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INTRODUCTION — Attention deficit hyperactivity disorder (ADHD) is a disorder that manifests in childhood with symptoms of hyperactivity, impulsivity, and/or inattention. The symptoms affect cognitive, academic, behavioral, emotional, and social functioning . (See 'Diagnostic criteria' below.)
This topic review focuses on the clinical features and evaluation of ADHD. The epidemiology, pathogenesis, management, and prognosis of ADHD in children and adolescents and ADHD in adults are discussed separately:
Core symptoms — ADHD is a syndrome with two categories of core symptoms: hyperactivity/impulsivity and inattention. Each of the core symptoms of ADHD has its own pattern and course of development. The complaint regarding symptoms of ADHD may originate from the parents, teachers, or other caregivers .
Hyperactivity and impulsivity — Hyperactive and impulsive behaviors almost always occur together in young children. The predominantly hyperactive-impulsive subtype of ADHD is characterized by the inability to sit still or inhibit behavior.
Symptoms of hyperactivity and impulsivity may include :
●Excessive fidgetiness (eg, tapping the hands or feet, squirming in seat)
●Difficulty remaining seated when sitting is required (eg, at school, work, etc)
●Feelings of restlessness (in adolescents) or inappropriate running around or climbing in younger children
●Difficulty playing quietly
●Difficult to keep up with, seeming to always be "on the go"
●Difficulty waiting turns
●Blurting out answers too quickly
●Interruption or intrusion of others
Hyperactive and impulsive symptoms typically are observed by the time the child reaches four years of age and increase during the next three to four years, peaking in severity when the child is seven to eight years of age [3,4]. After seven to eight years of age, hyperactive symptoms begin to decline; by the adolescent years, they may be barely discernible to observers although the adolescent may feel restless or unable to settle down. In contrast, impulsive symptoms usually persist throughout life. (See "Attention deficit hyperactivity disorder in children and adolescents: Overview of treatment and prognosis", section on 'Prognosis'.)
The focus of impulsivity is related to the environment. As an example, adolescents with ADHD who are untreated and in an environment where alcohol and other commonly abused substances are readily available are at greater risk of engaging in drug use or experimentation than are adolescents without ADHD .
Inattention — The predominantly inattentive subtype of ADHD is characterized by reduced ability to focus attention and reduced speed of cognitive processing and responding [6,7]. Children with the inattentive subtype often are described as having a sluggish cognitive tempo and frequently appear to be daydreaming or "off task" . The typical presenting complaints center on cognitive and/or academic problems. Among children born at <32 weeks gestational age, symptoms of inattention appear to be more prominent than hyperactivity and impulsivity . (See "Long-term neurodevelopmental outcome of preterm infants: Epidemiology and risk factors", section on 'Neurodevelopmental disability and academic achievement'.)
Symptoms of inattention may include :
●Failure to provide close attention to detail, careless mistakes
●Difficulty maintaining attention in play, school, or home activities
●Seems not to listen, even when directly addressed
●Fails to follow through (eg, homework, chores, etc)
●Difficulty organizing tasks, activities, and belongings
●Avoids tasks that require consistent mental effort
●Loses objects required for tasks or activities (eg, school books, sports equipment, etc)
●Easily distracted by irrelevant stimuli
●Forgetfulness in routine activities (eg, homework, chores, etc)
The symptoms of inattention typically are not apparent until the child is eight to nine years of age [3,4]. This delay may relate to reduced sensitivity of assessment of attention problems or increased variability in the normal development of the cognitive skills. Similar to the pattern of impulsivity, symptoms of inattention usually are a lifelong problem. (See "Attention deficit hyperactivity disorder in children and adolescents: Overview of treatment and prognosis", section on 'Prognosis'.)
Impaired functioning — In order to meet criteria for ADHD, core symptoms must impair function in academic, social, or occupational activities . Social skills in children with ADHD often are significantly impaired. Problems with inattention may limit opportunities to acquire social skills or to attend to social cues necessary for effective social interaction, making it difficult to form friendships. Hyperactive and impulsive behaviors may result in peer rejection . The negative consequences of impaired social function (eg, poor self-esteem, increased risk for depression and anxiety) may be long standing.
