Undiagnosed Autism in Adults: Why It Can Be Missed and How to Seek Answers

Getting a late diagnosis of autism spectrum disorder (ASD) can be a total game-changer. It can impact your entire sense of identity and how you interact with the world. It can also bring a profound feeling of relief while answering many questions, including: Why did it take so long to figure this out? 
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For Tobey, 41, the turning point after his clinical diagnosis was a deep sense of self-acceptance. “Once I stopped burning energy on hiding and masking, I was able to redirect that effort into becoming my true self,” he says. “The difference has been huge.” 
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Tobey is far from the only adult who spent decades living with undiagnosed autism. In fact, the rate of autism in adults has been steadily increasing. Between 2011 and 2022, the autism diagnosis rate increased by 450% among 26-to-34-year-olds alone. 
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Today, the Centers for Disease Control and Prevention (CDC) estimates that one in 45 adults is autistic, and even more are likely undiagnosed. An improved understanding of the condition (and acknowledgement that autism is a true spectrum, rather than a collection of specific traits) led to both updated diagnostic criteria and a rise in diagnoses.
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Whether you’re late-diagnosed yourself, are considering getting an adult autism evaluation, or are still curious about whether you might be autistic, you probably have a lot of questions. 
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(Prosper Health answers many of those initial questions about what autism can look like in adults here.)
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In this article, however, we’ll provide a neurodivergent-affirming breakdown of why many adults receive a late autism diagnosis. This includes why autism is missed in certain groups (women, LGBTQIA+, BIPOC, young adults), and how it gets mistaken for other conditions, as well as how to access support. 

When autism is diagnosed in adulthood, it doesn’t mean that someone only developed the signs of autism later in life. They had been living with undiagnosed ASD since childhood, and belong to what experts call “the lost generation.” 

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“These adults missed out on services, and therefore experience pretty significant challenges, including mental health conditions,” explains Jacqueline Shinall, PsyD, a clinical psychologist at Prosper Health. 

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There are many reasons for “lost-generation” autism: In the past, autism was primarily viewed through the lens of the “classic” presentation (the stereotypical autistic male), so more subtle signs were often missed. “In some cases, this relates to the broadening of the autism spectrum, as there are some individuals who would not have met the diagnostic criteria in the past, but now do meet the criteria as it has evolved and our understanding of autism continues to improve,” says Heather Flynn, PhD, a licensed clinical psychologist specializing in autism assessments for individuals of all ages.

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Other factors can include:

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• Masking: Many children learn how to “mask” or camouflage autistic traits by mirroring or mimicking peers. Masking may appear as though the individuals are coping well, but this practice can create autistic burnout or feelings of inauthenticity and isolation. 

• Good behavior and grades: When children are performing well academically and not acting out in class, it’s often assumed that they aren’t autistic, despite the struggles they experience internally

• Cultural and socioeconomic shifts: Because the initial autism diagnostic criteria was developed largely based on Caucasian boys, there has been a poor understanding of how it presents across different cultures.

• ADHD diagnosis: Before the release of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in 2013, doctors were unable to diagnose autism and ADHD simultaneously, and had to choose between one or the other — even if the person met diagnostic criteria.

• Wider acceptance: While prior stigma may have prevented some people from seeking a diagnosis for themselves or their child, more people now recognize that undiagnosed autism in adults exists.

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Below, we further examine the reasons behind undiagnosed autism in adults. Keep in mind that these categories aren’t mutually exclusive, and that these explanations can still apply to people who don’t fit neatly into one group. 
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Why autism is often missed in women

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Autism in women and people who are assigned female at birth (AFAB) can present differently. 

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“It was initially diagnosed mostly in boys, and the diagnostic criteria was largely understood in how it presented in boys,” Dr. Shinall explains, causing many who were AFAB with autism to go years undiagnosed or misdiagnosed. 

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Other reasons why women may have a missed autism diagnosis include:

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• Masking: Some research suggests autistic girls and women may camouflage autistic traits more often or in different ways than autistic boys and men, which can make those traits less apparent to others.

