New QIMR Berghofer and QUT research has found there is no strong genetic evidence that hearing loss causes Alzheimer’s
disease, despite both conditions sharing a significant number of genetic variants.
Alzheimer’s disease is the most common form of dementia with over 50 million people around the world currently living
with the condition. No new drugs have been developed to treat Alzheimer’s disease since 2003.
Hearing loss affects about 32 per cent of people aged 55 years and older.
The relationship between hearing loss and Alzheimer’s disease has been in the spotlight for decades, with recent
research focussing on risk factors that, if modified during a person’s lifetime, could potentially prevent a person
developing Alzheimer’s disease. Some other studies have suggested mild hearing loss doubles a person’s risk of dementia,
while people with severe hearing impairment are five times as likely to develop dementia.*
Senior author and researcher in QIMR Berghofer’s Genetic Epidemiology Research Group Associate Professor Michelle Lupton
said her team’s study found about a quarter of the genetic variants that influenced hearing loss were also involved in
Alzheimer’s disease.
“We did not find any genetic evidence however that one of the conditions caused the other. The lack of genetic evidence
sheds doubt on whether the treatment for hearing impairment would change a person’s chances of developing Alzheimer’s
disease in the future,” Associate Professor Lupton said.
“Most of the 25 per cent of genetic variants that were common in both conditions were also associated with inflammation
and the body’s immune response. This supports the mounting evidence of the importance of inflammation in Alzheimer’s
disease.
“It’s possible that the relationship between these two traits may be due to a common cause that hasn’t been identified
as yet.
“It is important that patients are always treated for their hearing loss to maintain quality of life, but this study
also importantly provides new information on Alzheimer’s disease and indicates that treating hearing loss may not
prevent the degenerative illness.”
First author and PhD candidate Brittany Mitchell said it was one of the largest genetic studies of its kind into the
relationship between hearing loss and Alzheimer’s disease.
“We examined DNA from more than 250,000 people with self-reported hearing loss and looked for an overlap in the genetic
variants of people who had been diagnosed with Alzheimer’s disease,” she said.