What is ADHD? What causes ADHD? | Pediatrics East

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ADHD Introduction

ADHD Introduction

Attention-deficit/hyperactivity disorder (ADHD) is a common neurobiologic disorder characterized by developmentally inappropriate levels of (1) inattention, (2) hyperactivity, and (3) impulsivity. Some children may not have the hyperactivity or impulsivity and may primarily exhibit inattention. ADHD is a behavioral disorder, making it difficult to quantify, but it is one of the most prevalent chronic health conditions affecting school-age children.

Read on to learn more about how ADHD is diagnosed, or contact us if you believe you have seen signs of ADHD in your family and have questions about testing and next steps.

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What is ADHD & How is it Diagnosed?

ADHD is defined as a mental health disorder in the Diagnostic and Statistical Manual 4th Edition (DSM IV) (Table 1). The diagnosis requires a comprehensive clinical evaluation based on identifying children who have the core symptoms of inattention, hyperactivity, and impulsivity. No single test is available to establish the diagnosis, but rather a physical examination and battery of standardized psychological tests are preformed to rule out other causes, either physical or psychological, for the child’s difficulties.

Studies show that as many as 67% of children who have ADHD may have a coexisting condition such as a psychiatric problem, learning disorder, or social immaturity. The most common comorbid psychiatric conditions that have been described include oppositional defiant disorder (35%), conduct disorder (30%), anxiety disorder (25%), and mood disorder (18%). It is important that any coexisting conditions be identified and treated.

The diagnosis is reported 2.5 times more frequently in boys than girls, with 9.2% of males and 2.9% of females found to have behaviors that are consistent with ADHD. According to a 2003 national survey of children’s health, 56% of children with ADHD were treated with medication and problems in school were the primary difficulty.

Table 1 Diagnostic Criteria for Attention-Deficit/Hyperactivity Disorder

A. Either 1 or 2

  1. Six or more of the following symptoms of inattention have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level:

    • Often fails to give close attention to details or makes careless mistakes in schoolwork, or other activities 
    • Often has difficulty sustaining attention in tasks or play activities 
    • Often does not seem to listen when spoken to directly 
    • Often does not follow through on instructions and fails to finish schoolwork, chores, or duties in the workplace (not due to oppositional behavior or failure to understand instructions) 
    • Often has difficulty organizing tasks and activities 
    • Often avoids, dislikes, or is reluctant to engage in tasks that require sustained mental effort (such as schoolwork or homework) 
    • Often loses things necessary for tasks or activities (toys, school assignments, pencils, books, tools) 
    • Often is easily distracted by extraneous stimuli 
    • Often is forgetful in daily activities
  2. Six (or more) of the following symptoms of hyperactivity-impulsivity have persisted for at least 6 months to a degree that is maladaptive and inconsistent with developmental level:


    • Often fidgets with hands or feet or squirms in seat
    • Often leaves seat in classroom or in other situations in which remaining seated is expected
    • Often runs about or climbs excessively in situations in which it is inappropriate (in adolescents or adults, may be limited to subjective feelings of restlessness)  
    • Often has difficulty quietly playing or engaging in leisure activities quietly 
    • Often is "on the go" or acts as if "driven by a motor" 
    • Often talks excessively 


    • Often blurts out answers before questions have been completed
    • Often has difficulty awaiting turn
    • Often interrupts or intrudes on others (eg, butts into conversations or games)

B. Some hyperactive-impulsive or inattentive symptoms that caused impairment were present before 7 years of age.

C. Some impairment from the symptoms is present in 2 or more settings (at school or at home)

D. There must be clear evidence of clinically significant impairment in social, academic, or occupational functioning.

E. The symptoms do not occur exclusively during the course of a pervasive developmental disorder, schizophrenia, or other psychotic disorder and are not better accounted for by another mental disorder (mood disorder, anxiety disorder, dissociative disorder, or personality disorder).

This page was authored by Dr. Edward C. Davis.