A study which followed people aged in their 50s for eight years found those with hearing loss had an increased risk of cognitive decline.
The research was conducted as part of the Brazilian Longitudinal Study of Adult Health with results published in the Journal of Alzheimer’s Disease on 8 May 2025.
Study author, physician Associate Professor Claudia Suemoto from the University of São Paulo’s Medical School, said results underscored the need for increased attention to hearing health as a way to prevent dementia.
She said hearing loss was a modifiable risk factor for dementia, including Alzheimer’s, because it could be detected and corrected.
“In addition to the individual burden, there’s also a collective burden,” she said.
The study has been monitoring data from 15,000 public servants from six universities and research centres since 2008. Participants underwent audiometry tests three times over eight years.
Tests of memory, language and executive function were carried out during the same period to measure the association between hearing loss and significant cognitive decline.
Of 805 participants, 62 (7.7%) had hearing loss. After eight years of follow-up, these individuals had faster overall cognitive decline than expected for their age. In addition, specific cognitive tests showed similar but less precise declines in memory, verbal fluency and executive function.
“This shows that it’s important to do an audiometry test because it usually takes a while for people to become aware of their hearing deficit,” A/Prof Suemoto said.
“They start to hear badly, but they don’t realise it and adapt to the new situation. But knowing that there’s a loss, it’s possible to correct it with the use of hearing aids. You also have to remove the stimulus that’s causing the problem.”
She said the main causes of hearing loss in middle age were work-related as many jobs involved a lot of noise.
“These people need to wear protective equipment to reduce hearing loss. There’s also the problem of using headphones at too high a volume. All of this is detrimental, so it’s important to get the problem diagnosed,” she adds.
A/Prof Suemoto said hearing loss was a recognised risk factor for dementia because it was an important input pathway for information to the brain.
“It depends on input pathways to deliver a response, along with the knowledge it’s already acquired. However, when a pathway is interrupted, important areas are no longer stimulated, which can accelerate cognitive decline,” she said.
The second mechanism was behavioural as hearing loss tended to lead to social isolation.
“Almost everyone knows someone older, be it a friend or relative, who doesn’t hear well. To talk to them, you must speak louder, repeat sentences and they end up being excluded from conversations,” she said. “In a way, it’s so hard for them to hear that they shut themselves out, lose interest and move away. So there’s also the mechanism of social isolation, which is another recognised risk factor for dementia.
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