Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental condition in U.S. children, and it affects 8.4% of children between two and 17 years of age (greater than 5 million).¹ Of the children who are affected, 62% are treated with medication, less than one-half have received behavioral treatment, and nearly one-fourth have not received treatment.¹ Children with ADHD are at risk of long-term morbidities, including poor academic performance, low self-esteem, difficult relationships, substance use, injury, and other maladaptive behaviors.² This article presents evidence-based answers to common questions about the evaluation and management of childhood ADHD.

What Are the Risk Factors for ADHD?

The etiology of ADHD involves a complex interaction of genetic, social, and environmental factors, including prenatal and childhood exposures.³

EVIDENCE SUMMARY

Research among families, twins, and children who are adopted support substantial heritability (74%) for ADHD.⁴ The search to identify specific genes responsible for ADHD implicates a complex polygenic mechanism.^3,4 Males are diagnosed with ADHD at nearly two times the rate of females^1,5; however, differences in presentation between sexes may result in missed or delayed diagnosis in females.^5,6 Males present with more recognizable externalizing symptoms and behaviors (e.g., impulsivity, defiant conduct), whereas females present with inattention and possibly impaired cognitive function.^5–7

Children born preterm (before 37 weeks' gestation) are diagnosed with ADHD two times as often as children born at term (odds ratio [OR] = 1.6; 95% CI, 1.3 to 1.8; 74 studies; N = 64,061]),⁸ and risk of ADHD diagnosis or symptoms may increase with the severity of prematurity or low birth weight.⁹ The risk of ADHD is greater for children whose mothers smoked during pregnancy (OR = 1.60; 95% CI, 1.45 to 1.76; N = 50,044)¹⁰ and had hypertensive disorders in pregnancy (OR = 1.29; 95% CI, 1.22 to 1.36; six studies; N = 1,395,605).¹¹ Despite ongoing public concern and scientific inquiry, the evidence is inconsistent in supporting direct links between ADHD and exposure to digital or “screen” media¹² or chemical toxins,³ including lead.¹³

When and How Should Physicians Evaluate a Child for ADHD?

Primary care physicians should initiate evaluation for ADHD when parents or caregivers present with concerns about a child's academic or behavior problems, including symptoms of inattention, hyperactivity, or impulsivity in children between four and 17 years of age.²

EVIDENCE SUMMARY

ADHD is diagnosed using criteria from the Diagnostic and Statistical Manual of Mental Disorders, 5th ed., (Table 1¹⁴ ) after a comprehensive history and physical examination, with attention to family, birth, and early childhood development^2,14–16 (Table 2^2,15–17 ). The assessment of symptoms should explore the duration and context in which they occur and the effects on function or development.^2,15 The dysfunction classified in ADHD must occur in more than one setting; therefore, clinicians should seek evaluations from other adults with whom the child interacts outside of the home (e.g., educators, school counselors, coaches).^2,18 Routine laboratory tests, genetic testing, and neuroimaging are not recommended unless specific concerns result from the history or examination.^15,19