Overview — The evaluation for possible ADHD includes comprehensive medical, developmental, educational, and psychosocial evaluation [2,11-16]. Comprehensive evaluation is necessary to confirm the presence, persistence, pervasiveness, and functional complications of core symptoms, exclude other explanations for core symptoms (table 1), and identify coexisting emotional, behavioral, and medical disorders. (See 'Diagnostic criteria' below and 'Differential diagnosis' below and 'Coexisting disorders' below.)
The evaluation should include review of the medical, social, and family histories; clinical interviews with the parent and patient; review of information about functioning in school or day care; and evaluation for coexisting emotional or behavioral disorders [11-16]. The necessary information may be obtained in several ways, including in-person discussions, questionnaires, and web-based tools, as described below.
The complete evaluation may require several office visits . It is important to discuss safety and injury prevention at each visit because children with ADHD or symptoms of ADHD are at increased risk of intentional and unintentional injury compared with children without these symptoms. (See "Attention deficit hyperactivity disorder in children and adolescents: Overview of treatment and prognosis", section on 'Prognosis'.)
Reevaluation of children with ADHD is warranted whenever symptoms worsen or new symptoms emerge because the differential diagnosis of ADHD is extensive and comorbidity is common. (See 'Differential diagnosis' below and 'Coexisting disorders' below.)
Medical evaluation — Important aspects of the medical history include prenatal exposures (eg, tobacco, drugs, alcohol), perinatal complications or infections, central nervous system infection, head trauma, recurrent otitis media, and medications . Family history of similar behaviors is important because ADHD has a strong genetic component. The review of systems should include information about sleep disturbances [15,17]. It is particularly important to obtain a dietary history (eg, appetite, picking eating) and history of sleep patterns before initiation of pharmacotherapy to avoid attributing preexisting problems to medications . It is also important to obtain a thorough child and family cardiac history and cardiac review of systems before initiating medications. (See "Attention deficit hyperactivity disorder in children and adolescents: Epidemiology and pathogenesis", section on 'Genetic factors' and "Cardiac evaluation of patients receiving pharmacotherapy for attention deficit hyperactivity disorder", section on 'Recommended approach'.)
The pediatric care provider can ask the parents the following questions to elicit concerns regarding school performance and behavior :
●How is your child doing at school?
●Have you or the teacher noticed any problems with learning?
●Is your child happy in school?
●Does your child have any behavioral problems at school or home, or when playing with friends?
●Does your child have problems completing school assignments at school or home?
The physical examination of most children with ADHD is normal. However, the examination is necessary to evaluate other possibilities in the differential diagnosis. Important aspects of the examination include [11,19]:
●Measurement of height, weight, head circumference, and vital signs
●Assessment of dysmorphic features and neurocutaneous abnormalities
●A complete neurologic examination, including assessment of vision and hearing
●Observation of the child's behavior in the office setting; however, this isolated assessment of behavior should be interpreted cautiously; symptoms of ADHD may not be apparent in the structured setting of the clinic visit
Developmental and behavioral evaluation — Important aspects of the developmental and behavioral history include :
●Specific information about the onset, course, and functional impact of ADHD symptoms
●Emotional, medical, and developmental events that may provide an alternative explanation for the symptoms (see 'Differential diagnosis' below)
●Developmental milestones, particularly language milestones (table 2)
●Observation of parent-child interactions
The behavioral assessment is focused on determining the age of onset of the core symptoms of ADHD, the duration of symptoms, the settings in which the symptoms occur, and the degree of functional impairment [2,11,12]. This information is necessary to establish the diagnosis of ADHD. (See 'Diagnostic criteria' below.)
Information about the core symptoms can be obtained through the use of open-ended questions or from ADHD-specific rating scales. If open-ended questions are used, the examiner must document the presence of the relevant behaviors from the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5). (See 'Diagnostic criteria' below.)
Behavior rating scales — Various scales have been developed to collect structured observations of behavior (table 3). Completion of these scales by parents and teachers during the diagnostic evaluation helps to establish the presence of core symptoms of ADHD in more than one setting. (See 'Diagnostic criteria' below.)
