A practical guide to ADHD and autism overlap for adults seeking clarity about their neurodevelopmental profile
TL;DR: ADHD and autism can overlap in areas such as attention, sensory processing, social interaction, emotional regulation and executive functioning. But they’re still separate neurodevelopmental conditions. A specialist assessment can help you understand whether ADHD, autism or both better explain your experiences.
You might read something about ADHD and think, that’s exactly me – only to find yourself doing the same thing with autism five minutes later.
Or perhaps you already have an ADHD or autism diagnosis, but it still feels as though there’s a piece of the puzzle missing.
That’s not unusual. ADHD and autism are separate conditions, but they can occur together and some traits can look very similar from the outside.
The important part is understanding why something is happening, how long it’s been happening and how it affects your life.
For late-diagnosed ADHD and autistic adults, that can mean looking back at experiences that may have been misunderstood for years.
At The ADHD & Autism Clinic, ADHD and autism are assessed through specialist adult assessment pathways designed to explore each condition properly.
Why are ADHD and autism so often found together?
ADHD and autism are both neurodevelopmental conditions. Put simply, that means they relate to differences in how the brain develops and processes the world.
You may also hear the term co-occurring ADHD and autism. This means someone independently meets the diagnostic criteria for both conditions.
Research has found significant overlap between ADHD and autism, although estimates of how often they occur together vary depending on who is being studied and how people are assessed.
It’s also worth knowing that ADHD and autism haven’t always been diagnosed together. Since the introduction of DSM-5 in 2013, clinicians have been able to diagnose both conditions in the same person.
But having a few traits associated with both doesn’t automatically mean you have both.
A diagnosis looks at the whole pattern, including:
- your experiences now
- your developmental history
- how those experiences affect everyday life
- whether the diagnostic criteria for each condition are met.
You can read more about research into the overlap between ADHD and autism.
Which ADHD and autism traits can look similar, but what’s different?
This is where it can become confusing.
ADHD and autism can both affect areas such as:
- executive functioning, including planning and organisation
- sensory processing
- emotional regulation
- social situations
- attention and focus
- routines
- managing everyday demands.
But similar behaviour doesn’t always have the same underlying reason.
For example, someone may find it difficult to follow a conversation.
With ADHD, their attention might keep shifting away from what’s being said.
An autistic person might be concentrating on interpreting social cues, processing language or dealing with sensory overload.
Someone with both may experience a combination.
What about apparently opposite traits?
ADHD and autism can sometimes pull in different directions.
You might:
- crave novelty but also need predictability
- act impulsively but become distressed by unexpected change
- struggle to start everyday tasks but become deeply absorbed in an interest
- rely heavily on routines while also finding it difficult to maintain them.
Sometimes one set of traits can even help compensate for another. A very structured routine, for example, might help someone manage ADHD-related forgetfulness or disorganisation.
For a closer comparison, read ADHD or Autism: Key Indicators and When Both Conditions Coexist.
Why can ADHD or autism be missed until adulthood?
For many adults, the signs haven’t suddenly appeared.
They’ve simply become harder to ignore.
You may have spent years finding ways to cope, adapting your behaviour or working much harder than other people realised.
Sometimes one diagnosis can also overshadow another.
Diagnostic overshadowing simply means that one recognised condition becomes the explanation for everything, so another condition is missed.
For example:
- sensory or social differences may be attributed to ADHD
- attention or organisational difficulties may be attributed to autism
- anxiety may become the main explanation for difficulties
- coping strategies may make underlying traits less obvious.
Why might things become clearer later in life?
Adults often start questioning ADHD or autism after a change puts more pressure on the strategies they’ve relied on.
That might include:
- burnout
- increased responsibility at work
- parenthood
- perimenopause
- relationship difficulties
- a child, friend or partner receiving a diagnosis.
Masking can also play a part. Masking means consciously or unconsciously changing your behaviour to fit social expectations or hide difficulties.
This can be particularly relevant for women and others whose presentation hasn’t matched traditional stereotypes. You can read more about this in our guide to autism assessments for women.
