Children with difficulties in attention and impulsivity have been recognized since the mid-1800s when compulsory school attendance became the rule. The 19th-century book Struwwelpeter
, a “morality” book for children by Heinrich Hoffmann, included the tales of Fidgety Philip, who could not sit still, and Johnny Look-in-the-Air, who could not pay attention (Struwwel, 1999
). The observation of difficulties after viral encephalitis in the early 20th century led to a presumption that these problems arose as a result of some subtle or “minimal” brain damage. Bradley’s observation in the 1930s that such children could improve their attention after administration of amphetamine led to one of the first pharmacologic treatments for childhood mental disorders (Bradley, 1937
). This led to the use of terms like minimal brain dysfunction
to describe the condition even though evidence of gross brain damage was not demonstrable. In 1957, Laufer used the term hyperkinetic impulse disorder
, and, in 1970, the second edition of the Diagnostic and Statistical Manual
) identified the syndrome as hyperkinetic reaction
(Laufer & Denhoff, 1957
). By 1980, the term attention-deficit disorder
began to be used, as was, subsequently, the term attention-deficit/hyperactivity disorder
(ADHD). By that time the importance of inattention symptoms had gained recognition, resulting in an appellation of attention-deficit disorder
that can be diagnosed with or without hyperactivity
DIAGNOSIS, DEFINITION, AND CLINICAL FEATURES
ADHD is characterized by symptoms of inattention, overactivity, and impulsivity along with deficits in the set of skills usually termed executive functioning
. The latter are a range of abilities involved in forward planning, self-control, and delay of gratification. Although similar in some ways, there are differences in approach between the DSM-5
(American Psychiatric Association, 2013
) and the International Classification of Diseases
) as well as the latest revision, ICD-11
(World Health Organization, 2019-2020
hyperkinetic disorder has been renamed ADHD and moved from the category of “behavioral and emotional disorders with childhood onset” to the category of “neurodevelopmental disorders” to recognize its developmental onset, characteristic disturbances in neurocognitive and social functions, and common co-occurrence with other neurodevelopmental disorders. Both the DSM
approaches provide a list of 18 symptoms that can involve both attentional problems and hyperactivity (the combined type) or only inattention or
impulsivity. In DSM-5
, the hyperactive type requires at least six of nine symptoms of overactivity, and the inattentive type requires at least six of nine listed symptoms of inattention. In the combined type, six of each are required. The ICD
approach emphasizes the overactivity aspect and is more stringent in making the diagnosis when other disorders such as anxiety or depression are present. These approaches to diagnosis are summarized in Table 10.1
. A notable difference in diagnostic criteria in the DSM-5
compared to its predecessor DSM-IV-TR
is that the age requirement for symptom onset was changed from 7 to 12 years. The distinctions between the subtypes of the disorder can be subtle, and debate continues about the best approach to conceptualizing the condition(s). For example, some children with predominately inattentive symptoms may be less active. It is the case that children whose difficulties relate to overactivity are likely to be more disruptive and thus may be more frequently referred for treatment and earlier diagnosis. For a diagnosis of ADHD to be made, the symptoms must be present in more than one setting (such as home, school, and friendships), must cause significant impairment in functioning, and cannot be exclusively attributable to another disorder or be better accounted for by it. As a practical matter, the diagnosis of ADHD should include information about symptoms and functioning from multiple sources including parents, teachers, and observations by clinicians experienced in the assessment of children with this disorder (Box 10.1
The degree to which any one of the three major areas of difficulty—overactivity, inattention, and impulsivity—impacts the child functioning at home and in school will color the diagnostic presentation. The child’s age and level of functioning are very important considerations for the diagnosis; for some children, difficulties only become apparent because of the age-expected demands placed by school for concentration and attention. Having lots of energy is not unusual for young children, and behaviors such as difficulty remaining seated, running about, and laughing and screaming loudly when having fun are expected of preschoolers. However, if older children have difficulty regulating these type of behaviors, it could be a sign of ADHD.
TABLE 10.1 Approaches to Diagnosis of Attention-Deficit/Hyperactivity Disorder in the Diagnostic and Statistical Manual 5
Onset and duration: Before the age of 12 years; symptoms must be present for at least 6 months.
Symptom presentation and impairment: Symptoms must be present in more than one setting and result in significant impairment; symptoms must be persistent and not attributable to developmental level and not occurring exclusively during psychosis or better explained by another disorder.
Subtypes: Three possible subtypes are identified: inattentive, hyperactive, or combined.
For the inattentive type, at least six symptoms of inattention (e.g., in school work, social interaction, following through on activities, troubles in organization and activities that require forward planning, readily disorganized, by extraneous environmental events)
For the hyperactivity type, at least six symptoms, such as inability to sit still, high activity level inappropriate to situation, trouble playing quietly, excessively verbal, trouble waiting turns, interrupts frequently, and so on
In the combined type, both hyperactive and inattentive symptoms are present.
