Unraveling Correlation, Causation, and Autism

Conversations around autism and neurodiversity continue to take place among researchers, practitioners, family members, and the broader community. This leads to an increased interest in obtaining information that is thoughtful, accurate, and grounded in research. Over the years, we have highlighted different aspects of autism, and in this blog post, we share resources and recommendations from leading scholars. Together, these materials offer timely perspectives that support and enrich these important conversations.

How Prevalent is Autism?

Once thought to be rare, autism is now recognized as more common. The latest numbers from the Centers for Disease Control and Prevention (CDC) tell us that 1 in every 31 children in the US are on the autism spectrum. This means that almost every classroom is likely to have a child diagnosed with autism. Boys are diagnosed more often than girls, and autism occurs across all racial, ethnic, and socioeconomic groups.

What Causes Autism?

Researchers have not been able to pinpoint a single cause for autism. What they do suggest is that autism likely comes from a mix of genetic and environmental factors. We’ve gathered a few resources that dive deeper into this topic.

Research Literature

• Environmental risk factors for autism: An evidence-based review of systematic reviews and meta-analyses
  • Researchers found that studies of environmental risk factors for ASD published between 2009 and 2016 suggest that while vaccines, maternal smoking, and assisted reproductive technologies are not linked to autism, factors like advanced parental age, certain birth complications, maternal obesity, diabetes, c-section, vitamin D deficiency, and exposure to heavy metals may increase risk. Evidence is still limited and inconsistent, and better-designed studies are needed to clarify how genes and environments interact as risk factors for ASD.
• Recurrence risk of autism in siblings and cousins: A multinational, population-based study
  • In a large study across six countries, researchers assessed the likelihood of an ASD diagnosis for children who were born between 1998-2007 and had an older sibling or cousin with an ASD. They found that children with an autistic sibling or cousin with ASD had an increased risk of being diagnosed with the disorder as well. These findings highlight strong familial recurrence, with risk varying by gender.
• Understanding autism: Causes, diagnosis, and advancing therapies
  • Researchers examined ASD in five areas: prevalence, genetics, early-life environmental risks, biomarkers, and interventions. They noted that ASD is a complex condition influenced by both genes and the environment, and its rising prevalence emphasizes the need for better understanding, early detection, and effective therapies. While researchers are identifying potential biomarkers and new treatments, reliance on behavioral assessments highlight the ongoing gaps in diagnostics and interventions.

Other Resources

• What Causes Autism?
• Is Autism Genetic?

What is Correlation? What is Causation? What’s the Difference?

It is important to understand the differences between association, correlation, and causation.

• Association is a nontechnical term used to describe the general relationship between two variables, such as getting a sunburn while on the beach and eating ice cream. The two events “getting sunburned” and “eating ice cream” both happen at the “beach,” BUT eating ice cream on the beach does not necessarily cause one to get sunburned!
• Correlation is a bit more technical. It is a statistical measure that tells us how closely two things move together. For instance, if ice cream sales go up on hot days, there might be a strong correlation between the two: temperature and ice cream sales.
• Causation is a conclusion of cause and effect between two variables that have been particularly well studied, such as those that show how smoking causes lung cancer.

Remember that “correlation does not imply causation.” Correlations show us that there is a pattern in the data, that the variables we are studying tend to move together, but it does not mean that one variable is causing the other to happen, these might just be coincidental or that there may be other factors linking the two events.

For a quick, easy-to-understand resource on this topic, watch the following video by Matthew B. Courtney, EdD:

Research Literature

• Correlation and causation: A logical snafu
  • Confusion between correlation and causation is common, and observed relationships do not necessarily imply a causal link. Misunderstandings arise when correlations are interpreted as evidence of cause-and-effect, particularly in educational research. Careful reasoning and rigorous methodology are needed to identify true causal relationships.
• Correlation, causation, and confusion
  • Understanding causation and correlation is essential for making sense of data. This paper focuses on practical aspects of these two concepts in medicine, politics, and everyday life. This manuscript also highlights advances in understanding cause-and-effect, drawing from science, statistics, and mathematics, which offer accessible insights despite some remaining limitations.

Other Resources

• Correlation vs. Causation
• The Difference Between Association, Correlation, and Causation
• Scientists Say: Correlation and Causation

This infographic from the European Food Information Council (EUFIC) highlights the differences between correlation and causation.

What are Autistic Children Like?

