For eight years, Marcus was treated for generalised anxiety disorder. He took SSRIs, tried CBT, practised breathing exercises, and kept a worry journal. His anxiety scores improved on paper, but he still could not finish a report without rewriting the first paragraph six times, still forgot to pay bills until they went to collections, and still felt like his brain was running 14 tabs at once with none of them loading. At 38, a new GP asked him a question no one had asked before: “Have you ever been assessed for ADHD?”
This is a composite scenario based on common patient experiences. It does not represent any individual patient.
What you will find in this article
- How ADHD and anxiety overlap in adults
- What being treated for the wrong condition looks like
- How structured assessment catches what a standard consult misses
- What changed when ADHD was properly assessed
- Why GPs miss ADHD in anxious adults
- Treating ADHD and anxiety together
How ADHD and anxiety overlap in adults
ADHD and generalised anxiety disorder share at least six symptoms that look identical in a clinical setting: restlessness, difficulty concentrating, racing thoughts, irritability, sleep disruption, and avoidance of tasks. A GP seeing an adult with these complaints has two plausible diagnoses, and anxiety is the one most clinicians reach for first.
The distinction matters because the underlying mechanism is different. In anxiety, poor concentration comes from worry. The brain is occupied by threat monitoring, leaving fewer resources for the task at hand. In ADHD, poor concentration comes from insufficient dopamine signalling in the prefrontal cortex. The brain is not occupied by worry; it is under-stimulated and seeking input from anywhere it can get it.
Marcus described his experience: “Everyone kept telling me I was anxious. And I was anxious. But the anxiety was because I kept forgetting things, losing things, and disappointing people. The anxiety was the result, not the cause.”
This pattern, where ADHD causes chronic underperformance which then generates anxiety, is one of the most common presentations in adult ADHD clinics. Research published in the British Journal of Psychiatry notes that ADHD is frequently misdiagnosed or missed entirely in adults presenting with anxiety, depression, or personality disorder symptoms.
What being treated for the wrong condition looks like
Marcus’s treatment history is typical of misdiagnosed ADHD. Over eight years, he tried three different SSRIs, two courses of CBT, a mindfulness program, and workplace stress leave. Each intervention helped partially and temporarily.
The SSRIs reduced his worry and tearfulness. They did nothing for his inability to start tasks, his chronic lateness, or his pattern of hyperfocusing on interesting work while neglecting urgent deadlines. CBT taught him useful skills for managing catastrophic thinking, but it could not address the executive dysfunction that made him unable to sequence a multi-step project.
“The breathing exercises would calm me down,” Marcus said. “But then I would sit in front of my computer, calm and focused on my breathing, and still not be able to start the report. The anxiety was gone but the problem was still there.”
This partial response to anxiety treatment is a clinical red flag for underlying ADHD. When mood improves but function does not, clinicians should consider whether the functional impairment has a separate cause. The Australian ADHD clinical practice guideline specifically recommends screening for ADHD when anxiety or depression treatment produces mood improvement without corresponding functional gains.
How structured assessment catches what a standard consult misses
Marcus’s previous GPs were not negligent. They asked about his symptoms, he described anxiety, and they treated anxiety. The problem was the consultation format, not the clinician’s competence.
A standard 15-minute GP consult relies on the patient describing their current concern. Adults with undiagnosed ADHD typically present with the downstream consequences (anxiety, depression, relationship breakdown, work problems) rather than the ADHD itself. They do not say “I have poor sustained attention and deficient executive function.” They say “I am anxious and I cannot cope.”
A structured ADHD assessment changes the diagnostic conversation in several ways:
- The ASRS v1.1 screening tool asks about specific ADHD behaviours (difficulty sustaining attention, losing things, fidgeting, interrupting) that patients would not volunteer in an anxiety-focused consultation. The ASRS has 91% sensitivity for ADHD.
- Observer reports from a partner, family member, or close friend provide an external perspective on behaviour the patient has normalised. Marcus’s partner reported that he started and abandoned projects constantly, a pattern Marcus considered normal.
- Developmental history traces symptoms back to childhood. Marcus’s school reports described him as “chatty” and “easily distracted” but academically strong. In a standard anxiety consult, no one would ask about primary school.
“The questionnaire was the turning point,” Marcus recalled. “I was ticking boxes I did not even know were symptoms. Interrupting people. Losing my phone five times a day. Not being able to watch a full movie. I thought that was normal.”
What changed when ADHD was properly assessed
Marcus’s GP used the structured telehealth assessment pathway. After reviewing his ASRS results (which scored well above the clinical threshold), observer report, and developmental history, she diagnosed ADHD combined presentation with comorbid generalised anxiety disorder.