Exclusionary rules: Features not attributable solely to (or occur during) schizophrenia or psychotic disorder or better viewed as part of some other condition such as anxiety or mood disorder
As children enter kindergarten, learning to participate in structured activities and follow classroom rules can take weeks and months for most. As typically developing children show consistent progress with acquisition of new behaviors such as sitting at their desk and listening to the teachers, children with ADHD would fall behind in building such age-appropriate competencies. A lack of precision regarding how “often” a behavior or feature must be present and how “persistent” it is means that there is considerable clinical judgment involved in
making the diagnosis. Also, the presence of comorbid conditions, such as learning difficulties, language problems, disruptive behavior, and so forth, frequently complicates the clinical picture. For some children, the burden of significant attentional problems and hyperactivity takes a toll on affective regulation as well as on peer relationships and social development. There has been growing awareness that, for many children, symptoms of overactivity may lessen with time, but attentional problems may persist. As a result, in adulthood, many individuals may continue to experience difficulties, although their impairment may be less immediately obvious (Nigg et al., 2020
In the doctor’s office setting, the difficulties with attention and impulsivity may not seem markedly different than those in other children, although when a child’s difficulties are severe, they are often noted even in office settings. For school-age children, problems with overactivity may be most dramatic in less structured settings (e.g., gym or recess), and problems with attention are reflected in academic areas. Rating scales, checklists, and some psychological tests (discussed subsequently) may be useful in helping to clarify the diagnosis. More complex academic tasks, which require organizational skills and forward planning, are particularly impacted by problems in attention and impulsivity. This is often reflected in forgotten homework or many different projects started but never finished and can be demonstrated on psychological testing. As a practical matter, the clinician should keep in mind the core features of the condition—hyperactivity, inattention, and impulsivity—and have a reasonable sense of what is and is not within the normal range for a child of a given age (Box 10.2
By definition, the essential feature of ADHD is a persistent pattern of inattention and/or hyperactivity-impulsivity that are developmentally inappropriate and interfere with functioning across important areas. In the DSM-5, the disorder must have its onset before the age of 12 years. Determination of the actual age of onset is difficult, because these data are invariably retrospective in nature. Most of the time, parents will have noted some difficulties in the preschool period, when the child may have had a “driven” quality as they rapidly explored the room. Often, parents provide detailed reports of family outings and birthday parties during which the child’s difficulties have led to major disruptions. In situations in which the major difficulties relate to sustained attention and organization, it may be only when the child enters school that difficulties pose a serious obstacle for learning and lead to diagnosis. Some children have difficulty remaining seated during class. Even in situations such as recess and sports, the child’s difficulties with attention and impulsivity may take a toll on social relationships. Inattention is characterized by difficulty staying focused, mind wandering off task, lacking persistence in tasks that require focused attention, and general difficulty organizing and sustaining mental effort. These symptoms are different from and should be carefully separated from lack of comprehension or noncompliance with academic assignments. In the absence of clear hyperactivity, attentional difficulties may not become obvious until middle school when academic tasks become more demanding of attentional resources. These difficulties may also continue into adulthood, and diagnosis and treatment of ADHD in adults are gaining greater recognition in the field of mental health.
EPIDEMIOLOGY AND DEMOGRAPHICS
ADHD is one of the more common psychiatric disorders, affecting approximately 5% of children and 2.5% of adults. The prevalence estimates vary across epidemiologic studies because of differences in samples, assessment methods, and diagnostic approaches. Boys are more likely to be affected than girls (2:1 or 3:1 ratio) and are more likely than girls to present with disruptive behaviors (Spetie & Arnold, 2018
). Girls with ADHD are more likely to have attentional problems and more co-occurring internalizing problems, such as depression and anxiety (Rucklidge, 2010
). ADHD is also found more frequently in younger children and in children from families with a lower socioeconomic status. Symptoms of hyperactivity decrease with age. As adults, many, perhaps more than 50% of individuals, continue to have symptoms. Younger individuals are more likely to show features of the hyperactive subtypes; attentional problems become more marked over time so that the combined type becomes predominant. By the junior high and high school
years, the inattentive type is most common. Compared with many other disorders, ADHD is often a diagnosis made by history from parents and teachers or, with adolescents and adults, by selfreport. A child with ADHD can appear calm and well organized in a novel setting, so reports of parents and teachers are often used in making the diagnosis.
As noted previously, ADHD is frequently associated with other conditions including oppositional defiant or conduct disorder (˜50% of cases), anxiety disorder (25%-30%), and learning disabilities (20%-25%) (Baweja & Waxmonsky, 2018
; Harvey et al., 2016
). The risk of developing tic disorder is also increased (Sukhodolsky et al., 2009
). It is important that co-occurring disorders are carefully evaluated and documented when they are present, because they may require additional interventions apart from those for ADHD. As children with ADHD become older, they are at increased risk for mood disorders and substance abuse. Comorbidity can arise from various sources (e.g., from genetic or environmental factors that contribute to both disorders or because ADHD increases risk for other problems). Comorbid conditions can further exacerbate the negative impact of ADHD on family life, peer relationships, and academic and occupational achievements.
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