IQ is generally expected to remain stable over time, but new research suggests that the measure for people with autism increases significantly in adolescence and early adulthood.
In a long-term study with 126 people in the spectrum, the IQ values between the ages of 12 and 23 increased by an average of 7.48 points. During the same period, the autism symptoms remained unchanged in the subjects examined.
The findings, published on Friday in the Journal of the American Academy of Child and Adolescent Psychiatry, looked at children who were part of the UK Special Needs and Autism Project, which was regularly followed up with a group of children from the spectrum in England to assess how they have changed.
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The study included children with severe intellectual disabilities through to those with IQs in the upper range. They were graded at ages 12, 16, and 23 years.
IQ tests are standardized for each age, so results are unlikely to change as children get older. The increases in the children with autism studied were significant enough to be noticed by parents and teachers, according to the researchers.
The study found that IQ gains were greatest in those with a history of early language regression. In this group the increase was 15.4 points compared to only 6.6 points for people without regression.
“While we cannot rule out improvement, it is partly due to increased motivation or the ability to access IQ tests, rather than an intrinsic improvement in learning ability. However, these alternatives are also important functioning aspects that can open up new educational and employment opportunities for people with autism, ”said Emily Simonoff, Professor of Child and Adolescent Psychiatry at King’s College London, who led the study.