Despite pharmacologic and psychotherapeutic treatment, Johnny A’s difficulties at school increased, and a school evaluation was conducted. The school's assessment raised the possibility that Johnny had an intellectual disability. His psychiatrist referred him for neuropsychological testing, which revealed normal intellectual functioning and specific learning disorders in reading and written expression, as well as selective difficulties in attention and executive functions (consistent with ADHD). Neuropsychological testing also raised concerns about an emerging depressive disorder and suggested that Johnny was achieving minimal benefit from the medications used to treat his ADHD symptoms. The psychiatrist and neuropsychologist worked together to provide feedback and recommendations regarding school placement and appropriate special education services. The psychiatrist also made adjustments to his medication regimen and therapeutic goals, resulting in significant improvement in the patient's level of functioning.
When should you suspect that an individual with ADHD also has a learning disorder?
ADHD alone is a risk factor for academic underachievement. In the classroom setting, children with attentional difficulties often miss new information as it is being presented, struggle to exhibit consistent effort and/or complete assignments, forget to complete or turn in assignments, and make careless errors. Children with symptoms of hyperactivity and impulsivity may have difficulty meeting classroom behavioral expectations (eg, sitting still or staying in line, keeping quiet during work times, waiting to be called on) and, as a result, are more likely to be disciplined or to receive negative feedback than children without ADHD. As such, the fact that ADHD is associated with general academic underachievement is unsurprising. Children with ADHD earn lower grades and score lower on standardized achievement tests than those without ADHD.31 They also have significantly higher rates of special education placement, grade retention, and school dropout.13,32
The risk of academic underachievement in childhood ADHD is compounded when children also have specific learning disorders, which have a high rate of comorbidity with ADHD. Learning disorders should be suspected when a gap is reported or observed between a child’s apparent level of cognitive functioning and his or her academic performance. The possibility of a comorbid learning disorder should also be explored when a child is acquiring academic skills at different rates (with isolated concerns about reading, writing, or math). This consideration is especially important if the child also has a history of developmental delays in aspects of language acquisition (early concerns regarding language development, including articulation) and/or the development of fine motor skills. Learning disorders are distinct from the learning difficulties that occur in the context of an intellectual disability, in that a child with a learning disorder has many intact cognitive abilities.
How are learning disorders defined and diagnosed?
Learning disorders are defined as a failure to learn despite adequate teaching and intact cognitive functioning. Formal diagnosis of a learning disorder requires psychological assessment to document both a child’s overall level of cognitive functioning (IQ) and his or her level of academic achievement.15,18 Traditionally, if a child had a significant gap between cognitive aptitude and academic achievement, then a learning disorder was diagnosed. This discrepancy model approach to defining learning disorders has been criticized, as it can result in missed diagnoses (false negatives) in children with below-average cognitive ability and false positives in children with higher-than-average cognitive ability. It has also been associated with instability of diagnosis over time.33,34 However, the discrepancy model approach is the one described in the DSM-5.15
The DSM-5 defines 3 specific learning disorders: impairment in reading, impairment in mathematics, and impairment in written expression (). When clear evidence of a specific learning disorder is lacking but the patient has well-defined learning issues, the diagnoses of Other Specified Neurodevelopmental Disorder or Unspecified Neurodevelopmental Disorder may apply.15
AV 2. DSM-5 Criteria for Specific Learning Disorder (00:34)
Impairment in reading. Reading disorders occur in approximately 5% to 10% of the population and have a high rate of comorbidity with ADHD.35 Between 25% and 40% of children with either disorder also have the other disorder.36 Developmental dyslexia is the most commonly recognized reading disorder and is believed to arise from deficits in phonological processing that initially interfere with the acquisition of early reading skills. A young child with dyslexia will struggle to appropriately map orthography (written letters) onto the elemental sounds of spoken language (phonemes); this skill quickly becomes automatic in children without dyslexia. As a result, children with dyslexia have particular difficulty accurately reading words that they do not visually recognize and typically also have difficulty with spelling, especially for irregular words. With intensive phonics-based instruction, a dyslexic child can explicitly learn to effectively decode single words, but difficulties achieving reading fluency often persist.37 Comorbid attentional issues can exacerbate difficulties with reading fluency and reading comprehension, especially if a child has additional weaknesses in higher-order language skills.38
Impairment in mathematics. Math disorder, also referred to as developmental dyscalculia, occurs in 5% to 6% of children.39 Among children with dyscalculia, approximately 26% also have ADHD, and 17% also have dyslexia.40 Approximately 18% of children with ADHD also have a diagnosis of a math disability.41 Young children with dyscalculia may have difficulty mastering counting skills and struggle to understand relational quantities (such as “more” or “less”). As they grow older, difficulties achieving automaticity with math facts is common (for example, they may have difficulty learning multiplication facts). They may also make inattentive errors (eg, use the wrong sign, misplace digits while “carrying” or “borrowing”). In early grades, a child will require intensive remedial instruction focused on boosting math fluency and quantitative reasoning skills, but academic accommodations may be required throughout the child’s years of formal schooling.39
Impairment in written expression. Writing disorder, or developmental dysgraphia, has not been as well defined as dyslexia and dyscalculia. This likely reflects the complex nature of writing; fluent writing requires the seamless integration of graphomotor and expressive language skills. Children with dyspraxia may struggle with the motor demands of writing in the absence of higher-order language disorders. By extension, children with language delays and weaknesses in executive functions may struggle with the retrieval and organization of their verbal output, both orally and/or in writing.42 They may require interventions aimed at improving their fine motor skills or speech and language therapy aimed at improving the retrieval and organization of language.
