Is It ADHD or OCD?
Untangling Racing Thoughts from Intrusive Thoughts
Clinical Psychologist | Behavioral Health
August 6, 2026
One of the questions I hear most often in consultation — from parents, from adults seeking their own evaluation, and sometimes from other clinicians — is some version of: "Is this ADHD or OCD? The thoughts won't stop either way." It's a genuinely hard distinction to make, and the research bears that out: estimates vary across studies, with reported ADHD prevalence among people with OCD ranging from roughly 12% in some samples to over 25% in others (Sheppard et al., 2010). The two conditions are frequently mistaken for one another, and just as often, missed entirely when they occur together.
The thoughts feel different — even when they look similar from the outside
On the surface, both conditions involve a mind that won't settle. But the relationship a person has with their thoughts tends to differ in a clinically meaningful way.
In OCD, intrusive thoughts are typically ego-dystonic — they feel foreign, unacceptable, and at odds with the person's values, which is precisely why they generate so much distress. A parent might have an unwanted thought about harm coming to their child and feel horrified by it, then develop rituals or mental compulsions specifically to neutralize that thought and the anxiety it creates (Abramovitch & Schweiger, 2009; Abramovitch & Mittelman, International OCD Foundation).
In ADHD, unwanted or racing thoughts happen too, but they tend to move rather than stick. A 2023 study distinguishing racing thoughts from ordinary mind-wandering in adults with ADHD found that racing thoughts — described by participants as multiple ideas occurring simultaneously or "constantly on the go" — were closely tied to emotional lability, while mind-wandering was a separate, unrelated phenomenon (Martz et al., 2023). Critically, the researchers found ADHD-related racing thoughts weren't inherently distressing in the way OCD obsessions are; they were more a feature of mental restlessness than of moral or safety-related fear.
Why the overlap gets missed clinically
Part of what makes differentiation difficult is that OCD can create real attentional problems that mimic ADHD. When a person is mentally occupied by an obsession or a compulsion running in the background, they may lose track of conversations, forget tasks, or appear distracted — not because their attention system is impaired, but because a significant share of their cognitive resources are tied up managing the obsession (Abramovitch & Mittelman, International OCD Foundation). This is sometimes called the "cognitive cost" of obsessions, and it means a clinician evaluating attention symptoms in isolation, without asking about the content and function of the thoughts, risks misdiagnosing OCD as ADHD, or vice versa.
A rough clinical heuristic (not a substitute for full evaluation):
OCD: thought is unwanted and distressing → person tries to suppress, neutralize, or ritualize in response → temporary relief, then the cycle repeats.
ADHD: thought arises, causes brief discomfort at most, and gets displaced by the next thought → no ritual, no sustained attempt at neutralization.
Why this matters for treatment
Getting the distinction right isn't academic — it changes treatment. OCD responds specifically to Exposure and Response Prevention (ERP), which involves not neutralizing the anxiety the thought creates. Applying ERP-style intervention to what is actually ADHD-driven mental restlessness misses the mark, and conversely, treating true OCD purely as an attention problem (e.g., with stimulant medication alone) can in some cases intensify obsessive symptoms.
A comprehensive evaluation that assesses both the presence and the function of intrusive or racing thoughts is the only reliable way to tell them apart — and comorbid presentations, which are common, require a treatment plan that addresses both. If you're trying to work out which one you or your child might be dealing with, that's exactly what a full evaluation is designed to sort out.
References
Abramovitch, A., & Schweiger, A. (2009). Unwanted intrusive and worrisome thoughts in adults with Attention Deficit/Hyperactivity Disorder. Psychiatry Research, 168(3), 230–233. https://doi.org/10.1016/j.psychres.2008.06.004
Abramovitch, A., & Mittelman, A. OCD and ADHD Dual Diagnosis, Misdiagnosis, and the Cognitive "Cost" of Obsessions. International OCD Foundation. https://iocdf.org/expert-opinions/expert-opinion-ocd-and-adhd-dual-diagnosis-misdiagnosis-and-the-cognitive-cost-of-obsessions/
Martz, E., Weiner, L., Bonnefond, A., & Weibel, S. (2023). Disentangling racing thoughts from mind wandering in adult attention deficit hyperactivity disorder. Frontiers in Psychology, 14, 1166602. https://doi.org/10.3389/fpsyg.2023.1166602
Sheppard, B., Chavira, D., Azzam, A., Grados, M. A., Umaña, P., Garrido, H., & Mathews, C. A. (2010). ADHD prevalence and association with hoarding behaviors in childhood-onset OCD. Depression and Anxiety, 27(7), 667–674. https://doi.org/10.1002/da.20691