Just how quickly can autism be determined during an assessment? It there a minimal time? How long should the evaluation be? Does length = efficiency?

I was inspired to cover this topic after a man told me he was given an autism diagnosis by a neuropsychologist after only 90 minutes of just talking with him; no tests.

When people get through childhood and many adult years without an autism diagnosis, and it turns out they’re indeed autistic, this means they have a mild form of autism spectrum disorder.

A more pronounced form – its associated behaviors and traits – will be easily observed by family members very early on in life, leading to an assessment and diagnosis.

However, a person with mild autism may still end up with an early diagnosis due to any number of factors such as 1) speech delay, 2) someone knowledgeable of ASD has observed the young child’s quirks or challenges, 3) a parent was diagnosed.

I myself didn’t receive my ASD diagnosis until middle age! And I’m not the only one getting the late diagnosis, either.

More and more people, well into adulthood, are finally getting an assessment and being diagnosed with this alternative neurotype.

Think of autism as a different processing software for the human brain.

“Every clinician approaches assessment differently,” says Dr. Meghan T. Lee, clinical neuropsychologist and practice owner, Horizon Neuropsychological Services in Colorado. (Dr. Lee did not conduct my assessment.)

“Some clinicians are only looking at the diagnostic question (e.g., to identify or rule out autism), while others take a more comprehensive approach to see if there are other diagnoses that can account for the presenting symptoms,” continues Dr. Lee.

“For example, a person with a language disorder can exhibit social weaknesses, as bidirectional communication can be difficult for them.

“If the clinician only administers social communication measures (e.g., ADOS-2, AQ, SRS-2, etc.), they are likely to miss the language piece, particularly if the language weakness is mild, and instead conceptualize the perceived social communication weaknesses as being secondary to a social communication disorder.

“Moreover, comprehensive evaluations allow a clinician to determine the person’s strengths and how to build upon those moving forward.

“Receiving a diagnosis can be hard and, in my opinion, it is, therefore, equally as important to talk about the person’s strengths.”

An autism assessment may be shortened also by omitting the IQ test. This takes some time, and an examiner may feel it’s not necessary based on the patient’s work and education history.

This was the case of the man who was given the diagnosis after 90 minutes.

However, the IQ portion doesn’t take long enough to account for only 90 minutes being left over. The 90 minutes also reflects exclusion of tasks (flying frogs, anyone?).

Though it’s very possible that my assessor detected I was on the Spectrum within the first 20 minutes (mainly due to setting up “traps” in our conversation for missed sarcasm and literal thinking), a full evaluation should always follow anyways.  

Can a timeframe be ascribed to an ASD assessment?

​“It is very difficult for me to provide an answer, as each clinician is different in how they approach testing,” says Dr. Lee.

“I would say that it’s important for the clinician to conduct a solid clinical interview (typically an hour) and combine that with one or more collateral interviews (each of which lasting for 15+ minutes).

“Behavior rating scales are also administered, which typically take 10-20 minutes each to complete.

“From here, clinicians differ in the supplemental testing. Some clinicians administer social communication tests, which can take anywhere from 30-60 minutes.

“Personally, I prefer to also administer a full neuropsychological battery to rule out any comorbidities or other diagnoses that mimic autism.

“For me, my batteries typically take 3-4 hours to administer. However, I also understand that I tend to be more comprehensive in my approach to testing than most.”

My assessment began with a lengthy, in-depth questionnaire that I filled out at home and then submitted through a secure portal.

The scheduler said it would take 45 minutes. It took me nearly three hours, but this was due to my tendency to heavily analyze and also make sure that everything was perfectly just right.

I read my answers two or three times, not just to proofread for typos but also to make sure they were efficacious.

I also had to think a bit on some of the questions.

The questionnaire also screened for depression, bipolar disorder and ADHD. Be leery of an evaluation process that doesn’t include an in-depth initial intake form.

Chances are exceedingly high that if you “feel autistic,” you probably are. Many people have self-diagnosed themselves with ASD.

It’s really, really unlikely that a neurotypical would come to this conclusion after reading a lot about how autism presents in mild form (minimal to zero support needs).

Nevertheless, a formal evaluation that’s all-encompassing seals the deal.

Horizon Neuropsychological Services, LLC, owned by Dr. Meghan T. Lee, conducts neuropsychological evaluations for all ages. Our doctors evaluate for many conditions including autism spectrum disorder, ADHD, anxiety, depression, OCD, psychosis and behavioral difficulties. Our doctors show how patients can build upon their strengths and work around their weaknesses to be the best version of themselves.
Lorra Garrick has been covering medical and fitness topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer. In 2022 she received a diagnosis of Level 1 Autism Spectrum Disorder. 


Top image: Freepik.com