In Brief
Getting a neurodivergence diagnosis as an adult is often a complex, costly, and emotionally intense journey. This practical guide aims to make it as clear as possible: which professional to see, what to expect, what it costs, and how to prepare to get the most out of it.
A diagnosis is not an obligation. But for many, it represents a turning point: finally understanding why you function the way you function, after years of confusion.
Disclaimer: Information on costs and timelines is indicative. It can vary depending on your region, insurance coverage, and evolving reimbursement policies. Always verify with the relevant organizations.
Which Professional for Which Profile?
HPI — High Intellectual Potential
Primary professional: neuropsychologist
The only validated tool for diagnosing HPI is a standardized intelligence test administered by a neuropsychologist. For adults, this is generally the WAIS-V (Wechsler Adult Intelligence Scale, 5th edition). For children and adolescents, the WISC-V is used.
What an HPI assessment generally includes:
- IQ test (WAIS-V or WISC-V): 2 to 4 hours
- Clinical interview on developmental history
- Possibly supplementary tests (memory, attention, executive functions)
- Written report with clinical interpretation
Can also diagnose: a licensed clinical psychologist, a psychiatrist (for associated clinical aspects).
Cannot diagnose: a coach, a general practitioner, a teacher — however well-intentioned.
ADHD — Attention Deficit Hyperactivity Disorder
Primary professional: psychiatrist or child psychiatrist (for children)
In most European countries, an ADHD diagnosis requires a psychiatric evaluation. A neuropsychologist can perform supplementary tests (Conners scales, DIVA-5 for adults, attention tests), but the formal diagnosis belongs to the psychiatrist.
Key diagnostic tools:
- DIVA-5 (Diagnostic Interview for ADHD in Adults): structured interview
- Conners scales (adult or parent): validated questionnaires
- Neuropsychological tests: CPT (Continuous Performance Test), sustained and selective attention tests
Important: there is no "blood test" or imaging to diagnose ADHD. The diagnosis is clinical, based on symptoms, developmental history, and their functional impact.
ASD — Autism Spectrum Disorder
Primary professional: psychiatrist, child psychiatrist, or multidisciplinary team
An adult ASD diagnosis is the most complex to obtain. Waiting lists in specialized autism assessment centers can exceed 2 to 3 years in many countries.
Key diagnostic tools:
- ADOS-2 (Autism Diagnostic Observation Schedule, 2nd edition): standardized behavioral observation, gold standard
- ADI-R (Autism Diagnostic Interview-Revised): structured interview with a close relative
- CARS-2: clinical rating scale for the autistic spectrum
For adults, adapted tools exist: RAADS-R (Ritvo Autism Asperger Diagnostic Scale-Revised) as a screening tool.
Adult particularity: many autistic adults, particularly women and Asperger profiles, were never diagnosed in childhood. Adult diagnosis relies heavily on retrospective history.
HSP — High Sensitivity
Special status: HSP is not a medical diagnosis. It is a temperament trait identified by Dr. Elaine Aron's research, but absent from ICD-11 and DSM-5 classifications.
There is no official "HSP diagnosis". What exists:
- Validated research questionnaires (see self-assessment section)
- Therapeutic support for associated difficulties (sensory overload, anxiety)
- A neuropsychologist or psychologist can confirm the trait and differentiate from co-occurring conditions (generalized anxiety, ASD, ADHD)
The Neuropsychological Assessment: What to Expect
Typical Process
A complete adult neuropsychological assessment generally takes place over 2 to 4 sessions of approximately 1.5 to 2 hours each:
Session 1 — Clinical interview: life history, current complaints, school and professional context, family history. No tests at this stage — just an in-depth conversation.
Sessions 2-3 — Standardized tests: depending on the reason for the consultation, a battery of tests is administered. For an HPI assessment, the WAIS-V takes about 2 hours. Supplementary tests (memory, attention, executive functions, language) may be added depending on clinical hypotheses.
Session 4 (feedback): the neuropsychologist presents and explains the results. This session is crucial — plan to attend without being rushed. Write down your questions in advance.
