Attention Deficit Hyperactivity Disorder � Diagnostic Perspectives
1.�������� Definitions
ADHD has been a known behavioral syndrome for a long time. A sample definition of this syndrome is: �A type of childhood behavior disorder, believed to be due to diencephalic dysfunction, characterized by hyperactivity, short attention span, poor concentration, and irritability� (Hinsie & Campbell, 1970, Psychiatric Dictionary).� Historically, it has been called Hyperactivity, Brain-Damage Behavior Syndrome, Central Nervous System Deviation, Strauss Syndrome, Post-Encephalitic (Encephalitis = inflammation of the brain) Behavior Syndrome, Hyperkinesis (too much movement), Choreatiform Syndrome (type of abnormal movement), and Minimal Brain Dysfunction (a diagnostic category indicating that there is something wrong with the brain, but the disturbances are minimal, scattered, and do not fit any other syndrome). This variety of names clearly indicates the persisting difficulty with the etiology of this syndrome.
In DSM-III-R, which used a behavioral-descriptive, rather than an etiological, approach, this syndrome received its current name and most behavioral characteristics were described (Sattler, 1992, Assessment of Children).� However, future research indicated that there are two behaviorally distinguishable subtypes of the disorder, and its definition in DSM-IV reflected these findings (American Psychiatric Association, 1994, DSM-IV).�
Consequently, the current definition subdivides ADHD into Inattentive, Hyperactive/Impulsive, and Combined types, depending on the predominant symptoms.� It requires the presence of at least six symptoms of inattention and/or hyperactivity/impulsivity in at least 2 settings, lasting for 6 months or more, with onset before 7 years of age, and clinically significant impairment in at least two settings and areas of functioning.� The symptoms of inattention include:� poor attention to detail and careless mistakes, difficulties with sustained attention, not listening when spoken to directly, not following through on various tasks, difficulties with organizing activities, avoidance of tasks that require sustained mental effort, loosing things necessary for tasks or activities, being easily distracted by extraneous stimuli, and being forgetful in daily activities.� The symptoms of hyperactivity include:� fidgeting with hands or feet or squirming in seat, leaving seat when remaining seated is expected, excessive running or climbing in situations where it is inappropriate, difficulties with engaging in leisure activities quietly, being overly active, and talking incessantly.� The symptoms of impulsivity include:� blurting out answers before questions are completed, difficulties with awaiting turn, and interruption of or intrusion on others.
����������� A number of literature reviews indicates that Hyperactive and Inattentive subtypes of ADHD are dissociable both cognitively and behaviorally (Snyder & Nussbaum, 1998, Clinical Neuropsychology), as detailed in the following table:
| Hyperactive Type | Inattentive Type |
| Motorically overactive | Motorically sluggish |
| Sustained attentional problems | Selective attentional problems |
| Impulsivity | Disorganization |
| Externalizing behavioral problems (aggressive, defiant, behavioral problems at school) | Internalizing behavioral problems (performance anxiety, depression, and withdrawal) |
| Higher incidence of learning disabilities | |
| Academic deficiencies related to underlying cognitive dysfunctions | |
| Possibly, primary deficits in response inhibition and sustained attention | Possibly, primary deficits in focusing and executive dimensions of attention |
����������� In terms of developmental course of the disorder, hyperactive subtype develops a discernable clinical picture by 3 or 4.� These children have difficulties with age-appropriate behavioral self-regulation, excessive motor activity, and adapting to unexpected changes in the environment.� In school, more structured and rule-governed environment elicits more disruptive behaviors, externalizing behavior disorders, and academic difficulties become apparent.� Inattentive subtype is more difficult to detect and usually is noticed during middle childhood with academic problems and internalizing and adjustment disorders emerging.� In adolescence symptoms of overt hyperactivity tend to decrease, while inattention and other cognitive deficits tend to persist.� By adulthood, approximately 80% of children with ADHD retain some primary symptoms, and 75% continue to have some form of social-emotional difficulties.