It is important to remember that autism is a neurodevelopmental disorder that affects each person differently. Each child with autism is unique, with their own strengths and needs, similar to Julia, the orange-haired, twinkly-eyed character in Sesame Street. Autism is a spectrum, and Dr. Stephen Shore reminds us that, “If you have met one person with autism, you have met one person with autism.”

Research Literature

• A lifespan approach to patient‐reported outcomes and quality of life for people on the autism spectrum
  • The authors of this survey study assessed quality of life across the lifespan for children, teens, and adults with autism. Some participants reported a positive quality of life, while others indicated that their lives were not meeting their expectations. Additionally, women and girls reported more difficulties in certain areas compared with men and boys.
• Autism spectrum disorder: Outcomes in adulthood
  • Researchers evaluated existing literature published from January 2015 through September 2016 with a broad focus on social and lifetime outcomes in adults diagnosed with ASD and a sample size greater than 20. This body of research showed limited social integration, poor employment prospects, and high rates of mental health challenges, though findings vary widely due to differences in methods and samples. The authors noted there is little consistent evidence on the factors that support better social and psychological outcomes for individuals with ASD, and research on older adults with ASD remains scarce. More research is needed to understand developmental patterns in adulthood and the influences that shape them.
• Quality of life among school-age children with autism: The Oak Hill School outcomes study
  • This 2-year study of 29 children (8 to 22 years old) at a specialized ASD school revealed that average ratings of participants’ Quality of Life (QOL) remained stable, with some participants experiencing improvement while others’ ratings declined. Gains were more common in younger children with less significant initial ASD characteristics; these were associated with improvements in behavior and social skills. The findings suggest that early intervention targeting social and behavioral skills may enhance QOL. The authors underscore the need for new, qualitative measures to better capture the life experiences of this population.

Other Resources

• ASD Levels of Severity
• Autistic Strengths
• Some Autistic People Report Poor Quality of Life, but Many Do Not
• Understanding the Levels of Autism

This visual from Luna at Autistic Dreams provides an overview of the three functional levels of autism.

We hope these resources offer both useful information and additional perspectives as we continue to learn about autism and neurodiversity. This is an area where knowledge and understanding are always growing, shaped by the contributions of scholars, practitioners, and the lived experiences of the community. We invite you to keep visiting this website for more on this and many other topics that matter in supporting military families of children with disabilities.

References

• Barrowman, N. (2014). Correlation, causation, and confusion. The New Atlantis, 23-44.
• Bent, S., Wahlberg, J., Chen, Y., Widjaja, F., McDonald, M. G., & Hendren, R. L. (2020, July). Quality of life among school-age children with autism: The Oak Hill School outcomes study. Seminars in Pediatric Neurology, 34, 100808.
• Games, P. A. (1990). Correlation and causation: A logical snafu. The Journal of Experimental Education, 58(3), 239-246
• Graham Holmes, L., Zampella, C. J., Clements, C., McCleery, J. P., Maddox, B. B., Parish‐Morris, J., Udhnani, M. D., Schultz, R. T., & Miller, J. S. (2020). A lifespan approach to patient‐reported outcomes and quality of life for people on the autism spectrum. Autism Research, 13(6), 970-987.
• Hansen, S. N., Schendel, D. E., Francis, R. W., Windham, G. C., Bresnahan, M., Levine, S. Z., Reichenberg, A., Gissler, M., Kodesh, A., Bai, D., Yip, B. H. K., Leonard, H., Sandin, S., Buxbaum, J. D., Hultman, C., Sourander, A., Glasson, E. J., Wong, K., Öberg, R., & Parner, E. T. (2019). Recurrence risk of autism in siblings and cousins: A multinational, population-based study. Journal of the American Academy of Child and Adolescent Psychiatry, 58(9), 866–875.
• Howlin, P., & Magiati, I. (2017). Autism spectrum disorder: Outcomes in adulthood. Current Opinion in Psychiatry, 30(2), 69-76.
• Modabbernia, A., Velthorst, E., & Reichenberg, A. (2017). Environmental risk factors for autism: An evidence-based review of systematic reviews and meta-analyses. Molecular Autism, 8, Article 13.
• Wang, M., Zhang, X., Zhong, L., Zeng, L., Li, L., & Yao, P. (2025). Understanding autism: Causes, diagnosis, and advancing therapies. Brain Research Bulletin, 111411.

Image Credit: Storyblocks.com, CC0