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Signs of Undiagnosed Autism in Adults

June 7, 2024

As the world at large is learning more about ASD, many adults are starting to recognize the possibility they have undiagnosed autism. While ASD is often associated with childhood, many individuals go through life without a formal diagnosis, independently navigating the complexities of undiagnosed autism in adults.

I’ve considered the possibility of having undiagnosed autism, especially since my sons are diagnosed. My wife sees similarities in my habits. A doctor suggested testing, but I prioritized my children’s support for now. If you’re like me, this article may help you discover the many complexities of undiagnosed autism in adults.

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Do you have an adult child with undiagnosed autism?

Many adults with undiagnosed autism typically fall into the category of high-functioning autism. Although some don’t favor this term in the autistic community, it accurately describes adults who weren’t diagnosed as children.

As our understanding of autism signs evolves, so do efforts to diagnose adults and children. Many adults went undiagnosed because their cases didn’t align with the known symptoms of their time.

Many adults who may suspect they are autistic and haven’t been diagnosed may not know exactly what to do next. Seeking guidance and understanding the range of emotions, from relief to shame, is crucial during this process.

Signs of undiagnosed autism in adults

There are several symptoms of undiagnosed autism in adult women and men. These signs cover social, sensory, communication, and behavioral aspects. Showing these signs doesn’t guarantee an autism diagnosis, but they serve as a starting point for consideration.

Social signs

One social sign is that the person may begin acting like the people they are socializing with. If their friend is bubbly and loud, they may become bubbly and loud. If the friend is sarcastic and humorous, that person may begin acting sarcastic and humorous.

Mimicking is one of many common signs of autism, and that can certainly be true for undiagnosed adults on the autism spectrum. If my wife is correct about me being on the spectrum but undiagnosed, I can certainly attest to this.

I’m more talkative around my more talkative friends. I’m more sarcastic around my more sarcastic friends. I certainly mimic the friends who surround me.

Autistic adults often exhibit rigid behavior, seen in preferences like organizing items in a specific way, similar to obsessive-compulsive disorder. For instance, I arrange my books and movies alphabetically and feel uneasy if things are moved.

Repetitive behavior is another social sign in adults with undiagnosed autism, ranging from simple habits to more complex routines. This can be observed in characters like Sheldon Cooper in The Big Bang Theory, highlighting the discomfort caused by deviation from their routines.

Sensory signs

There are loads of sensory signs that may be connected to any of the five primary senses. For example, autistic adults may be picky eaters or only want to visit certain restaurants. 

Those who crave touch may want deep squeezes or hugs, while others may not like touch. One of my autistic children loves deep-pressure hugs. It’s soothing for him.

As an adult who has questioned if I have undiagnosed autism spectrum disorder, I don’t like tight clothing. I hate the way it feels on my skin. I often buy shirts that are too big or too big because I prefer the looser fit.

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Communication signs

Autistic adults, especially those without an official diagnosis, may have communication difficulties, especially with eye contact and body language.

Some may not like to look others in the eye for too long. In contrast, other people may want to look into the eyes of the people around them constantly.

Autistic adults also may not understand how their body language can contribute to troubles with social interaction. Autistic people can have trouble reading social cues and often struggle with communication skills.

Adults on the autism spectrum may also prefer written communication to oral communication. That’s because it’s easier for them to understand a text or email than a face-to-face conversation or a phone call.

Behavioral signs

Autistic adults may also have plenty of behavioral patterns that are easier to recognize now. Many will fidget in some way.

Turning to my behaviors, I constantly rub my hands together. It’s a behavioral tic I’ve had since I was a kid. It’s often led to people asking if I was cold or excited. I really couldn’t control it.

Other signs of someone on the autism spectrum include over or under-reactions. Some of my family members fly off the handle very easily over things others perceive to be small. I’ve been known to do that as well. Still, other times, my wife will tell people I underreact.

She says I avoid confrontation to “obscene levels” sometimes, such as when a place gets my food order wrong, and I’d rather eat it than send it back.

Other times, when something happens that would make other people angry, I have little to no reaction. I thought I was easy-going, but it could be a sign of autism.

A table of potential signs of autism in adults

How can an adult get an autism diagnosis?

Simply knowing the symptoms of undiagnosed autism in adults isn’t always enough. Getting an autism diagnosis may give you the peace of mind you need.

Instead of self-diagnosing, any adult can seek a formal diagnosis by talking with their doctor or health professional. There is no medical test to diagnose autism, but doctors can review behaviors to make an ASD diagnosis.

Anyone seeking to learn more about autism in adults can schedule a visit. A trained healthcare professional will ask questions and see how you respond. Doctors also often take into account self-reported autism symptoms.

Support for autistic people

If you believe you have autism, but it is undiagnosed, I encourage you to seek out an ASD diagnosis. If you are diagnosed with autism or some other spectrum disorder, support groups are available to help you through your journey. 

You can also reach out to your state or town website. Many will offer support services for autism. Remember, each country, state, and town offers different support services, so it’s important to seek out the ones in your area.

There are also blogs written by autistic individuals who weren’t diagnosed until adulthood. They are trying to share their journey to make it easier for those with autism in a similar situation.

Support for Autistic People

Autism diagnosis isn’t the end of the world

Remember, a lot more is known about autism, especially autism in adults, today than was known just ten years ago. And more is being learned every day.

You or your adult child may have an undiagnosed case of autism. Autism in adults is not the end of the world, just like autism diagnosed in childhood is not the end. Let’s continue learning and growing together.


Q: What does undiagnosed autism look like in adults?

A: Undiagnosed autism in adults may manifest as social challenges, such as mimicking others or exhibiting rigid behaviors, and sensory sensitivities, like aversions to certain textures. Individuals may also engage in repetitive behaviors and prefer routines, potentially indicating traits on the autism spectrum.

Q: What happens if autism goes undiagnosed in adults?

A: Untreated autism alters brain function, making it challenging for individuals to control impulsive behavior and think rationally. This often results in difficulties living independently.

Q: How do you test for undiagnosed autism in adults?

A: Diagnosing undiagnosed autism in adults typically involves a comprehensive assessment by a qualified healthcare professional, considering behavioral observations, interviews, and standardized tests. There is no single definitive test, and the process often evaluates various aspects of an individual’s behavior, communication, and sensory experiences.

Q: How many adults have undiagnosed autism?

A: According to 2023 research, it’s estimated that in 2018, around 463,500 people in England may have been diagnosed with autism. Additionally, there could be between 435,700 and 1,197,300 people who are autistic but undiagnosed, representing 0.77%–2.12% of the English population.


Autism in England: assessing underdiagnosis in a population-based cohort study of prospectively collected primary care data

The misnomer of ‘high functioning autism’: Intelligence is an imprecise predictor of functional abilities at diagnosis

‘Anything but the phone!’: Communication mode preferences in the autism community

The Immediate Effects of Deep Pressure on Young People with Autism and Severe Intellectual Difficulties: Demonstrating Individual Differences

Self-reported autism symptoms in adults with autism spectrum disorders

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