How often do individuals with ADHD have other psychiatric disorders (especially anxiety and depression)?
ADHD is highly comorbid with other psychiatric disorders. In children and adolescents with ADHD, about two-thirds have at least one other psychiatric condition.32,43 The rates of anxiety and mood disorders in ADHD youth are particularly high. The relative risk of a comorbid anxiety disorder is more than 7 times greater than for those without an ADHD diagnosis, and the risk of comorbid depression is 8 times greater.32 The rates of anxiety and mood disorders as well as eating disorders are increased in girls with ADHD relative to those without ADHD.44 Childhood ADHD has also been associated with bipolar disorder.45
The considerable overlap between ADHD and other psychiatric disorders suggests commonalities in the genetic and neuroanatomical factors that contribute to their emergence.46 Functionally, the presence of ADHD symptoms can also create environmental circumstances that might be expected to increase the risk of anxiety and depression. For example, if a child with ADHD is underperforming in school, he or she may subsequently become anxious about his or her ability to meet task demands, eventually internalizing feelings of self-doubt and expecting failure. Such environmental factors may be potent triggers in children who have some underlying genetic predisposition to the development of anxiety or mood disorders.
In addition to anxiety and mood disorders, children with ADHD are also at increased risk for social difficulties and substance abuse. At a young age, children with ADHD have difficulty relating to their peers and are likely to experience peer rejection and to exhibit social withdrawal. Some research suggests that social difficulties stem from core deficits in emotion perception and regulation.47 Over time, this pattern of negative interactions may contribute to the development of maladaptive patterns of relating to others. By adolescence, children with ADHD are more likely than other children to develop and exhibit antisocial behaviors.48 Similarly, children with ADHD are at increased risk of developing substance use disorders. ADHD youth are particularly likely to develop nicotine dependence, which is associated with an increased risk of alcohol and drug abuse.48–50
How does age affect ADHD and comorbid psychiatric disorders?
ADHD symptoms, especially the hyperactive-impulsive symptoms, decline as children move through adolescence.51 By late adolescence, a little less than 50% of children continue to manifest significant ADHD symptoms.52 By adulthood, the rate of ADHD drops to about 4%,53 or approximately one-third of those who met ADHD criteria in childhood.54 However, the functional impairment associated with childhood ADHD may continue to affect many individuals who no longer meet ADHD criteria.51
The high rates of psychiatric comorbidity with ADHD persist into adulthood, especially in individuals with the combined subtype.55 Less than one-fourth of adults with ADHD have no comorbid psychiatric disorders.55,56 Adults with ADHD are more likely than those without ADHD to have anxiety disorders (including generalized anxiety disorder, agoraphobia, social phobia, specific phobias, posttraumatic stress disorder, and panic disorder) and mood disorders (ie, major depressive disorder, dysthymia, bipolar disorder).53
Given the high rate of psychiatric comorbidity with ADHD, clinicians must thoroughly assess patients prior to the initiation of psychopharmacologic treatment for ADHD to avoid adverse effects. For example, stimulants may exacerbate anxiety symptoms, and combination pharmacotherapy may be needed for successful management of the anxiety symptoms (perhaps sequencing the anxiety treatment to precede treatment for ADHD).13 Similarly, combination pharmacotherapy may be needed to treat comorbid ADHD and depression, but clinicians may wish to consider certain classes of antidepressants to treat both conditions.13
What is the role of neuropsychological testing in refining a differential diagnosis?
