What to Expect at an Adult Autism Assessment: A Step-by-Step Guide

If you’ve always felt different, misunderstood, or overwhelmed by the world in ways others seem to navigate easily, you may have wondered: Could I be autistic?

Autism Spectrum Condition (ASC) is often associated with childhood, but a growing number of adults are now being diagnosed later in life. Many have spent years masking their traits, living with anxiety, or being misdiagnosed with other conditions. A formal diagnosis can bring clarity, validation, and access to support that transforms daily life.

In this blog, we’ll walk you through what to expect at a private adult autism assessment, including:

• Pre-assessment questionnaires

• The diagnostic process

• The importance of developmental history and collateral information

• Differential diagnosis

• Post-diagnosis support and what comes next

• NICE guidelines and why they matter

Whether you’re seeking answers for the first time or considering a second opinion, this guide is here to help.

Why Consider an Autism Assessment as an Adult?

For many, an autism diagnosis in adulthood brings a powerful sense of relief. You may have:

• Always struggled with social communication or sensory sensitivities

• Been labelled as shy, sensitive, or awkward without understanding why

• Spent years “masking” or camouflaging your difficulties to fit in

• Felt persistently anxious, overwhelmed, or disconnected

An assessment doesn’t change who you are—but it can give you a framework to understand yourself and access the right support moving forward.

1. Pre-Assessment Questionnaires: Gathering the Foundations

Before your assessment, you'll be asked to complete several forms and questionnaires. These give your clinician essential insight into your history, current experiences, and potential autistic traits.

Common Pre-Assessment Tools May Include:

• RAADS-R (Ritvo Autism Asperger Diagnostic Scale-Revised): Helps identify subtle autistic features, especially in people with average or high intelligence.

• Developmental history form: Covers early development, education, social life, communication, sensory sensitivities, and more.

• Medical and mental health questionnaire: To identify co-occurring conditions.

Why These Questionnaires Are Important:

• They build the foundation of your assessment and make your appointment more productive.

• They offer a structured way to reflect on how autism may have been present from childhood.

• They help identify whether further exploration for differential diagnosis is needed.

Take your time completing these forms. They’re not tests—there are no “right” answers. The more honestly you respond, the better your clinician can support you.

2. The Autism Assessment Appointment: What to Expect

An adult autism assessment typically lasts between 90–120 minutes, depending on the complexity of your history and presentation. It is conducted by a specialist consultant psychiatrist.

This is a collaborative conversation, not a test or interrogation. Many people feel nervous beforehand—this is completely normal.

The Psychiatrist Will Explore:

• Current social and communication patterns

• Sensory sensitivities (to noise, light, textures, etc.)

• Routines, habits, or special interests

• Historical signs of autistic traits from childhood

• Masking or coping strategies

• Functional impact on your work, relationships, and daily life

They may use structured diagnostic tools such as:

• The ADOS-2 (Autism Diagnostic Observation Schedule): A semi-structured assessment used to evaluate communication and social interaction.

• The DIVA-5 or SCQ (Social Communication Questionnaire) may also be used, depending on the clinician's approach.

3. The Importance of Collateral Information

A key part of the autism diagnostic process is collecting collateral information—input from someone who has known you since childhood, such as a parent, older sibling, or close relative.

Why This Is Valuable:

• Autism is a lifelong developmental condition, so evidence of early signs is essential for diagnosis.

• Many adults can’t recall their early behaviours in enough detail.

• External perspectives offer a more complete, objective view of how traits have presented over time.

If a parent or relative isn’t available, the clinician may work with whatever historical information is accessible—school reports, old journals, or even self-reflection on childhood memories.

4. Assessing for Differential Diagnoses

Not all traits commonly associated with autism are unique to autism. During your assessment, your clinician will explore whether another condition—or a combination of conditions—might better explain your symptoms.