●ADHD-specific scales – ADHD-specific rating scales (also called narrow-band scales) focus directly on the symptoms of ADHD and can be used to establish the presence of the core symptoms of ADHD. The validity of ADHD rating scales in distinguishing children with ADHD from age-matched control children varies depending upon the age of the child, the scale that is used, and the informant (eg, parent, teacher, adolescent) .
ADHD-specific rating scales have a sensitivity and specificity of greater than 90 percent when used in an appropriate population [20,21]. However, most of the studies validating the use of rating scales have taken place in referral rather than primary care settings. The National Initiative for Children's Healthcare Quality (NICHQ) ADHD toolkit includes the Vanderbilt Assessment Scales, which can be downloaded and printed from the website. The Vanderbilt Assessment Scales have been validated in both community and referral settings using longitudinal assessment and follow-up [22-24].
Only the Conners Comprehensive Behavior Rating Scales and the ADHD Rating Scale IV have been validated in preschool-aged children [2,25]. The Vanderbilt rating scales were not designed for preschool children, but probably can be used in children ≥4 years [26,27].
●Broadband scales – Broadband scales assess a variety of behavioral symptoms, including, but not limited to, the core symptoms of ADHD; they assess internalizing behaviors (eg, feeling depressed, anxious, withdrawn) and externalizing behaviors other than ADHD (eg, aggression). Broadband scales (with the exception of the Conners' Long form) are not recommended to establish the presence of the core symptoms of ADHD because they are less sensitive and specific (<86 percent) than ADHD-specific scales . However, broadband scales can help to identify coexisting conditions and narrow the differential diagnosis . (See "Developmental and behavioral screening tests in primary care", section on 'Behavioral screening tests'.)
Educational evaluation — The educational assessment centers on documentation of the core symptoms in the educational setting. Important aspects of the educational evaluation include [2,15]:
●Completion of an ADHD-specific rating scale (see 'Behavior rating scales' above)
●A narrative summary of classroom behavior and interventions, learning patterns, and functional impairment
●Copies of report cards and samples of schoolwork
●Review of school-based multidisciplinary evaluations (if such evaluations have been performed)
The teachers who provide the information should have regular contact with the child for a minimum of four to six months if they are to comment reliably on the persistence of symptoms. In the United States, public schools are federally mandated to perform appropriate evaluations (eg, language, cognitive) at no cost to the family if a child is suspected of having a disability that impairs functioning (eg, ADHD or learning disability). (See "Support services for the care of chronically ill children", section on 'Education' and "Definitions of specific learning disability and laws pertaining to learning disabilities in the United States", section on 'Laws affecting the education of students with disabilities'.)
Obtaining information about the core symptoms of ADHD from professionals in after-school programs or other structured settings also may be helpful [2,15]. This information may be particularly useful in the evaluation of preschool children and adolescents, or if discrepancies exist between the parents' and teachers' reports of core symptoms. When such discrepancies occur, environmental factors (eg, different expectations, levels of structure, or behavior management strategies) may be contributing to the symptoms. (See 'Differential diagnosis' below.)
Coexisting disorders — The evaluation for ADHD should include assessment for coexisting behavior/emotional disorders including oppositional defiant disorder, conduct disorder, depression, anxiety disorder, and learning disabilities (table 4) [11,12,16,29-31]. Evaluation for these disorders may include history, broadband behavior scales (oppositional defiant disorder, conduct disorder, depression, anxiety) or psychometric testing (learning disability) (table 1).
Up to one-half of children with ADHD have one or more coexisting behavioral-emotional conditions [31-34]. The coexisting conditions can be primary or secondary (eg, disorders that are exacerbated by the ADHD). In either case, they require treatment in conjunction with treatment for ADHD [2,30]. (See "Attention deficit hyperactivity disorder in children and adolescents: Overview of treatment and prognosis", section on 'Treatment of coexisting conditions'.)
●Anxiety – Anxiety may develop in children with ADHD as a secondary disorder; however, in many cases anxiety appears to be independent of ADHD [32,35]. (See "Anxiety disorders in children and adolescents: Epidemiology, pathogenesis, clinical manifestations, and course".)
