VHOSPITAL.CLINIC · Differential Diagnosis
ADHD (Attention Deficit Hyperactivity Disorder) vs Autism Spectrum Disorder (ASD)
Clinical comparison — shared symptoms, key differences, distinguishing diagnostic tests, treatment pathways, and when to seek urgent evaluation.
Condition Overview
Condition A
ADHD (Attention Deficit Hyperactivity Disorder)
ADHD is a neurodevelopmental disorder causing inattention, hyperactivity, and impulsivity that impairs academic, occupational, and social functioning. Stimulant medications (methylphenidate, amphetamine salts) combined with behavioral therapy are effective.
Condition B
Autism Spectrum Disorder (ASD)
ASD is a neurodevelopmental condition characterized by difficulties in social communication and interaction, with restricted and repetitive behaviors and interests. It exists on a spectrum from mild to severe; early behavioral intervention improves outcomes.
Shared Symptoms — Why They're Confused
Both conditions present with 3 overlapping symptoms, making clinical differentiation essential.
Key Clinical Differences
ADHD (Attention Deficit Hyperactivity Disorder)
- Inattention, hyperactivity, impulsivity
- Difficulty with sustained attention tasks
- Social difficulties secondary to impulsivity
- Responds to stimulant medication
Autism Spectrum Disorder (ASD)
- Persistent difficulties in social communication and interaction
- Restricted interests, repetitive behaviours (stereotypies)
- Social difficulties from impaired social understanding, not just impulsivity
- No established pharmacological treatment for core features
Distinguishing Diagnostic Tests
| Test | ADHD (Attention Deficit Hyperactivity Disorder) | Autism Spectrum Disorder (ASD) |
|---|---|---|
| ADOS-2 / ADI-R | Below threshold for ASD — social difficulties from inattention/impulsivity | Meets criteria on ADOS-2 — impaired social understanding and communication |
| Eye contact and social reciprocity | Adequate eye contact; socially motivated but distractible | Reduced eye contact; difficulty with reciprocal social conversation |
| Repetitive behaviours | Absent — no stereotypies or restricted interests pattern | Present — restricted interests, routines, sensory sensitivities |
Treatment Approaches
ADHD (Attention Deficit Hyperactivity Disorder)
- •Methylphenidate or amphetamine salts
- •Behavioural interventions and parental training
Autism Spectrum Disorder (ASD)
- •Applied behaviour analysis (ABA)
- •Speech and language therapy
- •Occupational therapy for sensory processing
When Doctors Consider Each Diagnosis
🔵 Consider ADHD (Attention Deficit Hyperactivity Disorder) when:
- →Inattention/hyperactivity, social difficulties from impulsivity, stimulant response, no repetitive behaviours
🟢 Consider Autism Spectrum Disorder (ASD) when:
- →Impaired social understanding, restricted interests, repetitive behaviours, ADOS-2 positive
Explore Each Condition in Detail
Related Clinical Pages
ADHD (Attention Deficit Hyperactivity Disorder)
Medical References
Content on this page is informed by evidence-based clinical sources including:
- World Health Organization (WHO)Global health guidance and disease classification
- National Health Service (NHS)UK clinical guidelines and patient information
- National Institute for Health and Care Excellence (NICE)Evidence-based clinical practice guidelines
- Centers for Disease Control and Prevention (CDC)US public health data and clinical recommendations
- PubMed – NCBIPeer-reviewed biomedical literature and clinical studies
- Cochrane LibrarySystematic reviews and meta-analyses in evidence-based medicine
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