What are the steps and tools used to assess and diagnose Attention Deficit Hyperactivity Disorder (ADHD) in adults above 18 years?

Systematic Diagnostic Assessment for Adult ADHD (Age 18+)

Adults with ADHD must meet DSM-5 criteria requiring at least 5 symptoms of inattention and/or 5 symptoms of hyperactivity-impulsivity, with documented onset before age 12, functional impairment in at least two settings, and systematic exclusion of alternative diagnoses through comprehensive clinical interview and collateral information. 1

Step 1: Initial Clinical Interview and History

Conduct a comprehensive clinical interview focusing on current symptoms, childhood onset, and functional impairment across multiple life domains. 1, 2

• Establish that at least 5 symptoms of inattention and/or 5 symptoms of hyperactivity-impulsivity are present and rated as "often" or "very often" 1
• Document childhood onset before age 12 years through patient recall, collateral informants (parents, siblings, childhood friends), or historical records such as old report cards or school evaluations 1, 3
• Verify functional impairment in at least two independent settings: work performance, home responsibilities, social relationships, or academic functioning 1, 4
• Assess chronicity and pervasiveness of symptoms throughout the lifespan, noting that hyperactive symptoms typically decline while inattentive symptoms persist into adulthood 5, 2

Step 2: Standardized Rating Scales

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. 1, 6

• Administer self-report rating scales such as CAARS, Adult ADHD Self-Report Scale (ASRS), or Current Symptoms Scale (CSS) to quantify symptom severity 3, 6
• Obtain observer ratings from partners, family members, or close friends using other-report versions of standardized scales 3, 2
• Use the Wender Utah Rating Scale (WURS) specifically for retrospective assessment of childhood ADHD symptoms 3, 6
• Rating scales serve to systematically collect information but cannot replace clinical judgment or comprehensive evaluation 1, 7

Step 3: Collateral Information from Multiple Informants

Obtain detailed information from family members, partners, or close friends to corroborate symptom history and functional impairment, as adults often minimize their own symptoms. 1, 4

• Interview significant others about observed symptoms, childhood behaviors, and current functional difficulties 1, 2
• Review historical documentation including elementary and middle school report cards, prior psychological evaluations, or academic records 1, 3
• Gather workplace performance reviews or feedback from supervisors when available to document occupational impairment 4, 7

Step 4: Systematic Exclusion of Alternative Diagnoses

Rule out substance use disorders, trauma/PTSD, mood disorders, and anxiety disorders that can produce identical symptoms to ADHD before confirming the diagnosis. 1

Critical differential diagnoses to exclude:

• Substance use: Marijuana and stimulants produce inattention, impulsivity, and concentration problems identical to ADHD 1
• Trauma/PTSD: Hypervigilance, concentration difficulties, and emotional dysregulation mimic ADHD symptoms 1
• Mood disorders: Depression and bipolar disorder cause inattention, poor concentration, and restlessness 1, 2
• Anxiety disorders: Worry and rumination impair concentration and create subjective restlessness 1, 2

Diagnostic algorithm for ambiguous cases:

• Reassess symptoms after sustained abstinence from substance use (minimum 3-6 months) 1
• Treat PTSD symptoms first, then reassess attention and concentration after trauma treatment 1
• Optimize treatment for mood and anxiety disorders before diagnosing ADHD, as these conditions must be stabilized first 1

Step 5: Assessment of Comorbid Conditions

Screen systematically for psychiatric comorbidities that commonly co-occur with ADHD and may alter treatment approach. 5, 2

• Evaluate for substance use disorders, particularly alcohol, marijuana, and stimulant misuse 1, 2
• Screen for anxiety disorders and depression, which are highly comorbid with adult ADHD 5, 1
• Assess for personality disorders, particularly borderline and antisocial patterns that frequently co-occur 2
• Rule out sleep disorders (sleep apnea, insomnia) that can cause identical attention and concentration problems 5

Step 6: Documentation of Functional Impairment

Document specific impairments in social, academic, or occupational functioning across at least two major life domains using concrete examples. 1, 4

• Work/occupational: Chronic lateness, missed deadlines, disorganization, frequent job changes, underachievement relative to intelligence 4, 7
• Academic: Incomplete degrees, academic probation, difficulty completing assignments despite adequate intelligence 4, 2
• Social/relationships: Unstable relationships, difficulty maintaining friendships, impulsive decision-making in relationships 4, 2
• Home/daily functioning: Chronic disorganization, poor time management, procrastination on routine tasks 4, 7

Common Diagnostic Pitfalls to Avoid

Do not rely solely on self-report without collateral information, as adults with ADHD often minimize or lack insight into their symptoms. 1

• Never diagnose ADHD based on rating scale scores alone without comprehensive clinical interview and verification of childhood onset 1, 6
• Do not diagnose ADHD when symptoms are better explained by active substance use, untreated trauma, or inadequately treated mood disorders 1
• Avoid missing the diagnosis in women, who more commonly present with predominantly inattentive symptoms rather than hyperactive symptoms and have higher rates of comorbid anxiety and depression 8
• Do not skip establishing childhood onset before age 12, which is a non-negotiable diagnostic requirement per DSM-5 criteria 1, 3
• Recognize that physical examination cannot rule out medical mimics (thyroid disorders, sleep apnea, neurological conditions) without appropriate laboratory or sleep studies when clinically indicated 8

Referral Considerations

Refer to a psychiatrist, developmental-behavioral specialist, or neuropsychologist when the clinical picture is complex, atypical, or involves significant comorbidity. 8

• Complex comorbidity requiring specialized medication management (multiple psychiatric diagnoses) 5, 8
• Diagnostic uncertainty after initial evaluation, particularly when substance use or trauma history complicates the picture 1
• Need for comprehensive neuropsychological testing to evaluate learning disabilities or executive function deficits 8, 3
• Treatment resistance or significant adverse effects from initial medication trials 1