above
does not tell the whole story of the ADHD child's
adult outcomes, however, and the total picture is
not as grim as you might think. Mannuzza and Klein
(2000) reported that nearly all of the children
followed into adulthood were gainfully employed,
and some had achieved a higher-level education
(such as a Master's degree or enrollment in medical
school) and occupation (e.g., accountant, stock
broker). For the studies they reviewed, the authors
found that a full two thirds of the children showed
no evidence of any mental disorder in adulthood
(but as noted earlier, some studies estimate that
up to two thirds of children with ADHD will
continue to have problems in adulthood). They
conclude that although ADHD children, as a group,
fare poorly when compared with their non-ADHD
peers, ADHD does not preclude attaining high
educational and vocational goals, and that most
children no longer exhibit clinically significant
emotional or behavioral problems once they reach
their mid-twenties.
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