Dementia is a general term used to describe clusters of symptoms associated with an ongoing decline of brain functioning. There are many types of dementia but Alzheimer’s disease is the most common type in the UK. The symptoms, such as memory loss, worsen over time and often require full-time support in the severe stages.
Unfortunately, there’s no known way to prevent Alzheimer’s disease, but headway has been made in identifying the risk factors.
This is crucial because identifying risk factors in advance can help to mitigate the risk of developing brain decline.
Research published today in the journal Alzheimer’s and Dementia advances our understanding of the environmental factors that may underpin Alzheimer’s.
The research suggests those who lived in areas of higher noise pollution may be at an increased risk of developing dementia.
To investigate the link, volunteers in the US over the age of 65 took memory and thinking tests every three years.
The researchers also estimated the noise 5,227 people experienced. They used recordings taken during the daytime and then factored in noise hotspots such as traffic lights and busy roads.
They then compared this information with memory and thinking performance, and a clinician’s diagnosis of mild cognitive impairment (MCI) or Alzheimer’s disease.
MCI is the stage between the cognitive decline characteristic of normal ageing and the more serious decline of dementia.
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What did the researchers find?
The researchers found an increment of 10 decibels in sound intensity – roughly the noise of someone breathing – was linked to an increased likelihood of developing MCI and Alzheimer’s disease.
Noise level was also associated with worsened ability to quickly compare or recognise symbols or figures.
However, noise level was not associated with a decline in memory and thinking over the study.
Commenting on the findings, Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said: “There are nearly one million people in the UK living with dementia and it’s caused by devastating diseases.
“This new US-based research suggests a link between noisier areas to live and early-stage thinking problems, but if any causal link exists between these two factors, it is not confirmed by this study.
“The researchers estimated the noise levels someone experienced with readings taken during the daytime and during non-rush hour traffic, ten years ago in the US, so it’s difficult to say whether this research maps to the lives of people in the UK.
“Research has already implicated hearing loss in midlife as a risk factor for dementia and as the diseases causing dementia develop in the brain up to two decades before symptoms show, understanding what may be causing this link will be crucial for further research.
“While we can’t know from this study whether reducing noise pollution could reduce people’s dementia risk, policies to tackle this could have many other benefits for people living in noisy areas.”
She added: “For reducing dementia risk, the best current evidence indicates staying physically and mentally active, eating a healthy balanced diet, not smoking, drinking only within the recommended limits and keeping weight, cholesterol and blood pressure in check.”
Research suggests that other factors are also important, although this does not mean these factors are directly responsible for causing dementia.
According to the NHS, these include:
Hearing lossUntreated depression (although this can also be a symptom of dementia)Loneliness or social isolationA sedentary lifestyle.
“The research concluded that by modifying all the risk factors we’re able to change, our risk of dementia could be significantly reduced,” the NHS added.