During early childhood, girls with autism tend to show greater reduction and less rise in their autism symptom severity than boys with autism, a UC Davis MIND Institute study has found.
Early childhood is a period of substantial brain growth with critical ability for learning and development. It also is the typical time for an initial diagnosis of autism and the best time for early intervention. In the U.S., about 1 in 54 children has been identified with autism, with four times as many boys with autism as girls.
Previous studies indicated inconsistent results in terms of changes in autism severity during childhood. The general sense was that the severity of autism at diagnosis would last a lifetime.
The MIND Institute’s study, published May 14 in the Journal of Autism and Developmental Disorders, evaluated changes in symptom severity in early childhood and the potential factors associated with those changes. It included 125 children (89 boys and 36 girls) with autism from the Autism Phenome Project (APP), a longitudinal project in its 14th year at the MIND Institute. The children received substantial community-based autism intervention throughout their childhood.
The researchers used a 10-point severity measure called the ADOS Calibrated Severity Score (CSS) derived from the Autism Diagnostic Observation Schedule (ADOS), the gold standard assessment tool in autism research. They computed a severity change score for participants as the difference between their ADOS CSS scores at age 6 and at age 3. A change of two points or more was considered a significant change in symptom severity.
The study classified participants based on their severity change score into a Decreased Severity Group (28.8%), a Stable Severity Group (54.4%) and an Increased Severity Group (16.8%). One key finding was that children’s symptom severity can change with age. In fact, children can improve and get better.
“We found that nearly 30% of young children have less severe autism symptoms at age 6 than they did at age 3. In some cases, children lost their autism diagnoses entirely,” said David Amaral, a distinguished professor of psychiatry and behavioral sciences, faculty member at the UC Davis MIND Institute and senior author on the study.
“It is also true that some children appear to get worse,” Amaral said. “Unfortunately, it is not currently possible to predict who will do well and who will develop more severe autism symptoms and need different interventions.”
Girls and boys might be characterized with different manifestations of autism symptoms. Girls might show better developmental results than boys in cognition, sociability and practical communication skills.
“We found that girls with autism decrease in severity more than boys and increase in severity less than boys during early childhood,” said Einat Waizbard-Bartov, a graduate researcher at the MIND Institute and the first author of the paper.