2. Epidemiology (American Psychiatric Association, 1994, DSM-IV; Snyder & Nussbaum, 1998, Clinical Neuropsychology)
The prevalence of ADHD is 3-5% in school-age children.� It is four times more common in males than females in general population and 9 times � in clinical population.�
Children with ADHD have higher incidence (than in the general population) of Oppositional Defiant Disorder & Conduct Disorder (in up to 2/3 of children with ADHD), Mood Disorders & Anxiety Disorders (in 25-30%), Learning Disorders (in 9-63%), Tourette�s Disorder, Mental Retardation, minor physical abnormalities, histories of child abuse/neglect, multiple foster home placements, neurotoxin exposure, encephalitis, drug exposure in utero, and low birth weight.
ADHD is more common in families with history of ADHD, Mood Disorders, Anxiety Disorders, Learning Disorders, Substance-related Disorders, and Antisocial Personality Disorder.
3. Etiology (Snyder & Nussbaum, 1998, Clinical Neuropsychology)
Currently, common view is that ADHD is a behavioral syndrome resulting from various etiological factors, some of which remain unknown.� Genetic predisposition may account for up to 50% of variance in ADHD.� A variety of perinatal, neonatal, and early childhood insults to the brain (likely affecting frontal areas and their connections to the limbic system) may predispose a child to the development of ADHD.� Psychosocial factors can produce a phenotype of ADHD without any neurobiological substrate.� Finally, this behavioral syndrome may be produced by a number of other conditions, such as undiagnosed hearing or vision impairment, thyroid disorders, systemic lupus, seizure disorders, brain trauma, anoxic or hypoxic brain damage, hypoglycemia, HIV-I, medications (e.g., phenobarbital, theophylline), and a host of other conditions.� Even though the etiological distinctions are not taken into account in the taxonomy of DSM-IV, they do have significant implications for treatment planning.
4. Diagnosis (Snyder & Nussbaum, 1998, Clinical Neuropsychology; Sattler, 1992, Assessment of Children)
In order to create a reasonable treatment plan, the diagnosis of ADHD, which we can base on behavioral information fulfilling the DSM-IV criteria, is usually insufficient.� As we have seen, this is a complex syndrome with multiple etiologies.� Medications that are likely to be effective will depend on the precise etiology.� Behavioral plans will depend on the specifics of attentional difficulties and other cognitive and emotional components of the disorder.� So will educational aides and family and therapeutic interventions.� For example, if there is evidence of organic brain trauma producing attention deficits, medications and teaching cognitive skills to work around the deficit are likely to be more helpful.� However, if psychosocial factors are primary, mood or anxiety, as well as the family systems interventions are likely to be more helpful.� Once these factors are dealt with, the child can be directly taught attention skills.
Given the variety of medical conditions that produce ADHD-like symptoms, a thorough medical exam, including hearing and vision tests, is necessary.� Only after the underlying medical condition is treated an assessment for ADHD makes sense.��
As is usual with such complex disorders, an attempt to untangle the symptomatic picture often becomes a �chicken and an egg� question.� However, if we are able to find some historical evidence of early brain trauma, we are on firmer ground.� A thorough history including familial history, medical history, prenatal, perinatal, and childhood trauma history, as well as psychosocial history is essential for this.
Attention is one of the most basic cognitive functions.� It is crucial for the appropriate development of more complex functions, such as learning, organization, planning, and problem solving.� It is also a complex function.� For ADHD assessment, we want to know not only how long can the child keep attention on the task (sustained attention), but also how well can he/she focus, ignore irrelevant distracters, how easily can he/she shift attention, how large is his/her working memory, and how complex a task can he/she perform before he/she becomes overwhelmed and �tunes out�.� It is important to note that in neuropsychological assessment we are looking for the best performance, not for the usual performance, as in most psychodiagnostic tests.� We want to know the child�s ability.� Ideally, the assessment of attention should be a part of a thorough neuropsychological workup.
In terms of behavioral symptoms evaluation, we need to interview not only the child and parents, but also a teacher, in order to establish the �two settings� criteria.� Observing the child at school and with parents during a play task or some other direct interaction could be extremely helpful, since their idea of what �appropriate attention� or �appropriate level of activity� is may be quite different from that of the DSM-IV.� Additionally, it is invaluable for designing therapeutic interventions.�
