Autism and ADHD Together: Can Your Child Be Assessed for Both at the Same Time?

Autism and ADHD frequently co-occur. Research suggests that somewhere between 50 and 70 per cent of autistic people also meet the criteria for ADHD, and a significant proportion of people with ADHD are also autistic. For many families, the question is not “which one is it?” but “could it be both — and can we find out at the same time?”

The good news is yes: combined autism and ADHD assessments are increasingly available, and there are very good clinical reasons to pursue them together rather than separately.

Why do autism and ADHD so often co-occur?

Autism and ADHD are both neurodevelopmental conditions — they affect the way the brain develops and processes information. They share some genetic risk factors and some common neurological features. They also share some surface-level traits, which is one reason they can be difficult to disentangle clinically.

Both conditions can affect attention, executive function (the ability to plan, organise, and regulate behaviour), and emotional regulation. Both can involve sensory sensitivities. Both can affect social interaction, though for different underlying reasons. This overlap is part of why assessment for one should ideally consider the other.

How are autism and ADHD different?

Despite the overlap, autism and ADHD are distinct conditions with different presentations and different underlying profiles:

• Social communication. Autistic people may find the rules of social interaction confusing or exhausting; people with ADHD may be impulsive in conversation and find it hard to wait their turn, but generally find the social world less baffling.
• Routines and rigidity. Strong preference for routine and significant distress at unexpected change is more characteristic of autism than ADHD.
• Attention patterns. ADHD involves inconsistent attention — difficulty sustaining focus on low-interest tasks, alongside the ability to hyperfocus on high-interest ones. Autistic people may have a very focused attention pattern tied to their areas of interest.
• Hyperactivity and impulsivity. More characteristic of ADHD, though autistic people can also be hyperactive.

In practice, when both conditions are present together, the picture is more complex than either alone — and both need to be understood and addressed.

Can both be assessed at the same appointment?

Many private providers in the UK now offer combined autism and ADHD assessments, conducted in the same appointment or across a short series of sessions. This is increasingly the standard approach because it allows the clinician to build a holistic picture of the child’s profile and to understand how the two conditions interact.

On the NHS, assessments have historically been separated — one for autism, one for ADHD — sometimes by different teams with separate waiting lists. NHS services are moving towards more integrated neurodevelopmental pathways, but the pace of change varies significantly by area.

What does a combined assessment involve?

A combined autism and ADHD assessment typically includes all the components of a standard autism assessment — a detailed developmental history, parent interview, and direct observation of the child — plus the specific components needed for ADHD assessment:

• Standardised ADHD rating scales completed by parents and school (such as the Conners or SNAP-IV)
• A clinical interview exploring attention, hyperactivity, impulsivity, and executive function
• Consideration of other conditions that can look like ADHD, such as anxiety, sleep disorders, and learning difficulties

The combined assessment will produce a report that addresses both conditions, explains how they interact in your child’s specific case, and provides recommendations for support across both profiles. Read our guide on what happens during a private autism assessment for more detail on the autism component.

How much does a combined assessment cost?

Combined autism and ADHD assessments are typically more expensive than a single-condition assessment because they involve more clinician time and more assessment tools. Costs in the UK generally range from £2,500 to £4,500, depending on the provider and the complexity of the assessment. Some providers offer combined assessments for less, particularly if the two conditions are assessed sequentially as part of the same package.

For full cost information, read our guide on how much a private autism assessment costs in the UK.

What if only one condition is confirmed?

If your child has a thorough combined assessment and only one condition is confirmed, that is still a valuable outcome. You have ruled out the other, which means support can be more precisely targeted. If autism is confirmed but ADHD is not, the recommendations will focus on autistic support strategies. If ADHD is confirmed but not autism, the focus shifts accordingly.

Clinicians who conduct combined assessments are experienced in distinguishing between the two conditions and in identifying when traits that look like one condition are better explained by the other.

What about PDA (Pathological Demand Avoidance)?

PDA — also described as a Demand Avoidant profile of autism — is increasingly recognised in the UK, though it remains a contested term clinically. Children with a PDA profile often have a complex mix of autistic and anxiety-driven traits and can be very difficult to support without an understanding of their specific profile.

If PDA is suspected alongside autism and ADHD, it is worth finding an assessor with specific experience in identifying demand avoidance profiles. Ask about this specifically when choosing your provider.

What if my child is also anxious?

Anxiety is extremely common in autistic children and in children with ADHD. It can be caused by the experience of being in a world that is not designed for neurodivergent brains. A good combined assessment should address co-occurring anxiety and include recommendations for managing it, rather than treating it as a separate, unconnected issue.

Can a combined assessment affect EHCP applications?

Yes — positively. An EHCP application that is supported by a thorough combined assessment report is generally more informative for the local authority than two separate, narrower reports. A combined assessment produces a holistic picture of your child’s needs across both conditions, which can result in more comprehensive and accurately specified provision in the EHCP.

Read our guide on what to do after an autism diagnosis for more on EHCP applications.

Find a specialist who assesses both autism and ADHD

The SEND List directory includes autism assessors across the UK. Many also offer combined autism and ADHD assessments — browse by location to find a specialist near you:

• Autism assessors in Edinburgh
• SEND support in London
• SEND support in Birmingham
• SEND support in Manchester
• SEND support in Bristol
• SEND support in Glasgow

Also useful: our guide on NHS autism waiting lists and what to do while you wait.