"Can You Just Test Me for ADHD?"

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It is one of the most common questions in a first appointment, and it is a reasonable one. If ADHD is neurological, there should be something to measure. A blood panel, a scan, a test that returns a number.

There is something to measure. It is just not the thing most people are hoping for.

What the Test Actually Measures

Computerised attention tests, of which QbTest is the one this practice uses, work on the same basic principle. The person watches a screen for fifteen to twenty minutes and responds to some stimuli while withholding responses to others. It is deliberately boring, because boredom is the condition under which attention regulation problems become visible.

Three things get recorded. Inattention, measured as missed targets and as variability in reaction time. Impulsivity, measured as responses to stimuli that should have been withheld. And motor activity, tracked continuously through the task, which turns restlessness from something a clinician estimates into something with a number attached.

The most useful of those is often the least obvious. What the measurement captures that a conversation cannot is inconsistency: not how fast someone responds, but how much their responding varies from minute to minute across a task long enough for that variation to show. Inconsistency is closer to how ADHD is actually described by the people who have it than slowness is, and it is close to impossible to observe reliably inside a single appointment.

Those numbers are then compared against a normative sample matched for age and sex. The output is not an opinion. It is a set of measurements with reference ranges, and that is genuinely different from a questionnaire.

What the Evidence Says About Accuracy

Here is where honesty matters more than marketing.

A 2023 systematic review and meta-analysis pooled 15 studies covering 2,058 participants, of whom 48.6% had an ADHD diagnosis. For the combined QbTest score, sensitivity was 0.78 and specificity was 0.70, with a pooled area under the curve of 0.72.¹ Individual subscales performed worse, with sensitivity between 0.48 and 0.65.

Translated out of statistics: if you tested a hundred people who genuinely have ADHD, roughly 78 would screen positive and roughly 22 would not. If you tested a hundred people who do not have ADHD, roughly 70 would screen negative and roughly 30 would look positive anyway.

The authors were direct about what follows from that. Used on their own, QbTest scores are not sufficiently accurate to discriminate between ADHD and non-ADHD clinical cases, and the test should not be used as a standalone screening or diagnostic instrument.¹

One further caveat belongs here. Most of that literature was conducted in children and adolescents. Adult-specific accuracy data is thinner than the headline numbers imply, and anyone quoting those figures for adults, including this article, is extrapolating somewhat.

Why That Does Not Make It Useless

A test that cannot diagnose on its own is not the same as a test that adds nothing. The same review found that when QbTest is used as an adjunct to a full clinical assessment, it can produce efficiencies in the assessment pathway and reduce time to diagnosis.¹

The reason is worth understanding, because it is not really about accuracy. It is about what the rest of the assessment depends on.

An ADHD evaluation is built almost entirely on retrospective self-report. It asks an adult to accurately recall their own childhood, estimate how often they lose things, and judge whether their concentration is worse than other people's, which requires knowing what other people's concentration is like. People are unreliable narrators of their own attention in both directions. Some minimise, because they have been managing so long that the effort feels normal. Others attribute everything to ADHD once the idea is in play.

An objective measurement does not fix that, but it is not subject to it either. It is one input that does not depend on memory, or on how the person happens to feel about themselves that morning.

That is a narrower claim than it sounds. It does not mean the number is more true than the history. The history is still where the diagnosis is made. It means the number fails in different ways than the history does, and two measures that fail differently are more useful together than either is alone.

What It Is Actually Good For

In practice the test earns its place in three situations.

When self-report and the rest of the history disagree, it provides a third data point that is not an opinion held by either party.

When the question is not whether but how much, a baseline measurement makes it possible to compare against a repeat test on medication. That turns "I think it is helping" into something closer to a measurement, which matters in a process built around systematic medication trials rather than a single prescription.

And when someone has been told for years that their difficulties are imagined or self-inflicted, seeing a measured result outside the normal range can change what they are willing to consider about themselves. That is not a diagnostic function. It is still worth something.

What a Test Cannot Tell You

No computerised test establishes that symptoms were present in childhood, which the diagnostic criteria require. None of them establish impairment across more than one setting, which the criteria also require.

Most importantly, none of them rule out the alternatives. Poor performance on an attention task is a finding, not a cause. Untreated sleep disorders, depression, thyroid dysfunction and anxiety all degrade sustained attention, and a test that measures attention will register that degradation without saying anything about where it came from. Working out which explanation the history supports is the part that separating ADHD from the conditions that imitate it actually requires, and no machine does it.

What to Ask

If a practice offers objective testing, the useful question is not whether they have the equipment. It is what they do with the result.

A test used as a shortcut, where a positive result produces a prescription, is worse than no test at all, because it lends a number to a conclusion the number does not support. A test used as one input inside a full evaluation, alongside developmental history, collateral information, and a genuine differential, is doing what the evidence supports it doing.

What the diagnosis rests on, and what treatment reliably changes once it is made, is covered in the guide to adult ADHD.

Reference
1. Bellato A, Hall CL, Groom MJ, Simonoff E, Thapar A, Hollis C, Cortese S. Practitioner review: clinical utility of the QbTest for the assessment and diagnosis of attention-deficit/hyperactivity disorder, a systematic review and meta-analysis. Journal of Child Psychology and Psychiatry. 2023. doi:10.1111/jcpp.13901

The content on this website is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.