ADHD and autism together in adults

Some adults look into ADHD and keep running into descriptions of autism that also sound familiar. Others were diagnosed with autism as children and now wonder whether their distractibility is something more. Both questions make sense. ADHD and autism are separate conditions, but they often occur together, and some of their features look alike from the outside. This page covers how often they co-occur, how an adult evaluation handles the overlap, and what guidelines say about treating ADHD when autism is also present.

If you are trying to work out whether your experience is ADHD or autism, see ADHD or autism: how they differ. This page is about having both.

Can you be diagnosed with both?

Yes. That has not always been true. As a 2022 review in Frontiers in Psychiatry explains, the older DSM-IV and ICD-10 manuals gave ADHD and autism as mutually exclusive diagnoses. DSM-5, published in 2013, mentions each condition in its description of the other and allows both to be diagnosed in the same person.

The UK's NICE guideline NG87 goes further. It says ADHD diagnosis should not exclude someone because of a pervasive developmental disorder (the older umbrella term that included autism), and it lists people with other neurodevelopmental conditions, including autism, among the groups in whom ADHD is more common than in the general population.

How often ADHD and autism occur together

The largest summary of the research is a 2019 meta-analysis in Lancet Psychiatry. Pooling 96 studies of people with a confirmed autism diagnosis, it estimated that:

• 28% had ADHD, the most common co-occurring condition in the analysis.
• 20% had an anxiety disorder.
• 13% had a sleep-wake disorder.
• 11% had a depressive disorder, and 9% had obsessive-compulsive disorder.

The authors found that figures from clinic-based studies were higher than those from population or registry studies, and that age, gender, intellectual functioning and country explained part, but not most, of the wide variation between studies. In short: co-occurrence is common, and exact rates depend heavily on who was studied.

Because anxiety and sleep problems are also common in autistic adults, an evaluation often has more than two pieces to sort out. See ADHD and anxiety together and ADHD and insomnia.

Where the two overlap, and where they differ

Both conditions can involve trouble with attention, organization and social situations. The underlying descriptions are different:

The 2022 Frontiers review raises a caution worth knowing: some attention difficulties seen in autism, such as trouble disengaging attention or a strong focus on details, may be part of autism itself rather than a sign of separate ADHD. That is why a symptom checklist alone cannot settle the question.

How the evaluation works when autism might be part of the picture

NIMH says diagnosing autism in adults is often more difficult than in children, partly because some autism symptoms overlap with those of anxiety disorders or ADHD. It advises adults who wonder about autism to ask for a referral to a neuropsychologist, psychologist or psychiatrist with autism experience, and notes that the evaluation may include talking with family about early development.

Dr. Shershow's practice evaluates and treats adult ADHD. The evaluation covers current symptoms, childhood and school history, work, health, sleep and substances, and other explanations for the symptoms, either instead of ADHD or alongside it. If autistic traits seem to be part of the picture, the evaluation can say so, but the practice does not perform autism evaluations. A separate autism assessment would come from a clinician who does that work.

A few things help either evaluation:

• School report cards and teacher comments, which often describe both attention and social patterns.
• A parent or older relative who can describe early childhood. See how to ask family about childhood symptoms.
• Any earlier evaluations or testing reports. The difference between a psychiatric evaluation and formal testing is explained in ADHD evaluation vs neuropsychological testing.

More preparation tips are in how to prepare for an adult ADHD evaluation.

Treating ADHD when autism is also present

NICE gives two recommendations that apply directly:

• Same options. Recommendation 1.7.18 says people with ADHD and autism should be offered the same ADHD medication choices as other people with ADHD.
• More care with changes. Recommendation 1.7.28 calls for slower dose adjustment and more frequent monitoring when a neurodevelopmental condition such as autism is present.

NICE also asks that information be given in a form that takes account of a person's communication style and any coexisting conditions. NIMH lists attention and hyperactivity among the symptoms that medication may be prescribed for in autistic people.

The research base in adults is thin. A 2017 Cochrane review of methylphenidate in autistic children and adolescents found low-quality evidence that it reduced hyperactivity, no evidence that it worsened core autism features, and more reduced appetite than placebo. That review covered only young people, so it says little directly about adults. The 2022 Frontiers review notes concern that stimulant treatment can have unwanted effects in some autistic people. Both points support the NICE advice to go slowly and check in often. Background on the medicines themselves is in the medication guide.

Medication treats ADHD symptoms. It is not a treatment for autism itself, and autistic adults may also benefit from supports that NIMH describes, such as help with life skills, education and employment, which come from other services.

When to talk to a clinician

If attention, organization or impulsivity problems have been with you since childhood and cause trouble at work or at home, an ADHD evaluation can help, whether or not autism is also a question. The adult ADHD self-test is a quick way to organize what you notice before a visit; it is not a diagnosis. To arrange an ADHD evaluation, see ADHD testing in NYC or ADHD testing in New Jersey, or call the office.