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A high level of activity and short attention span are part of
normal development in infants and toddlers. Many typically developing preschool
children continue to manifest these same characteristics. When they
develop impulse control around 4 years of age, overactive and distractible
behaviors diminish. Attention span, activity level, persistence, and
adaptability to change also reflect a child’s temperament
or behavioral style. These traits may affect learning and social
interactions when they are discordant with expectations of the child’s
environment—of teachers, parents, and peers.
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More than a century ago, British physician George Still described
a behavior pattern that presented with restlessness and inattentive
and overaroused behaviors and that involved a child’s inability
to internalize rules and limits. He attributed the condition to
a defect in moral character. Following the worldwide epidemic of
influenza with encephalitis of 1917 to 1918, some of the recovering
children displayed symptoms of restlessness, inattention, impulsivity,
easy arousability, and hyperactivity; it was described as a postencephalitic
behavior disorder. A description of attention deficit hyperactivity
disorder (ADHD) has appeared in subsequent versions of the Diagnostic
and Statistical Manual of Mental Disorders (DSM) of the
American Psychiatric Association. As newer neuropsychological and
clinical research emerged, the name of the disorder changed from
hyperkinetic impulse disorder (DSM-II), to attention deficit disorder
(DSM-III), and most recently to attention deficit hyperactivity
disorder (DSM-IIIR, DSM-IV, and the latest version, DSM-IV-TR, published
in 2000).
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Core symptoms of ADHD are inattention, hyperactivity, and impulsivity.
ADHD is the most common and most extensively studied biopsychosocial
problem in school-aged children. It is a chronic condition that
persists into adolescence and adulthood in 60% to 80% of individuals
diagnosed with ADHD during childhood.1,2
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Attention deficit hyperactivity disorder (ADHD) has been identified
in children in every country and culture studied. The prevalence rate
of ADHD varies depending on diagnostic criteria, the population
studied, and the number of sources used to establish a diagnosis. The
absence of a biologic marker to establish a diagnosis of ADHD and
dependency on parent and teacher reports of behavior is a challenge
to research on prevalence. A prevalence of 4% to 12% was
found in an analysis of 11 studies using community samples. In a
recent national study, 8.7% of children met DSM-IV criteria
for ADHD.3 Poor children were more likely to fulfill
criteria for ADHD. However, wealthier children were more likely
to receive regular medication treatment. Less than half of children
meeting DSM criteria for ADHD in this study had received either
a diagnosis or regular treatment for ADHD. There is a male predominance
of ADHD with a male-female ratio of 3:1 for the combined type and
2:1 for the predominantly inattentive type. In community
samples, predominantly inattentive ADHD is the most prevalent subtype,
about 1.5 times more common than the combined type
and twice as common as the hyperactive/impulsive subtype.
School-aged and adolescent girls are more likely to comprise the
inattentive subtype. ADHD does occur in ...