Put a list of adult ADHD traits beside one of adult autism traits and something awkward appears: several items are on both. Trouble in conversations. Exhaustion after socialising. Being told you are too much, or too blunt, or not listening.
The overlap is not a flaw in the lists. ADHD and autism are distinct conditions that share territory, and many adults have both. For them, being assessed for only one leaves the other invisible.
Why so many adults ask about both
Adults are now far more likely to recognise either condition in themselves, often after a child, sibling or colleague is diagnosed. Descriptions written by and for adults — rather than of eight-year-old boys — have made both recognisable.
Diagnostic thinking has changed too. The two were once treated as mutually exclusive, so someone with features of both was given whichever label fitted best. That is no longer how they are understood: both are neurodevelopmental conditions, both begin in childhood, and they commonly occur together.
Where they overlap
The shared ground is wide enough that a short appointment can mistake one for the other.
Attention that does not behave. Autistic people can be absorbed in a subject and unable to attend to anything else. People with ADHD hyperfocus much the same way. From outside, both look like attention that is either total or absent.
Social difficulty. ADHD makes conversations hard through interrupting, losing the thread or missing what was said. Autism makes them hard through differences in reading tone, expression and unwritten rules. The outcome — conversations that go wrong, friendships that do not stick — looks the same.
Sensory sensitivity, emotional intensity and burnout. Long linked to autism, all three are widely reported in ADHD too. Both conditions involve constant compensation, and that is tiring.
Anxiety and low mood on top. Both raise the likelihood of anxiety and depression, usually what brings someone to a GP first. The NHS notes it can be hard to see signs of autism in someone who also has anxiety, depression, an eating disorder or ADHD.
Where they differ
The differences are less about which traits are present and more about why they are there.
| ADHD | Autism | |
|---|---|---|
| Core difficulty | Regulating attention, activity and impulse | Social communication, and a preference for predictability |
| Change | Often craved; sameness is intolerable | Often distressing; sameness is regulating |
| Social problems arise from | Impulsivity, interrupting, inattention | Interpreting and using social signals |
| Interests | Intense but often shifting | Intense and typically enduring |
| Medication | Often highly effective | Nothing treats autism itself |
That last row matters most. ADHD has effective medication. Autism does not — medication may help co-occurring anxiety, but nothing treats autism itself, and no responsible clinician will offer one.
How one diagnosis can mask the other
Diagnostic overshadowing. Once a label is in the notes, later difficulties get read through it. An autistic adult who cannot start tasks, loses things and misses deadlines may be told this is part of being autistic — when it is untreated ADHD. Someone diagnosed with ADHD whose social life has never worked may be told that is the ADHD, when it is autism.
One condition hiding the other’s signs. ADHD impulsivity can make an autistic person appear more socially forthcoming than they find comfortable, because they speak before caution kicks in. Autistic rule-following can hide ADHD disorganisation, because the systems do the work attention is not.
Masking in the social sense. Both groups learn to perform. The NHS says of autistic adults that signs “are not always noticeable”, that some learn to copy how other people behave, and that this can make everyday activities exhausting. It notes this is more often described in autistic women, though autistic men mask too — see the NHS page on signs of autism in adults. The same pattern is documented in ADHD: see ADHD in women.
Why assessment order matters
If you suspect both, the practical question is which to pursue first. There is no single right answer, but the reasoning matters.
Assessing ADHD first makes sense when the problems wrecking your week are attention, organisation, impulsivity and restlessness. ADHD is the treatable one, and treatment can start quickly. It also clarifies: once ADHD is treated it is easier to see what remains. Some people find their social difficulties resolve; others find them unchanged, which is itself informative.
Assessing autism first makes sense when the central problems are social communication, sensory overload, difficulty with change and repeated burnout, and what you need is understanding and adjustments rather than medication. It is also the longer of the two.
Either way, a good clinician assesses the whole picture. NICE guidance on ADHD says assessment should consider coexisting conditions, and its autism guidance says the same in reverse.
One warning: if ADHD medication is started while nobody knows about the autism, effects can be misread — new sensory sensitivity, or new awareness of social difficulty, blamed on the medicine.
What a combined picture means for treatment
Medication. ADHD medication works in adults who are also autistic, and is usually worth trying if ADHD is diagnosed. It is started low and increased gradually with physical health monitoring, as NICE recommends. Autistic adults sometimes report sensory or appetite effects more strongly, which argues for slower titration, not for avoiding treatment.
Therapy needs adapting. Standard CBT can be less effective delivered in a standard way to someone autistic. Concrete language, written summaries, longer processing time and clear structure make a real difference. Happy Clinic does not provide psychological therapy, but a psychiatrist can advise what to look for in a therapist.
Adjustments become more precise. ADHD adjustments are about structure: written instructions, deadline support, shorter tasks, movement. Autism adjustments are about predictability and sensory load: notice of change, quieter space, fewer unplanned meetings, communication in writing. Needing both means asking for both.
Expectations shift. Treating ADHD will not remove autistic social difficulty or sensory sensitivity. Expecting it to makes people think the medication failed.
How assessment works privately
Both can be assessed by video, which suits people who find clinics difficult.
Happy Clinic’s consultant psychiatrists assess adult ADHD and provide adult autism screening and assessment, for adults aged 18 and over anywhere in the UK, with no GP referral needed. Consultations are provided by Happy Clinic, which is registered with the Care Quality Commission (CQC). An ADHD assessment is £400 for 60 minutes, autism screening £450 for 60 minutes, a full autism assessment £1,650, and follow-ups £200. Fees are paid in advance. Fees checked September 2026 — see the fees page for the current list.
Preparation makes the appointment work. Bring childhood information, essential for both: school reports, and the recollections of anyone who knew you young. Bring specific examples rather than adjectives — the meeting you walked out of, the friendship that ended, the task undone for six weeks. Bring your medicines list.
The NHS route is free and worth knowing even if you pay. For autism, the NHS says you cannot usually self-refer and should speak to a GP about an assessment, that a referral can take a few months or longer, and that in England you can use Right to Choose to look for shorter waits. Its page on what an autism assessment involves describes the process accurately.
One honest note: no assessment can promise a diagnosis, and for people who suspect both, a careful assessment sometimes concludes only one fits. That is a useful outcome too. The point is not to collect labels but to end with an explanation that matches your life.
See adult autism assessment and adult ADHD, or book a consultation.
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Book a secure video consultation with Happy Clinic. No GP referral needed, with appointments usually available within days.
This article is general information and is not a substitute for personal medical advice. If you are in crisis, call 999, go to A&E, call NHS 111 or call Samaritans free on 116 123.