ROCHESTER, Minn., July 26 (UPI) -- A hearing test may help doctors identify children at higher risk for autism spectrum disorder, allowing therapy to start earlier and prevent larger health issues caused by a delayed diagnosis.
Researchers at the University of Rochester say measuring otoacoustic emissions to check for hearing problems could tip off doctors to the potential for ASD based on research linking hearing impairment and the severity of symptoms linked to the disorder.
Although many signs of ASD can be seen before age 2, most children are not diagnosed until age 4, delaying treatment.
Auditory communication issues are a hallmark of ASD, though testing speech rather than hearing at ages when signs of ASD are observable may cause doctors to miss the diagnosis.
By using a hearing test similar to those used with newborns -- otoacoustic emissions tests measure the response of inner ear outer hair cells to certain tones or clicking sounds -- doctors would be able to test whether cochlear function is impaired, researchers say.
"Auditory impairment has long been associated with developmental delay and other problems, such as language deficits," Dr. Loisa Bennetto, an associate professor in the University of Rochester Department Of Clinical and Social Sciences in Psychology, said in a press release. "While there is no association between hearing problems and autism, difficulty in processing speech may contribute to some of the core symptoms of the disease. Early detection could help identify risk for ASD and enable clinicians to intervene earlier. Additionally, these findings can inform the development of approaches to correct auditory impairment with hearing aids or other devices that can improve the range of sounds the ear can process."
For the study, published in the journal Autism Research, researchers measured otoacoustic emissions in 35 high-functioning ASD patients between the ages of 6 and 17, comparing them to 42 age-matched children with typical development.
The tests revealed children with ASD had hearing deficiencies at frequencies between 1 and 2 kilohertz, which is key to speech processing, and researchers linked the degree of inner ear impairment in ASD children to the severity of their symptoms.
Additional research is currently being done to see if the differences are apparent in newborns, as well as the older children included in the study, researchers said.
"This study identifies a simple, safe, and non-invasive method to screen young children for hearing deficits that are associated with autism," said Dr. Anne Luebke, an associate professor at the University of Rochester's departments of biomedical engineering and neuroscience. "This technique may provide clinicians a new window into the disorder and enable us to intervene earlier and help achieve optimal outcomes."