tic/occupational adjustment.
Academic deficits, school-relat ed problems, and peer neglect tend to be most associ-
ated with elevated symptoms of  inattention, whereas peer reje ction and, to a lesser extent,
accidental injury are most salient with mark ed symptoms of hyperactivity or impulsivity.
Differential Diagnosis
Oppositional defiant disorder. Individuals with oppositional defiant disorder may re-
sist work or school tasks that require self-application because they resist conforming to
others' demands. Their behavior is characte rized by negativity, hostility, and defiance.
These symptoms must be differentiated from aversion to school or mentally demanding
tasks due to difficulty in sustaining mental effort, forgetting instructions, and impulsivity
in individuals with ADHD. Complicating the di fferential diagnosis is the fact that some
individuals with ADHD may develop secondary oppositional attitudes toward such tasks
and devalue their importance.
Intermittent explosive disorder. ADHD and intermittent expl osive disorder share high
levels of impulsive behavior. However, indi viduals with intermitte nt explosive disorder
show serious aggression toward others, which is not characteristic of ADHD, and they do
not experience problems with sustaining atte ntion as seen in ADHD. In addition, intermit-
tent explosive disorder is rare in childhood. Intermittent explosive disorder may be diag-
nosed in the presence of ADHD.
Other neurodevelopmental disorders. The increased motoric acti vity that may occur in
ADHD must be distinguished from the repetiti ve motor behavior that  characterizes stereo-
typic movement disorder and some cases of autism spectr um disorder. In stereotypic
movement disorder, the motoric be havior is generally fixed and repetitive (e.g., body rock-
ing, self-biting), whereas the fidgetiness and restlessness in ADHD are typically general-