More children are being diagnosed with autism, a study by Murdoch Children's Research Institute has found. However, whether autism is becoming more prevalent or being diagnosed earlier is still under question.
Researchers from the Institute studied the development of 10,000 children in two separate waves at two yearly intervals. Half of the children were recruited into the study at birth (0-1 years) and half were recruited into the study in preschool (4-5 years). When the children were 6-7 years and 10-11 years old respectively, parents were asked if their child had been diagnosed with an autism spectrum disorder (ASD) and if so, the age and severity of diagnosis. Children’s quality of life, behavioural strengths and difficulties, vocabulary abilities and intellectual development were also measured.
Researchers found the prevalence of ASD diagnosis before age of seven was higher (2.5 per cent) in the younger age group compared with 1.5 per cent in the older age group. In both groups parents of children with ASD reported their children had poorer quality of life and more emotional and behavioural problems than their non-ASD peers.
“The prevalence of ASD of over two per cent for the younger group is higher than in previous Australian studies,” said lead researcher Professor Katrina Williams, “however, it is still not clear whether the difference in prevalence represents a shift to a younger age of diagnosis or a continued increase in diagnosis.”
Researchers also found most but not all children with moderate to severe ASD (91-93 per cent) or mild ASD (80-88 per cent) had one or more social problems. Interestingly, over 30 per cent of children who did not have ASD were also reported to have one or more social problems.
“While the presence of deficits in social communication reported by both parents and teachers of children with ASD is not surprising, the proportion of children with autism who did not have any social problems was unexpected,” Professor Williams said.
The study showed the majority of children diagnosed with ASD were male; 84 per cent in the younger age group and 81 per cent in the older age group. There were no differences found in maternal or paternal age between groups and socioeconomic status was similar.
Further studies will clarify whether ASD has been diagnosed earlier. Future waves will also provide crucial information about the types and severity of problems experienced during later primary and secondary years by children an ASD.
The study was done in collaboration with researchers from the University of Melbourne and Latrobe University.