Essentials of Diagnosis
Either (1) or (2):
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:Inattention
Often fails to give close attention to details or makes careless mistakes in schoolwork, work, 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 (e.g., toys, school assignments, pencils, books, or tools)
Is often easily distracted by extraneous stimuli
Is often forgetful in daily activities
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: Hyperactivity
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 playing or engaging in leisure activities quietly
Is often “on the go” or often 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 (e.g., butts into conversations or games)
Some hyperactive-impulsive or inattentive symptoms that caused impairment were present before age 7 years.
Some impairment from the symptoms is present in two or more settings (e.g., at school [or work] and at home).
There must be clear evidence of clinically significant impairment in social, academic, or occupational functioning.
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 (e.g., Mood Disorder, Anxiety Disorder, Dissociative Disorder, or a Personality Disorder).
- Attention-Deficit/Hyperactivity Disorder, Combined Type: if both Criteria A1 and A2 are met for the past 6 months
- Attention-Deficit/Hyperactivity Disorder, Predominantly Inattentive Type: if Criterion A1 is met but Criterion A2 is not met for the past 6 months
- Attention-Deficit/Hyperactivity Disorder, Predominantly Hyperactive-Impulsive Type: if Criterion A2 is met but Criterion A1 is not met for the past 6 months
General Considerations
Attention-deficit hyperactivity disorder (ADHD) is the most common emotional, cognitive, and behavioral disorder treated in youth. It is a major clinical and public health problem because of its associated morbidity and disability in children, adolescents, and adults. Data from cross-sectional, retrospective, and follow-up studies indicate that youth with ADHD are at risk for developing other psychiatric difficulties in childhood, adolescence, and adulthood including delinquency as well as mood, anxiety, and substance-use disorders.
Early definitions, such as the Hyperkinetic Reaction of Childhood in DSM-II, placed the greatest emphasis on motoric hyperactivity and overt impulsivity as hallmarks of the disorder. The DSM-III represented a paradigm shift as it began to emphasize inattention as a significant component of the disorder. DSM-IV now defines three subtypes of ADHD: predominantly inattentive, predominantly hyperactive–impulsive, and a combined subtype. Criteria for each DSM-IV subtype require six or greater of nine symptoms in each respective category. There are four additional criteria that include age of onset by 7 years, ADHD-specific adaptive impairments, pervasiveness, and separation from other existing conditions. The combined subtype is the most commonly represented subgroup accounting for from 50% to 75% of all ADHD individuals, followed by the inattentive subtype (20–30%), and the hyperactive–impulsive subtype (less than 15%).
Epidemiologic studies indicate that ADHD is a prevalent disorder affecting from 4% to 7% of children worldwide including the United States, New Zealand/Australia, Germany, and Brazil. Although previously thought to remit largely in adolescence, a growing literature supports the persistence of the disorder and/or associated impairment into adulthood in a majority of cases.
Prevalence estimates of childhood ADHD in the United States are estimated to be 5–8%. Estimates vary predictably depending on methodology. Definitions that require both symptom dimensions (hyperactivity/impulsivity and inattention) are more restrictive than those that require only one of these dimensions. Thus, estimates based on pre-DSM III definitions or the ICD codes of hyperkinetic disorder produce lower estimates. In addition the surveys that estimate based on symptoms alone and do not include impairment yield higher estimates. As recently by Faraone et al. (2003), other factors that affect apparent prevalence estimates include pervasiveness criteria, informants (teacher, parent, child), use of rating scales versus clinical interviews as well as ascertainment issues. Community samples have higher rates than school samples.
Gender and age of the sample also affect estimates prevalence. Girls more commonly have the inattentive type and also less commonly have accompanying ODD/CD, disruptive disorders, factors leading to lower rates of diagnosis. The original descriptions were derived from a child-focused perspective, and do not reflect what are thought to be more salient aspects of adult ADHD: the executive function disorders of poor organization, poor time management, and memory disturbance associated with academic and occupational failure. The lack of appropriate description of adult symptoms may reduce the true prevalence of ADHD in adulthood.
