How is attention deficit hyperactivity disorder diagnosed in adults?

Short answer: There is no single lab test. Adult ADHD is diagnosed by a qualified clinician (psychiatrist, psychiatrist-trained primary care doctor, clinical psychologist, or neuropsychologist) using a clinical interview, past-history evidence of childhood symptoms, structured diagnostic criteria (DSM-5 or ICD), symptom rating scales, and often collateral information or testing to rule out other causes.

What clinicians look for
- Symptom criteria (DSM-5):
- For adults (age 17+): five or more symptoms of inattention and/or five or more symptoms of hyperactivity-impulsivity, present for at least six months, and inconsistent with developmental level.
- Symptoms must have been present before about age 12 (DSM-5) and must cause clear functional impairment.
- Symptoms must be present in two or more settings (e.g., work and home).
- Symptoms cannot be better explained by another mental disorder (depression, anxiety, bipolar, personality disorder, substance use, etc.).

- Examples of core symptoms:
- Inattention: difficulty sustaining attention, careless mistakes, trouble organizing tasks, frequently losing things, forgetfulness.
- Hyperactivity/impulsivity: fidgeting, difficulty remaining seated, talking excessively, interrupting, acting without thinking.

Typical diagnostic process
1. Clinical interview: detailed history of current problems, functional impact, medical history, medication and substance use, sleep, and family psychiatric history.
2. Childhood history: ask about school performance, report cards, teacher comments, or family recall because ADHD must have started in childhood.
3. Symptom checklists and rating scales: e.g., Adult ADHD Self-Report Scale (ASRS), Conners’ Adult ADHD Rating Scales, or clinician-administered instruments.
4. Collateral information: reports from partner, parents, or employer when available to confirm symptoms across settings.
5. Rule out other causes: assess for mood disorders, anxiety, substance use, sleep disorders, thyroid disease, medication side effects, or cognitive disorders. Basic labs or drug screens are sometimes ordered if indicated.
6. Additional testing when needed: neuropsychological testing or continuous performance tests (e.g., TOVA) can document attention/executive deficits or clarify complex cases, but they are not required for routine diagnosis.

Who can diagnose
- Psychiatrists, clinical psychologists, some neurologists, or primary care clinicians experienced in ADHD may diagnose adults. Neuropsychological assessment is useful when the picture is unclear or to evaluate cognitive strengths/weaknesses.

What you can do before an evaluation
- Bring or obtain childhood records (report cards, IEP/504 plans, old evaluations), a list of current symptoms with examples of how they impair work/home life, a medication/substance history, and contact info for someone who can provide collateral history.

Other important points
- Comorbidity is common (depression, anxiety, substance use, learning disorders); accurate diagnosis matters because treatment differs.
- There is no single blood test or brain scan that proves ADHD.
- Stimulant medications are a common treatment but should be started only after careful assessment because of side effects and misuse potential.

If you want, I can:
- Walk you through an adult self-screen (ASRS) now.
- List typical interview questions clinicians ask.
- Explain treatment options after diagnosis.