6
Clinical Characteristics of Attention Deficit Hyperactivity Disorder
DIAGNOSIS AND ASSESSMENT
Attention deficit hyperactivity disorder (ADHD) has been diagnosed with increasing frequency over the past several decades (see Chapter 12 for an in-depth review). Most diagnoses are made in school-aged children and often based on teacher and parent concerns about school and home performance and behaviors. Diagnoses are made by a range of health professionals, including primary care physicians, psychologists, and child psychiatrists. A number of organizations have developed diagnostic and treatment guidelines, including the American Academy of Pediatrics (AAP, 2011) and the American Psychiatric Association (APA, 2011), but adherence to guidelines is inconsistent, particularly for uncomplicated cases (Garner et al., 2013).
The current diagnostic criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) require that a child’s behavior be developmentally inappropriate (i.e., the child’s behavior is substantially different from other children of the same age and developmental level) and that the symptoms must begin before age 12 and be present for at least 6 months; must be present in two or more settings; must cause significant impairments in home, school, occupational, or peer settings; and must not be secondary to another disorder (APA, 2013). There are three different presentations of ADHD that are identified in the DSM-5. The first is ADHD, predominantly inattentive; the second is ADHD, predominantly hyperactive-impulsive; and the third is ADHD, combined. Symptoms may vary from motor restlessness and aggressive, disruptive behavior, which is
common in preschool-aged children, to disorganized, distractible, and inattentive symptoms, which are more typical in older adolescents and adults. ADHD is often difficult to diagnose in preschoolers as distractibility and inattention are within the range of developmental norms during this period (APA, 2013).
A diagnosis of ADHD is made primarily in clinical settings after a thorough evaluation which includes a careful history and clinical interview to rule in or to identify other causes and contributing factors, behavior rating scales, a physical exam, and any necessary or indicated laboratory examinations. It is important to systematically gather and evaluate information from a variety of sources, including the child, parents, teachers, physicians, and, when appropriate, other caretakers (APA, 2013). Though the evaluation of impairment in ADHD is thought to be more subjective than in that of intellectual disability, there are objective measures of impairments that are increasingly used in ADHD (Gordon et al., 2006), such as the measures of adaptive functioning in general and specific ADHD impairment measures (Biederman et al., 1993; Fabiano et al., 2006).
Clinical interviews allow for a comprehensive analysis of whether or not the symptoms meet the diagnostic criteria for ADHD. During an interview, information pertaining to the child’s history of the presenting problems, overall health and development, and social and family history should be gathered. Moreover, an interview should emphasize factors that might affect the development or integrity of the central nervous system or reveal the presence of chronic illness, sensory impairments, or medication use that might affect the child’s functioning. Disruptive social factors, such as family discord, situational stresses, abuse, or neglect may result in hyperactive or anxious behaviors. Finally, a family history of first-degree relatives with ADHD, mood or anxiety disorders, learning disability, antisocial disorder, or alcohol or substance abuse may indicate an increased risk for ADHD and comorbid conditions (Larsson et al., 2013). In addition to performing a clinical interview, health care providers should assess the number and severity of ADHD symptoms within the home and school settings, using parent and teacher behavior checklists. Behavior rating scales are useful in establishing the magnitude and pervasiveness of the symptoms but are not sufficient by themselves to make a diagnosis of ADHD. Nonetheless, there are a variety of well-established behavior rating scales that reliably discriminate between children with ADHD and controls as well as between ADHD and other childhood psychiatric disorders (APA, 2013).
Currently, there are no laboratory tests available to identify ADHD in children. Although genetic and neuroimaging studies are able to discriminate between subjects with ADHD and normal subjects, these findings apply to differences among groups and are not sufficiently precise to identify single individuals with ADHD. Competing medical and biological
explanations for ADHD must first be ruled out. Thus, the presence of hypertension, ataxia, or thyroid disorder should prompt further diagnostic evaluations. Fine motor coordination delays and other “soft signs” are common but are not sufficiently specific to contribute to a diagnosis of ADHD. Vision or hearing problems should also be evaluated. Children with ADHD may also have histories consistent with exposure to neurotoxins such as lead, infections such as meningitis, or prenatal exposure to alcohol. It is important to note that behavior in a doctor’s office or in a structured laboratory setting may not reflect the child’s typical behavior in the home or school environment. Therefore, a reliance on observed behavior in a physician’s office may result in an incorrect diagnosis. Similarly, computerized attention tasks and electroencephalogram assessments cannot be used to make the diagnosis. Standard office tests for vision and hearing are an essential part of the overall examination in order to rule out such factors as contributing causes (APA, 2013).