Conditions Commonly Considered Include:

• ADHD

• Social anxiety

• Generalised anxiety disorder (GAD)

• Depression

• Bipolar disorder

• Trauma-related conditions

• Obsessive-Compulsive Disorder (OCD)

• Personality disorders

Why This Matters:

Getting the right diagnosis ensures the right treatment and support. For example, social withdrawal might stem from anxiety rather than autism—or from both. This part of the assessment ensures the diagnosis is accurate and tailored to your unique experiences.

5. NICE Guidelines for Autism Diagnosis

The National Institute for Health and Care Excellence (NICE) offers guidance on the diagnosis of autism in adults. According to NICE:

“Diagnosis of autism should be made by a team of professionals experienced in the diagnosis and management of autism, using a range of assessment tools, including direct observation and history-taking.” (NICE CG142, 2012)

At Matter of Health, we follow NICE-aligned procedures using structured tools and a multi-disciplinary approach, ensuring your diagnosis is evidence-based and robust.

6. What Happens After the Diagnosis?

If Autism Is Diagnosed:

You’ll receive a detailed diagnostic report that includes:

• Confirmation of diagnosis

• An overview of assessment findings

• Recommendations for support and reasonable adjustments

• Signposting to local and national services

This report can be used to request:

• Workplace adjustments under the Equality Act 2010

• University or college support

• Access to benefits or funding (e.g., PIP or Access to Work)

If Autism Is Not Diagnosed:

You may still receive support. Sometimes assessments identify other conditions that better explain your experiences, or highlight areas for personal development. Whatever the outcome, our team provides sensitive, non-judgemental feedback and next-step guidance.

7. Is Medication Prescribed for Autism?

There is no medication that treats autism itself, but your clinician may discuss options if there are:

• Co-occurring conditions (e.g., ADHD, anxiety, depression)

• Severe sleep disturbances

• Emotional regulation issues

If medication is appropriate (e.g., for co-existing ADHD), a separate titration appointment may be scheduled. This ensures safety, monitoring, and optimal dosage over time.

8. Do I Need Ongoing Follow-Up Care?

Yes, if your diagnosis is confirmed or if additional support is needed. Follow-up may include:

• Psychiatric reviews (typically every 6–12 months)

• Therapeutic support (e.g., CBT, autism-specific counselling)

• Occupational therapy (for sensory sensitivities or daily living support)

• Peer support groups

• Advice on reasonable adjustments at work or in education

At Matter of Health, we provide tailored care plans, with the option to return for further advice or reviews depending on your consultant’s recommendation.

The Emotional Impact of Late Diagnosis

Being diagnosed as autistic later in life can trigger a mix of emotions: relief, grief, understanding, sadness, and hope.

Common Emotional Responses:

• Relief at finally having an explanation

• Anger or grief about missed support earlier in life

• Re-evaluation of past relationships or challenges

• Hope for future changes in how you live and interact

This is completely normal. Many people benefit from post-diagnostic counselling or peer support as they process this new understanding of themselves.

Frequently Asked Questions

How long does an adult autism assessment take?

The main appointment typically lasts around 90 minutes, with time needed beforehand for questionnaires and afterward for feedback or follow-up.

Do I need to bring someone with me?

No, but if possible, input from someone who knew you in childhood is very helpful. This can be done via forms, phone call, or written statement.

Is a diagnosis valid for workplace or university support?

Yes. Your written report from a registered clinician can be used to request reasonable adjustments under the Equality Act 2010.

What if I'm diagnosed with autism and ADHD?

Co-occurrence is common. Your care plan will be tailored to support both diagnoses, and may include behavioural, occupational, and/or medical support.

Ready to Take the Next Step?

Autism isn’t something to be “fixed” or “treated.” It’s a neurological difference—a different way of processing the world. But understanding it can help you build a life that’s more authentic, manageable, and fulfilling.

At Matter of Health, we specialise in private adult autism assessments, led by experienced clinicians and guided by NICE best practice. Whether you’re seeking clarity, support, or both, we’re here to help you every step of the way.

Book your private adult autism assessment today and take your next step toward self-understanding and support.