The short answer
A proper autism or ADHD assessment brings together your history, information from people who know you, observation and standardised tools, and the clinical judgement of experienced professionals. No single test gives a diagnosis on its own. At the end you receive a written report and a conversation about what it means.
What a good assessment includes
NICE, which sets the standard for the NHS, is clear that an assessment should be thorough. For children (CG128) it lists a developmental history, observation of social and communication skills, a medical history, consideration of other explanations, a check for conditions that often come alongside autism, and a profile of the child’s strengths and needs. For adults (CG142) it adds how you function at home, in education and at work. For ADHD (NG87), NICE says a diagnosis should rest on a full clinical and psychosocial assessment and a full developmental history, not on rating scales alone.
Our assessments are built the same way: a review of your history, a clinical interview, a clinical and medical assessment, standardised screening and diagnostic tools, the ADOS-2 for autism where appropriate, and ADHD assessed against DSM-5 criteria.
Step by step
- 1. A free first call. You tell us what is going on and ask anything you like. No obligation.
- 2. Questionnaires and documents. You share relevant background, such as school reports or earlier assessments. The clinical team reviews this before anyone travels.
- 3. A confirmed date. You know when your assessment is before you commit, and your personal coordinator helps with the practical side.
- 4. The assessment itself. Carried out in person, in English, by licensed clinical psychologists, over one or more sessions depending on what is needed.
- 5. The results. A conversation with the clinicians about what they found, and a written report, normally within 14 working days.
What is the ADOS-2?
The ADOS-2 is one of the most widely used autism assessment tools. Its publisher, WPS, describes it as a semi-structured, standardised assessment of communication, social interaction, play and repetitive behaviours. It has five modules for different ages and language levels, from toddlers to adults, and each takes about 40 to 60 minutes. For a child it often looks like play and conversation; for an adult it is a structured conversation with a few activities.
Like every tool, it supports the clinician’s judgement rather than replacing it. The National Autistic Society and NICE both say a diagnosis should never rest on one instrument alone. Our clinicians are ADOS-2 certified.
At a glance
- NICE: do not rely on any autism-specific tool alone to diagnose autism.
- ADOS-2: five modules from toddler to adult, about 40 to 60 minutes each.
- ADHD: symptoms must meet DSM-5 or ICD-11 criteria and show up in at least two settings.
- Adults: information from someone who knew you as a child is helpful but not essential.
Sources: NICE CG128, NICE NG87, WPS, NHS. Checked 30 September 2026.
How ADHD is assessed
For ADHD, the clinician looks at whether symptoms meet DSM-5 criteria and appear in at least two important settings, such as home and school, or home and work (NICE NG87). Rating scales, such as questionnaires completed by parents and teachers, are helpful extra tools. For adults, the clinician will ask how things were in childhood, and the NHS notes they may want to speak to someone who knows you well.
How to prepare
- Write down the things you have noticed, with examples and roughly when they started.
- Gather school reports, earlier assessments or letters from professionals.
- For adults: if possible, ask a parent or older sibling what you were like as a child. The National Autistic Society says this can help, with your consent.
- For children: explain simply what will happen, for example that they will meet someone kind who wants to understand how they think, play and learn.
- Tell us about any sensory or communication needs, so the day can be arranged around them.
What you get at the end
The NHS describes a good report as one that says what the team found, what the person is good at, what they need help with and whether any other conditions were found. That is what you receive from us: a detailed written report in English with the findings and practical recommendations, and a conversation with the clinicians to go through it. You can share it with your GP, school or employer; each of them decides for themselves how to use it (see private diagnoses and your GP).
Want to know your earliest date? We arrange assessments for children and adults, including autism and ADHD together, and the first call is free.
Frequently asked questions
How long does an autism assessment take?
It depends on age and needs. The ADOS-2 itself takes about 40 to 60 minutes, and the full assessment also includes your history and a clinical interview. We tell you how many sessions you need before you book.
Can I be diagnosed from a questionnaire alone?
No. NICE says a diagnosis should not be made on the basis of any single tool or rating scale alone.
Do adults need someone who knew them as a child?
It helps build the picture of your early development, but it is not essential.
When do I get the report?
Normally within 14 working days of the assessment, followed by a conversation with the clinicians.