●Oppositional defiant disorder – Children with the combined or hyperactive-impulsive subtype of ADHD are at increased risk for developing coexisting behavior problems, including oppositional defiant disorder [35-37]. Their excessive activity, impulsive response style, and disinhibited emotional expression frequently put them in conflict with parents and other adults. The increased conflict may lead to increased discipline and less positive reinforcement for the child. Under these circumstances, a potentially self-perpetuating pattern of oppositional defiant behavior can emerge (the oppositional acts bring parental attention, which is reinforcing for the child who rarely receives parental praise) [37-39].
●Learning disabilities – Learning disabilities are more common in children with the inattentive and combined subtypes of ADHD [40,41]. (See "Specific learning disabilities in children: Clinical features", section on 'Comorbidities'.)
●Depression – Depression is common in children with the inattentive and combined subtypes of ADHD [40,41]. Children with ADHD and comorbid mood disorder may have family members with a history of major depressive disorder . During adolescence, they are at increased risk for attempting suicide [43-45]. (See "Pediatric unipolar depression: Epidemiology, clinical features, assessment, and diagnosis", section on 'Epidemiology' and "Suicidal behavior in children and adolescents: Epidemiology and risk factors", section on 'Psychiatric disorder'.)
●Substance use – Adolescents with newly diagnosed ADHD should be assessed for substance abuse . Those with signs and symptoms of substance abuse should undergo evaluation and treatment for addiction before treatment for ADHD with medications (if possible) . (See "Attention deficit hyperactivity disorder in children and adolescents: Treatment with medications", section on 'Prerequisites' and "Substance use disorder in adolescents: Epidemiology, pathogenesis, clinical manifestations, course, assessment, and diagnosis".)
Psychometric testing — Psychometric testing is not necessary in the routine evaluation for ADHD and does not distinguish children with ADHD from those without ADHD [12,47]. However, psychometric testing can be valuable in excluding other disorders. The public school system often is the best place to perform psychometric testing (ie, intellectual and academic testing), though more specialized neuropsychological testing requires consultation with a specialist. Testing for learning disabilities can be completed in whole or in part by the school system. (See 'Differential diagnosis' below.)
Children with learning, language, visual-motor, or auditory processing problems can be difficult to distinguish from those with ADHD. These problems tend to be pervasive and persistent and can impair academic function through decreased comprehension or excessive frustration. Children with these problems may attempt to avoid tasks through inattention, getting out of their seats, or impulsively guessing at answers. On the other hand, children with ADHD may perform poorly on language and visual-spatial tasks [48-50], particularly those that require sustained mental effort or are sensitive to impulsive responding (eg, multiple-choice formats).
Comprehensive neuropsychologic testing may help to clarify the diagnosis. Children with learning, language, visual-motor, or auditory processing problems usually perform poorly only in their particular problem area, whereas children with ADHD may perform poorly in several areas of evaluation. Assessment of verbal and nonverbal/performance skills with an intelligence measure such as the Wechsler Intelligence Scale for Children – Fifth Edition  or the Differential Abilities Scale-II  will help to identify language and/or visual-spatial processing deficits. Assessment of academic skills/achievement testing with a tool such as the Wechsler Individual Achievement Test – Third Edition , or the Wide Range Achievement Test – Fourth Edition  will help to identify potential learning disabilities. (See "Specific learning disabilities in children: Clinical features" and "Specific learning disabilities in children: Evaluation", section on 'Comprehensive evaluation'.)
Psychometric testing also can help to identify specific problem areas for children with ADHD, including abstract reasoning, mental flexibility, planning, and working memory, a collection of skills broadly categorized as "executive functions" [6,7,48,55]. Neuropsychological assessment of these skills, as well as direct assessment of attention and behavioral disinhibition, often is desirable to facilitate diagnosis, plan environmental and behavioral interventions, and track progress of treatment [56-59].
EEG — Quantitative EEG (qEEG) is a method of analyzing the electrical activity of the brain to derive quantitative patterns that may correspond to diagnostic information and/or cognitive deficits .
