The characteristics of autism can change significantly from ages 3 to 11, research finds

The severity of the symptoms of autism in children can change significantly between the ages of three and eleven, researchers from the UC Davis MIND Institute have found. 

Children in the study were all part of the MIND Institute’s long-term Autism Phenome Project (APP), and the findings in the recent study build on previous work by the same researchers on changes to autism characteristics in early childhood. 

Professor David G. Amaral and graduate student Einat Waizbard-Bartov were interviewed in relation to their findings. An extract of their conversation appears below . 

Study findings 

In the 2020 study, which focused on children from three to six years of age researchers explored symptom severity change only during early childhood, Ms Waizbard-Bartov explained.

“Then, because the APP is a long-term study, we were able to extend our observations all the way up to age 11. When we started this process, we thought that symptom severity remained stable across time, based on several previously published studies. But what we saw, surprisingly, is that about half of the kids changed significantly in early childhood; they either increased or decreased in terms of the severity of symptoms.” 

When the researchers extended the study to middle childhood, “we found basically the same. In fact, a slightly higher percentage of kids’ symptoms changed into middle childhood.”

These findings are significant because, based on the literature, the prevailing wisdom was that “however severe you were at diagnosis, that’s how you’d be for the rest of your life. These two studies showed that’s not necessarily the case.”

Measurement and trajectory 

Researchers used a well-established, objective measure called the ADOS [Autism Diagnostic Observation Schedule]. 

“It is a clinician-administered test that involves observation of a child carrying out different behaviors. It’s the best possible measure for looking at severity across time,” Professor Amaral  explained. 

“The children are clinically evaluated at different ages across time for social interaction, communication and other behaviors. The ADOS provides a score called the Calibrated Severity Score which allows comparison across ages and in children with different levels of challenges.”

To understand autism, he continued, “you can’t simply take a snapshot at any one point in time. Just like children develop over time, the features of autism also develop and change over time.”

Nearly a third of children’s symptoms decreased with time 

Approximately 30 per cent of the children in the study decreased by two or more ADOS severity scores across childhood. 

“This is a metric that runs from 1-10, so a two-point change is a substantial change,” Ms Waizbard-Bartov explained.
“It means that the symptoms of autism, which can be quite impairing when they are severe, are decreasing over time. For these children, their autism affected their daily lives less.”

The relationship between IQ and symptom severity was mostly significant during early childhood, she continued. 

The children who had higher IQs at three and six years of age decreased in their symptoms in early childhood and also gained in IQ during early childhood. The children who increased in symptom severity during early childhood had lower IQs that tended to remain stable. 

“IQ is a much better predictor of symptom-severity change at earlier ages.We also found that kids whose symptom severity was increasing were experiencing a decrease in the rate at which they gain adaptive functioning skills, like the ability to be independent or be social with other kids,” she added. 

The study was published in Autism Research and may be accessed here. For the full conversation transcript please see here.