A 10-year-old girl is referred to the psychiatry clinic for evaluation of inattention and poor academic performance. Her parents report that she frequently daydreams in class, forgets homework, loses school supplies, and has difficulty organizing tasks. She does not exhibit hyperactivity or impulsivity; rather, she appears quiet and withdrawn. Her teacher notes that she is not disruptive but seems 'lost in her own world.' Developmental history is unremarkable. On mental status examination, she is cooperative but shows poor sustained attention and slow processing speed. Which subtype of ADHD is most consistent with this clinical presentation?

Explanation

## DSM-5 ADHD Subtypes and Diagnostic Criteria **Key Point:** ADHD is classified into three subtypes based on the predominant symptom pattern: predominantly inattentive, predominantly hyperactive-impulsive, and combined type. Accurate subtyping is essential for treatment planning and prognosis. ## Predominantly Inattentive Type: Clinical Features This patient exhibits the cardinal features of inattentive ADHD: - **Persistent inattention** (daydreaming, forgetfulness, difficulty sustaining focus) - **Organization and planning deficits** (loses belongings, forgets homework) - **Absence of hyperactivity-impulsivity** (quiet, withdrawn, not disruptive) - **Functional impairment** in academic domain - **Early onset** (symptoms present before age 12) **High-Yield:** Predominantly inattentive ADHD is often underdiagnosed, particularly in girls, because it lacks the disruptive hyperactive-impulsive behaviors that draw adult attention. These children are frequently labeled as "lazy" or "unmotivated" rather than recognized as having a neurodevelopmental disorder. ## DSM-5 Diagnostic Criteria Summary by Subtype | Subtype | Inattention Symptoms | Hyperactivity-Impulsivity Symptoms | Minimum Threshold | |---------|----------------------|-----------------------------------|-------------------| | **Inattentive** | ≥6 present (age ≥17: ≥5) | <6 present | Inattention ≥6 | | **Hyperactive-Impulsive** | <6 present | ≥6 present (age ≥17: ≥5) | H-I ≥6 | | **Combined** | ≥6 present | ≥6 present | Both criteria met | **Clinical Pearl:** Inattentive ADHD often presents with slower processing speed, sluggish cognitive tempo, and working memory deficits. These children may also have higher rates of anxiety and mood disorders as comorbidities. ## Why This Patient Does NOT Have Other Subtypes ```mermaid flowchart TD A["10-year-old with inattention<br/>No hyperactivity/impulsivity"]:::outcome A --> B{"Hyperactivity-impulsivity<br/>symptoms present?"}:::decision B -->|"No (quiet, withdrawn)"| C["Predominantly Inattentive Type"]:::action B -->|"Yes (disruptive, fidgety)"| D["Consider Hyperactive-Impulsive<br/>or Combined Type"]:::action A --> E{"Both inattention AND<br/>H-I symptoms ≥6?"}:::decision E -->|"No"| C E -->|"Yes"| F["Combined Type"]:::action ``` **Mnemonic:** **QUIET** — Quiet presentation, Underdiagnosed, Inattention predominant, Executive dysfunction, Time-consuming to recognize (often missed in girls). ## Clinical Significance - **Gender differences:** Inattentive ADHD is more common in girls; hyperactive-impulsive type is more common in boys - **Prognosis:** Inattentive type may have better long-term social outcomes but greater academic/occupational impairment if untreated - **Treatment:** Stimulant medications are effective; cognitive-behavioral therapy and environmental modifications are also important [cite:DSM-5, American Academy of Pediatrics ADHD Clinical Practice Guideline]