We do not suggest qEEG for the evaluation of children with ADHD. Although the US Food and Drug Administration (FDA) has licensed the first EEG test for assessment of children (6 to 17 years of age) for ADHD , and several studies have demonstrated differences in qEEG between children with ADHD and normal children [62-67], the studies were limited by non-random assignment, lack of blinding, failure to consider comorbidities, and/or failure to control for pharmacologic therapy [60,65,68]. In addition, the EEG patterns differ in boys and girls . A 2013 meta-analysis of nine studies (including 1253 children with ADHD and 517 without ADHD) found significant heterogeneity and concluded that EEG profiles (specifically an increased theta to beta ratio) cannot be used to reliably diagnose ADHD (although they may be helpful for prognosis) . Current evidence is insufficient to support the use of qEEG over clinical evaluation of symptoms and functional impairment for the diagnosis of ADHD. (See 'Diagnosis' below.)
Ancillary evaluation — Other evaluations are not routinely indicated to establish the diagnosis of ADHD, but may be warranted to evaluate conditions remaining in the differential diagnosis after the initial assessment. (See 'Differential diagnosis' below.) These evaluations may include [11,12,15,71]:
●Speech and language evaluation (language or communication disorder) (see "Evaluation and treatment of speech and language disorders in children", section on 'Speech and language evaluation')
●Occupational therapy evaluation (motor coordination disorder) (see "Developmental coordination disorder: Clinical features and diagnosis", section on 'Clinical features')
●Mental health evaluation (mood disorder, anxiety, oppositional defiant disorder, conduct disorder, obsessive compulsive disorder, post-traumatic stress disorder, adjustment disorder) (see 'Coexisting disorders' above and 'Indications for referral' below)
●Blood lead level (lead poisoning) [72,73] (see "Childhood lead poisoning: Clinical manifestations and diagnosis")
●Thyroid hormone levels (thyroid disorder) [74,75] (see "Clinical manifestations and diagnosis of hyperthyroidism in children and adolescents", section on 'Diagnostic evaluation')
●Genetic testing and/or genetics consultation (fragile X syndrome) [76,77] (see "Fragile X syndrome: Clinical features and diagnosis in children and adolescents", section on 'Diagnosis')
●Overnight polysomnography for children with symptoms suggestive of and/or risk factors for obstructive sleep apnea syndrome or restless legs syndrome (see "Evaluation of suspected obstructive sleep apnea in children" and "Restless legs syndrome/Willis-Ekbom disease and periodic limb movement disorder in children")
●Neurology consultation or electroencephalography (neurologic or seizure disorder) (see "Clinical and laboratory diagnosis of seizures in infants and children")
ADHD — The American Psychiatric Association has defined consensus criteria for the diagnosis of ADHD, which are published in the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5) . For children <17 years, the DSM-5 diagnosis of ADHD requires ≥6 symptoms of hyperactivity and impulsivity or ≥6 symptoms of inattention. For adolescents ≥17 years and adults, ≥5 symptoms of hyperactivity and impulsivity or ≥5 symptoms of inattention are required. (See 'Hyperactivity and impulsivity' above and 'Inattention' above.)
The symptoms of hyperactivity/impulsivity or inattention must :
●Be present in more than one setting (eg, school and home)
●Persist for at least six months
●Be present before the age of 12 years
●Impair function in academic, social, or occupational activities
●Be excessive for the developmental level of the child
In addition, other physical, situational, or mental health conditions that could account for the symptoms must be excluded. (See 'Differential diagnosis' below.)
Adherence to the DSM-5 criteria can help to minimize over- and under-diagnosis of ADHD. The diagnostic criteria have high interrater reliability for individual items and for overall diagnosis even though the behavioral characteristics specified in the definition are subject to different interpretation by different observers [15,78,79].
Limitations of the DSM-5 criteria include their derivation from studies of children who were evaluated in psychiatric rather than primary care settings and lack of data supporting the number of items required for diagnosis. In addition, the criterion that symptoms of hyperactivity/impulsivity or inattention be present before the age of 12 years is controversial. (See "Attention deficit hyperactivity disorder in adults: Epidemiology, pathogenesis, clinical features, course, assessment, and diagnosis", section on 'Course'.)
