An ADHD assessment is how a specialist works out whether you have ADHD, whether something else explains your difficulties, or both. There is no single test. Instead, it’s a careful look at your history, your current life and your mental health.
Who can diagnose ADHD
NICE guidance says a diagnosis of ADHD should only be made by “a specialist psychiatrist, paediatrician or other appropriately qualified healthcare professional with training and expertise in the diagnosis of ADHD”. For adults, this is most often a psychiatrist, although some services use specialist nurses or psychologists with ADHD training.
A GP can’t usually diagnose ADHD on their own. The NHS says that if your symptoms are affecting your life, a GP will ask about them and may refer you to a specialist for assessment.
What NICE says it should include
According to NICE, a diagnosis should be based on:
- a full clinical and psychosocial assessment, including your behaviour and symptoms in different areas and settings of your everyday life
- a full developmental and psychiatric history
- observer reports
- an assessment of your mental state
NICE also says symptoms should meet recognised diagnostic criteria and cause at least moderate psychological, social, educational or work-related impairment. It says a diagnosis should not be made only on the basis of rating scales or observation, although questionnaires can be a useful part of the process.
What happens in an assessment
The details vary between services, but most adult ADHD assessments include the steps below.
Before the appointment
Many services send questionnaires to fill in beforehand. These may include an ADHD symptom rating scale, questions about your mental health, and sometimes a form for someone who knew you as a child.
The consultation
The main part is a long, structured conversation with the specialist. You can expect questions about:
- Your current symptoms: attention, organisation, restlessness, impulsivity and emotions
- Impact: how symptoms affect your work or study, relationships, money and home life
- Childhood: what you were like at primary and secondary school, and at home
- Development: early milestones, if you or a relative know them
- Mental health: past and present anxiety, depression, mood swings, trauma or other conditions
- Physical health: conditions, medicines, sleep, and heart health in you and your family
- Alcohol, drugs and caffeine: honest answers help the specialist rule other causes in or out
- Family history: whether relatives have ADHD or similar traits
Why childhood matters
ADHD is a neurodevelopmental condition, so symptoms should have started in childhood. The NHS says they usually start before the age of 12. Specialists will look for signs that difficulties were there early on, even if nobody called it ADHD at the time.
Informants and school reports
NICE includes observer reports as part of a diagnosis. For adults, this usually means someone who knew you as a child, such as a parent or older sibling, and sometimes someone who knows you well now, such as a partner.
The informant might fill in a questionnaire, join part of the appointment, or both. If nobody is available who knew you as a child, tell the service. Assessments can still go ahead, and the specialist will rely more on other evidence.
Old school reports can be very helpful. Comments like “easily distracted”, “could do better if she concentrated” or “disrupts others” give real-life evidence from the time.
How to prepare
A little preparation helps you get the most from the appointment.
- Write down examples. Note specific situations from the last few months where symptoms caused problems.
- Think about childhood. Jot down memories of school, homework, friendships and being told off.
- Find school reports or anything else from childhood, if you can.
- Ask a parent or sibling what they remember, and whether they could act as an informant.
- List your medicines and any past mental health diagnoses or treatments.
- Know your family heart history. Before medication is considered, specialists ask about heart problems in close relatives.
- Check your tech. For a video appointment, find a quiet, private space with a stable connection.
- Bring your questions. Write them down so you don’t forget.
It’s normal to feel nervous. Try to describe how things really are, not how you manage to look on a good day.
Possible outcomes
At the end of an assessment, or soon after, the specialist will explain their conclusions. Common outcomes include:
| Outcome | What it usually means |
|---|---|
| ADHD diagnosed | Your symptoms meet criteria and cause significant impairment. Next comes a discussion of treatment and support. |
| ADHD and another condition | For example, ADHD with anxiety or depression. Both may need treatment. |
| Not ADHD | Your difficulties are real but better explained by something else, or don’t meet criteria. You should be told what may help instead. |
| More information needed | The specialist may want informant reports, records or a further appointment before deciding. |
You should receive a written report or clinical summary. With your consent, a copy can be sent to your GP.
If you disagree with the outcome, you can ask the specialist to explain their reasoning, and you can ask your GP about a second opinion.
After a diagnosis
A diagnosis doesn’t mean you have to take medication. Treatment is a shared decision and may include practical changes, psychological support, medication, or a combination. See ADHD treatment and, if medication is started, titration.
If you were diagnosed privately and later want your NHS GP to prescribe, see shared care. Some NHS services and GPs accept private diagnoses and others don’t. Healthwatch England has heard from people whose private diagnosis was not accepted by NHS services. It’s worth asking your GP practice about its approach before you start.
ADHD assessment with Happy Clinic
Happy Clinic is a private online psychiatry service for adults aged 18 and over across the UK. Its ADHD assessments are carried out by GMC-registered consultant psychiatrists by video.
- What it is: a structured ADHD assessment with a consultant psychiatrist
- Length: 60 minutes
- Fee: £400, paid in advance
- Referral: no GP referral needed
- Availability: appointments are often available within a few days, depending on clinician availability
- After the appointment: a treatment plan, which may include medication where clinically appropriate, advice on therapy options and follow-up appointments. You receive a clinical summary, and your GP can receive one with your consent.
If medication is started, it may need physical health checks and monitoring, and titration reviews follow. Happy Clinic’s psychiatrists also consider related conditions such as depression and anxiety. Fees checked September 2026. See Happy Clinic’s pricing page for current fees, or the fees page on this site for a summary.
If you’re still deciding between routes, compare NHS and private assessment.