ADHD News & Research

Children with Tourette Syndrome Meet Criteria for Autism

More than 20 percent of children with Tourette Syndrome may also exhibit symptoms that appear to warrant an autism diagnosis — though this overlap doesn’t necessarily mean autism spectrum disorder is present, researchers warn.

July 21, 2017

A significant segment of children with Tourette Syndrome — more than 20 percent — also meet the diagnostic criteria for autism, a new study finds. But researchers aren’t convinced that the two conditions truly overlap at such a high rate, and wonder if the staggering overlap actually reflects clinicians’ “difficulty in discriminating complex tics and OCD symptoms from ASD symptoms.”

Tourette Syndrome is a tic disorder characterized by severe vocal and motor tics. Autism Spectrum Disorder is a developmental disorder that can lead to social difficulties, repetitive behavior, and academic delays. Since both conditions can — and often do — coexist with other mental health and behavioral issues, researchers at the University of California, San Francisco, examined more than 500 children and adults with Tourette Syndrome to observe how the disorders overlapped

Out of the 224 children tested, 22.8 percent met the diagnostic criteria for autism — compared to just 8.7 percent of the 241 adults in the study.The UCSF team wasn’t convinced that all the children actually had autism, however — particularly since the autism rate in adults was so low. Tourette symptoms usually diminish over time, the researchers said, while autism lasts a lifetime. Confusing symptoms of the two may be more likely when a patient is young.

“Assessing autism symptom patterns in a large Tourette’s sample may be helpful in determining whether some of this overlap is due to symptoms found in both disorders, rather than an overlapping etiology,” said author Sabrina Darrow, Ph.D. “Our results suggest that, although autism diagnoses were higher in individuals with Tourette’s, some of the increase may be due to autism-like symptoms, especially repetitive behaviors that are more strongly related to obsessive-compulsive disorder.”

Of the children who met the autism criteria, 83 percent also met the criteria for OCD — another condition that frequently coincides with Tourette Syndrome.

Senior author Carol Mathews, MD, further explained the significance of the results: “Previous studies have shown that children with mood and anxiety disorders also have higher rates of autism symptoms,” she said. “This suggests that some of the increase may reflect underlying psychiatric impairment rather than being specific for autism.

“Some of the children in the study probably have autism,” she continued. “Others have symptoms that mimic autism, but are not really due to autism.” It’s critical that doctors take both conditions into account when making a diagnosis, the authors conclude.

The results of the study were published in June in the Journal of the American Academy of Child and Adolescent Psychiatry.