The response to stimulant medication cannot be used to confirm or refute the diagnosis of ADHD . Stimulant medications improve behavior in children with ADHD, children with conditions other than ADHD (eg, learning disabilities, depression), and normal control children [80,81].
ADHD subtype — Depending upon the predominant symptoms, ADHD can be categorized into one of the three subtypes listed below . The subtype of ADHD in a given patient can change from one to another over time [1,82-84].
●Predominantly inattentive – ≥6 symptoms of inattention for children <17 years; ≥5 symptoms for adolescents ≥17 years and adults (see 'Inattention' above)
●Predominantly hyperactive-impulsive – ≥6 symptoms of hyperactivity-impulsivity for children <17 years; ≥5 symptoms for adolescents ≥17 years and adults (see 'Hyperactivity and impulsivity' above)
●Combined – ≥6 symptoms of inattention and ≥6 symptoms of hyperactivity-impulsivity for children <17 years; ≥5 symptoms in each category for adolescents ≥17 years and adults (see 'Inattention' above and 'Hyperactivity and impulsivity' above)
Hyperkinetic disorder — In Europe, the diagnosis of hyperkinetic disorder (HKD) is defined by the International Classification of Diseases (10th edition, ICD-10) criteria (table 5) [11,14]. The ICD-10 criteria for HKD are more restrictive than the DSM-5 criteria for ADHD, requiring that at least six symptoms of inattention, at least three symptoms of hyperactivity, and at least one symptom of impulsivity are present in more than one setting . HKD is subdivided into HKD with and without conduct disorder.
Diagnosis in preschool children — The diagnostic criteria for ADHD (without subtyping) can be applied to children as young as four years of age [2,85]. Longitudinal studies suggest that severe hyperactivity, which is present in only a small subset of preschool children, persists into the school years [86-89].
The criterion that impairment is present in at least two settings may be difficult to meet if the child does not attend preschool or a child care program . In such circumstances, clinicians who suspect ADHD can recommend that the parents attend a parent-training program or that the child be enrolled in a qualified preschool program (eg, Head Start, public prekindergarten programs, Early Childhood Special Education services) . The clinician can then obtain information about core symptoms of ADHD and functional impairment from the instructors of the preschool program or the parenting program (if the child is directly observed).
Diagnosis in adolescents — Establishing a new diagnosis of ADHD in adolescents can be challenging. Adolescents may underreport core symptoms or functional impairment and may spend too little time at home for parents to be accurate informants [2,90]. In such cases, it is important for clinicians to obtain information from at least two teachers and/or other adults with whom the adolescent interacts (eg, guidance counselor, coaches, etc) . Strict adherence to the criterion that symptoms of hyperactivity/impulsivity or inattention be present before the age of 12 years may fail to identify adolescents and adults with more subtle attentional or organizational problems. (See "Attention deficit hyperactivity disorder in adults: Epidemiology, pathogenesis, clinical features, course, assessment, and diagnosis", section on 'Diagnosis'.)
DIFFERENTIAL DIAGNOSIS — The symptoms of ADHD overlap with a number of other conditions, including developmental variations, neurologic or developmental conditions, emotional and behavioral disorders, psychosocial or environmental factors, and certain medical problems (table 1) [1,2,91-93]. Some of these conditions can coexist with ADHD and may or may not be responsible for some of the symptoms (eg, children who have learning disabilities may develop inattention as a result of inability to understand new information) . These conditions usually can be differentiated from ADHD with a thorough history and/or the use of a broadband behavior rating scale. If the diagnosis remains uncertain, psychometric testing or a mental health evaluation may be necessary. (See 'Coexisting disorders' above.)
●Developmental variations – Developmental variations include intellectual disability; giftedness; and behaviors that are within the normal range for the child's level of development and do not impair function (eg, a short-attention span or increased motor activity in a preschool child; occasional impulsivity in a school-age child) [91,92,95]. (See "Intellectual disability in children: Definition, diagnosis, and assessment of needs" and "Intellectual disability in children: Evaluation for a cause".)
