Autism (ASD) vs ADHD — Clinical Trial Comparison
Autism (ASD)
Differences in social communication and restricted interests
ADHD
Persistent inattention, hyperactivity, and impulsivity
Autism and ADHD are the two most common neurodevelopmental conditions, and they co-occur in 30–50% of cases. While both affect executive function and daily life, their clinical trial landscapes are very different. Autism trials focus on supportive interventions, sensory processing, and co-occurring conditions, while ADHD trials concentrate on medication optimisation, behavioural therapies, and digital interventions.
Key Differences at a Glance
| Feature | Autism (ASD) | ADHD |
|---|---|---|
| Core features | Social communication differences, restricted/repetitive behaviours | Inattention, hyperactivity, impulsivity |
| Diagnosis | ADOS-2, ADI-R, clinical assessment | Conners, DIVA-5, clinical interview |
| UK prevalence | ~1–2% of population | ~2–5% of adults, ~5% of children |
| Co-occurrence rate | 30–50% also have ADHD | 30–50% also have autism features |
| NICE first-line | Adapted CBT, social skills, occupational therapy | Medication (methylphenidate) + behavioural therapy |
| Adult diagnosis | Growing but under-recognised | Growing, especially in women |
Clinical Trial Availability
| Trial Aspect | Autism (ASD) | ADHD |
|---|---|---|
| UK trials actively recruiting | 20–35 studies | 40–60 studies |
| Most common trial phase | Phase 2–3 | Phase 2–3 |
| Top interventions tested | Social cognition training, sensory interventions, anxiety management, gut microbiome | Medication optimisation, digital CBT, neurofeedback, organisational skills |
| Medication trials | Focused on co-occurring conditions (anxiety, irritability) | Core ADHD symptom management (stimulant, non-stimulant) |
| Digital/app-based trials | Growing (social skills, employment support) | Growing rapidly (cognitive training, reminders) |
| Paediatric vs adult | Predominantly paediatric | Both paediatric and adult |
Exciting Emerging Treatments
Autism (ASD) Trials
- Gut-brain axis interventions — microbiome-based therapies for GI and behavioural symptoms
- Social cognition training — VR-based social scenarios and emotion recognition
- Sensory processing interventions — targeted therapies for sensory sensitivities
- Oxytocin and vasopressin — targeting social communication pathways
- Employment support trials — workplace accommodation and neurodiversity programmes
- Co-occurring anxiety/mental health trials — adapted CBT for autistic adults
ADHD Trials
- Non-stimulant medications — viloxazine, new formulations of existing drugs
- Digital therapeutics — FDA/EMA-approved app-based ADHD treatment (Akili Interactive)
- Neurofeedback — real-time brain activity training for attention regulation
- Long-acting formulations — extended-release methylphenidate and amphetamine
- Organisational skills training — structured programmes for adult executive function
- Women-focused ADHD research — addressing underdiagnosis in women and girls
💡 Neurodiversity-affirming trials are growing
Historically, autism research focused on "correcting" autistic traits. A growing number of trials now take a neurodiversity-affirming approach — supporting autistic people with co-occurring challenges (anxiety, sensory overload, employment) rather than trying to make them "less autistic." When considering trials, ask whether the research aligns with your values and goals.
Eligibility Differences
Autism (ASD) Trial Criteria
- Confirmed autism spectrum diagnosis (DSM-5/ICD-11) usually required
- Many trials specify IQ range (some exclude, others require average or above)
- Co-occurring ADHD may be allowed or excluded depending on trial focus
- Language ability matters — some trials require verbal communication
- Age-specific cohorts common (children, adolescents, adults separately)
- Current medication regimens may need to be stable for specified period
ADHD Trial Criteria
- Confirmed ADHD diagnosis (any presentation: inattentive, hyperactive, combined)
- Severity thresholds using standardised rating scales (Conners, ASRS)
- Autism as co-diagnosis may affect eligibility depending on trial design
- Medication-naïve vs medication-experienced cohorts vary by trial
- Cardiovascular screening may be required for medication trials
- Substance use history relevant for stimulant medication trials
🧩 Autism Trials
Find actively recruiting autism clinical trials across the UK
View Autism (ASD) Trials