Assessment in adulthood

Why some people only receive a diagnosis as adults

The international classification ICD-11 states: autism begins in the developmental period, but its features sometimes only become fully visible later – when social demands exceed a person’s capacities. ^[2] In Germany, the official classification for diagnoses in outpatient and inpatient care is still ICD-10-GM; according to the BfArM, introducing ICD-11 for this purpose will take several more years. ^[7] If your documents show an older diagnostic label, you can ask the professionals about it during the assessment.

Late or incorrect diagnoses are also associated with masking, that is, hiding or compensating for features of autism. Studies show a link, but the direction is unclear: late diagnoses could contribute to masking or be a consequence of it. ^[5] More in the article Masking: when adapting is exhausting.

How assessment works for adults

In principle, the path is the same as for children: ^[1]

1. Initial assessment at a psychiatric practice or outpatient clinic, through conversation, observation and, where appropriate, questionnaires.
2. Physical examination.
3. Autism-specific assessment with standardised methods at a specialised service. For adolescents and adults with fluent speech, behavioural observation takes place as a semi-structured conversation.
4. Differentiation and co-occurring conditions, then diagnosis and recommendations.

The article How an autism assessment works describes the general process in detail.

What makes it different

Reconstructing childhood. For the diagnosis it must be clarified whether features were already present in early childhood. For adults this is a major challenge. The expert overview therefore recommends asking relatives and looking at old documents. According to its account, differentiation from other disorders is hardly possible without this information. ^{[1; 4]}

Differentiation from other diagnoses. In adults, the following diagnoses in particular are to be considered, because they can share some similar features: ^[1]

• personality disorders,
• obsessive-compulsive disorders,
• attention disorders (ADHD),
• affective disorders,
• social phobia,
• schizophrenia.

This does not mean that autism is ruled out if one of these diagnoses is present. Both can also exist together.

Bringing in your own experience. Professionals make the diagnosis on the basis of all the information. ^[1] According to the expert overview, screening questionnaires are not suitable for making a diagnosis. ^[1] More in the article Screening questionnaires.

How you can prepare

Suggestions from the editorial team, derived from the information needed in an assessment (not a guideline recommendation):

• Collect old documents, for example school reports, reports from childhood, earlier findings. ^[1]
• Ask relatives whether they would be willing to have a conversation, for example parents, siblings or long-standing close people. ^[1] According to the expert overview, differentiation from other disorders is hardly possible without asking relatives and old documents. ^[1] If neither is possible for you, say so openly and ask how the professionals deal with this.
• Write down examples from childhood and today: social situations, routines, interests, sensitivity to stimuli, exhaustion.
• Clarify your needs for the appointments, such as written communication, a low-stimulus environment or breaks. You can ask about this when booking; whether a service can accommodate it depends on the service.

How to get an appointment and who bears the costs is explained in the article Referral, costs and waiting times.

After the findings

A diagnosis in adulthood can put a lot into a new perspective – and at the same time raise new questions. The article Late diagnosis: what can change takes this up. If no autism diagnosis is made, No autism diagnosis – and now? can help.

Sources and literature

1. Höhne E, Kamp-Becker I. Diagnostik der Autismus-Spektrum-Störung. Pädiatrie 2024;(4+5):27–32. – Expert overview (in German)
2. World Health Organization. ICD-11 MMS, 6A02 Autism spectrum disorder, Version 2025-01. – Classification system. Release-Seite: https://icd.who.int/browse/2025-01/mms/en
3. DGKJP, DGPPN et al. S3-Leitlinie Autismus-Spektrum-Störungen, Teil 1: Diagnostik. AWMF 028-018, Textstand 23.02.2016. – Guideline (in German) (expired; according to the document note under revision)
4. Höhne E, Kamp-Becker I. Diagnostik der Autismus-Spektrum-Störung bei Kindern und Erwachsenen. Psychiatrie + Neurologie 2024;(1):14 ff. – Expert overview (in German) (text identical to Q-PAED-2024, not an independent second source)
5. Klein J, Krahn R, Howe S, et al. A systematic review of social camouflaging in autistic adults and youth: implications and theory. Development and Psychopathology 2025;37(3):1320–1334 (online 2024). https://doi.org/10.1017/S0954579424001159 – Systematic review
6. DGKJP. Aktuelle Leitlinien (Eintrag 028-018: „Gültig bis 04.04.2021“). https://www.dgkjp.de/wissen/aktuelle-leitlinien/ – Professional society (website in German)
7. Bundesinstitut für Arzneimittel und Medizinprodukte (BfArM). ICD-11 (Informationsseite zur Einführung in Deutschland). https://www.bfarm.de/DE/Kodiersysteme/Klassifikationen/ICD/ICD-11/_node.html – Authority (in German)