Every person’s development unfolds in a unique way. In autistic people, some aspects of development differ from neurotypical patterns—but the differences vary from person to person. Some of those differences remain constant across the life span. Others change. 

Researchers at the University of California, Davis looked at how the brain changes in autistic individuals over the course of a lifetime. They identified close to 200 gene differences between autistic and neurotypical individuals. Some of those genes were linked to differences in the brain’s immune response, inflammation, and neural connectivity—all of which can affect how a person changes with age (Zhang et al., 2023). 

Here's a brief look at how autism traits can evolve as people mature. 

How Autism Can Look and Feel in Early Childhood 

As clinicians and educators, you are likely familiar with the diagnostic criteria for autism. The Centers for Disease Control and Prevention (CDC) notes that delays or differences in developmental milestones may be present in autistic infants and toddlers. Here are some indicators:  

• avoids eye contact 
• doesn’t respond to name or show emotion in facial expressions (by 9 months) 
• doesn’t play interactive games or use a variety of gestures (by 1 year) 
• doesn’t share interests or attention with others (by 15 months) 
• doesn’t seem to notice when someone else is hurt or upset (by 2 years) 
• doesn’t seem to notice or want to interact with other children (by 3 years) 
• doesn’t use imaginative or imitative play (by 4 years) 
• has strongly preferred interests  
• repeats certain words or phrases (a behavior sometimes called echolalia) 
• prefers a predictable order for events, activities, and objects 
• prefers to follow routines exactly or carefully 
• moves in ways that are not neurotypical (spinning, stimming, hand flapping) 
• responds to sensory stimulation in ways that are neurodiverse 

Every autistic child won’t have all these characteristics (CDC, 2022). How autism presents can also be shaped by co-occurring language differences and intellectual disabilities. 

Download the infographic: Early Childhood Development and Beyond 

Other Considerations for Young Children 

As you evaluate each child, it’s important to keep these factors in mind.  

“Motherese” as a Clue 

A study published in 2023 found that autistic toddlers between the ages of 1 and 2 years were less attentive than neurotypical toddlers to “motherese”—a voice tone mothers often use with very young children. Researchers tracked eye movements to measure children’s attention. Autistic toddlers who focused more on motherese tended to have more developed social and language abilities, researchers said (Pierce et al., 2023).  

Age at Identification 

Universal autism screening aims to identify autism in infants and toddlers so behavioral interventions can begin at a young age. Early interventions have been linked to better outcomes. In at least one study, researchers found that toddlers diagnosed between 25 and 41 months had greater developmental delays in several key areas than those diagnosed between 12 and 18 months (Miller et al., 2021).  

Learn more about the autism assessment called "the gold standard." 

How Autism Can Look and Feel in Childhood  

Traits that emerge in the toddler years may continue during later childhood. For some people, new behaviors, experiences, or co-occurring conditions may develop as school interactions present new challenges. For example, autistic students may 

• have a hard time interpreting social cues with friends, 
• take the lead in determining what to talk about in conversation, 
• speak in literal or concrete terms and have trouble understanding figurative language, 
• have some trouble with complex sets of instructions, and 
• become overwhelmed with the stimuli and social demands in classroom settings. 

Learn more about assessing social communication and pragmatic language. 

Data shows the following: 

• Nearly 40% of autistic children have an anxiety disorder which may be related to autism characteristics or to another co-occurring health condition (Lai et al., 2022). 
• Close to 35% also have attention-deficit/hyperactivity disorder (ADHD; Brown et al., 2021). 
• Approximately 27% have sleep disorders (Mutluer et al., 2022). 

• Gastrointestinal problems such as diarrhea, constipation, and feeding problems are much more common among autistic children than in the wider population (Krigsman & Walker, 2021) 

Read about the complex interplay between autism and ADHD. 

How Autism Can Look and Feel in Adolescence   

The core features of autism are the same in teens as they are in children. Even so, as social relationships become more important and puberty places new demands on the mind and body, core features may intensify. Experts say autistic teens may 

• have fewer of the challenging behaviors common among young children;  
• be more likely to have depression than typically developing teens, which can erode self-care, intensify inflexibility, and affect preferred interests (Pezzimenti et al., 2020); 
• behave in ways that put their health at risk (including violence, unprotected sex, self-injury, and unhealthy eating or exercise habits) especially when they feel uncomfortable or unhappy at school or they’re experiencing depression (Sun et al., 2021); and 
• be more likely to experience gender dysphoria or to be gender diverse or transgender (Cooper et al., 2022). 

Challenges to Understand 

As you work with autistic teens, be aware of these potential challenges: 

• When an autistic teen also has intellectual disability, it can increase the likelihood of aggression, weight changes, bathroom accidents, and self-injury (Pezzimenti et al., 2020). 
• Depression symptoms and certain autism traits can overlap. Both can increase irritability, withdrawal, and negative rumination. Both are linked to less emotional facial expression and to executive dysfunction. 
• There’s some evidence that eating disorders such as anorexia and binge eating are more common among autistic individuals (Numata et al., 2021). 

