The latest review in our Clinical Practice series is, “Attention Deficit-Hyperactivity Disorder in Children and Adolescents,” from Dr. Heidi M. Feldman of Stanford University School of Medicine and Dr. Michael I. Reiff of University of Minnesota.
ADHD in children is characterized by inattention, hyperactivity, impulsivity, or a combination of these symptoms, which compromise basic everyday functions such as learning to read and making friends. In the absence of biomarkers, diagnostic criteria focus on behavioral symptoms.
• How often is ADHD diagnosed in the United States?
ADHD is the most prevalent neurodevelopmental disorder among children. In the United States, approximately 5.4 million children between 6 and 17 years of age (9.5% of all U.S. children) have received an ADHD diagnosis. The prevalence of this condition increased by 33% between 1997-1999 and 2006-2008. High prevalence rates suggest overdiagnosis. Among children in community-based samples in the United States, inattention alone is more prevalent than inattention and hyperactivity combined. Thus, children with disruptive and hyperactive behaviors are the most likely to be referred for clinical evaluation, and in children who do not have these behaviors, ADHD may remain unidentified or untreated.
• What are the pathogenesis and risk factors for ADHD in children and adolescents?
Family, twin, and adoption studies provide evidence that ADHD has a genetic component. Heritability has been estimated at 76%. Meta-analyses of candidate-gene association studies have shown strong associations between ADHD and several genes involved in dopamine and serotonin pathways. Nongenetic factors (e.g., maternal smoking during pregnancy or exposure to environmental lead or polychlorinated biphenyls) may also interact with genetic predisposition in the pathogenesis of ADHD. Neuroimaging studies have shown that ADHD is associated with a delay in cortical maturation. ADHD has long been thought to reflect dysfunction of prefrontal-striatal circuitry. Recent studies suggest that the pathophysiological features also encompass large-scale neural networks, including frontal-to-parietal cortical connections.
Morning Report Questions
Q: What conditions should be in the differential when considering a possible diagnosis of ADHD?
A: Other medical and psychosocial conditions with manifestations similar to those of ADHD should be considered in the diagnostic process. These conditions include seizure disorders, sequelae of central nervous system trauma or infection, sleep disorders, hyperthyroidism, physical or sexual abuse, and substance abuse. However, no medical, psychological, or neuropsychological tests are required to establish the diagnosis unless relevant signs or symptoms are noted in the history or physical examination.
Q: What is the appropriate treatment for ADHD in children and adolescents?
A: In the Multimodal Treatment Study of ADHD, the longest trial of ADHD treatment (14 months), medication (predominantly methylphenidate hydrochloride) was superior to behavioral therapy for reducing the core symptoms of ADHD; the combination of medical and behavioral therapy was not significantly more effective than medication alone for these symptoms. Secondary analyses showed that, as compared with medication alone, combined therapy resulted in greater improvements in academic performance and reductions in conduct problems, higher levels of parental satisfaction, and the use of lower doses of stimulant medication. The two most common side effects of these stimulant medications are appetite suppression and delayed onset of sleep. A meta-analysis of cohort studies and clinical trials concluded that height attenuation with the use of stimulant medication is dose-dependent and approximately 1 cm per year for up to 3 years of medication use.