A recent Brazilian study highlights a potential link between hearing loss in midlife and an increased risk of dementia. Published in the Journal of Alzheimer’s Disease, the study followed adults in their 50s for eight years, exploring the connection between auditory decline and cognitive health.
Importance of Hearing Health in Dementia Prevention
The University of São Paulo’s Medical School (FM-USP) researchers conducted the study within the framework of the Longitudinal Study of Adult Health (ELSA-Brazil), which has been monitoring 15,000 public servants since 2008.
The study’s results stress the importance of prioritising hearing health as part of dementia prevention efforts, especially in rapidly ageing nations.
The Link Between Hearing Loss and Cognitive Decline
The study involved 805 participants in their 50s, each undergoing audiometry tests and cognitive assessments—focusing on memory, language, and executive function—three times over the eight-year period. Of those tested, 62 individuals (7.7%) were found to have hearing loss.
These individuals experienced faster cognitive decline than their peers without hearing loss. The decline was observed not only in overall cognitive performance, but also in more specific areas like 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,” said lead researcher Claudia Suemoto. “They start to hear badly, but they don’t realise it and adapt to the new situation.”
Hearing Loss as a Modifiable Dementia Risk Factor
One of the most significant takeaways from the study is that hearing loss is a modifiable risk factor—meaning it can be addressed to potentially prevent more serious outcomes like dementia.
“Hearing loss is what we call a modifiable risk factor for dementia, including Alzheimer’s, precisely because it can be detected and corrected,” Suemoto explained. “That’s why it’s important to have studies that identify our reality and the factors that can be prevented. In addition to the individual burden, there’s also a collective burden.”
The study emphasises early intervention, including the use of hearing aids and reducing noise exposure. According to Suemoto, “But knowing that there’s a loss, it’s possible to correct it with the use of hearing aids. And you also have to remove the stimulus that’s causing the problem.”
Mechanisms Linking Hearing Loss to Cognitive Decline
The study proposes two mechanisms linking hearing loss to cognitive decline. The first is neurological. “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,” Suemoto said.
The second mechanism is behavioural—linked to social isolation. Suemoto noted: “Almost everyone knows someone older, be it a friend or relative, who doesn’t hear well. To talk to them, you have to speak louder, repeat sentences and they end up being excluded from conversations.”
“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,” she added.
Public Health Implications for Ageing Populations
The urgency of these findings lies in their broader context. According to Suemoto, “By 2050, more than 70% of people with dementia are expected to live in low- and middle-income countries like Brazil.” For countries with limited resources, the rising tide of dementia cases could be devastating.
Untreated hearing loss, then, is not just a personal issue—it represents a looming public health challenge. It is a challenge that can be mitigated, with proper attention.
Conclusion
The study makes it clear: hearing protection could be critical in reducing dementia risk. Awareness is still growing around the connection between hearing loss and cognitive decline, but Suemoto emphasises the need for swift action, saying, “There’s no way that Brazil and other low- and middle-income countries can grow old with dementia.”