• Some autistic students reported that the biggest challenges of university included the constant pressure to socialize, the tendency to study one subject to the exclusion of others, understanding academic expectations, and sensory overload (Gurbuz et al., 2019).  

Discover assessments to help you identify depression and anxiety in children and teens. 

How Autism Can Look and Feel in Adulthood    

Increasingly, autism is being identified in adults. Whether it’s identified in childhood or in adulthood, autism can present new physical, adaptive, and mental health challenges as people work and live in neurotypically oriented environments.  

The CDC reports that the adult years often carry these additional concerns for autistic people: 

• unemployment or underemployment 
• limited post high school education 
• continued living with family members 
• less opportunity to spend time with friends or in social/community engagement 

When autistic adults have difficulty with employment, it may be related to problems managing, interpreting, or responding to emotions and social situations. These difficulties can also make personal relationships more challenging. Difficulties may exist, in part, because it can be so hard for autistic adults to access mental health services, allied health services, and healthcare transition services (Maddox et al., 2021). 

Areas for Ongoing Support 

Autistic adults may also need extra support in these areas: 

• In adulthood, many autistic people—especially those who don’t have intellectual or language disabilities—learn to suppress repetitive behaviors in social situations. Adapting to neurotypical expectations can cause extra anxiety and even exhaustion. On the plus side, many autistic adults can leverage their preferred interests in their education, hobby, and career choices (Goldstein, 2019).  

• For those assigned female at birth, autism has been linked to a greater risk of endocrine dysfunction, including conditions such as polycystic ovary syndrome, premenstrual syndrome, and some reproductive cancers (Simantov et al., 2022). 

• In early adulthood (20–39 years) and middle adulthood (40–59), sleep may continue to be a problem, especially for people who take certain medications or who have mental health conditions (Joveveska et al., 2020). 

The Role of Camouflage in How Autism Presents     

Camouflaging is a set of skills that enable autistic individuals to appear more neurotypical in social settings. Those skills are usually categorized as 

• assimilation (strategies that help people fit into social environments); 
• compensation (strategies that help people learn and use social behaviors); and 
• masking (strategies that help people hide traits or behaviors). 

People of all backgrounds and identities camouflage from time to time. In one 2022 study, however, researchers found that autistic females tended to score higher on self-report scales measuring all three camouflaging skills. In that study, gender diverse autistic people had higher scores on the compensation subtest. Those diagnosed with autism as adults showed more assimilation and compensation behaviors (McQuaid et al., 2022).  

While camouflaging has perceived benefits, it also has costs. Children, teens, and adults can experience autism burnout, fatigue, and other mental health consequences because of the pressure to adapt to neurotypical expectations in their environments. And camouflaging can be so skillful that it keeps autism from being identified.  

Explore autism assessment best practices here. 

Key Messages    

Autism characteristics and behaviors can change as people mature. While some or all core features of autism may remain present from early childhood onward, the degree of impairment or the outward appearance of some traits and behaviors may change. Understanding how and when these changes may occur can be helpful to those who support autistic individuals. 

AUTISM RESOURCES  

Further Reading on Autism 

• The WPS In-Depth Guide to Autism and ADHD  
• Why So Many Autistic Girls & Women Are Still Missing Out on Early Identification 
• Understanding the Complicated Interplay of Autism and ADHD 
• How Autism and ADHD Can Disrupt Interoception 
• How to Choose the Best Autism Assessment for Your Client 
• Best Practices in Autism Assessment 
• Autism Conversations: Individualizing Educational Interventions with the MIGDAS-2 Evaluation Process 

Videos and Webinars on Autism 

• How Cyberbullying Impacts Students On and Off the Autism Spectrum 
• Conversation Over Labels: A Better Way to Understand Autism 
• Autism Spectrum Brains 'Get Energy' from These Things 

Research and Resources: 

Brown, K. A., Sarkar, I. N., & Chen, E. S. (2021). Mental health comorbidity analysis in pediatric patients with autism spectrum disorder using Rhode Island medical claims data. AMIA Annual Symposium Proceedings. AMIA Symposium, 2020, 263–272. 

