What are the diagnostic criteria for adult Attention Deficit Hyperactivity Disorder (ADHD)?

Diagnostic Criteria for Adult ADHD

Adult ADHD diagnosis requires meeting DSM-5 criteria with at least 5 symptoms of inattention and/or hyperactivity-impulsivity persisting for 6+ months, documented childhood onset before age 12, cross-situational impairment in at least 2 settings, and systematic exclusion of mimicking conditions through comprehensive psychiatric evaluation with collateral information. 1, 2

Core DSM-5 Symptom Requirements

Adults must demonstrate at least 5 symptoms (rather than the 6 required for children) from either the inattention domain or hyperactivity-impulsivity domain, with symptoms persisting for a minimum of 6 months. 1, 2 The four diagnostic presentations are:

• Predominantly Inattentive Presentation (314.00 [F90.0]) 3
• Predominantly Hyperactive-Impulsive Presentation (314.01 [F90.1]) 3
• Combined Presentation (314.01 [F90.2]) 3
• Other Specified/Unspecified ADHD (314.01 [F90.8]) 3

Mandatory Childhood Onset Documentation

You must establish that ADHD symptoms were present before age 12 years, even when diagnosing adults. 3, 1, 2 This requires:

• Direct questioning about childhood behaviors and school performance 1
• Use of the Wender Utah Rating Scale (WURS) to assess retrospective childhood symptoms 1, 4
• Collateral information from parents, siblings, or childhood records when available 1, 5

Critical pitfall: Adolescents and adults attempting to obtain stimulants may feign symptoms—substances like marijuana can mimic ADHD, and some patients seek medication for performance enhancement. 3

Cross-Situational Impairment Requirement

Functional impairment must be documented in at least 2 distinct settings such as work, home, or social relationships. 3, 1, 2 This is non-negotiable for diagnosis and distinguishes ADHD from situational difficulties. 3

Structured Assessment Tools

The American Academy of Child and Adolescent Psychiatry recommends using validated instruments to supplement clinical interview: 1

• Adult ADHD Self-Report Scale (ASRS-V1.1): Screens positive when patient endorses "often" or "very often" for 4 or more of 6 questions 1
• Wender Utah Rating Scale: Assesses retrospective childhood symptoms 1, 4
• Conners Adult ADHD Rating Scales (CAARS): Quantifies current symptoms using Likert scales 4

These rating scales are essential but not diagnostic alone—they supplement, not replace, comprehensive clinical interview. 1, 4

Systematic Differential Diagnosis

You must systematically screen for and rule out conditions that mimic or co-occur with ADHD: 1, 2

Psychiatric Mimics to Exclude:

• Mood disorders: Bipolar disorder and major depression can present with concentration difficulties and restlessness 1, 2
• Anxiety disorders: Generalized anxiety and social phobia cause distractibility and motor tension 1, 2
• Substance use disorders: Active use or withdrawal states mimic ADHD symptoms 3, 1
• Personality disorders: Particularly borderline and antisocial presentations 1

Medical Conditions to Screen:

• Thyroid disorders: Obtain thyroid function tests 1
• Sleep disorders: Sleep apnea causes daytime inattention and fatigue 3, 1
• Neurological conditions: Rule out seizure disorders, traumatic brain injury 1

High-Prevalence Comorbidities:

The majority of adults with ADHD meet criteria for another mental disorder. 3 Screen systematically for:

• Depression and anxiety (most common) 3, 1
• Oppositional defiant disorder and conduct disorders 3
• Learning disabilities 3
• Substance use disorders 3, 1

Step-by-Step Diagnostic Algorithm

Follow this sequential approach: 1, 5

1. Initial screening: Administer ASRS-V1.1 1

2. Comprehensive clinical interview: Document current symptoms, childhood onset, and functional impairment across multiple domains 1, 5

3. Collateral information: Obtain reports from family members, partners, or close friends using informant rating scales 1, 5

4. Childhood symptom documentation: Use WURS and direct questioning about school performance, peer relationships, and family observations before age 12 1, 4

5. Cross-situational verification: Confirm impairment in at least 2 settings (work, home, social) 1, 2

6. Comorbidity screening: Systematically evaluate for mood, anxiety, substance use, and personality disorders 1, 2

7. Medical screening: Obtain focused history and consider thyroid function tests, basic metabolic panel if clinically indicated 1

8. Functional impairment assessment: Document specific deficits in occupational performance, relationships, daily organization 1, 5

When to Refer to Psychiatry

Refer when: 1

• Diagnostic uncertainty persists after comprehensive evaluation 1
• Complex comorbid psychiatric conditions are present (e.g., bipolar disorder, severe personality disorder) 1
• Specialized treatment beyond primary care scope is needed 1
• Patient has history of substance abuse requiring specialized monitoring 1

Critical Diagnostic Pitfalls

Avoid these common errors: 2, 5

• Failing to gather information from multiple sources: Single-informant diagnosis is insufficient 2, 5
• Inadequate childhood onset documentation: Cannot diagnose adult ADHD without establishing pre-age-12 symptoms 3, 2
• Insufficient comorbidity screening: Missing depression, anxiety, or substance use leads to treatment failure 1, 2
• Accepting self-report alone: Collateral information is essential to detect malingering and improve diagnostic accuracy 1, 5
• Overlooking predominantly inattentive presentations: These are more common in adults and easily missed 2