Attention Deficit Hyperactivity Disorder

Essential Concepts

ADHD is a clinical diagnosis based on careful history taking, clinical examination, and information from multiple sources and multiple settings (school, home, community).
The clinician must differentiate the core symptoms of ADHD from the secondary effects of other psychiatric disorders.
Hyperactivity does not need to be present during the mental status exam to make the diagnosis of ADHD.
Concomitant learning disabilities and comorbid psychiatric disorders should be evaluated.
Baseline and follow-up rating scales are helpful in monitoring the effectiveness of treatment interventions and medication regimens.

Attention deficit hyperactivity disorder (ADHD) is the most commonly diagnosed psychiatric disorder of childhood and is characterized by deficits in attention, concentration, activity level, and impulse control. ADHD tends to run in families and is often associated with significant comorbidity with other psychiatric disorders, both externalizing (such as oppositional defiant disorder and conduct disorder) and internalizing (such as depression and anxiety), as well as bipolar disorder. The impact of ADHD on the child, his or her family, schools, and society is enormous, with billions of dollars spent annually for school services, mental health services, and increased use of the juvenile justice system. In contrast with historic notions, children do not typically “outgrow” ADHD. Morbidity and disability often persist into adult life. It is not infrequent that I have revealed the
previously undiagnosed ADHD symptoms of a parent in the course of assessing his or her offspring. When his son was diagnosed with ADHD, one father exclaimed, “I am just like that—every little thing distracts me and I can’t get my work done!” He was later evaluated and placed on a stimulant medication for ADHD, much to the benefit of his job effectiveness.

Clinical Description

The core symptoms needed to make a diagnosis of ADHD cover cognitive and/or motor symptoms grouped as inattention, and/or hyperactivity and impulsivity (Table 6.1).

Table 6.1 Diagnosis of ADHD

Inattentive Symptoms
When the child is inattentive, CALL FOR FrEd. This is a mnemonic to recall the nine criteria for the Inattentive symptoms of ADHD (6 of 9). Careless mistakes Attention difficulty Listening problem Loses things Fails to finish what he/she starts Organizational skills lacking Reluctant to do tasks that require sustained mental effort Forgetful in Routine activities Easily Distracted
Hyperactive-Impulsive Symptoms
With hyperactivity-impulsive symptoms the child RUNS FASTT. This mnemonic covers the nine criteria for hyperactivity and inattention (6 of 9). Runs or is restless Unable to wait for his/her turn Not able to play quietly Slow—oh no, on the go Fidgets with hands or feet Answers are blurted out Staying seated is difficult Talks excessively Tends to interrupt
Adapted from American Psychiatric Association (2000), Diagnostic and Statistical Manual of Mental Disorders, 4th ed. Text revision. Washington, DC. American Psychiatric Association.

The onset of ADHD impairment must be in early childhood, at least before the age of 7, even if it was not diagnosed until later in life. Additionally, the symptoms must be functionally impairing and present in a variety of life settings (home, school, work, etc.). ADHD should not be diagnosed if it presents only concomitantly with a pervasive developmental disorder or psychotic disorder, or if symptoms are likely a manifestation of another psychiatric disorder. If a child presents with 6 months of six or more of the inattentive symptoms, the disorder is identified as ADHD, Predominantly Inattentive Type. If there are 6 months of six or more hyperactive-impulsive symptoms, the criteria for Predominantly Hyperactive-Impulsive Type are met. If there are both, it is Combined Type.

Key Point

Historically, the concept of ADHD has changed dramatically since its original description by Still in 1902 as a “morbid defect of moral control.” Views of the disorder have been dominated by 1) behavior (e.g., hyperactivity); 2) etiology (e.g., minimal brain dysfunction); 3) and cognition (e.g. attention deficit disorder). The fluctuations in conceptualization over time have led to changes in diagnostic criteria, research designs, epidemiologic prevalence rates, and treatment interventions.

Tip

Don’t rule out ADHD just because a child is able to attend and focus in your office one-on-one in an interesting activity or game. Many children with ADHD are able to sit still and pay attention in a highly structured or novel setting, when they are alone with an interested adult doing something they enjoy, or when engaged in a highly stimulating activity (such as videogames). Many ADHD children are able to attend to videogames for long periods of time. Symptoms typically worsen in situations that are unstructured, boring, or that require sustained attention or mental effort in a minimally stimulating venue (e.g., school work).

Epidemiology

ADHD is relatively common, affecting an estimated 3 to 12% of school-aged children, depending on the definition and study.
Epidemiological estimates have increased with DSM-IV classification of ADHD into three subtypes (inattentive, hyperactive-impulsive, and combined). In community samples of children, boys are diagnosed with ADHD-Combined Type at a frequency of 3:1 as compared to girls. Clinic samples tend to be 9:1 boys to girls, most likely due to the higher proportion of disruptive boys with ADHD-Combined Type, which may promote referral for treatment. Up to half of all children referred for mental health services are diagnosed with ADHD. The Inattentive Type of ADHD is not associated with an increase in disruptive behaviors and is more nearly equal in prevalence between boys and girls. This type is probably markedly underdiagnosed, as many of these children may be described as “dreamy,” “slow,” or “lazy,” with lack of appreciation for the core inattentive symptoms.

Key Point

ADHD is a disorder with major public health ramifications. Children have a higher injury rate, an increased risk for conduct disorder (one-third), criminal behavior, substance abuse, coordination deficits, and other psychiatric disorders (over half). There is an increased risk of physical punishments and abuse, and more stress within the family. Additionally, there is the economic cost to schools (over $3 billion/year), criminal justice system, health care system, social service agencies, and an increased risk for removal from the home.

Etiology

The etiology of ADHD remains unclear. However, it is certainly both multidetermined and complex. A mnemonic to remember the complex etiology is GET TOPPS.

Genetic—runs in families, but genetics not clear and likely polygenic; also fragile X, phenylketonuria, glucose-6-phosphate dehydrogenase deficiency correlated
Environmental—malnutrition, severe abuse and neglect in infancy
Toxic—lead or other poisoning
Trauma—head trauma
Other psychiatric disorders with comorbidity
Prenatal—maternal use of substances, poor health, very young mother, viral illness
Perinatal—low birth weight, hypoxia, prolonged labor, postmaturity, CNS infection
Subtle neurological deficits—smaller frontal lobe and hypoperfusion, asymmetry of the caudate nucleus, and smaller volume of cerebellar vermis

ADHD is a heterogeneous syndrome, with multifactorial etiology. Relative dysfunction of the prefrontal cortex, with subsequent deficits in “executive function” (planning, organization, and impulse control) is a common feature. Genetic determinants are suggested by family studies—up to one-third of children diagnosed with ADHD will have parents with ADHD. ADHD is two to three times more common in siblings. Candidate genes within the dopamine system are suspected, although genetics is most certainly complex, with the likelihood of multiple microchromosomal alterations leading to a similar phenotype (inattention). Fragile X and other specific genetic syndromes are associated with ADHD as well. Child-rearing practices do not cause ADHD. However, it is suspected that a severely chaotic early environment may adversely affect neuronal pruning and central nervous system (CNS) maturation. Any insult to the brain that results in subtle neurological deficits (hypoxia, head trauma, CNS infections, and suboptimal pre- and perinatal conditions) may predispose to ADHD. Imaging findings are not specific enough to be used for diagnosis. However, there is a correlation with smaller and hypoperfused frontal lobes, asymmetry of the caudate nucleus, and smaller cerebellar vermis. Functional magnetic resonance imaging (fMRI) research may more clearly elucidate some of the subtle neurological deficits associated with difficulties with attention and impulse control.

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