A local study on Singaporeans has revealed that people aged 55 and above with hearing loss are more likely to develop dementia. As more than 60 per cent of Singaporeans aged above 60 years old experience varying forms of hearing loss, the findings could prove to be significant; opening the possibility that early diagnosis and intervention for hearing loss could potentially delay dementia and cognitive decline.
The study, published in 2017, was conducted through the analysis of data from the Singapore Longitudinal Ageing Study, a long-term, population-based research, led by NUS Yong Loo Lin School of Medicine (NUS Medicine) Associate Professor Ng Tze Pin, which investigates the ageing and health of community-living elderly in Singapore.
A total of 1,515 Singaporeans aged 55 and above were involved in the research study linking hearing and dementia. The participants had normal memory and thinking skills at the start of the study and were observed through two rounds of follow-up at regular intervals over a period of about three years. Using cognitive and clinical assessments, it was found that cognitively normal participants with hearing loss were about 2.3 times more likely to develop mild cognitive impairment or dementia.
The results are consistent with findings conducted in Western populations — US, UK and Australia — which adds weight to the potential link between hearing loss and cognitive decline and dementia.
Assoc Prof Ng said that risk and protective factors for dementia, including hearing loss, are modifiable with suitable lifestyle changes. “It is indeed feasible now for us in Singapore to consider screening for risk of dementia, and to design appropriate community-based multidomain lifestyle interventional programmes, to help older Singaporeans ‘age without dementia’,” he said.
While there is not yet enough evidence to show how the link between hearing loss and dementia occurs, Dr Rebecca Heywood of Ng Teng Fong General Hospital and Principal Otolaryngology researcher of the published study offered some theories. “Those with hearing loss need more effort to hear a degraded sound, so less brain resources are available for thinking and memory. Hearing loss results in less auditory stimulation and as a result the hearing areas in the brain, which are also involved in memory, become underused and decline in function. It is also possible that hearing loss may give rise to social isolation, which is itself a risk factor for cognitive decline.”
Dr Heywood added that hearing loss is easily diagnosed and treated and should not be seen as an inevitable part of ageing, urging sufferers to seek help.
Assoc Prof Ng and Dr Heywood plan to conduct a follow-up intervention study to examine how the use of hearing aids can help to reduce the rate of cognitive decline and delay the onset of dementia in older adults with hearing loss.