Neuropsychological evaluations are recommended to assist with differential diagnosis when learning disorders are suspected.18 A comprehensive neuropsychological evaluation assesses 3 domains of functioning: 1) cognitive development, 2) social, emotional, and behavioral functioning, and 3) academic functioning.57 A neuropsychologist also takes a comprehensive developmental history and reviews educational and medical records. This information is then integrated to address any concerns of clinicians, patients, and family members. At the end of the evaluation, the neuropsychologist will be able to describe an individual’s strengths and weaknesses, to determine the need for and type of intervention services, to establish a baseline by which to assess developmental progress and treatment efficacy, and to assist with creation of a differential diagnosis.
Recommendations will be targeted to address all aspects of an individual’s life (school, work, the development of life skills) and may include further evaluation (such as a medical evaluation) and treatment (eg, psychopharmacology, psychotherapy, occupational therapy, speech and language therapy). In addition, the neuropsychologist should offer individualized feedback, often in conjunction with treatment providers. For children and adolescents, these feedback sessions may be family-focused so that the parents and their child have a greater understanding of their current functioning and understand the recommendations that were made.
On neuropsychological testing, individuals with ADHD commonly demonstrate selective weaknesses in aspects of executive functions. These aspects are higher-order cognitive skills involved in responding appropriately to novel and complex situations.58 Individuals with ADHD tend to exhibit weakness on measures of response inhibition, vigilance, spatial working memory, and planning and organization but may also have impaired processing speed and set-shifting.59 However, among children with ADHD, considerable variation occurs in the degree of executive dysfunction shown on neuropsychological testing. In other words, the extent of ADHD symptomatology is only modestly correlated with performance on measures of executive function.60 This modest correlation probably, at least in part, reflects the heterogeneity of the disorder—for example, children with only symptoms of inattention may have neuropsychological profiles different from those of children who also have symptoms of hyperactivity or impulsivity. In fact, recent genetic studies have moved toward defining neuropsychological endophenotypes of ADHD, such as grouping individuals who exhibit weakness in inhibition.59,61 Thus, neuropsychological assessment allows for the identification of specific deficits in executive functions, as these cannot be predicted from a diagnosis of ADHD alone.
A neuropsychological assessment typically also assists the referring clinician in determining whether the patient has additional comorbid psychiatric or neurodevelopmental conditions.57 For example, a clinical neuropsychologist can identify symptoms of anxiety and depression and their potential impact on cognitive functioning, as well as identify whether ADHD symptoms exist in the context of more widespread developmental conditions such as autism.
When should an inattentive child be referred for a neurological assessment or for further medical evaluation?
Current diagnostic and treatment guidelines18 recommend that the physician who is considering a diagnosis of ADHD rule out possible medical conditions that may contribute to inattention. It is important to carefully assess the history and course of inattentive symptoms. In most cases of straightforward ADHD, inattentive symptoms are longstanding (dating to early childhood) and have a relatively stable course. Inattentive symptoms that wax and wane and are associated with altered states of awareness are more suggestive of seizure disorders, especially if the patient also has stereotyped patterns of behavior (eg, automatisms). However, many children with seizure disorders also meet diagnostic criteria for ADHD and benefit from stimulant medication.62
Clinically significant symptoms of ADHD are also quite common in the context of autism spectrum disorder (ASD).15 Accurate identification of children with mild ASD symptoms can be difficult, especially in the context of a routine check-up. Referral to a developmental pediatrician, a neurologist specializing in ASD, and/or a neuropsychologist is warranted if the clinician has significant concerns about social communication skills and/or peer relationships, especially if the patient has a history of developmental delays in or atypical patterns of language and/or motor skills. A more comprehensive evaluation is especially important as children with ASD are also at increased risk of learning disorders, seizure disorders, and psychiatric disorders.63–65 In these complex cases, a neuropsychological evaluation is particularly important in clarifying a child’s strengths and weaknesses and helping to monitor the effectiveness of treatment interventions and developmental course.
