How Is Autism Diagnosed in Adults?

Looking for a diagnosis in adulthood is a strange business. For thirty years you managed somehow, nobody said anything, and you told yourself "everyone is like this." Then something you read somewhere shakes you loose, and you do not know where to start.

I went through this on the ADHD side. I received my diagnosis at 23, and the hardest part of that process was not the symptoms but the uncertainty of the process itself. I did not know where to go, what to ask for, what to bring.

I do not have an autism diagnosis, and I do not intend to give myself one. I am writing this article not as a personal account but as a map of the process: what happens in an adult autism assessment, who looks at it, what is looked at.

First, set the expectation correctly

There is no single test. None of the things circulating online under the title "autism test" makes a diagnosis.

The assessment usually consists of these parts: a detailed clinical interview, a developmental history, an evaluation of everyday functioning, if possible information from someone close to you, and ruling out other conditions that could produce a similar picture.

The NICE adult guideline (CG142) states that a short screening tool can be used in adults without a moderate or severe learning disability; but this tool does not make a diagnosis, it only refers you for a comprehensive assessment. The diagnosis is made at the end of the comprehensive assessment.

So the process is not filling in a questionnaire; it is building a file.

It is worth being realistic about time too. It is not something expected to finish in a single interview; it is normal for it to be spread over several sessions, with information gathered in between, and sometimes to take months. This slowness is not a hitch; it is the nature of the work. An autism diagnosis, or a refusal of one, given quickly in a single session deserves to be questioned in both directions.

Who carries out the assessment

In Turkey the first stop for adults is usually adult psychiatry. The psychiatrist carries out the assessment; a clinical psychologist may take part on the scales and testing side.

There is a practical fact to know here: most clinicians who specialize in autism have been trained on the child and adolescent psychiatry side. The number of clinicians who see the adult picture well is limited, and this makes waiting times longer and reaching the right address harder.

It is reasonable to ask openly before making an appointment: "Do you carry out adult autism assessments?" This question is not rude, it is to the point. I recommend the same for ADHD, and I described it in the article where to get an ADHD diagnosis as an adult.

What is looked at

DSM-5-TR defines the autism diagnosis through two main areas (American Psychiatric Association, 2022):

The first is social communication and reciprocal interaction. Establishing reciprocity, using and reading nonverbal communication, forming and maintaining relationships.

The second is restricted and repetitive patterns. Repetitive behavior or speech, insistence on sameness and adherence to routine, interests unusual in intensity or focus, and over- or under-reaction to sensory input.

Three more conditions are added to this: that the symptoms began in the early developmental period, that they produce a genuine loss in everyday functioning, and that they cannot be better explained by another condition.

I underline the last item: the presence of a symptom is not enough, it needs to be making your life harder. This is a threshold that applies to both diagnoses.

Why the developmental history matters so much

This is the most decisive and most often skipped piece of the process.

The early-period condition is hard to ask about in adulthood: who remembers in detail what happened thirty years ago? That is why information from outside is valuable.

What can be collected:

• Report cards and teacher comments. Sentences like "does not join in play with friends" or "in his own world" are useful in the assessment.
• Health record book, developmental notes. The course of language development in particular is asked about.
• Videos and photographs. The form of play, the way of relating to others.
• What the family or elders say. Many people cannot get this, and not being able to does not make the process impossible, only harder.

For someone who cannot get information from their family there are alternative sources: old friends, relatives, old notebooks you wrote yourself, old messages. Telling the clinician about this limitation openly is part of the process too.

One more warning: information from the family is not always neutral. Some families tend to play down difficulties in childhood, and some tell it the way they themselves remember. This does not mean the information is useless; looking at more than one source is exactly for this reason. For the clinician, the information of "who said what" is as valuable as the account itself.

Which tools are used

Knowing the tools makes it easier to understand what is happening when you walk into the room.

Screening scales. Short scales such as the AQ-10, named in the NICE guideline, serve to refer you for a detailed assessment. A high result is not a diagnosis, it is a reason.