• Interests that appear socially typical: Some autistic girls and women have highly focused interests whose subject matter may resemble their peers’ interests, making the intensity or function of the interest easier to overlook.

• Dismissed as shy: Women and girls tend to be written off as “just being shy” rather than acknowledging their differences in social communication. 

• More social pressure: “Social expectations can also lead to more girls internalizing feelings of distress, confusion, etc. because it was more common for males to act out,” Dr. Shinall says.

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If any of these examples sound familiar, it may be worth bringing up with your healthcare provider, even if you were never flagged as a child. 
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Why autism is often missed in LGBTQIA+ individuals

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Like other autistic adults, LGBTQIA+ individuals may receive a late diagnosis. “I can see people getting overlooked for ‘feeling different’ from others believing it was due to gender dysphoria or sexuality when it was also due to autism,” Dr. Shinall says. 

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While recent research has shown that autistic individuals are more likely to identify as LGBTQIA+ than the neurotypical population, the diagnosis is complicated by measurement tools being less sensitive to the intersection of gender identity, sexual orientation, and race.

According to a 2020 study published in the Journal of Autism and Developmental Disorders, however, LGBTQIA+ individuals indicated that they “had significantly higher rates of mental illness, poor physical health days per month, and smoking compared to straight, cisgender respondents with [autism spectrum disorder].” 

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If you’re an LGBTQIA+ individual who was “overlooked” when you were younger, especially after reading the aforementioned studies, you may want to revisit the “feeling different” conversation with a clinical provider. 
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Why autism is often missed in BIPOC individuals

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Racial and ethnic disparities in autism identification have been documented for decades. Although gaps in overall identification rates have narrowed or shifted in recent years, inequities can remain in how early autism is recognized, who is referred for evaluation, and access to culturally responsive assessment and services.

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• Diagnostic criteria: The diagnostic criteria for autism was developed largely based on white males. As a result, differences in social communication or behaviors are attributed to cultural differences rather than an actual developmental difference (i.e. autism). 

• Misdiagnosis: Autism in BIPOC populations is often misdiagnosed and confused with other conditions. According to a 2025 study published in BMJ Quality & Safety, “culturally inequivalent assessment measures” can cause misdiagnosis and delayed diagnosis.

• Fewer childhood diagnoses: Historically, BIPOC children were less likely to receive an autism diagnosis, but recent estimates suggest they are now diagnosed at higher rates than white peers. Despite this progress in identification, BIPOC children with autism still often have limited access to support services.

• Cultural differences: Some misdiagnoses are the result of language barriers and cultural differences. 

• Lack of research: BIPOC individuals are often underrepresented in autism research. Additionally, although conversations around the impact of racial and ethnic discrimination on BIPOC with autism have been growing in the field, this data hasn’t been reflected in the research yet. 

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If you’re a BIPOC individual who can relate to anything you’ve read in this section, it may be time for a conversation with your healthcare provider. 
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Why it might be surfacing only now

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Many young adults may go through childhood and adolescence without a diagnosis because things like school structure, family routines, and living at home might have camouflaged the autistic traits that were always there.

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This invisible scaffolding, in the form of parents and/or caregivers, may have covered executive-functioning gaps, enforced a schedule, and limited the number of novel social situations a person had to navigate on any given day.

But when these young adults shift to college, their first apartment, and/or full-time work, the scaffolding is suddenly gone. Now, traits once supported by parents and teachers might be more visible and overwhelming. 

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Those missed homework assignments weren’t a big deal in high school, but now you’re responsible for missed rent payments and/or work deadlines. Perhaps that preference for solitude now feels more isolating because your family isn’t around 24/7.

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This overall feeling of the rug being pulled out from under you is often the moment young adults may start searching phrases like “undiagnosed autism in young adults” — or more specifically, “undiagnosed autism in young adult male.”

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Such a sudden loss of structure may look like a new problem at first, but it could actually be revealing an old one that was there all along.

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Although it’s common for autistic adults to have co-occurring mental health conditions, many may also spend years in therapy or on medication for anxiety, depression, obsessive-compulsive disorder (OCD), or are told they have borderline personality disorder (BPD), before autism ever enters the conversation. 

