What’s Involved in a Combined Autism and ADHD Assessment?

Many people seek clarity when they or someone they care about struggles with focus, social interaction, emotional regulation, or sensory sensitivities. Often, these signs lead to questions about autism, ADHD, or sometimes both. Because these two neurodevelopmental conditions frequently co-occur, some individuals are referred for a combined autism and ADHD assessment.

But what exactly does that process involve?

This blog outlines what typically happens during a combined autism and ADHD assessment—including the different stages, diagnostic tools that might be used, and what to expect if a diagnosis is or is not given.

Why Combine Autism and ADHD Assessments?

Autism and ADHD often overlap, both in how they present and in how they impact day-to-day life. Research shows that a significant number of people with autism also meet criteria for ADHD, and vice versa. Because symptoms can interact and influence each other, a combined assessment can provide a more accurate understanding of someone’s experiences. A good assessment for either will should look at both even if this is just in the remit of a differential diagnosis.

What Might Be Involved?

The exact process can vary depending on the provider, age of the person being assessed, and the type of service (e.g. NHS or private). However, most assessments involve the following steps:

Initial Screening and Referral

The process usually begins with a referral—commonly made by a GP, school, or another professional. Some services also accept self-referrals. After referral, there may be a screening stage, where questionnaires or brief interviews help determine whether a full assessment is appropriate.

This stage might include:

• Basic screening questionnaires for autism and ADHD (e.g. AQ-10, ASRS)

• A review of past medical, developmental, and educational history

• Consideration of other factors like mental health or learning needs

Information Gathering

If a full assessment goes ahead, a detailed history is usually collected. This could involve:

• Parent or caregiver interviews (for children, or adults being assessed retrospectively)

• School or workplace reports if available

• Questionnaires from multiple sources (e.g. parents, teachers, partners)

Some commonly used tools might include:

• Conners rating scales or the Weiss Symptom Record

• Social Communication Questionnaire (SCQ)

• Autism Quotient (AQ-10/50)

Diagnostic Interviews and Observations

A key part of the assessment involves structured interviews and/or observation sessions. These might include:

For ADHD:

• DIVA-5 (Diagnostic Interview for ADHD in Adults) – a structured clinical interview that assesses ADHD symptoms in childhood and adulthood, focusing on how they affect everyday life.

For younger individuals, other tools or age-appropriate interviews are used to assess attention, hyperactivity, and impulsivity.

For Autism:

• ADOS-2 (Autism Diagnostic Observation Schedule) – a semi-structured, play- or conversation-based session designed to observe communication, social interaction, and behaviour.

• ADI-R (Autism Diagnostic Interview – Revised) – a detailed interview with parents or carers that explores early development and autism traits across time.

Some assessments may also include cognitive tasks or tests to understand executive functioning, attention, or processing speed.

Multi-Disciplinary Team Review

In most cases, assessments are carried out or reviewed by a team of professionals from different disciplines (e.g. psychology, psychiatry, speech and language therapy). Together, they look at all the evidence and consider:

• Whether the person meets criteria for autism, ADHD, both, or neither

• The presence of any other conditions that might explain the difficulties

• The functional impact of symptoms across different settings (home, school, work, social life)

Feedback and Outcome

After the assessment is complete, feedback is usually given in a meeting or report. This may include:

• An explanation of whether any diagnoses are being made

• A summary of the person’s strengths, challenges, and developmental profile

• Recommendations for support, adjustments, or further referrals

What If a Diagnosis Is Not Given?

Not everyone who goes through the assessment process will receive a diagnosis. This doesn’t mean the person’s difficulties aren’t real or valid—it may mean:

• The criteria for a diagnosis weren’t fully met

• Another explanation (e.g. trauma, anxiety, sensory sensitivity, or learning difficulties) better accounts for the difficulties

Even without a diagnosis, the assessment may lead to useful insights and support recommendations. Services might still suggest:

• Mental health support

• Educational or workplace adjustments

• Strategies for managing attention, sensory needs, or social interactions

• Follow-up referrals or monitoring

After Diagnosis: What Happens Next?

When a diagnosis is given, it can bring clarity and access to support. This might include:

• Educational plans (like EHCPs)

• Workplace adjustments under the Equality Act

• Occupational therapy or ADHD coaching

• Peer support groups or psychoeducation courses

• Further referrals for mental health or social care services

While a diagnosis isn’t a solution in itself, it can be the first step toward understanding and adapting the environment to better suit the person’s needs.

A combined autism and ADHD assessment is a thorough process that brings together different sources of information to form a clear picture. Whether or not a diagnosis is given, the process can provide meaningful insights, direction, and support. A starting point is a short appointment with us and book in for an ASD/ADHD screening consultation.