Structured interview and observation tools. The best known internationally are the observation-based ADOS and the ADI-R, which takes the developmental history closely. These tools are used by trained practitioners and are not available in every clinic.

What is done for differential diagnosis. Anxiety disorders, social anxiety, post-traumatic conditions, depression, personality organization and ADHD can produce similar pictures. Ruling them out is part of the process. I covered this side in the articles ADHD or anxiety and ADHD or trauma.

There is also the matter of online tests. Self-completed scales can be a starting point for the decision to go for an assessment; indeed many people reach the right door that way. But when the lists are written too broadly, nearly everyone finds themselves in them. I discussed this side in detail in the article are online ADHD tests reliable, and the same limits apply to autism tests.

How masking spoils the assessment

This is the biggest structural problem in adults.

Someone who has spent thirty years learning to fit in also fits in in the interview room. Eye contact has been memorized, turn-taking in conversation calculated, restlessness hidden under the table. In those forty-five minutes the clinician sees someone who is managing well.

The review by Lai and colleagues (2015) discusses how this covering-up behavior blurs the picture, especially in women, and contributes to delayed diagnosis.

The practical consequence is this: showing your best self when you go to an assessment harms you. Even knowing this helps. I wrote about the matter of masking in detail in the article masking in autism and ADHD.

The assessment is not an exam where you prove you manage well. It is an interview where you tell what you manage and at what cost.

How to prepare

What helped most in my own ADHD process was preparation, so I am leaving a concrete list here.

• Write examples, not adjectives. The sentence "I struggle in social settings" says nothing. The sentence "last month I went to a dinner for three, and the next day I canceled two meetings" does.
• Write the cost. Write not what you do, but what the things you do cost you. Recovery time, canceled work, postponed meetings.
• Prepare the childhood section separately. Write separately what you remember, what you have heard from family and the documents you have. Which piece of information came from whom matters.
• List what you avoid. Under the sentence "I no longer have problems" there usually lies "I never go into that setting."
• Bring someone close to you or get a written account from them. Someone looking from outside says things you have not noticed.

I described the ADHD counterpart of this preparation in the article how adult ADHD is diagnosed, and the two processes are very similar in terms of preparation.

Diagnostic overshadowing: the delay of the second diagnosis

If you already have a diagnosis, there is something you need to know.

Clinicians tend to attribute everything that can be explained by the existing diagnosis to it. The social difficulty of someone with an ADHD diagnosis can be put down to impulsivity, and their sensory difficulty to distractibility. The reverse happens too: the attention problems of someone with an autism diagnosis may go unincluded in the picture for years.

Until 2013 it was not possible to give the two diagnoses together anyway; after that restriction was lifted, it was seen that the co-occurrence is common. I covered this picture in the article AuDHD and where the two headings part ways in the article are ADHD and autism the same thing.

Asking about overshadowing openly is a reasonable thing to do. The question "Is there a part of these symptoms that the existing diagnosis cannot explain?" opens the way for the process.

If the diagnosis comes, if it does not

Both outcomes have an aftermath, and it is good to be prepared for both.

If the diagnosis comes, the first thing is most often relief, and right after it a kind of grief. Looking back and saying "I wish I had known earlier" is a common reaction. I wrote the ADHD version of this in the article grief after diagnosis, and the emotional course is largely similar.

If the diagnosis does not come, the difficulties you live with do not go away. Then the question turns to this: what else explains these difficulties, and what can be done about it? In complicated pictures, getting a second opinion is also a common and legitimate step.

There is a third possibility, and nobody talks about it: no clear result. The clinician may say that some features are present but the diagnostic threshold is not met. This is the most frustrating outcome but not the most useless one. Because which arrangements do you good stays valid regardless of the name of the diagnosis: a quiet workspace, a written agenda, a predictable schedule. None of these requires a document.

What I have learned for my own part is this: a diagnosis is not an identity document, it is a set of directions. The part that works is not that it gets a name, but what changes after it.