The treatment plan addressed both conditions, in the right order. She started Marcus on a low-dose stimulant while maintaining his current SSRI. The rationale: treat the ADHD first and see how much of the anxiety resolves on its own.
Within six weeks, Marcus reported that his anxiety had dropped significantly without any change to his SSRI dose. “When I could actually finish tasks and remember appointments, there was nothing to be anxious about,” he said. His GP subsequently tapered his SSRI dose over several months under careful monitoring.
Not all anxiety resolves with ADHD treatment. Some adults have both conditions independently, and both require ongoing treatment. The clinical skill lies in distinguishing primary anxiety from ADHD-generated anxiety, which is why structured assessment matters.
Why GPs miss ADHD in anxious adults
ADHD is missed in anxious adults for predictable, systemic reasons.
Availability bias. GPs see anxiety and depression daily. They see adult ADHD far less frequently (or they think they do, because they are not screening for it). Clinicians diagnose what they know and what they look for.
Presentation bias. Adults with ADHD present with the problem that bothers them most, which is usually the emotional distress (anxiety, depression, frustration), not the cognitive dysfunction they have lived with since childhood and consider normal.
Training gaps. Most Australian GP training programmes historically included minimal content on adult ADHD. The condition was positioned as paediatric, and GPs were taught to refer rather than assess. Queensland’s 2025 prescribing reform is changing this by putting ADHD within the GP scope of practice.
Time constraints. A 15-minute standard consult does not allow for the developmental history, structured screening, and differential diagnosis that ADHD assessment requires. Longer consultations with pre-collected questionnaires solve this problem.
As many as 75% of adults with ADHD have no idea they have the condition, according to research by Dr Len Adler at New York University. For many of them, the barrier is not awareness but the structure of the healthcare consultation that treats the symptom (anxiety) without investigating the cause (ADHD).
Treating ADHD and anxiety together
When ADHD and anxiety coexist, treatment order matters. The Australian ADHD clinical practice guideline recommends starting stimulant medication for ADHD even in the presence of anxiety, as ADHD treatment often reduces anxiety symptoms. If anxiety persists or worsens after ADHD is treated, anxiety-specific treatment is added or adjusted.
For Marcus, the combined approach included:
- Low-dose lisdexamfetamine (Vyvanse) for ADHD, titrated over 6 weeks to an effective dose
- Maintenance SSRI at a reduced dose for residual anxiety
- ADHD-focused psychological strategies (external structure, task breakdown, time-blocking)
- Regular follow-up reviews via telehealth, initially fortnightly then monthly
Stimulants do not cause anxiety in most adults with ADHD. Some patients experience a transient increase in physical arousal (higher heart rate, mild jitteriness) during the first week, which typically settles. If anxiety worsens on stimulants, the GP may consider a non-stimulant option like atomoxetine or adjust the stimulant dose.
Frequently asked questions
How do I know if my anxiety is actually ADHD?
Key indicators include: anxiety treatment improves your mood but not your ability to function, you have had concentration and organisational difficulties since childhood (not triggered by a specific stressor), and your symptoms include losing things, chronic lateness, difficulty finishing tasks, and restlessness beyond what worry alone explains. A structured ADHD screening is the best starting point.
Can you have both ADHD and anxiety at the same time?
Yes. Approximately 50% of adults with ADHD also meet criteria for an anxiety disorder. The two conditions frequently coexist, and the ADHD often drives the anxiety through a cycle of underperformance, missed commitments, and self-criticism. A structured assessment distinguishes between ADHD-generated anxiety and a separate anxiety disorder so both can be treated appropriately.
Will ADHD medication make my anxiety worse?
For most adults, no. Research and clinical experience show that treating ADHD often reduces anxiety because the source of the anxiety (task failure, disorganisation, chronic stress) improves. A small number of patients experience transient physical arousal in the first week of stimulants, which typically settles. If anxiety worsens on stimulants, your GP may adjust the dose or consider a non-stimulant alternative like atomoxetine.
Should I stop my anxiety medication before starting ADHD treatment?
No. Do not change your current medication without medical guidance. Most GPs start ADHD medication alongside existing anxiety treatment and then review the anxiety medication once ADHD symptoms are stable. Stopping an SSRI abruptly causes withdrawal effects and should only be done under GP supervision with a gradual taper.
How long does ADHD assessment take if I am already being treated for anxiety?
The assessment process is the same whether or not you have an existing anxiety diagnosis.
Marcus spent eight years treating a symptom instead of a cause. If your anxiety treatment helps your mood but not your ability to function, it is worth asking whether ADHD is part of the picture. You can book an ADHD assessment or book a structured assessment with a specialist GP to find out.
General health information
This article is general health information only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always speak with a qualified health professional before making any changes to your medication or treatment plan.
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