DEMOGRAPHIC FACTORS AND DURATION OF THE DISORDER
A diagnosis of ADHD is most frequently made during elementary school years. The demands for attentiveness and orderly behavior are increased in an educational environment, and children with an inability to control their hyperactivity and impulsiveness and an inability to stay focused on the educational lesson become more noticeable because their behaviors can disrupt the classroom environment. In general, ADHD symptoms do not wax and wane, but rather they tend to be consistent up until early adolescence, when the symptoms of hyperactivity may be less obvious, but the inattentive and unmindful characteristics persist, as do the problems with restlessness and impulsiveness.
Age
Clinical manifestations of ADHD may change with age (APA, 2013). A childhood diagnosis of ADHD often leads to persistent ADHD throughout the lifespan. Sixty to 80 percent of children diagnosed with ADHD will continue to experience symptoms in adolescence, and up to 40 to 60 percent of adolescents exhibit ADHD symptoms into adulthood (APA, 2013). Symptoms such as inattention, impulsivity, and disorganization exact a heavy toll on young adult functioning. In addition, a variety of risk factors can affect untreated children with ADHD as they become adults. These factors include engaging in risky behaviors (sexual, delinquent, substance use), educational underachievement and employment difficulties, and relationship difficulties.
Sex
Boys are more likely to be diagnosed with ADHD than girls. Estimates of prevalence have consistently put the rate of reported ADHD diagnoses in male children at approximately twice the rate of ADHD diagnoses in female. In the 2011 National Health Interview Survey, the estimated prevalence of ADHD in males was 12 percent; by contrast, in females the estimated prevalence was only 4.7 percent (Perou et al., 2013). Similarly, a recent meta-analysis of 86 studies of ADHD in children estimated that the ratio of male to females diagnoses for all subtypes of ADHD ranges from 1.9-to-1 to 3.2-to-1 (Wilcutt, 2012).
Race/Ethnicity
Recent population-based studies have found no clear evidence for racial/ethnic differences in the rates of ADHD diagnoses in children. In some estimates of prevalence, the rate of ADHD diagnoses appears to be higher in white than in African Americans or Hispanic Americans; however, this may be due to a lag in clinical identification of nonwhite children who have ADHD (Miller et al., 2009; Morgan et al., 2013). In addition, there may be cultural differences in the attitudes toward or the interpretation of children’s behaviors; cultural differences in acceptance of an ADHD diagnosis in children are another barrier to convincing some parents to seek treatment for their children and to comply with that treatment (Bailey et al., 2010).
COMORBIDITIES
Although ADHD is primarily thought of in terms of impairments in attention, impulse control, and motor activity, there are a number of other psychiatric disorders that regularly appear alongside it. Research studies based on clinical populations have shown that 15 to 25 percent of children with ADHD also experience learning disabilities; 30 to 35 percent of children with ADHD also have language disorders; 5 to 20 percent of children with ADHD are also diagnosed with mood disorders; and 20 to 33 percent of these children have coexisting anxiety disorders. Children diagnosed with ADHD may also have co-occurring sleep disorders, memory impairment, and decreased motor skill function (APA, 2013; MTA Cooperative Group, 1999). A diagnosis of oppositional defiant disorder (ODD) co-occurs in approximately 50 percent of children with ADHD (Gillberg et al., 2004). Conduct disorder (CD) is seen in conjunction with about 7 to 20 percent of the patients with ADHD. The 2009 National Research Council and Institute of Medicine report Preventing Mental, Emotional,
and Behavioral Disorders Among Young People presented findings from a meta-analysis showing significant odds ratios (ORs) for ADHD to co-occur with ODD and CD (OR greater than 10), depression (OR greater than 5), and anxiety disorders (OR greater than 2).