Several biologic factors have been proposed as contributors to ADHD, including food additives/diet, lead contamination, cigarette and alcohol exposure, maternal smoking during pregnancy, and low-birth weight. Although the Feingold diet for ADHD was popularized by the media and accepted by many parents, systematic studies showed that this diet was ineffective and that food additives do not cause this disorder. Several investigators have shown that lead contamination can cause symptoms of ADHD. However, lead does not account for the majority of ADHD cases, and many children with high-lead exposure do not develop ADHD. An emerging literature documents that maternal smoking and alcohol exposure during pregnancy, low-birth weight, and psychosocial adversity are additional independent risk factors for ADHD.
Pregnancy and delivery complications (i.e., toxemia, eclampsia, poor maternal health, maternal age, fetal postmaturity, duration of labor, fetal distress, low-birth weight, antepartum hemorrhage) appear to have a predisposition for ADHD. Several studies documented that maternal smoking during pregnancy is an independent risk factor for ADHD.
Findings of recent studies stress the importance of adverse family–environment variables as risk factors for ADHD. In particular, chronic family conflict, decreased family cohesion, and exposure to parental psychopathology (particularly maternal) are more common in ADHD families compared with control families. It is important to note that, although many studies provide powerful evidence for the importance of psychosocial adversity in ADHD, such factors tend to emerge as universal predictors of children’s adaptive functioning and emotional health, rather than specific predictors of ADHD. As such, they can be conceptualized as nonspecific triggers of an underlying predisposition or as modifiers of the course of illness.
Because ADHD is believed to be highly genetic, studies of twins have been used to establish its heritability or the degree to which this disorder is influenced by genetic factors. Based on numerous studies of twins, which varied considerably in methodology and definitions of ADHD, the mean heritability for ADHD was shown to be 77%. Seven candidate genes show statistically significant evidence of association with ADHD on the basis of the pooled odds ratio (1.18–1.46) across studies: DRD4, DRD5, DAT, DBH, 5-HTT, HTR1B, and SNAP-25.
Clinical Findings
The diagnosis of ADHD is made by careful clinical history. A child with ADHD is characterized by a considerable degree of inattentiveness, distractibility, impulsivity, and often hyperactivity that is inappropriate for the developmental stage of the child. Other common symptoms include low-frustration tolerance, shifting activities frequently, difficulty organizing, and daydreaming. These symptoms are usually pervasive; however, they may not all occur in all settings. Adults must have childhood-onset, persistent, and current symptoms of ADHD to be diagnosed with the disorder. Adults with ADHD often present with marked inattention, distractibility, organization difficulties and poor efficiency, which culminate in life histories of academic and occupational failure.
Rating scales are extremely helpful in documenting the individual profile of ADHD symptoms as well as assessing the response to treatments. It is important to emphasize that they should not be used for diagnosis without careful clinical confirmation and elicitation of the other criteria necessary for diagnosis. Although neuropsychological testing is not relied upon to diagnose ADHD it may serve to identify particular weaknesses within ADHD or specific learning disabilities co-occurring with ADHD.
Rating scales are available for all age groups and can be useful in assessing and monitoring home, academic and occupational performance. Increasingly, there has been a congruence of opinion in this area with a number of the most widely used scales consisting of Likert ratings of the existing DSM-IV criteria. There are two types of scales in wide use, the so-called “narrow” scales that are specific for ADHD and “broad” scales that measure additional dimensions including comorbidity. The broad scales are useful for separating straightforward and complex cases, and the narrow scales are most useful for honing in on exclusively ADHD dimensions both diagnosis and to monitor specific responses to treatment. In looking to the future, there are proposals to expand the set of diagnostic symptoms to include executive functions (such as time management and multitasking) especially in older individuals.
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