Differential Diagnosis of ADHD in School-Age Children

Adelaide S. Robb, MD


September 26, 2006

In This Article

Combined Type or Primary Hyperactive-Impulsive Subtype ADHD

School-age children with the combined type or primary hyperactive-impulsive subtype of ADHD present early, sometime between kindergarten and second grade. Presentation is usually prompted by teachers' or parents' observation of the child's difficulties with school performance and/or peer interactions. Characteristics that bring a child to treatment include impulsive, hyperactive, and inattentive symptoms such as excessive motor activity, fidgeting, running, leaving his or her seat, talking, interrupting, and problems waiting his or her turn.[3]

Although the most likely diagnosis for a 7-year-old boy who runs around, makes noise, loses everything, refuses to do homework, and interrupts his parents is ADHD combined type, a thorough evaluation to exclude other psychiatric and medical diagnoses on the differential is essential. Psychiatric diagnoses that can present with symptoms similar to those of hyperactive/impulsive subtype ADHD include other disruptive behavioral disorders, anxiety disorders, affective disorders, adjustment disorders, developmental speech and language disorders, reactive attachment disorder, and other developmental disorders.[3]

Disruptive behavioral disorders include oppositional defiant disorder (ODD) and conduct disorder (CD). These disorders frequently are comorbid with ADHD. Children with ODD refuse to follow rules at home and at school, and exhibit argumentative, angry, and acting out behaviors. Children with CD deliberately violate social norms and the rights of others, and present with behaviors including truancy, cruelty to people and animals, stealing, lying, and fire setting.

Some anxiety disorders that present in childhood can look like combined type ADHD. For example, children with posttraumatic stress disorder (PTSD)can experience agitation, easy startle, poor concentration, flashbacks, motor restlessness, and impairments in relationships, and thus can have symptoms similar to those of ADHD. Some children with generalized anxiety disorder (GAD) and panic disorder may also resemble ADHD patients.

Bipolar disorder is the affective disorder that most closely resembles combined type ADHD, with hyperactivity, irritability, distractibility, dangerous and reckless behavior, and poor school performance. Several cardinal symptoms distinguish bipolar disorder from ADHD, including hypersexuality, reduced need for sleep, increased productivity, racing thoughts, and grandiosity.

Mixed expressive and receptive language disorders can present with inattentive and hyperactive behavior because when a child cannot understand or communicate verbally, he or she may become disruptive and agitated. Likewise, children with hearing impairment or severe hearing loss and those who are not native English speakers may also exhibit behaviors that mimic ADHD as a result of the children's inability to understand verbal communication in the classroom.

Children who experience major alterations or stresses in their lives such as divorce, death or illness of a parent, and even bullying may be preoccupied with these stresses and present with signs and symptoms of ADHD. Children who have suffered severe deprivation such as those institutionalized in orphanages or those who have been severely neglected may have reactive attachment disorder and may exhibit some signs and symptoms of ADHD.

The child with mental retardation may appear to have ADHD, because attention and motor activity are appropriate for their mental age but not for their chronologic age. Such children would be identified by their low IQ and impairments in age-appropriate activities of daily living such as feeding, bathing, and dressing. Children with pervasive developmental disabilities may also have difficulties with impulsivity, hyperactivity, and inattention. However, their primary difficulty lies in the impairment in verbal and nonverbal communication and preoccupation with certain activities or hobbies.


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