A proper adult ADHD assessment is a conversation with structure, not a test. There is no blood test, no scan, and no questionnaire score that settles it. That can feel unsatisfying — people arrive hoping for something definitive — but it is an accurate reflection of what is being decided, which is whether a long-standing pattern of behaviour meets a threshold of impairment and is not better explained by something else.
Details vary between clinicians and countries. This is the shape.
What is actually being established
Four things, and all four have to hold:
- A pattern of inattention and/or hyperactivity-impulsivity, across a defined set of specific behaviours.
- Present since childhood. Not necessarily diagnosed or noticed then, but present. Adult-onset attention difficulty is, by definition, something else.
- Across more than one setting. Work and home, not only work.
- Causing real impairment, and not better accounted for by another condition.
That last clause is where most of the clinical work goes.
The history is the assessment
Expect most of the time to go here. A clinician will ask about school — reports, whether you were the one talked to about "potential", whether anything was ever raised. About work: patterns of jobs, why they ended, what you are good at and what reliably goes wrong. About home: bills, admin, the state of the kitchen, whether someone else is quietly absorbing the logistics.
They will ask for specifics, and specifics are what to bring. "I am disorganised" tells them very little. "I have been fined four times for late filings I had the money for and the letters for, sitting on the table" tells them a great deal.
School reports, if you still have them, are unusually valuable — they are contemporaneous evidence of childhood, which is otherwise reconstructed from memory thirty years later. Comments like "could do much better if she applied herself" and "careless errors" are the standard historical record of an undiagnosed inattentive child.
The questionnaires, and what they are for
You will probably complete one or more standard rating scales. These are screeners. They are designed to be over-inclusive: they catch almost everyone who has the condition, at the cost of also flagging people who do not. A high score means "this warrants a proper look", not "you have it".
Anyone who tells you a questionnaire has diagnosed you has skipped the assessment.
Someone else's account, if possible
Many clinicians will ask whether a partner, parent or long-standing friend can give their impression, either in writing or on a call. This is not a check on your honesty. It is that self-report on your own attention is systematically unreliable in both directions — people underestimate how much others compensate for them, and overestimate how visible their internal effort is.
What is being ruled out first
This is the part people are least prepared for, and the part that makes an assessment worth having. Several conditions produce the same complaint and have different treatments:
- Sleep disorders. Untreated sleep apnoea or chronic insufficient sleep produces inattention that is indistinguishable in conversation. This is common and frequently missed.
- Thyroid dysfunction, anaemia, B12 deficiency. Mundane, bloodwork-detectable, and genuinely present in some proportion of people presenting with "I cannot think".
- Depression and anxiety. Both impair concentration. Both are also common consequences of untreated ADHD, so the question is rarely either/or — it is which came first and what is driving what.
- Trauma. Hypervigilance and a difficulty with sustained attention can look extremely similar from outside.
- Substance use, including alcohol and cannabis, and including the amount nobody counts.
- Autism, which overlaps substantially and frequently co-occurs.
- Perimenopause, where attention and memory changes are commonly reported and often attributed elsewhere.
A clinician who has not asked about your sleep has not finished.
What a good assessment produces
- A clear statement of what was found, including if the answer is "not this".
- An account of what else was considered.
- A plan that is not only a prescription — structure, environment, and often treatment for a co-occurring condition.
- A named next step, with a date.
What to bring
- The concrete pattern, written down, with rough dates. Actual consequences, not adjectives.
- A list of every medication and supplement you take.
- School reports if they exist.
- Your sleep, honestly. Time to bed, time actually asleep, times waking, whether you snore.
- Family history — undiagnosed relatives count, and "my father was exactly like this" is real information.
- Any previous attempt at treatment, what it was, and what happened.
On remote assessment
Adult ADHD assessment can be done well remotely; the process above is a conversation and a history. Two caveats worth holding.
The first is that a thorough one takes time, usually more than one appointment. A service that produces a diagnosis in fifteen minutes has sold you something faster than it can responsibly be done.
The second is prescribing. The rules for prescribing stimulants without an in-person visit have changed repeatedly and vary by jurisdiction. Whatever the assessment concludes, ask early and specifically what can be prescribed to you, where you are.