Understanding Psychology (10th Ed)

disorder 
, or  ADHD  , a disorder marked by inattention, impulsiveness, a low tolerance 
for frustration, and generally a great deal of inappropriate activity. Although all children 
borderline personality disorder
A disorder in which individuals have 
diffi culty developing a secure sense 
of who they are.
narcissistic personality disorder
A personality disturbance charac-
terized by an exaggerated sense of 
self- importance.
attention-defi cit hyperactivity 
disorder (ADHD)
A disorder marked 
by inattention, impulsiveness, a low 
tolerance for frustration, and a great 
deal of inappropriate activity.
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Module 47 
The Major Psychological Disorders 
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show such behavior some of the time, it is so common in children diagnosed with 
ADHD that it interferes with their everyday functioning (Barkley, 2005; Swanson, Harris, 
& Graham, 2003; Smith, Barkley, & Shapiro, 2006). 
ADHD is surprisingly widespread with estimates ranging between 3–5% of the 
school-age population—or some 3.5 million children under the age of 18 in the 
United States. Children diagnosed with the disorder are often exhausting to parents 
and teachers, and even their peers fi nd them diffi cult to deal with. 
The cause of ADHD is not known, although most experts feel that it is produced 
by dysfunctions in the nervous system. For example, one theory suggests that 
unusually low levels of arousal in the central nervous system cause ADHD. To 
compensate, children with ADHD seek out stimulation to increase arousal. Still, 
such theories are speculative. Furthermore, because many children occasionally 
show behaviors characteristic of ADHD, it often is misdiagnosed or in some cases 
overdiagnosed. Only the frequency and persistence of the symptoms of ADHD 
allow for a correct diagnosis, which only a trained professional can do (Barkley, 
2000; Sciutto & Eisenberg, 2007).