Study suggests inner-ear glitch interferes with language development and may help identify babies at risk for autism
Researchers at the University of Rochester Medical Center have identified an inner-ear deficiency that is particularly common among children with autism and may affect their ability to recognize speech. The findings, published in the journal Autism Research, might be used someday to identify babies at risk for developing autism so that they can receive early intervention support.
The University of Rochester Medical Center is one of 14 sites in the Autism Speaks Autism Treatment Network (ATN).
“This technique may provide clinicians with a new window into the disorder and enable us to intervene earlier and help achieve optimal outcomes,” says study co-author Anne Luebke.
Current diagnostic methods rely on behavior symptoms that may not appear until 18 to 24 months of age. However, research suggests that earlier interventions can help promote brain development for at least some children predisposed to the disorder.
In their study, researchers evaluated a test similar to one commonly used to screen newborns for hearing problems. It employs a miniature speaker paired with a highly sensitive microphone in an earplug to detect abnormalities in sound processing. (See image above.)
The researchers played tones and clicks through the miniature speaker and then analyzed minute sound emissions made in response by hair cells in the inner ear. A lack of response by these cells indicates impairment of the inner ear, or cochlea.
The researchers tested the hearing of children between age 6 and 17 years – 35 of whom had autism and 41 who did not.
The children in both groups scored in the normal range on standard hearing tests. However, as a group, the children with autism had reduced inner ear function in a specific frequency (1-2 kHz) that is important for processing speech. Within the autism group, the researchers also found a direct correlation between the degree of a child’s inner-ear impairment and the severity of his or her autism symptoms.
“Auditory impairment has long been associated with developmental delay and other problems, such as language deficits,” says study co-author Loisa Bennetto. “While there is no association between hearing problems and autism, difficulty in processing speech may contribute to some of the core symptoms.” In addition, Dr. Bennetto says, the findings suggest that correcting the hearing impairment with hearing aids or other devices might improve language and social development in these children.
Because the test is non-invasive and inexpensive and does not require a verbal response, it might be suitable for screening infants for autism risk, the researchers conclude. They are now seeking funding to study younger, minimally verbal children on the autism spectrum.