Comorbid diagnoses may lead to diagnostic and treatment complications (and may also lead to greater functional impairments, as discussed below). Biederman and colleagues demonstrated that the baseline rates of depression among children with ADHD increase from an initial rate of approximately 30 percent to 40 percent at 4-year follow-up, in contrast to a 5 percent base rate in control subjects (Biederman et al., 2006). Those with comorbid ADHD and depression also manifested additional disorders, including bipolar disorders and anxiety, more hospitalizations, and lower ratings on a global assessment of functioning.
FUNCTIONAL IMPAIRMENT
The relationship between ADHD symptoms and functional impairments takes a wide variety of forms. Symptoms may be present without any functional impairments, particularly among those with ADHD and no co-occurring disorders (about 30 percent of children; Jensen et al., 2001a,b). ADHD symptoms can also be viewed dimensionally; there is evidence that externalizing symptoms are associated with more functional impairment and differentially associated with impairment (Evans et al., 2005; Zoromski et al., 2015). Approximately one in five children with ADHD has extremely severe impairment across all of their life contexts and even with optimally delivered medications and intensive behavioral interventions may continue to show pronounced disabilities (APA, 2013; Jensen et al., 2001b).
Seventy percent of children with ADHD also have one or more co-occurring mood, anxiety, learning, and oppositional and conduct disorders. The many difficulties such children face result in substantial functional impairment (Jensen et al., 2001a,b). Symptoms may cause impairments at some points in development and not at others. Impairments result from a complex interplay of risk and protective factors; thus impairment will vary across contexts and will be observed and reported differently by youth, parents, teachers, and clinicians.
Delays in speech, language, motor, and social development are common in youth with ADHD, and they can lead to the common findings of impairments in academic performance and the development of comorbid learning disabilities. In addition, irritability, low frustration tolerance, and affect dysregulation are often present in youth with ADHD, resulting in similar consequences for a wide range of social and interpersonal outcomes, including difficulty forming friendships and participating in social activities, and often leading to an increasing accumulation of diagnoses and functional
impairments. The core ADHD symptom of impulsivity has been linked to numerous other functional impairments, including engagement in risk behaviors that affect health and safety, such as poor driving performance and accidents, arrests, alcohol and substance abuse, smoking, acquisition of sexually transmitted diseases, and early pregnancies.
Barkley, in particular, has noted that the correlations between ADHD diagnosis and any particular functional impairment tend to be modest, but that the construction of omnibus impairment scales that can sum across different life domains demonstrates much more robustly the risk of untoward outcomes for youth with ADHD (Barkley, 2012). Functional consequences across domains are more visible to parents, teachers, and other observers than to self-reporting youth.
A recent large study (Garner et al., 2013; N = 5,663) used parent and teacher ratings of child or adolescent impairment across domains in the International Classification of Functioning, Disability and Health as well as symptoms of ADHD and comorbid disorders and then carried out hierarchical regression analyses to identify predictive relationships between specific symptoms and functional outcomes. Notably, symptoms of inattention best predicted academic functioning, while symptoms of hyperactivity/impulsivity predicted disruptive classroom behavior, even after accounting for learning disabilities and oppositional behaviors (Garner et al., 2013). Oppositional and aggressive symptoms were significantly involved; however, ADHD symptoms account for minimal variance in the outcomes of interpersonal functioning and ability to participate in organized activities.
The emerging area of executive functioning (Barkley, 2012) shows promise for elucidating core neuropsychological variables which may be particularly affected by or in ADHD, leading to varied and striking functional impairments. For example, Sjöwall and Thorell have demonstrated that reduced working memory is particularly implicated in the acquisition of language skills, while variability in reaction time and working memory are predictors of difficulties in acquiring mathematical skills (Sjöwall and Thorell, 2014). Furthermore, the ability to regulate anger is a significant predictor of peer problems for children with ADHD, independent of comorbid oppositional defiant or conduct disorder diagnoses.
TREATMENT AND OUTCOMES
Treatment for ADHD generally falls into two categories, either behavioral and psychosocial or medication treatments. This section offers a review of behavioral and psychosocial treatments for ADHD, followed by a review of standards for medication treatment.
