What is the diagnostic approach for Adult Attention Deficit Hyperactivity Disorder (ADHD)?

Diagnosing Adult ADHD

Adult ADHD diagnosis requires a comprehensive psychiatric evaluation documenting that symptoms began before age 12, demonstrating current functional impairment in at least two settings (work, home, social), using validated rating scales like the Adult ADHD Self-Report Scale (ASRS), obtaining collateral information when possible, and systematically ruling out mimicking conditions including mood disorders, anxiety, substance use, and medical causes. 1

Core Diagnostic Requirements

The diagnostic process must establish three critical elements through direct clinical interview 1:

• Childhood onset documentation: Confirm ADHD symptoms were present before age 12 years, even when retrospective documentation is limited, as mandated by DSM-5 criteria 1, 2
• Current symptom assessment: Evaluate for at least 5 symptoms of inattention and/or hyperactivity-impulsivity that have persisted for at least 6 months 1
• Cross-situational impairment: Document that symptoms cause functional impairment in at least 2 settings such as work, home, or social relationships 1, 2

Structured Assessment Tools

Primary Screening Instrument

Use the Adult ADHD Self-Report Scale (ASRS-V1.1) as your initial screening tool 1, 3:

• The ASRS screens positive when the patient endorses "often" or "very often" for 4 or more of 6 questions 1
• This tool identifies adults requiring comprehensive evaluation but does not diagnose ADHD by itself 1

Retrospective Childhood Assessment

The Wender Utah Rating Scale assesses retrospective childhood symptoms to establish the required childhood onset 1, 4, 5:

• This addresses the critical requirement that symptoms were present before age 12 years 1
• Patient recall or third-party information from family members strengthens this assessment 5

Comprehensive Rating Scales

Additional validated instruments supplement clinical interview 5:

• Conners Adult ADHD Rating Scale (CAARS) provides both self-report and observer forms 5
• Brown ADD Rating Scale can be used by clinicians or significant others 5

Critical Differential Diagnosis

Systematically evaluate conditions that overlap with or mimic ADHD symptoms 1, 6:

Psychiatric Conditions to Rule Out

• Mood disorders: Bipolar disorder and major depression can mimic ADHD symptoms, particularly inattention and disorganization 1, 6
• Anxiety disorders: Generalized anxiety and social phobia present with concentration difficulties and restlessness 1, 6
• Substance use disorders: Active substance use can cause attention problems; also assess for self-medication patterns 1, 6
• Personality disorders: Borderline and unstable emotional personality disorders are commonly misdiagnosed when adult ADHD is the actual diagnosis 6
• Trauma-related conditions: PTSD and toxic stress can present with attention and behavioral symptoms 7

Medical Conditions to Exclude

Perform focused medical assessment to rule out conditions that mimic ADHD 1:

• Thyroid disorders (obtain thyroid function tests) 1
• Sleep disorders (assess sleep quality and screen for sleep apnea) 1
• Neurological conditions 1

Mandatory Comorbidity Screening

The majority of adults with ADHD meet criteria for another mental disorder, making systematic comorbidity screening essential rather than optional 7, 1:

• Screen for anxiety disorders, depression, and substance use disorders 1
• Assess for learning disabilities and other developmental conditions 7
• Evaluate for antisocial behavior patterns and relationship instability 6

Diagnostic Algorithm

Follow this step-by-step approach 1:

1. Initial screening: Administer ASRS-V1.1 1
2. Comprehensive clinical interview: Assess current symptoms, functional impairment, and developmental history 1
3. Collateral information: Obtain information from family members or significant others when possible 1, 5
4. Structured rating scales: Use CAARS or similar validated instruments 1
5. Retrospective childhood assessment: Use Wender Utah Rating Scale 1
6. Comorbidity screening: Systematically evaluate for mood, anxiety, substance use, and personality disorders 1
7. Medical screening: Rule out thyroid disorders, sleep disorders, and other medical causes 1
8. Functional impairment assessment: Document specific impairments in work, relationships, and daily functioning 1

Common Diagnostic Pitfalls to Avoid

Relying solely on questionnaire scores without clinical interview and multi-informant data leads to misdiagnosis 8, 7:

• Rating scales systematically collect symptom information but do not diagnose ADHD by themselves 8
• Failing to establish childhood onset before age 12 years violates mandatory diagnostic criteria 7, 1
• Not screening for comorbid conditions that may explain symptoms or coexist with ADHD is a significant oversight 7, 1
• Assigning an ADHD diagnosis when symptoms are better explained by trauma, substance use, or other psychiatric conditions leads to inappropriate treatment 7

When to Refer to Psychiatry

Consider referral when 1:

• Diagnostic uncertainty persists after initial evaluation 1
• Complex comorbid psychiatric conditions are present 1
• Specialized treatment or medication management is needed 1
• The patient has not responded to initial treatment approaches 1