When considering behaviors that are within the normal range for the child's level of development, age and maturity are more important than grade level . In observational studies, younger age for a particular grade level was associated with increased diagnosis of ADHD [92,97,98], suggesting that developmental immaturity may account for some behaviors that are attributed to ADHD.
Children with developmental variations do not meet the full criteria for ADHD. (See 'Diagnostic criteria' above.)
●Neurologic or developmental conditions – Neurodevelopmental conditions that can mimic or co-occur with ADHD include [91,99,100]:
•Learning disabilities (see "Specific learning disabilities in children: Clinical features")
•Language or communication disorders (see "Etiology of speech and language disorders in children")
•Neurodevelopmental syndromes (eg, fragile X, fetal alcohol syndrome, Klinefelter syndrome) (see "Fragile X syndrome: Clinical features and diagnosis in children and adolescents" and "Fetal alcohol spectrum disorder: Clinical features and diagnosis")
•Seizure disorder (see "Seizures and epilepsy in children: Classification, etiology, and clinical features")
•Sequelae of central nervous system infection or trauma (see "Bacterial meningitis in children: Neurologic complications", section on 'Neuropsychologic impairment')
•Metabolic disorders (eg, adrenoleukodystrophy, mucopolysaccharidosis type III) (see "Adrenoleukodystrophy" and "Mucopolysaccharidoses: Clinical features and diagnosis", section on 'MPS type III (Sanfilippo syndrome)')
•Motor coordination disorders (see "Developmental coordination disorder: Clinical features and diagnosis")
These disorders usually can be distinguished from ADHD through history and examination. Specialized testing may be necessary in some circumstances (eg, psychometric testing for learning disabilities; genetic testing for fragile X syndrome; electroencephalography for seizure disorder; occupational therapy evaluation for motor coordination disorder, etc).
●Emotional and behavioral disorders – Emotional and behavioral disorders that can mimic or co-occur with ADHD include anxiety disorder, mood disorders, oppositional defiant disorder, conduct disorder, obsessive compulsive disorder, post-traumatic stress disorder, and adjustment disorder. The use of a broadband behavior scale may be helpful in the assessment of these disorders. However, evaluation by a mental health professional generally is necessary for diagnosis. (See 'Coexisting disorders' above and 'Behavior rating scales' above and 'Indications for referral' below.)
●Psychosocial and environmental factors – Environmental factors that can contribute to inattention, impulsivity, or hyperactivity include a stressful home environment or an inappropriate educational setting. In contrast to ADHD, psychosocial and environmental factors generally affect behavior only in one setting (eg, at home but not at school, or at school but not at home). Parent-child temperament or "personality" mismatch and parental mental health conditions (particularly maternal depression) can contribute to parent report of ADHD-type symptoms in the home setting. However, mothers of ADHD children with limited resources or support may also develop stress-related mental health conditions; in such circumstances, multiple respondent (eg, teacher, coach) reports help to confirm the diagnosis of ADHD.
●Medical conditions – Medical conditions that may have clinical features that mimic ADHD include hearing or visual impairment, lead poisoning, thyroid abnormalities, sleep disorders (eg, obstructive sleep apnea, restless-leg/periodic limb movement disorder), medication effects (eg, albuterol), and substance abuse disorders [15,17,101]. (See appropriate topic reviews.) These conditions usually can be differentiated from ADHD because their symptoms fluctuate with the disease course or exposure to medication. In contrast, the symptoms in ADHD are persistent and pervasive.