Behavioral and Psychosocial Treatment for ADHD
Once the diagnosis of ADHD has been established, parents and children should be educated about the ways in which ADHD can affect learning, behavior, self-esteem, social skills, and family function. Treatment goals for the family should be to enhance parenting skills, improve the child’s interpersonal relationships, develop the child’s study skills, and decrease the child’s disruptive behaviors.
Families are profoundly affected by children with ADHD diagnoses, including having increased stress and a higher occurrence of health and mental health problems in both parents and siblings. Divorce rates among parents of children with ADHD under age 8 have been found to be nearly twice that of comparable age cohorts (22.7 percent versus 12.6 percent), with a number of factors increasing the risk for divorce even further, including the child having more severe symptoms and comorbid oppositionality, the family members being minorities, the father having a history of antisocial or criminal behavior, and the mother having a lower level of education (Wymbs et al., 2008). Families are often in acute need of assistance in managing the disruptive behaviors associated with ADHD in the home context, and they are also critical contributors to their children’s success in school and community venues (Power et al., 2012). A model program developed by Power and colleagues, the Family School Success (FSS) program, demonstrated that parental involvement and strong school–family relationships improve both academic performance and social skills (Power et al., 2008). Building upon the behavioral intervention utilized in the National Institute of Mental Health (NIMH) Multimodal Treatment of ADHD (MTA) studies, FSS utilizes a systematic partnership model using structured, collaborative problem solving (conjoint behavioral consultation) and more focused attention to homework performance using a daily report card shared between home and school. While these interventions place substantial demands on families, they also create an additional venue of support and greater environmental consistency for the child.
The goal of behavioral treatment is to target behaviors that create impairment (e.g., disruptive behavior, difficulty in completing homework, failure to obey home or school rules) for the child to work on progressively improving. Parents and teachers should be guided in establishing a clear communication of expectations and strategies for effective teaching, as well as contingency management, in order to help the child succeed. Federally funded studies performed on large-scale multisite randomized controlled trials lasting up to 24 months have found that, while both behavioral treatments and stimulants improve outcomes, when they are used alone, stimulants are more effective than behavioral treatments, with behavioral interventions alone being only modestly successful at improving
behavior (Hechtman et al., 2004a,b; MTA Cooperative Group, 1999). The most severely impaired children with ADHD (usually with co-occurring conditions) benefit the most from the combination of carefully managed medication and behaviorally oriented therapy (Jensen et al., 2001a). The relative effectiveness of the two therapeutic modalities remains an area of some controversy. One recent meta-analysis of large-scale randomized trials found psychotherapeutic interventions to have little to no benefit on core ADHD symptoms (Sonuga-Barke et al., 2013), but it did provide evidence that these interventions were effective in reducing oppositional defiant and conduct disorder symptoms. Others researchers, citing many smaller studies with different study designs (e.g., single case designs), have argued that behavioral therapy may be more effective than generally assumed by most ADHD researchers (Fabiano et al., 2009).
The American Academy of Pediatrics treatment guideline for ADHD (AAP, 2011) clearly states that a care plan should include behavioral treatment along with any prescribed medication. In the MTA, the major NIMH reference study examining the effects of multimodal treatment for ADHD, combined treatment was found to be usually superior to medication alone or behavioral intervention alone on specific measures of anxiety, academic performance, oppositionality, parent–child relations, and social skills (APA, 2013; Jensen et al., 2001b; MTA Cooperative Group, 1999). These are precisely the comorbid conditions and functional impairments that routinely complicate the course—and the treatment—of ADHD symptoms.
Research studies have documented the potential benefits of such academic interventions as task modifications, reinforcement for on-task behaviors by teachers, organizational skills training, and homework strategies with parents’ involvement (APA, 2013). However, the most commonly provided school-based accommodations (e.g., allowing the child extended time to take tests) have not shown evidence of helping children with ADHD (APA, 2013). Studies of well-diagnosed clinical populations indicate that more than a quarter of children identified with ADHD receive special education services (APA, 2013). Similarly, national surveys have documented that a relatively high prevalence of children with ADHD (more than one-third) receive special education and that children with ADHD make up the majority of those in the Other Health Impairment and Emotional Disturbance categories of disability under the Individuals with Disabilities Education Act (APA, 2013).