How to Prepare Well
Before
- Note your concrete difficulties: "I forget appointments", "I can't finish what I start", "loud sounds hurt me" — not "I feel different"
- Gather old school reports if possible (very useful for adult assessments)
- List current medications (some affect cognitive performance)
- Sleep well the nights before the tests
On the day
- Eat normally (hypoglycemia affects cognitive performance)
- Don't try to "behave well" or "appear normal" — the tests are designed to identify your actual functioning, not your social performance
- Ask questions if you don't understand an instruction
After
- Request a written report (you are entitled to one)
- If the results surprise you or seem inaccurate, you can seek a second opinion
- The written report belongs to you — you choose who to share it with
Costs and Timelines Across Europe
United Kingdom
- ADHD/ASD (NHS): free but waiting lists of 2 to 5+ years in many regions
- Private ADHD assessment: £800 to £2,000 for a full assessment
- Private ASD assessment: £1,500 to £3,500 for a full assessment
- Right to Choose pathway can accelerate NHS referrals in England
France
- HPI assessment (private neuropsychologist): €300 to €600
- ADHD (psychiatrist): €60 to €150 per consultation, 70% reimbursed in sector 1
- ASD (specialized center / CPEAP): covered by national health insurance but 2 to 4 year waiting lists
- Some supplementary health insurance plans cover psychological assessments — check your contract
Spain
- Private neuropsychologist: €80 to €200 per session (full assessment: 3 to 5 sessions)
- Via private health insurance: some assessments partially covered depending on the contract
- Via public system (Seguridad Social): accessible but very long waiting times (1 to 3 years), and adult access to HPI/ADHD assessments is inconsistent across autonomous communities
Germany
- ADHD (psychiatrist, GKV covered): covered by statutory health insurance; waiting times 3 to 12 months
- ASD assessment: specialist centers (Autismuszentren) have 1 to 3 year waiting lists
- Private assessment: €500 to €2,000 depending on profile and scope
Adult Diagnosis: Important Specifics
Why Adult Diagnoses Are Different
Most diagnostic tools were developed on pediatric populations. DSM-5 and ICD-11 criteria for ADHD, for example, require that symptoms be present "before age 12" — which is difficult to prove retrospectively for an adult who was never evaluated.
Furthermore, neurodivergent adults have often developed elaborate compensation strategies that mask their difficulties during evaluations. An HPI adult with ADHD may appear "organized" in a consultation because they have spent years building compensation systems — but these systems collapse under load.
Gender Bias in Diagnosis
Numerous studies show that women and AFAB individuals are diagnosed later than men for ADHD and ASD, often in adulthood, after a long diagnostic wandering including incorrect diagnoses of depression, anxiety, or personality disorders.
Clinical criteria were largely developed on male populations. The "internal" presentation (inattentive ADHD, "masked" autism) is more common in women and less visible to untrained clinicians.
Validated Self-Assessment Tools
These tools do not replace a professional diagnosis. They can help you clarify your observations and prepare a clinical interview.
ADHD
- ASRS-v1.1 (Adult ADHD Self-Report Scale) — WHO-developed screening tool, available free online, scientifically validated. 18 questions, 10 minutes.
- Brown ADD Scales (self-assessment) — measures executive functions associated with ADHD
ASD
- RAADS-R (Ritvo Autism Asperger Diagnostic Scale-Revised) — 80 questions, designed for adults with subtle autistic presentation. Must be interpreted by a clinician.
- CAT-Q (Camouflaging Autistic Traits Questionnaire) — specifically measures masking
HPI
There are no validated self-assessment tools for HPI (IQ can only be measured by a professional). Informal online tests exist but are not scientifically validated.
HSP
- Elaine Aron's HSP Scale — available on hsperson.com, 27 items, translated into multiple languages. Validated by Aron's original research (1996).
When Is Self-Identification Enough?
This is a legitimate question, especially given the cost and delays of a formal diagnosis.
Self-identification may be sufficient if:
- You are seeking to understand yourself better, not to obtain legal accommodations
- The profile (like HSP) has no formal diagnosis anyway
- You already have sufficient understanding of your functioning and the strategies that help you
A formal diagnosis is important if:
- You need academic or workplace accommodations (they require an official document)
- You are considering medication (impossible without a psychiatric diagnosis for ADHD)
- You are experiencing significant distress and need an adapted therapeutic framework
- Legal or family decisions involve your neurological profile
A nuanced position: in neurodivergent communities, self-identification is widely respected. It does not replace a formal diagnosis for practical and medical matters, but it is a legitimate form of self-knowledge.
Getting assessed is not about proving you are "really" neurodivergent. It is about giving yourself the tools to understand your own brain with precision.