Researchers have linked autism to hearing loss.
Scientists at the Medical University of South Carolina (MUSC) say they have discovered hearing loss in a mouse model of autism.
Left to right: Dr Jeffrey Rumschlag, a senior researcher on the study linking autism and hearing loss, with professors Christopher Cowan and Hainan Lang
The researchers said they found mild hearing loss and defects in the auditory nerve.
A closer examination of the nerve showed abnormal supportive cells called glia. They also found ageing-like degeneration and inflammation.
Importance of sensory organs
The researchers say the findings show the importance of sensory organs and their interactions with the brain in understanding autism.
Many people with autism show increased sound sensitivity.
In the past, scientists have looked to the brain for an underlying cause. However, the MUSC team took a different approach by studying the peripheral hearing system.
Impact of hearing problems
Professor Hainan Lang is one of the study’s two lead authors.
She said hearing problems may impact the “higher-level auditory system and, eventually, cognitive function”.
The researchers looked at mice with only one working copy of the MEF2C gene. Previous work has shown it is important for regulating circuit formation in the brain and inner-ear development.
Patients with autism-like symptoms had been identified with MEF2C mutations.
In addition, mice with the defective gene showed autism-like behaviours. These included repetitive behaviour and communication deficits.
Tests showed mild hearing loss in the mice with only one working copy of MEF2C.
And the nerves from mice showed degeneration, much like that seen in age-related hearing loss.
The researchers also saw signs of increased inflammation.
‘Tremendous applicability’
Professor Christopher Cowan chairs Neuroscience at MUSC.
He said understanding how the gene “may be participating in ear development and how the inner ear development is affecting brain development has tremendous applicability”.
The study appeared in the Journal of Neuroscience.
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Published: 28 January 2023
