New research shows that almost one-third of children aged between 4 and 8 years who are diagnosed with autism spectrum disorder (ASD) also have attention-deficit/hyperactivity disorder (ADHD). Additionally, those who have both are far more likely to have lower cognitive function, to be more severely impaired socially, and to have greater delays in adaptive functioning than those children with an ASD alone.
The research, conducted at the Baltimore-based Kennedy Krieger Institute, involved 162 participants. Of the total, 63 children were diagnosed with an ASD, of whom 29% showed clinically significant ADHD symptoms. Of the children with both disorders, 61% had significant cognitive delays and more severe autism mannerisms, such as repetitive behaviors, versus 25% of those with an ASD alone. Also, those with both disorders had significantly more problems at school and in their functioning abilities in everyday situations.
Most previous research on the topic used as subjects children who were receiving clinic-based help, which preselects a population more likely to have both problems or more severe impairments. However, this longitudinal child development study used parent reports and included children enrolled in the protocol as toddlers, which is before most cases of ADHD are identified.
Researchers focused specifically on younger children because the earlier this subset of children is identified, the earlier appropriate interventions can be offered, which may, in turn, improve outcomes.