Being diagnosed later doesn’t mean your ADHD or autistic traits started in adulthood. That’s why a specialist assessment looks at both your current experiences and your developmental history.
How do clinicians work out whether it is ADHD, autism or both?
It’s not a case of ticking a few boxes and counting how many ADHD or autistic traits you recognise.
Clinicians look at the pattern behind those experiences.
An adult neurodevelopmental assessment may consider:
- childhood and developmental history
- current experiences
- work, relationships and everyday life
- the impact of particular difficulties
- coping and masking strategies
- whether another condition could better explain what you’re experiencing.
This process is sometimes called differential diagnosis. That simply means considering several possible explanations and working out which diagnosis – or combination of diagnoses – best fits the evidence.
Why are ADHD and autism assessed separately?
ADHD and autism have different diagnostic criteria and require different clinical assessment processes.
At The ADHD & Autism Clinic, they aren’t compressed into one quick assessment.
Instead, the clinic offers a specialist private ADHD assessment and a separate multidisciplinary private autism assessment.
That allows each condition to be explored thoroughly rather than assuming that one diagnosis automatically explains everything.
What changes when you understand that you have both ADHD and autism?
For many adults, diagnosis isn’t about collecting labels.
It’s about finally having an explanation that makes sense.
If you have both ADHD and autism, some things that previously seemed contradictory may become easier to understand.
For example:
“Why do I desperately need structure but struggle to maintain routines?”
“Why do I want new experiences but find unexpected changes overwhelming?”
“Why can I focus intensely on one thing but struggle to start something simple?”
Understanding your full neurodevelopmental profile can also help you choose strategies that actually fit you.
That might include:
- adapting routines rather than forcing rigid systems
- managing sensory needs
- finding better ways to support executive functioning
- communicating your needs more clearly
- requesting appropriate workplace adjustments
- understanding why previous strategies haven’t worked.
It can also help replace years of “Why can’t I just do this?” with a much clearer understanding of what you need.
You can find more practical information in our guide to understanding and managing co-occurring conditions in autism.
Frequently Asked Questions
Can you have ADHD and autism at the same time?
Yes. ADHD and autism are separate neurodevelopmental conditions, but you can meet the diagnostic criteria for both. This is often described as co-occurring ADHD and autism. A specialist assessment looks beyond shared traits to understand whether each condition independently fits your developmental history and current experiences.
How can I tell whether I have ADHD, autism or both?
It can be difficult to tell by yourself because some ADHD and autism symptoms overlap. The reason behind a difficulty matters as much as what it looks like from the outside. A specialist assessment can explore whether your experiences are best explained by ADHD, autism, both or another condition.
Can ADHD hide autism in adults?
It can sometimes make autistic traits less obvious. For example, ADHD-related talkativeness or spontaneity may not fit common stereotypes of autism. Equally, strong routines may help someone compensate for ADHD-related organisation difficulties. That’s why clinicians look at the whole pattern rather than individual behaviours.
Why are women often diagnosed with ADHD or autism later?
Some women become very skilled at masking, copying social behaviours or developing strategies that hide difficulties from other people. Traits may become more noticeable when life demands increase, such as during work, parenthood, relationships, burnout or perimenopause.
Do I need assessments for both ADHD and autism?
Not necessarily. It depends on your individual experiences. If there are meaningful signs of both conditions, however, each needs to be considered against its own diagnostic criteria. A specialist clinician can help you understand which assessment pathway is appropriate.
Understanding the whole picture
Recognising yourself in descriptions of both ADHD and autism doesn’t mean you need to work out the answer alone.
There can be a lot of overlap, but the same outward behaviour can have very different explanations.
A thorough assessment is about understanding the pattern across your life, not simply adding up traits.
For adults who’ve spent years wondering why certain things seem harder than they “should” be, that understanding can be valuable. It can help you recognise your strengths, identify the support you need and make more informed choices about what comes next.
If ADHD, autism or a combination of both could explain experiences you’ve struggled to make sense of for years, explore our private ADHD assessments or private autism assessments to understand your next step.