ADHD vs autism: the differences and the overlap

The question often starts with a passing comment. One person says a habit of yours sounds like ADHD, and someone else says it sounds autistic. You might see yourself in descriptions of each, and that can leave you more confused than before. Wanting to know which one fits is a fair question, and the answer can be one, the other, or both.

Is ADHD a form of autism?

No, ADHD isn’t a type of autism, even though the two often get mentioned together. A 2019 research review found the conditions share some features but differ enough to need separate diagnoses [1]. NICE places autism in a group called neurodevelopmental conditions, which affect how the brain develops [2]. We explain what autism is and what ADHD is on their own pages.

In clinical letters you’ll see attention deficit hyperactivity disorder and autism spectrum disorder (ASD). An autism diagnosis rests on the autism criteria in DSM-5 or ICD-11, the two main diagnostic manuals [3]. ADHD is diagnosed on its own criteria in those same manuals [2]. “The autism spectrum” describes the wide range of ways autism can show, and ADHD isn’t a point on it.

The difference between ADHD and autism

ADHD symptoms involve attention, energy levels and impulse control [4]. Autism’s core characteristics are differences in social communication and interaction, and repeated behaviours and interests, including sensory processing differences [3]. The table shows how that can look day to day. Our guides to the signs of ADHD and the signs of autism go into more detail.

A clinician looks at how the whole pattern fits together, and how long it has been there.

Where the two conditions overlap

The two conditions share some everyday difficulties, which is why they’re easy to confuse. A 2019 research review linked both to difficulties with social functioning and executive functions [1]. Executive functions are the skills you use to plan, start and switch tasks. When those skills are hard to use, the result is often called executive dysfunction. The same review found a shared genetic heritability, meaning some of the same inherited factors play a part in each [1].

Sharing a difficulty doesn’t mean sharing its cause. The review found the same problem can show in different ways, and to a different degree, in each condition [1]. Attention is a good example. A 2022 review article argues that some attention problems in autistic people come from autism itself, not ADHD [8]. One example the authors give is difficulty sharing attention with another person [8]. From the outside, restlessness and repeated movements such as stimming can look alike too.

Why one gets mistaken for the other

One condition can hide the other, or be confused with it. A GP seeing an adult about possible ADHD may consider whether autism, or something else, explains the symptoms [4]. Signs of autism can also be harder to see when an adult has ADHD as well [6].

Years of adapting how you come across, often called autistic masking, can hide autism signs [6]. ADHD is also recognised less often in women than in men, possibly because inattentive symptoms are harder to spot [4]. Getting one diagnosis doesn’t rule out the other, so it’s fair to ask about the second if it still fits.

What if it’s both?

One person can have the two conditions together. Older diagnostic manuals treated them as mutually exclusive, so a person could only be given one of them [8]. A 2022 review article explains that DSM-5 changed this, and now allows a dual diagnosis [8]. The change matters if you were once told you could only ever have one of them.

NICE guidance says autism shouldn’t be used to rule out an ADHD diagnosis [2]. ADHD is also more common in autistic people than in others [9]. The everyday name for having both is AuDHD, and our hub explains what AuDHD means.

How clinicians tell the two apart

A clinician asks how and why a difficulty shows up across your life, not only whether you have it. Under NICE guidance, ADHD should be diagnosed by a specialist after a full clinical and psychosocial assessment [2]. That assessment covers your developmental history, reports from people who know you, and any coexisting conditions [2].

For autism in adults, another NICE guideline describes a team-based assessment that involves someone who knows you, where possible [10]. It also asks about other neurodevelopmental conditions, which is where ADHD comes into view [10]. Our guides explain how ADHD is diagnosed and how autism is diagnosed step by step.

How to find out which one fits

An assessment looks at your whole history to work out which one fits, or whether both do.

An assessment may help if:

• you’ve noticed these patterns since childhood.
• they cause problems at work, study, home or in relationships.
• you’ve had one label, and the other still seems to fit.

It might not be right today if:

• you need urgent help now. Call NHS 111 and choose the mental health option, or in Northern Ireland call Lifeline free on 0808 808 8000, any time. In an emergency, call 999 or go to A&E [11].
• you’re asking about a child. Our child assessments cover ages 6 to 17, and a parent can be present.

AuDHD Psychiatry offers an adult ADHD assessment, an adult autism assessment and an assessment for ADHD and autism together. Our autism assessment includes an interview with someone who knows you well. If there’s no one who can take part, we can still assess you. The free ADHD test and the free autism test look for traits but don’t diagnose. You can also ask questions on a free 15-minute call, which isn’t an assessment.

Questions people ask

In short

ADHD and autism are separate conditions, and they can share difficulties such as planning and social life for different reasons. One person can have one, the other or the two together. A list of traits can’t settle it, but a clinician who looks at your whole history can. If you’re still unsure which fits, AuDHD Psychiatry can talk your options through with you before you decide anything.