Research shows a significant overlap between autism and ADHD. Meta-analysis of 63 studies found 28-40% of people with autism also meet ADHD criteria¹. Understanding the differences and similarities can help you work out whether you need assessment for one or both conditions.
How Diagnosis Has Changed
Before 2013
Autism and ADHD were considered mutually exclusive. Doctors had to choose one or the other. This led to many incomplete diagnoses.
Now
The DSM-5 allows dual diagnosis since May 2013, recognising that these conditions¹:
- Share genetic and brain pathways
- Often occur together in the same person
- Need different but complementary treatments
This change finally matched what clinicians were seeing in practice.
Key Differences Between ADHD and Autism
How Attention Works
ADHD:
- Attention changes based on interest level
- Easily distracted by external or internal things
- Hard to focus on routine tasks
- Can hyperfocus on various activities
- Needs an external structure to maintain attention
Autism:
- Intense focus on special interests
- Deep, sustained focus that doesn’t like interruption
- Hard to shift attention when needed
- Internal motivation drives attention
- May get upset when interrupted during focused activities
Social Communication
ADHD:
- Impulsive social behaviour (interrupting, speaking out of turn)
- Want social connection but struggle with execution
- Social performance varies by situation
- Emotional reactions affect social interactions
- May miss social cues due to not paying attention
Autism:
- Different social communication style (direct, literal)
- Consistent social patterns across situations
- May prefer being alone or in small groups
- Difficulty reading facial expressions and body language
- May learn social behaviours through copying, but find it exhausting
Sensory Differences
ADHD:
- Seeks stimulation to help focus
- Sensory needs change based on attention state
- Uses fidgeting and movement for regulation
- May not consciously notice sensory differences
Autism:
- Specific sensory preferences and dislikes
- Consistent sensory patterns over time
- Uses stimming for emotional regulation
- Very aware of the sensory environment and its impact
Routine and Structure
ADHD:
- Needs external structure but struggles to create it
- May resist routines that become boring
- Works better under pressure or with variety
- Prefers a flexible structure that adapts to interests
Autism:
- Creates personal routines and systems
- Gets distressed by unexpected changes
- Prefers predictable environments
- May have very specific requirements for daily activities
Surprising Similarities Between ADHD and Autism
Executive Function
Both conditions affect:
- Planning and organisation abilities
- Time management and meeting deadlines
- Starting tasks, especially boring ones
- Working memory and information processing
- Adapting to changes
Emotional Regulation
Shared experiences include:
- Strong emotional reactions
- Difficulty with emotional transitions
- Sensitivity to criticism and rejection
- Anxiety about performance
- Tiredness from managing symptoms
Masking Behaviours
Both groups may:
- Learn to copy social behaviours
- Hide obvious symptoms in public
- Work much harder to appear ‘normal’
- Feel exhausted from constant self-monitoring
- Get diagnosed late due to effective masking
Why Wrong Diagnosis Happens
Common Patterns
- Social difficulties blamed on the wrong condition
- Attention patterns misunderstood
- One condition hides the other
- Not enough time for a thorough assessment
Gender Bias
Boys show 5.6-fold higher rates of combined diagnosis, but this likely reflects:
- Diagnostic bias affecting both conditions
- Girls may be better at masking symptoms
- Different presentations in females are not being recognised
What This Means
- Incomplete treatment approaches
- Continued unexplained symptoms
- Self-blame when treatments don’t work fully
- Missing out on appropriate support
Benefits of Full Assessment
Clinical samples show higher comorbidity (simultaneous) rates (40.4-61.8%) compared to community samples (29.5%), suggesting people with both conditions are more likely to need professional help¹.
Complete Picture
- Understanding how conditions interact
- Recognition of masking behaviours
- Identification of all strengths and challenges
- Better prediction of what treatments will work
Better Outcomes
- Medication decisions considering both conditions
- Therapy approaches addressing everything
- Appropriate workplace accommodations
- Access to relevant support communities
Deciding on Assessment
When Full Assessment Is Recommended
- A previous single diagnosis doesn’t fully explain your experiences
- Treatment effectiveness has been limited
- You experience internal conflicts (need routine but crave variety)
- Family history includes both conditions
- You relate to the symptoms of both conditions
Questions to Consider
- Do you have both attention difficulties AND social communication challenges?
- Do you need both structure AND variety?
- Have people said you have traits of both conditions?
- Would understanding your complete profile help with accommodations?
Current UK Context
NHS waiting times have reached crisis levels:
- 131,000 people waiting for ADHD assessments³
- 204,876 people waiting for autism assessments⁴
- Some waits reaching 10+ years
This makes private comprehensive assessment a realistic option for many people, with costs averaging £1,267 for ADHD and £1,800-£3,500 for autism assessments⁵.
Making the Right Choice
Individual Assessment Might Be Right If:
- You have a clear sense that you have one condition but not the other
- A previous assessment ruled out one condition thoroughly
- Symptoms clearly fit one pattern
- Treatment for one condition has been highly effective
Full Assessment Is Better If:
- You’ve been diagnosed with one, butthe symptoms don’t fully fit
- Treatment hasn’t been as effective as expected
- You have a family history of both
- You experience conflicts between needing routine and craving variety
Expert consensus guidelines recommend a comprehensive assessment when there are signs of both conditions, as this leads to better treatment outcomes and proper support access¹.
Ready to understand your complete neurodivergent profile?
Stop wondering whether you have ADHD or autism – you might have both.
- Speak to specialists who understand both conditions
[Book Your Online Combined Assessment] - Get initial insights
[Take Our Free ADHD Screening]
References:
- Rong et al. (2021). Research in Autism Spectrum Disorders. DOI: 10.1016/j.rasd.2021.101759
- ADHD UK Report (2023)
- National Autistic Society (2024)
- UK Private Assessment Cost Analysis (2024)