Medication Treatment for ADHD
The most widely researched medicines used in the treatment of ADHD are the psychostimulants, including methylphenidate (e.g., Ritalin, Concerta, Metadate), amphetamine, and various dextroamphetaminic preparations
(Dexedrine and Adderall) (APA, 2013). Longer acting, once-daily forms of each of the major types of stimulant medications are available and appear to facilitate adherence. A stimulant treatment, either methylphenidate or an amphetamine-based compound, should be prescribed. As suggested by the results of the NIMH MTA study, the careful monitoring of medication is a necessary component of treatment in children with ADHD (APA, 2013). Optimal treatment in most instances will require somewhat higher doses than routinely prescribed in routine practice settings (Garner et al., 2013). Four or more medication follow-up visits should be offered (APA, 2013).
Evidence suggests that the majority of children who receive careful medication management accompanied by frequent treatment follow-ups, all within the context of an educative, supportive relationship with the primary care provider and appropriate behavioral interventions and supports, are likely to experience behavioral gains for up to 24 months (APA, 2013).
It is worth noting that, with proper treatment, the risks associated with ADHD can be significantly reduced in nearly two-thirds of children (Swanson et al., 2001), although “treatment as usual” (as delivered across the United States by most health care providers) has not been shown to yield lasting benefits. This unfortunate outcome for many youth has numerous roots: Youth and young adults with ADHD usually stop taking medications; clinicians tend to deliver medications in a nonoptimal fashion (e.g., doses being too low, failing to regularly monitor progress, etc.); and primary care referral to and coordination with providers of behavioral interventions is often lacking (APA, 2013). Sixteen-year follow-up data from the MTA study indicate that by ages 23–27, 40 percent of adults with ADHD diagnosed between ages 7 and 10 years old continue to experience significant impairment, despite early intensive treatment. While intensive interventions (carefully managed medication and behavioral therapy) do ameliorate most symptoms in most children with ADHD, these intensive treatments are not generally provided in the community (Jensen et al., 2001a). Nonetheless, three randomized controlled trial follow-up studies indicate that optimal treatments (i.e., usually the combination of carefully titrated and monitored stimulant medication, plus intensive behavior therapy services) substantially reduce functional impairment in up to two-thirds of children compared to less intensively treated control subjects (Abikoff et al., 2004a,b; Gilberg et al., 1997; MTA Cooperative Group, 1999; Swanson et al., 2001). Within the United States, nearly all children with ADHD generally receive “some” treatment, so the outcomes of untreated children have become increasingly difficult to fully assess. For the majority of cases, monotherapy is described although in the community it is more likely that children receive combination and intensities of psychosocial and pharmacological treatment (dosReis et al., 2005), and very little is known about how to sequence these interventions (Foster et al., 2007).
In a study of the 1996 Medical Expenditure Panel Survey, Chan and colleagues examined total costs of care for children with ADHD, children with asthma, and the general population. They found that total yearly costs were $1,151 for ADHD, $1,091 for asthma, and $712 for the general population. These differences persisted after adjustment for multiple sociodemographic characteristics. The ADHD population did not have higher hospital discharge rates than the general population, although out-of-pocket expenses were substantially higher for the ADHD group, at $386 per year, compared with asthma at $246 and the general population at $202 (Chan et al., 2002). In general hospitalization rates for children and youth with ADHD are not higher than in the general population; however, children with ADHD hospitalized for injuries have more severe injuries than other children, are more likely to receive intensive care, and have longer length of stay (DiScala et al., 1998).
FINDINGS
- Diagnosis requires a detailed, comprehensive clinical assessment. Adherence to diagnostic guidelines is variable. There are no laboratory tests to identify ADHD.
- The diagnosis of ADHD usually occurs during the early elementary school years.
- Boys are diagnosed with ADHD approximately twice as frequently as girls.
- The functional impairments caused by ADHD may change as a child matures; however, a childhood diagnosis of ADHD can often mean persistent impairments into adulthood.
- ADHD co-occurs with another mental, emotional, or behavioral disorder very frequently—in approximately 70 percent of cases. Children with ADHD and co-occurring conditions have more significant functional impairments.
- Evidence-based treatments benefit many children with ADHD. However, there is also evidence that many children with ADHD do not receive optimal, evidence-based treatment.
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