OCD and ADHD occur together considerably more often than their descriptions suggest they should. One is defined by too little inhibition and the other by far too much, so the pairing sounds like a contradiction, and that impression is a large part of why it gets missed.
A systematic review across the lifespan put lifetime ADHD at roughly 16 per cent of people with OCD. [sharma-2021-ocd-comorbidity]
Why they look like opposites
The two conditions describe failures of control that point in opposite directions. ADHD involves difficulty holding attention on something and difficulty stopping a response; OCD involves difficulty letting go of a thought and difficulty stopping a behaviour once it starts.
Put like that, they cancel out. Somebody who cannot stick to anything and somebody who cannot leave anything alone are not obviously the same person.
But both are problems of where attention and action go, rather than of how much control exists in general. One overshoots and one undershoots, and there is no rule that a single person has to do only one of those.
How often they actually co-occur
Reported rates vary a great deal, and the honest version includes that variation. The systematic review that produced the roughly 16 per cent lifetime figure also found neurodevelopmental conditions among the commonest comorbidities in obsessive-compulsive disorder overall. [sharma-2021-ocd-comorbidity]
Reviewers of this literature repeatedly flag the same methodological problems: few community samples, exclusion criteria that differ between studies, and the real possibility of symptoms of one condition being read as the other. That last one is not a footnote. If clinicians sometimes score a compulsion as distractibility, the comorbidity rate and the misdiagnosis rate become impossible to separate.
Treat the figure as evidence that this is common rather than as a precise proportion.
A schematic of the distinction described in this article and in the sources cited. Not measured data.
The useful question is the second bar: was there a specific thought holding your attention there, and did doing the thing reduce anxiety? If yes, that is the OCD pattern. If attention simply went elsewhere with no distressing content attached, that is closer to the ADHD one.
Where each one gets mistaken for the other
The confusion runs in both directions and each has a characteristic error.
OCD read as ADHD. Somebody whose attention is consumed by intrusive thoughts looks inattentive. They miss what was said, lose track in meetings and cannot concentrate on reading. Nothing about that presentation announces that a distressing thought is occupying the foreground, and people rarely volunteer intrusive thoughts unprompted because of their content. Our guide to Pure O covers the form with no visible compulsions at all, which is the one most often missed this way.
ADHD read as OCD. Elaborate lists, rigid routines and checking can be compensation rather than compulsion. Somebody who has lost enough things learns to check, and that is a workaround built from experience, not anxiety about a feared outcome. The distinguishing question is whether skipping the check produces dread or merely risk.
Our guides to ADHD in adults and the psychological causes of OCD cover each condition on its own terms.
Which pattern is driving it?
Tick anything true. This is a reflection prompt rather than a test, and it produces no diagnosis.
0 of 8 ticked
Items one, two, four and six describe the obsessive-compulsive pattern; three, five and seven describe the attentional one. If both sets have ticks, that is worth saying out loud at an assessment rather than resolving on your own. The last item is the most actionable: a diagnosis of one is not a reason nobody asked about the other.
The useful distinction is whether anxiety is driving the behaviour. If skipping a check would produce dread rather than mere risk, that points at the obsessive-compulsive side; if attention simply goes elsewhere, it points at the attentional one.
Nothing here matched. If starting tasks is the main difficulty rather than checking or intrusive thoughts, our guide to ADHD paralysis covers that pattern instead.
No screener on this site measures ADHD or OCD, deliberately. Both need a clinical assessment, and for ADHD that includes developmental history going back to childhood, which no questionnaire can supply. The hub lists what we do cover.
Why naming both changes the treatment
The two treatments pull against each other, which is the practical reason this matters.
The recommended psychological treatment for OCD is exposure and response prevention, which asks you to sit with discomfort deliberately and not perform the compulsion, plus structured homework between sessions. [nice-cg31-ocd] Sustaining attention on something unpleasant and remembering repeated between-session tasks are exactly the demands ADHD makes hardest.
On the other side, treatment for ADHD in adults commonly involves medication alongside non-pharmacological support. [nice-ng87-adhd-ocd] Where OCD is also present, its effect on anxiety and repetitive behaviour is something a prescriber weighs individually, so they need to know.
Say both out loud, to both clinicians. That sentence is most of the value here. It rarely means a treatment is refused; it usually means the exposure work is restructured into shorter, more supported pieces, and the monitoring changes.
When to seek help
See a doctor if intrusive thoughts or rituals are taking up more than an hour a day, if you avoid places or activities because of them, or if difficulties with attention, organisation and follow-through have been present since childhood and are affecting your work or relationships.
Mention both if both fit. Being assessed for one condition does not mean the other gets looked at, and it is common for the second to be found only because somebody raised it.
Go urgently if you have thoughts of harming yourself.
How MyFreud can help
Telling these two apart depends on noticing what was happening in the moments attention went missing, which is the detail memory discards first. MyFreud gives you daily mood tracking that takes seconds, so the difference between a day lost to dread and a day lost to distraction becomes something you can show rather than describe.
Download MyFreud and start today: App Store or Google Play.