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This can happen for several reasons: First of all, overlapping autistic traits like emotional dysregulation, social withdrawal, or different types of thinking patterns can look identical to several other conditions. Secondly, clinicians without autism-specific training may not screen for it, especially for adults. Also, anxiety and depression are frequently secondary responses to years of unaccommodated autistic experience; so while those diagnoses may not be wrong, they’re not taking the entire picture into consideration.

There are also higher rates of trauma experienced by autistic children and adults than in non-autistic populations, including some with trauma associated with missing an autism diagnosis. 

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“I agree with the statement that ‘society doesn’t produce untraumatized autistic people,’” says Aaron, 34, who received a clinical autism diagnosis in 2025. “I know a few people who have complex PTSD (CPTSD) who attribute it to their autistic experience.” He says that he has experienced trauma himself, largely from his sensory difficulties and being unaccommodated.

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If you've been treated for one of these conditions without any of them fully explaining your experience, or you've moved through multiple diagnoses without one ever quite fitting, that's reason enough to ask a provider specifically about autism.

After living with undiagnosed autism for most of your life, finally getting a diagnosis may be a relief. At the same time, it can come with several obstacles — as well as benefits.
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The emotional and practical impact

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Being diagnosed with autism as an adult can be a very emotional experience. Dr. Shinall and Dr. Flynn share that people are likely to feel:

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• Relief: It’s the feeling of knowing your concerns and experiences are being taken seriously, and there can be clear steps to accessing support.

• Validation: Finally feeling that there’s not something “wrong” with you, and understanding that your brain operates differently.

• Grief: Experiencing grief for “what could have been,” had you gotten the diagnosis when you were younger.

• Anger: Anger that your diagnosis wasn’t provided sooner and that people in your life didn’t realize you were struggling.

• Shame: A sense of shame related to feelings of self-doubt, worthlessness, or inadequacy connected to your perception of your autistic traits.

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Tobey’s adult autism diagnosis brought a mix of relief and grief. “Relief because I finally understood myself,” he explains. “Grief because I looked back on decades of unnecessary struggle. Over time, the relief has taken over, but the grief is still there in moments.”

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When Jessica, 37, was diagnosed with autism last year, she felt relieved more than anything. “I had been considering this for so long that I almost felt crazy and was stressed about what the other possibilities could be if this wasn't autism,” she says. “So when that was the diagnosis, I was so relieved and felt like things just made way more sense.”

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The autism shame spiral

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Some people who have late-diagnosed autism may experience something called an “autism shame spiral.” This is an informal phrase sometimes used to describe a recurring pattern of negative self-judgment related to autistic experiences. It is not a diagnosis or established clinical construct, and people may experience shame for many different reasons.

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Dr. Shinall describes an autism shame spiral as when “someone who has had experience of accidentally saying upsetting things to others may then avoid going to an event where they would have to talk to other people.” The spiral builds because “they then feel bad about avoiding [the event] and continue to feel bad that they sometimes say upsetting things.” 

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Access and cost barriers

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From a practical standpoint, access to services and cost, continues to be a barrier for autistic adults. “There are very few providers who specialize in adult autism assessments, and even fewer that accept insurance,” Dr. Shinall explains. Out-of-pocket costs for adult autism screenings and subsequent evaluations can cost more than $5,000 in some places in the United States, which is not realistic for many people, she notes.

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The two greatest barriers Aaron faced when getting his autism diagnosis were time and money. “I self-diagnosed around July or August 2020 when a lot of services were still affected by Covid,” he says. Although he tried to schedule an evaluation with a clinic at that time, “they had a waitlist and it never happened.” Financial constraints, even with insurance, prevented Aaron from getting a clinical diagnosis until five years later.

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What an autism diagnosis can offer

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Adults diagnosed with autism have the unique opportunity to reframe their negative past experiences and be more accepting of their autism diagnosis and themselves. 

