Children with ADHD (attention deficit hyperactivity disorder) are significantly more likely to have autism traits compared to other kids, researchers found in a study published in the journal Pediatrics.
A team from Massachusetts General Hospital, Harvard Medical School, and SUNY Upstate Medical University reported that 18% of kids with ADHD showed an autism trait profile in their study compared to 0.87% of the controls (kids without ADHD).
Joseph Biederman, MD, and team found that children with ADHD plus autism traits had more severe psychological problems, as well as difficulties at school, socially and with their families, compared to those with ADHD but without autism traits.
Previous studies had reported ADHD symptoms in children with an ASD (autism spectrum disorder).
A research team at the Kennedy Krieger Institute wrote in the journal Autism: The International Journal and Practice (June 2013, issue) that almost one third of children with ASDs also showed clinically significant symptoms of ADHD.
In August, 2011, a Canadian study found that several genes linked to ADHD overlap with some of the genes associated with autism.
Those with ADHD plus autistic traits had more problems
In this latest study, the authors reported that children with both ADHD and autistic traits were more likely to be shunned by their peers, have problems with siblings, and get into fights compared to ADHD children with no ASD traits.
Dr. Biederman explained that language disorders, anxiety disorders, mood disorders and other psychiatric conditions were much more common among children with both ADHD and autistic traits.
The study involved 469 children. 242 of them had ADHD and 227 did not (controls). They were aged from eight to 14 years. Their parents were asked about their child's behavior and health.
Although none of the children in the study had been diagnosed with autism, the team wanted to find out whether any of them had some autism traits, such as social disability and withdrawnness.
If autism traits are found, it does not mean the child has an ASD.
Amelia Kotte PhD, an ADHD researcher, said it is important to be able to identify ADHD children who also have autism traits, because their treatment will be different from what other children with ADHD receive. Those with autism traits require a stronger focus on social skills.
In an Abstract in Pediatrics, the authors concluded:
"A substantial minority of ADHD children manifests ATs (autistic traits), and those exhibiting ATs have greater severity of illness and dysfunction."
Core ADHD symptoms are part of autism
In an article published in 2012 in the journal Research in Autism Spectrum Disorders, researchers from the Department of Psychiatry, Penn State College of Medicine explained that children with autism can easily be distinguished from kids with ADHD based on their symptoms profiles.
The core ADHD symptoms - hyperactivity, impulsivity and attention deficit - are part of autism.
The authors added that ADHD and autism have similar underlying neuropsychological deficits.
However, they emphasized that autistic symptoms are not common in ADHD.
As ADHD symptoms are commonly found within the spectrum of autism symptoms, children with autism may be misdiagnosed with ADHD initially.
However, in this study they found that none of the children with ADHD had symptoms of autism. "All children with autism had 15 or more of the 30 Checklist for Autism Spectrum Disorder symptoms, and none of the children with ADHD did."