Estimates suggest that 25% to 50% of children with ADHD experience sleep-related difficulties.66 Assessment and management of sleep difficulties are important as these difficulties can exacerbate ADHD symptoms and serve as a significant source of family stress. Children with ADHD have longer sleep-onset latency. Sleep is also likely to be more fragmented and less efficient. Contributing factors to this may be increased movement during sleep and disordered sleep-breathing.67 Indeed, up to 44% of children with ADHD have been found to have restless legs syndrome.66 Children with ADHD may also be at increased risk of nocturnal enuresis.68 Given these abnormal sleep patterns, it is perhaps not surprising that children with ADHD are often sleepier during the day.67 Thus, when assessing a child with ADHD, the practitioner should ask about sleep behaviors and consider formal assessment (such as overnight polysomnography).66 Regarding treatment, in patients with adenotonsillar hypertrophy and obstructive sleep disordered breathing as well as ADHD, adenotonsillectomy has been associated with a reduction of ADHD symptoms.69 Use of melatonin has been associated with decreased sleep-onset latency and increased sleep duration in children with ADHD.70 Use of stimulants has been associated with resolution of nocturnal enuresis in youths diagnosed with ADHD.71 Finally, behavior therapy may improve sleep-related behaviors and help reduce parents’ anxiety about their child’s sleep but does not change ADHD symptoms.72
Children with ADHD are also at increased risk for movement disorders, including developmental coordination disorder, motor stereotypies, and tics.73,74 Occupational therapy evaluations can be helpful in determining the functional impact of motor delays on everyday function, especially in school. Neurological evaluations and neuropsychological evaluations are also often warranted for children who meet diagnostic criteria for Tourette’s Disorder. These children are at increased risk for anxiety (typically presenting as symptoms of obsessive-compulsive disorder) and learning disabilities, and they may have social difficulties that overlap with ASD symptoms.75 Their neuropsychological profiles are often remarkable for more severe cognitive deficits than would be expected of children with ADHD alone.76
Does effective and early treatment of ADHD improve long-term prognosis?
A growing body of evidence indicates that early treatment of ADHD symptoms may result in a better long-term prognosis, although interventions do not bring about functioning equivalent to that of youths without ADHD.77 Pharmacologic treatment of ADHD symptoms in children and adolescents has been associated with a reduced risk of later development of major depressive disorder,78,79 disruptive behavior disorders, and anxiety disorders.79 ADHD treatment has also been shown to have a protective effect against the development of substance use80,81; children with ADHD who are treated with stimulants are at decreased risk for cigarette smoking, alcohol use, and drug use.25,82–84
Treatment of childhood ADHD may mitigate some future functional impairment. Adults who had ADHD in childhood have a greater likelihood of being financially dependent on parents or, if they are financially independent, of having a lower socioeconomic status than those who never had ADHD, despite receiving treatment at some point.48 ADHD has also been associated with decreased educational achievement compared with no ADHD,48 but some evidence suggests that children who receive stimulant treatment for ADHD have less grade repetition than those not treated.79 Additionally, teenagers and young adults with ADHD are more likely to have motor vehicle accidents and to exhibit reckless driving behaviors than those without ADHD,85 but treatment with stimulants has been shown to reduce these behaviors. In general, however, people with ADHD have an increased risk of unintentional injuries or trauma.86 Altogether, these findings indicate that effective treatment of ADHD symptoms is needed to improve long-term prognosis and quality of life.
How can health care providers help to coordinate medical/educational care and improve family function?
Primary care health providers are often the first line of contact for families who have children with ADHD. Providers are also likely to have more contact with these families than with other families, as childhood diagnosis of ADHD is associated with greater use of health and education services, especially if comorbid conditions are present.32,87,88 High rates of systemic stress and family conflict occur in families of children with ADHD.89 Mothers of children with ADHD report more marital problems and depressive symptoms than mothers whose children do not have ADHD.90,91
Effective treatment of the child may be an important first step in improving family functioning. However, assessing the function of individual parents and the family system is important to determine whether treatment at those levels is also necessary. Because ADHD has a high rate of heritability, at least one parent may also have symptoms of the disorder. Children who have both ADHD and conduct problems or oppositional defiant disorder are more likely than children with just ADHD to have parents who are dependent on stimulants or cocaine, have alcohol problems, and have psychological disorders such as mood and anxiety disorders.91 Such children are clearly at high risk for worse functional outcomes than other children, especially if the systemic issues are not adequately addressed. Parent guidance training, family therapy, and/or treatment of the parent’s mental health issues may all be necessary treatment components, and, in most cases, these issues will first come to the attention of a primary care provider.