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A sense of self-understanding and belonging

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“Many adults report a lifelong feeling of being ‘different’ and even feeling like an ‘alien’ in their own family,” Dr. Shinall says. “Getting an autism diagnosis allows them to understand that they do indeed belong and that their brain is just wired a little differently.” 

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Finally receiving an autism diagnosis as an adult gave Tobey a framework and language he had been missing his whole life. “Suddenly I wasn’t broken, I was autistic,” he says. “That shift opened doors to community, books, resources, and most importantly self-acceptance.” It also shifted his identity. “I went from seeing myself as someone constantly failing to fit in, to recognizing that I had been succeeding in spite of huge invisible challenges,” he says.

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The most significant benefit Aaron received from his diagnosis was understanding what his experience is and having a name for all of it. “Learning about executive dysfunction, demand avoidance, time blindness, to name a few, has completely reshaped how I see myself.”

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Connection and community

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For Jessica, an autism diagnosis allowed her to discover more community and connection than ever before. “I joined some neurodivergent business owners’ groups on Facebook and that has been super helpful,” she says. “Even if we can't come up with a solution, it's so nice to know that I'm not the only one trying to navigate the world like this and having these types of situations pop up.”

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Accommodations and understanding at work

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Another diagnostic benefit is workplace accommodations. These can vary widely, but some might include:

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• Lowered lighting
• Reduced sound
• Breaks from busy or loud spaces
• Having a separate office
• Having a more flexible work schedule (like being able to work from home some days)

Whether you're a recently diagnosed autistic adult, are in the process of seeking a diagnosis, or are still weighing your options, help is available. The good news is you don’t need an autism diagnosis to receive support.  

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• Education: Turn to trusted sources of information to learn more about living with autism. “At Prosper Health, we offer a post-diagnostic education group for newly diagnosed adults to help answer questions and discuss the ‘what now,’” notes Dr. Shinall.

• Therapy: Dr. Shinall highly recommends seeking out a neurodivergent-affirming therapist, which Prosper Health also offers. These knowledgeable and compassionate clinicians provide tailored therapy to help you navigate common challenges among autistic adults, including coping with the emotional impact of receiving a late autism diagnosis.

• Support networks: Online and community support groups can help you connect with other autistic people so you can share experiences and resources. Some groups specialize in newly diagnosed autism in adults.

• Formal autism evaluation: Prosper Health can guide you through your diagnostic journey via telehealth assessments from providers who specialize in working with autistic adults. Assessments (and therapy) with Prosper Health are 100% virtual and are covered by insurance in most cases. If you’re ready to get started, get in touch to be connected with a neurodiversity-affirming clinician within days.

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Remember: a late diagnosis can be valid and empowering.

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Can you be autistic and not know it?

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Yes, it is possible to be autistic and not know it until adulthood. This is due to several reasons: One is an improved understanding of the condition in recent years, which led to both updated diagnostic criteria and a rise in diagnoses. Other reasons can include masking since childhood, good behavior and grades, as well as co-occurring diagnoses with overlapping traits like ADHD, anxiety, and depression, which may have caused autism to be overlooked. 
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What are the signs of autism in adults?

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The signs of autism in adults vary by individual, but when conducting an evaluation, clinicians will look for characteristics in the following categories:

• Social interaction and communication differences
• Self-soothing and self-regulatory behaviors like “stimming”
• Sensory and processing differences
• Special interests and activities
• Emotional regulation and cognitive traits
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What age is considered a late diagnosis for autism?

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There is no universally accepted age cutoff for a “late” autism diagnosis. The term generally refers to autism that is recognized substantially later than is typical, including diagnoses made in adolescence or adulthood. This is because the diagnosis was missed throughout the entire childhood, depriving the child of potential services, support, and accommodations. 
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How is autism diagnosed in adults?

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The diagnostic process for adult autism varies by provider, but at Prosper Health, an evaluation begins with written assessments. Clients, as well as a loved one/caregiver, first complete several standardized assessments that analyze their social communication, interests, behaviors, habits, and day-to-day functioning.

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Then, a Prosper clinician will conduct a structured clinical interview (usually over multiple appointments), followed by a session to discuss the clinician’s findings.