ADHD Diagnostic Tools
Use DSM-5 criteria as your primary diagnostic framework, systematically collecting information through standardized rating scales from multiple informants (parents, teachers, and the patient), with the Vanderbilt Assessment Scales for children and the Conners Adult ADHD Rating Scales (CAARS) for adults serving as the most practical and validated tools. 1, 2
For Children and Adolescents (Ages 4-18)
Primary Diagnostic Approach
Obtain Vanderbilt ADHD Diagnostic Rating Scales from both parents and teachers to document symptoms across multiple settings, as this tool demonstrates robust psychometric properties with test-retest reliability exceeding 0.80 and internal consistency of 0.88-0.91. 3 When combined with clinical interview, the Vanderbilt scale achieves sensitivity of 0.80, specificity of 0.75, and negative predictive value of 0.98. 3
DSM-5 Criteria Requirements
You must document the following to make the diagnosis: 1, 2
- At least 6 symptoms of inattention and/or hyperactivity-impulsivity that have persisted for at least 6 months (rated "often/very often" on rating scales) 3
- Symptom onset before age 12 (DSM-5 changed this from DSM-IV's requirement of age 7) 1
- Impairment documented in more than one major setting (home, school, social situations) using information from parents, teachers, and other observers 1, 2
- Symptoms not better explained by another mental disorder through systematic exclusion of alternative diagnoses 1
Specific Symptom Domains to Assess
For inattentive symptoms, document at least 6 of these persisting for 6+ months: lack of attention to details/careless mistakes, lack of sustained attention, poor listener, failure to follow through on tasks, poor organization, avoids tasks requiring sustained mental effort, loses things, easily distracted, forgetful. 4
For hyperactive-impulsive symptoms, document at least 6 of these persisting for 6+ months: fidgeting/squirming, leaving seat, inappropriate running/climbing, difficulty with quiet activities, "on the go," excessive talking, blurting answers, can't wait turn, intrusive. 4
Critical Comorbidity Screening
Screen systematically for these conditions as they occur frequently with ADHD and impact treatment decisions: 2, 3
- Anxiety disorders and depression 2, 3
- Oppositional defiant disorder and conduct disorders 2, 3
- Learning disabilities and language disorders 2, 3
- Sleep disorders and tics 2, 3
- Autism spectrum disorder (if social communication difficulties present) 2
Important Clinical Pitfalls
Girls are more likely to present with predominantly inattentive symptoms rather than hyperactive symptoms, leading to underdiagnosis, and they have higher rates of comorbid anxiety and depression compared to boys. 3 Actively look for inattentive presentation in girls who may not display disruptive behavior.
Rating scales are screening tools, not standalone diagnostic instruments. 3, 5 The Vanderbilt has high specificity (99%) but low sensitivity (66.7%), making it inappropriate for screening but excellent as a confirmatory test. 5 You must conduct a comprehensive clinical interview to verify the diagnosis.
For Adults (Ages 18+)
Primary Diagnostic Approach
Use the Conners Adult ADHD Rating Scales (CAARS) for comprehensive symptom assessment with validated normative data, but recognize that rating scales do not diagnose ADHD by themselves—clinical interview is mandatory. 6, 7
Modified DSM-5 Criteria for Adults
Adults require at least 5 symptoms (not 6) of inattention and/or 5 symptoms of hyperactivity-impulsivity, with all other DSM-5 criteria remaining the same. 6
Essential Collateral Information
Obtain collateral information from family members, partners, or close friends to establish childhood onset and current functional impairment, as adults often minimize symptoms. 6, 7 Review old report cards, school records, or prior evaluations to document elementary and middle school functioning. 6
Critical Differential Diagnosis Considerations
Before diagnosing ADHD in adults, systematically rule out these conditions that produce identical symptoms: 6
- Substance use (marijuana and stimulants produce identical symptoms)—reassess after sustained abstinence 6
- Trauma and PTSD (cause hypervigilance, concentration problems, emotional dysregulation)—treat PTSD before reassessing attention symptoms 6
- Mood and anxiety disorders—optimize treatment before diagnosing ADHD 6
Mandatory Diagnostic Requirements
Establish childhood onset before age 12 through patient recall, collateral informants, or historical records—this is non-negotiable. 6 Document functional impairment in at least two independent settings (work, home, social relationships, academic). 6
Common Diagnostic Errors to Avoid
Do not rely solely on self-report without collateral information. 6 Do not use rating scale scores alone without comprehensive clinical interview. 6 Do not diagnose ADHD when symptoms are better explained by substance use, trauma, or mood disorders. 6
Practical Implementation Algorithm
Step 1: Initial Screening
Distribute Vanderbilt scales (children) or CAARS (adults) to multiple informants. 3, 6
Step 2: Clinical Interview
Conduct detailed developmental history focusing on elementary/middle school years, current symptom severity, and functional impairment across settings. 1, 6
Step 3: Rule Out Alternatives
Screen for medical conditions (thyroid disorders, sleep disorders, neurological conditions) through history and physical examination. 2, 3 Assess for psychiatric comorbidities systematically. 2, 6
Step 4: Verify DSM-5 Criteria
Confirm symptom count (6 for children, 5 for adults), duration (6+ months), onset (before age 12), pervasiveness (2+ settings), and impairment. 1, 6, 3
Step 5: Document Functional Impairment
Use structured assessment of academic performance, occupational functioning, social relationships, and daily living activities. 1, 6
When to Refer to Specialists
Refer to a psychiatrist, developmental-behavioral specialist, or neuropsychologist when: 6, 3