A 7-year-old boy is brought to the paediatric clinic by his mother with complaints of difficulty concentrating in school and frequent interruptions during classroom activities. The teacher reports that he fidgets constantly, leaves his seat without permission, and blurts out answers before questions are completed. His academic performance has declined over the past 6 months. On examination, he is restless and has difficulty sustaining attention during the clinical interview. His developmental history is unremarkable, and there is no history of seizures or head trauma. Hearing and vision are normal. What is the most likely diagnosis?

Explanation

## Diagnosis: ADHD, Combined Presentation ### Clinical Features Presented The vignette demonstrates the classic triad of ADHD symptoms: **Key Point:** The three core symptom domains in ADHD are inattention, hyperactivity, and impulsivity. This patient exhibits all three: - **Inattention:** Difficulty concentrating, declining academic performance - **Hyperactivity:** Fidgeting, leaving seat without permission, restlessness - **Impulsivity:** Blurting out answers, interrupting classroom activities ### DSM-5 Diagnostic Criteria | Criterion | Status in This Case | |-----------|--------------------| | **Onset before age 12** | Present (age 7) | | **Symptoms in ≥2 settings** | Yes (school and home) | | **Functional impairment** | Yes (academic decline) | | **Duration ≥6 months** | Yes (past 6 months) | | **≥6 symptoms of inattention OR ≥6 of hyperactivity-impulsivity** | Yes (multiple symptoms across domains) | | **Not better explained by another disorder** | Organic causes ruled out | ### Presentation Subtype Classification ```mermaid flowchart TD A[ADHD Presentation Types]:::outcome A --> B{Symptom Profile}:::decision B -->|≥6 inattention + <6 hyperactivity-impulsivity| C[Predominantly Inattentive]:::action B -->|<6 inattention + ≥6 hyperactivity-impulsivity| D[Predominantly Hyperactive-Impulsive]:::action B -->|≥6 inattention + ≥6 hyperactivity-impulsivity| E[Combined Presentation]:::action E --> F[This Case]:::outcome ``` **High-Yield:** Combined presentation is the most common subtype (~70% of cases) and typically presents with the most severe functional impairment. ### Differential Diagnosis Exclusion **Clinical Pearl:** The normal developmental history, absence of seizures/head trauma, and normal hearing/vision rule out secondary causes (hearing impairment, neurological conditions, developmental regression). **Mnemonic: ADHD vs ODD — ADHD is about CONTROL, ODD is about DEFIANCE** - ADHD: Child *cannot* control behaviour (neurobiological) - ODD: Child *will not* control behaviour (oppositional attitude) **Key Point:** While ODD can co-occur with ADHD, the primary presentation here is neurodevelopmental (ADHD), not primarily oppositional. ### Why Combined Presentation? The presence of symptoms meeting threshold for BOTH inattention AND hyperactivity-impulsivity domains classifies this as Combined Presentation, the most common and typically most impairing subtype.