DSM-5 Diagnostic Criteria for ADHD
The diagnosis of ADHD requires at least 6 symptoms (5 for adults ≥17 years) from either inattention or hyperactivity-impulsivity domains, persisting for at least 6 months, with onset before age 12, present in two or more settings, causing functional impairment, and not better explained by another mental disorder. 1
Core Symptom Domains
ADHD is defined by two primary symptom dimensions that determine clinical presentation 1:
Inattention Domain (requires ≥6 symptoms for children, ≥5 for adults ≥17 years)
- Lack of attention to details/careless mistakes 2
- Lack of sustained attention 2
- Poor listener 2
- Failure to follow through on tasks 2
- Poor organization 2
- Avoids tasks requiring sustained mental effort 2
- Loses things 2
- Easily distracted 2
- Forgetful 2
Hyperactivity-Impulsivity Domain (requires ≥6 symptoms for children, ≥5 for adults ≥17 years)
- Fidgeting/squirming 2
- Leaving seat 2
- Inappropriate running/climbing 2
- Difficulty with quiet activities 2
- "On the go" 2
- Excessive talking 2
- Blurting answers 2
- Can't wait turn 2
- Intrusive 2
Mandatory Temporal Requirements
Symptoms must have been present before age 12 years (DSM-5 changed this from DSM-IV's requirement of age 7) 3, 1. For adolescents and adults, you must establish retrospective evidence of childhood onset even when documentation is limited 1, 4. This is critical—the age-at-onset criterion distinguishes ADHD from adult-onset attention problems due to other psychiatric conditions 5.
Duration and Persistence
Symptoms must persist for at least 6 months to meet diagnostic criteria 1, 6, 2. This duration requirement helps distinguish ADHD from transient behavioral problems related to situational stressors 7.
Functional Impairment Across Multiple Settings
Impairment must be documented in more than one major setting (social, academic, or occupational) 3, 1, 6. This is non-negotiable—symptoms confined to a single setting suggest environmental factors rather than ADHD 2. Information must be obtained from multiple sources: parents/guardians, teachers, school personnel, and mental health clinicians 3, 1, 6.
Exclusion of Alternative Causes
The diagnosis requires ruling out that symptoms are better explained by another mental disorder 3, 1, 2. This is where many diagnostic errors occur—symptoms must not be better accounted for by anxiety, depression, trauma, substance use, or other psychiatric conditions 4, 5.
Mandatory Comorbidity Screening
You must systematically screen for comorbid conditions during evaluation, including anxiety, depression, oppositional defiant disorder, conduct disorders, substance use, learning and language disorders, autism spectrum disorders, and physical conditions like tics or sleep apnea 3, 6, 4. The majority of children with ADHD meet criteria for another mental disorder, making this screening essential rather than optional 4.
Diagnostic Assessment Tools
Use DSM-based ADHD rating scales to systematically collect information from parents and teachers 1. For adults, the Adult ADHD Self-Report Scale (ASRS-V1.1) is the first-line screening tool 1, 5.
Subthreshold ADHD and Treatment Considerations
Behavioral interventions like parent training in behavior management (PTBM) are beneficial for children with ADHD-like behaviors who don't meet full criteria 1, 4. These programs do not require a specific diagnosis to benefit the family 4. This approach allows treatment of functionally impairing symptoms while avoiding premature diagnostic labeling 4.
Age-Specific Diagnostic Considerations
Preschool-Aged Children (4-6 years)
- DSM-5 criteria can appropriately identify ADHD in this age group 4
- Determining symptoms across multiple settings is particularly challenging, especially for children not attending preschool or childcare 4
- PTBM is recommended as the primary intervention for both diagnosed preschool ADHD and ADHD-like behaviors whose diagnosis is not yet verified 4
Adolescents
- Strongly consider whether substance use, depression, or anxiety are present rather than or in addition to ADHD 6, 4
- Must establish that manifestations were present before age 12 even when retrospective documentation is limited 4
Adults
- Requires at least 5 symptoms (rather than 6) from either domain 1, 8
- Manifestations of inattention or hyperactivity/impulsivity must have been present before age 12 6, 8
Critical Diagnostic Pitfalls to Avoid
- Failing to gather information from multiple sources and contexts before diagnosis 1, 6, 4—this is the most common error leading to misdiagnosis
- Failing to screen for comorbid conditions that may explain or coexist with symptoms 1, 6, 4
- Assigning an ADHD diagnosis when symptoms are better explained by trauma, substance use, or other psychiatric conditions 4
- Underdiagnosing girls who present with predominantly inattentive symptoms 6
- Withholding beneficial behavioral interventions while waiting to establish a formal diagnosis 4