Changes Seen in Autism Symptoms and Cognition From Adolescence to Adulthood

August 26, 2020

Population-Based Study Aims to Identify Features to Predict Functioning Level in Later Life

Planning a meaningful future for a child with autism can give even the calmest parents anxiety. Especially when they are tasked with making educational, employment and/or vocational decisions while research gaps regarding autism symptoms experienced in adulthood exist. A recent SafeMinds Shares article reported on a new study that examined changes in autism symptom severities from preschool to early elementary school years. The study found around half (54.4%) of the young participant’s autism severities remained unchanged and about half of the cohort experienced a change. Twenty-eight percent saw a reduction in their autism symptoms while, sadly, 16% had their symptoms worsen.

But what about predicting changes in later developmental years? A study published earlier this year in the Journal of American Academy of Child Adolescence Psychiatry may help provide anxious parents with guidance with this issue. This population-based longitudinal study from Great Britain is the first to investigate autism symptom changes in late childhood through early adult life. Using data from the Special Needs Autism Project (SNAP), the study’s authors examined latent growth curve models at three time points 12, 16, and 23 years. At each of these intervals, IQ and parent reported Social Responsiveness Scale Autism Symptoms were measured in order to plot trajectory changes of development and functioning throughout these years.

The study’s results contained a few surprises. On an extremely positive note, the 126 participants experienced an unexpected and significant IQ increase by a mean of 7.48 points. Since IQ tests are normed for all ages, this considerable rise would not be seen in the general population. This increase suggests that there is continued cognitive development in the adolescent/early adulthood period for individuals with autism that is not experienced in typically developing individuals.

Interestingly, the researchers also found that participants who had a history of early language regression exhibited significantly greater IQ gains during this time period. The authors suggest that individuals who experienced early regression may continue to have a different developmental course into their second decade of life compared to those with autism who did not have a history of regression.

While there was good news for cognitive functioning, there was disappointing news when it came to autism symptoms. Between ages 12 and 23 years, most of the study’s participants did not show any improvements. Their autism symptoms, for the most part, remained the same. However, there was one exception, individuals who attended mainstream schools showed fewer autism disorder symptoms at age 23 compared to those who were educated in specialist settings. In fact, the authors maintain that their research points to school experience trumping IQ when it comes to the effect on autism symptoms over the course of development.

The study’s conclusion states, “In summary, the finding that mean IQ increases from late childhood to adult life points to ongoing development in the second decade of life and the importance of future research to identify experiences and interventions promoting cognitive development in people with autism. In particular, the role of educational and social experiences, for both cognitive and social communicative development, in adolescence and adult life needs further study to improve our understanding of how best to support people with autism across the lifespan.”

While this study may not have every answer that worried parents have about the future for their children on the spectrum, there are a few important findings from this research. Parents should take solace that there is still time for IQ increases during the second decade of life. Additionally, for parents of an individual who experienced an early regression, there may be even a greater opportunity for their child’s IQ to increase later in life. Lastly, it appears that a mainstream school placement may be critically important in reducing autism symptoms later on in life.


SafeMinds Shares. Autism Severity Can Change During Childhood. August 10, 2020.

Einat Waizbard‐Bartov, Emilio Ferrer, Gregory S. Young, Brianna Heath, Sally Rogers, Christine Wu Nordahl, Marjorie Solomon, David G. Amaral. Trajectories of Autism Symptom Severity Change DuringEarly Childhood. Journal of Autism and Developmental Disorders. May 2020.

Emily Simonoff, Rachel Kent, Dominic Stringer, Andrew Pickles, Tony Charman, Gillian Baird. Trajectories in Symptoms of Autism and Cognitive Ability in Autism from Childhood to Adult Life: Findings From a Longitudinal Epidemiological Cohort. Journal of American Academy of Child Adolescence Psychiatry. January 2020.

Gillian Baird, Emily Simonoff, Andrew Pickles, Susie Chandler, Tom Loucas, David Meldrum, Tony Charman. Prevalence of Disorders of the Autism Spectrum in a Population Cohort of Children in South Thames: the Special Needs and Autism Project (SNAP). Lancet. July 15, 2006.

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