Centers for Disease Control & Prevention. (2022 March 28). Signs and symptoms of autism spectrum disorder.  https://www.cdc.gov/ncbddd/autism/signs.html 

Centers for Disease Control & Prevention. (2022 April 6). Autism spectrum disorder in teenagers & adults. https://www.cdc.gov/ncbddd/autism/autism-spectrum-disorder-in-teenagers-adults.html

Cooper, K., Butler, C., Russell, A., & Mandy, W. (2022). The lived experience of gender dysphoria in autistic young people: A phenomenological study with young people and their parents. European Child & Adolescent Psychiatry, 1–12. Advance online publication. https://doi.org/10.1007/s00787-022-01979-8 

Goldstein, Sam. (2019). Current trends in autism spectrum disorder across the lifespan. https://www.youtube.com/watch?v=o--_q_Fq9R4 

Gurbuz, E., Hanley, M., & Riby, D. M. (2019). University students with autism: The social and academic experiences of university in the UK. Journal of Autism and Developmental Disorders, 49(2), 617–631. https://doi.org/10.1007/s10803-018-3741-4 

Jovevska, S., Richdale, A. L., Lawson, L. P., Uljarević, M., Arnold, S. R. C., & Trollor, J. N. (2020). Sleep quality in autism from adolescence to old age. Autism in Adulthood: Challenges and Management, 2(2), 152–162. https://doi.org/10.1089/aut.2019.0034 

Krigsman, A., & Walker, S. J. (2021). Gastrointestinal disease in children with autism spectrum disorders: Etiology or consequence? World Journal of Psychiatry, 11(9), 605–618. https://doi.org/10.5498/wjp.v11.i9.605 

Lai, A. G., Chang, W. H., & Skuse, D. (2022). Autism and mental illness in children and young people require standardised approaches for assessment and treatment. The Lancet Regional Health. Europe, 16, 100360. https://doi.org/10.1016/j.lanepe.2022.100360 

Maddox, B. B., Dickson, K. S., Stadnick, N. A., Mandell, D. S., & Brookman-Frazee, L. (2021). Mental health services for autistic individuals across the lifespan: Recent advances and current gaps. Current Psychiatry Reports, 23(10), 66. https://doi.org/10.1007/s11920-021-01278-0  

McQuaid, G. A., Lee, N. R., & Wallace, G. L. (2022). Camouflaging in autism spectrum disorder: Examining the roles of sex, gender identity, and diagnostic timing. Autism, 26(2), 552–559. https://doi.org/10.1177/13623613211042131 

Miller, L. E., Dai, Y. G., Fein, D. A., & Robins, D. L. (2021). Characteristics of toddlers with early versus later diagnosis of autism spectrum disorder. Autism, 25(2), 416–428. https://doi.org/10.1177/1362361320959507 

Mutluer, T., Aslan Genç, H., Özcan Morey, A., Yapici Eser, H., Ertinmaz, B., Can, M., & Munir, K. (2022). Population-based psychiatric comorbidity in children and adolescents with autism spectrum disorder: A meta-analysis. Frontiers in Psychiatry, 13, 856208. https://doi.org/10.3389/fpsyt.2022.856208 

Numata, N., Nakagawa, A., Yoshioka, K., Isomura, K., Matsuzawa, D., Setsu, R., Nakazato, M., & Shimizu, E. (2021). Associations between autism spectrum disorder and eating disorders with and without self-induced vomiting: An empirical study. Journal of Eating Disorders, 9(1), 5. https://doi.org/10.1186/s40337-020-00359-4

Pezzimenti, F., Han, G. T., Vasa, R. A., & Gotham, K. (2019). Depression in youth with autism spectrum disorder. Child and Adolescent Psychiatric Clinics of North America, 28(3), 397–409. https://doi.org/10.1016/j.chc.2019.02.009

Pierce, K., Wen, T. H., Zahiri, J., Andreason, C., Courchesne, E., Barnes, C. C., Lopez, L., Arias, S. J., Esquivel, A., & Cheng, A. (2023). Level of attention to motherese speech as an early marker of autism spectrum disorder. JAMA Network Open, 6(2), e2255125. https://doi.org/10.1001/jamanetworkopen.2022.55125 

Simantov, T., Pohl, A., Tsompanidis, A., Weir, E., Lombardo, M. V., Ruigrok, A., Smith, P., Allison, C., Baron-Cohen, S., & Uzefovsky, F. (2022). Medical symptoms and conditions in autistic women. Autism, 26(2), 373–388. https://doi.org/10.1177/13623613211022091

Sun, Y. J., Xu, L. Z., Ma, Z. H., Yang, Y. L., Yin, T. N., Gong, X. Y., Gao, Z. L., Liu, Y. L., & Liu, J. (2021). Health-related risky behaviors and their risk factors in adolescents with high-functioning autism. World Journal of Clinical Cases, 9(22), 6329–6342. https://doi.org/10.12998/wjcc.v9.i22.6329

Zhang, P., Omanska, A., Ander, B. P., Gandal, M. J., Stamova, B., & Schumann, C. M. (2023). Neuron-specific transcriptomic signatures indicate neuroinflammation and altered neuronal activity in ASD temporal cortex. Proceedings of the National Academy of Sciences of the United States of America, 120(10), e2206758120. https://doi.org/10.1073/pnas.2206758120