What is the diagnostic approach for Attention Deficit Hyperactivity Disorder (ADHD) in a patient with symptoms of inattention, hyperactivity, and impulsivity?

How to Diagnose ADHD

The diagnosis of ADHD requires meeting DSM-5 criteria through a structured evaluation that includes obtaining standardized behavioral reports from multiple sources (parents, teachers, other observers), documenting at least 5 symptoms of inattention and/or hyperactivity-impulsivity persisting for 6+ months with onset before age 12, confirming impairment across multiple settings, and systematically screening for comorbid conditions that could mimic or coexist with ADHD. 1

Core Diagnostic Criteria

DSM-5 Requirements:

• At least 5 symptoms (6 for children) from either the inattentive or hyperactive-impulsive domain must persist for at least 6 months 1, 2, 3
• Onset before age 12 years with documented or reported manifestations from childhood 1, 3
• Symptoms present in 2 or more settings (home, school, work, social activities) 1, 3
• Clear evidence of functional impairment in academic, occupational, or social functioning 1, 3
• Symptoms not better explained by another mental disorder 1, 4

Systematic Evaluation Process

Step 1: Multi-Informant Data Collection

Obtain standardized behavioral information from multiple sources using DSM-5-based rating scales: 1

• Parents/guardians for home behavior and developmental history 1
• At least 2 teachers or school personnel for academic/classroom functioning 1
• For adolescents: coaches, guidance counselors, or community activity leaders (with adolescent's agreement) 1
• Collateral information is essential because patients, especially adolescents and adults, often underestimate symptom severity 1, 2, 5

Step 2: Clinical Interview

Conduct comprehensive interview focusing on: 6, 5

• Specific DSM-5 symptom criteria for inattention (poor attention to detail, difficulty sustaining attention, seems preoccupied, difficulty completing tasks, organizational challenges, avoids sustained mental effort, loses things, easily distracted, forgetful) 2, 3
• Hyperactive-impulsive symptoms (fidgeting, leaving seat, inappropriate running/climbing, difficulty with quiet activities, "on the go," excessive talking, blurting answers, can't wait turn, intrusive) 3
• Childhood manifestations to establish onset before age 12, particularly critical for adolescents and adults 1
• Functional impairment across multiple life domains using tools like the Weiss Functional Impairment Rating Scale-Self (WFIRS-S) 2, 7

Step 3: Screening Tools

Use validated screening instruments: 2, 7

• Adult ADHD Self-Report Scale (ASRS-V1.1) Part A as first-line screening in adults 2, 7
• Positive screen: 4 or more of 6 questions checked "often" or "very often" 2, 7
• Follow positive screens with Part B assessment and functional impairment evaluation 2

Step 4: Rule Out Alternative Diagnoses

Systematically screen for conditions that mimic ADHD: 1, 4

• Depression: difficulty concentrating is a core DSM-5 symptom of major depression 4
• Anxiety disorders: can present with concentration deficits 4
• Substance use: marijuana and other substances mimic ADHD symptoms 1
• Sleep disorders: particularly sleep apnea causes attention deficits 1
• In older adults: dementia and minimal hepatic encephalopathy cause prominent attention abnormalities 4

Step 5: Assess for Comorbid Conditions

Screen for common comorbidities that alter treatment: 1

• Emotional/behavioral: anxiety, depression, oppositional defiant disorder, conduct disorders (approximately 10% of adults with recurrent depression/anxiety have underlying ADHD) 1, 2
• Developmental: learning disabilities, language disorders, autism spectrum disorders 1
• Physical: tics, sleep apnea 1
• In adolescents specifically: substance use, mood disorders, anxiety, self-harm risk, risky sexual behaviors 1

Age-Specific Considerations

Adolescents (12-18 years)

Critical diagnostic challenges: 1

• Adolescents minimize their own symptoms and reports often differ from observers 1
• Less overt hyperactivity makes diagnosis more subtle 1
• Must establish childhood onset before age 12 through historical documentation or collateral reports 1
• High risk for substance use that mimics or complicates ADHD 1
• Some may feign symptoms to obtain stimulants for performance enhancement 1

Adults

Diagnostic approach differs: 2, 5

• Poor insight about symptom severity requires collateral information 2
• Childhood documentation of symptoms before age 12 is mandatory unless previously diagnosed 1
• Broader psychiatric assessment needed given high comorbidity rates 5

Common Diagnostic Pitfalls

Avoid these errors: 4, 2

• New-onset psychiatric symptoms in any age require medical evaluation to rule out underlying medical illness 4
• Assuming depression is "pseudodementia" in older adults—it may represent early dementia 4
• Relying solely on patient self-report without collateral information 2, 5
• Missing comorbid conditions that require concurrent treatment 1
• Diagnosing ADHD when symptoms are better explained by depression, anxiety, or substance use 1, 4

Medical Evaluation

Complete medical history and examination to rule out: 3, 6

• Organic conditions that cause attention deficits 6
• Medication effects particularly in older adults 4
• Thyroid disorders, anemia, other systemic conditions 6