Anxiety and ADHD co-occur frequently. Estimates from the National Comorbidity Survey Replication and subsequent epidemiologic work, summarized by the National Institute of Mental Health and by CHADD, place the comorbidity rate at roughly 25 to 40 percent of adults with either condition. The two often look similar from outside, restlessness, difficulty concentrating, racing thoughts, but the underlying mechanisms differ. Treating the wrong one doesn't help; treating the correct primary condition often resolves the apparent symptoms of the other. A careful clinical evaluation is the way to sort them apart.
A patient comes in saying they can't focus, their mind races, they can't sit still, they wake at 3 a.m. with thoughts running. Are these anxiety symptoms or ADHD symptoms? The honest answer is "both could produce this, and they often coexist." The clinical work is to figure out which is primary and how to treat both when both are present.
Why the overlap is real
ADHD and anxiety are among the most commonly co-occurring conditions in adult psychiatry. Approximately 25 to 40 percent of adults with one of the two conditions have the other, per the NIMH and CHADD comorbidity summaries linked above. Several reasons.
Shared symptoms. Restlessness, difficulty concentrating, sleep disruption, and racing thoughts appear in both. From symptom report alone, the two can be indistinguishable.
Secondary anxiety from untreated ADHD. A person who has spent decades missing deadlines, losing keys, forgetting appointments, and disappointing themselves develops legitimate anticipatory anxiety about all of these. The anxiety is a reasonable response to an underlying disorder that has been making life unreliable.
Compensation patterns. People with ADHD often develop perfectionism, over-preparation, and constant vigilance as ways to compensate. These compensation strategies look exactly like generalized anxiety from outside.
Shared neurobiology. Both conditions involve dysregulation in prefrontal cortex function and in dopamine and norepinephrine signaling.
How to tell them apart
Several patterns help distinguish them, though a clinical evaluation is the appropriate way to sort it out.
Time course. ADHD is a neurodevelopmental condition. The pattern is present in childhood, even if it wasn't diagnosed. An adult who never had attention problems as a child but developed them in their thirties is more likely experiencing anxiety, depression, or another condition than newly emerging ADHD.
The flavor of "racing thoughts." ADHD racing thoughts often feel like jumping between topics, generating ideas, getting distracted by one's own thinking. Anxious racing thoughts often feel like the same worry running on repeat, with a tight, urgent quality.
Performance under interest. A classic ADHD pattern: difficulty sustaining attention on boring or routine tasks; relatively preserved attention on activities that are deeply engaging. Pure anxiety often impairs concentration across the board.
Where the symptoms peak. ADHD symptoms are present throughout the day, particularly in unstructured time. Anxiety symptoms often peak in specific situations or at specific times (mornings before work, evenings, while trying to fall asleep).
Why anxiety and ADHD are sometimes confused, and why the distinction matters
Anxiety and ADHD share several features that make them hard to tell apart in a short visit. Both can produce trouble focusing, restlessness, racing thoughts, sleep disruption, and irritability. Many patients with one of these conditions also have the other; the comorbidity rate is meaningful, and treating only one when both are present often leaves the patient feeling that nothing has worked.
Overlap isn't equivalence. The conditions are mechanistically different, the treatments are different, and several other things produce attention problems and deserve to be ruled out before a clinician settles on either diagnosis.
In clinical practice the distinction usually comes down to a few specific questions. ADHD-pattern attention difficulty is lifelong, present in childhood, and shows up across contexts (work, social, household tasks, hobbies). Anxiety-pattern attention difficulty is more episodic, tied to the worry, and improves when the underlying worry settles. ADHD doesn't typically produce the autonomic features of anxiety (chest tightness, palpitations, the adrenaline-driven surge). Anxiety doesn't typically produce the executive function pattern of ADHD (working memory load, time blindness, difficulty initiating tasks despite wanting to start them).
Several conditions that are neither anxiety nor ADHD also produce overlapping symptoms and deserve specific evaluation:
- Chronic sleep deprivation, including untreated obstructive sleep apnea, produces attention problems and irritability that mimic both conditions.
- Major depressive disorder, particularly with anxious features, produces concentration difficulty, fatigue, and a sense that the mind isn't working the way it should.
- Trauma-related conditions, including PTSD, produce hypervigilance, sleep disruption, and difficulty focusing that overlap with both anxiety and ADHD.
- Hypothyroidism, vitamin B12 deficiency, and iron deficiency in menstruating people each contribute in some patients.
- Substance use, particularly stimulant or daily cannabis use, alters the picture in ways that aren't always obvious from the patient's report.
When these are sorted out, the clinical picture is usually clearer. The implication for treatment is direct. An SSRI for anxiety may not address an underlying ADHD pattern, and a stimulant for ADHD can worsen anxiety if used without addressing the underlying anxious arousal first. The decision about which condition to treat first, and whether to treat both at once, is made with a clinician who has the full picture.
Why it matters for treatment
The treatment for ADHD is typically a stimulant (methylphenidate or amphetamine class) or a non-stimulant option (atomoxetine, guanfacine, viloxazine). The treatment for anxiety is typically an SSRI plus therapy. These are very different interventions.
Treating only the anxiety when ADHD is present often leaves the underlying executive function difficulties intact, which means the anxiety keeps coming back as the person continues to miss deadlines and disappoint themselves.
Treating only the ADHD when anxiety is present can sometimes make the anxiety worse, stimulants can increase anxiety in susceptible patients, particularly at higher doses.
Most patients with co-occurring conditions do best with treatment of both. The order matters: treating the more impairing condition first, then adding treatment for the second, is often the cleanest sequence. For many adults, this means treating the anxiety first with an SSRI, then assessing whether ADHD symptoms persist once anxiety is controlled. If they do, treatment for ADHD follows.
A specific clinical observation
A pattern worth naming. Many adults who were diagnosed with anxiety in their twenties and thirties are eventually re-evaluated and found to also have ADHD. The anxiety treatment helped but didn't fully resolve their experience of struggling. When ADHD was identified and treated, function improved beyond what anxiety treatment alone had achieved.
This isn't a reason to retroactively assume that every anxious adult has ADHD. It's a reason to keep the possibility on the table, particularly when childhood difficulties with attention or organization are present, when a first-degree relative has ADHD, when anxiety treatment has produced partial response but ongoing functional difficulties, or when specific executive function challenges (procrastination, time management, working memory, emotional regulation) persist even when anxiety has decreased.
External references
The NIMH page on ADHD covers the diagnostic and treatment approach. The APA practice guidelines include resources for ADHD evaluation in adults.
Related: Generalized anxiety disorder · Anxiety and depression · How CBT and SSRIs actually work for anxiety
For the clinical encyclopedia entry on this condition, see Shrinkopedia →