INDICATIONS FOR REFERRAL — Evaluation by a pediatric specialist (eg, a psychologist, psychiatrist, neurologist, educational specialist, or developmental-behavioral pediatrician) is indicated for children in whom the following diagnoses are of concern :
●Intellectual disability (mental retardation)
●Developmental disorder (eg, speech or motor delay)
●Visual or hearing impairment
●History of abuse
●Coexisting learning and/or emotional problems
●Chronic illness that requires treatment with a medication that interferes with learning
●Children who continue to have problems in functioning despite treatment (see "Attention deficit hyperactivity disorder in children and adolescents: Overview of treatment and prognosis", section on 'Response to treatment')
RESOURCES — The National Initiative for Children's Healthcare Quality (NICHQ), in conjunction with North Carolina's Center for Child Health Improvement, and the American Academy of Pediatrics (AAP), has developed a toolkit to assist primary care practitioners in the evaluation and management of children with ADHD. The toolkit includes information for parents, copies of ADHD-specific questionnaires for parents and teachers, and an initial primary care evaluation form. It can be downloaded without charge through the NICHQ but requires registration. A revised edition of the toolkit, which also includes tools and resources for preschool children and adolescents, is available for purchase through the AAP.
Resources for families of children with ADHD are provided in the table (table 6).
Information for teachers of children with ADHD is available through the National Resource Center on ADHD.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topics (see "Patient education: Symptoms and diagnosis of attention deficit hyperactivity disorder in children (Beyond the Basics)" and "Patient education: Treatment of attention deficit hyperactivity disorder in children (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Attention deficit hyperactivity disorder (ADHD) is a behavioral condition with persistent and pervasive core symptoms of inattention, hyperactivity, and impulsivity. The symptoms affect cognitive, academic, behavioral, emotional, and social functioning. (See 'Clinical features' above.)
●The differential diagnosis for ADHD includes developmental variations, neurologic or developmental conditions, emotional and behavioral disorders, psychosocial or environmental factors, and certain medical problems (table 1). Most of these conditions may coexist with ADHD and require simultaneous treatment. (See 'Differential diagnosis' above and 'Coexisting disorders' above.)
●The diagnosis of ADHD requires that the child meet the criteria defined by the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-5). The response to stimulant medication cannot be used to confirm or refute the diagnosis. (See 'Diagnostic criteria' above.)
●Evaluation for ADHD requires comprehensive medical, developmental, educational, and psychosocial evaluation to confirm the presence, persistence, pervasiveness, and functional complications of core symptoms, exclude other causes of core symptoms (table 1), and identify coexisting learning and psychiatric disorders (table 4). (See 'Overview' above and 'Coexisting disorders' above.)
●The evaluation for ADHD requires information about the child's behavior in more than one setting (eg, home and school or after-school program). ADHD-specific behavior scales (table 3) can be used to gather this information from the parents and teacher(s). (See 'Educational evaluation' above and 'Behavior rating scales' above.)
●Psychometric testing is not necessary in the routine evaluation for ADHD. However, it is valuable in narrowing the differential diagnosis and planning the approach to management. (See 'Psychometric testing' above.)
●The evaluation for ADHD does not require blood lead levels, thyroid hormone levels, neuroimaging, or electroencephalography unless these tests are indicated by findings in the clinical evaluation. (See 'Ancillary evaluation' above.)
●Reevaluation of children with ADHD is warranted whenever symptoms worsen or new symptoms emerge because the differential diagnosis of ADHD is extensive and comorbidity is common. (See 'Differential diagnosis' above and 'Coexisting disorders' above.)
- American Psychiatric Association. Attention-deficit/hyperactivity disorder. In: Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, American Psychiatric Association, Arlington, VA 2013. p.59.
- Subcommittee on Attention-Deficit/Hyperactivity Disorder, Steering Committee on Quality Improvement and Management, Wolraich M, et al. ADHD: clinical practice guideline for the diagnosis, evaluation, and treatment of attention-deficit/hyperactivity disorder in children and adolescents. Pediatrics 2011; 128:1007.
- Applegate B, Lahey BB, Hart EL, et al. Validity of the age-of-onset criterion for ADHD: a report from the DSM-IV field trials. J Am Acad Child Adolesc Psychiatry 1997; 36:1211.
- Lahey BB, Applegate B, McBurnett K, et al. DSM-IV field trials for attention deficit hyperactivity disorder in children and adolescents. Am J Psychiatry 1994; 151:1673.
- Levin FR, Kleber HD. Attention-deficit hyperactivity disorder and substance abuse: relationships and implications for treatment. Harv Rev Psychiatry 1995; 2:246.
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