Alzheimer's / Dementia Public Health Seniors / Aging

Community noise may increase the risk of dementia

According to new studies, older adults living in noisy communities can face greater chances of developing Alzheimer’s disease or other forms of dementia.

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Image credit: Max Milne/Getty Images

Researchers have analyzed a broad variety of variables to assess if they increase a person’s risk of dementia, from sedentary activity to exposure to airborne toxins to isolation.

However, only a handful of epidemiological studies have investigated the impact of community noise on cognitive impairment in older adults, which relates to noise originating from vehicles, trains, aircraft, construction sites, and similar sources.

This new research published in Alzheimer’s & Dementia, the journal of the Alzheimer’s Association, is the first in the United States to carry out such research.

This research is significant, considering that over 100 million people in the U.S. encountered annual noise levels in 2013 that exceeded the limits recommended by the Environmental Protection Agency (EPA) to protect against hearing loss.

In studying noise and dementia, we remain in the early stages, but the signals so far, including those from our report, indicate that we should pay more attention to the likelihood of noise influencing cognitive risk as we age,” says lead study author Jennifer Weuve, an associate professor of epidemiology at the School of Public Health of Boston University.”

Researchers performed 3-year cognitive tests of 5,227 individuals aged 65 years and older who were participants in the Chicago Health and Aging Project for the study. This research project has involved more than 10,000 older adults living on the south side of Chicago since its initiation in 1993.

By using a prediction model developed for an earlier study, the study’s authors estimated the noise levels in the neighborhoods where participants lived in the 5 years prior to the evaluations.

They discussed how different factors could also raise the risk of dementia, such as race, physical activity, and socioeconomic status (SES).

The study found that older adults living with 10 A-weighted decibels more noise during the daytime had 36 percent higher chances of developing moderate cognitive impairment and 29 percent higher odds of Alzheimer’s disease after accounting for these other factors.

The only thing that influenced this partnership was SES.

Several explanations are possible

“These results indicate that higher noise levels can damage the brains of older adults in traditional urban communities in the U.S. and make it more difficult for them to work without support says Sara Adar, senior study author and associate professor of epidemiology at the University of Michigan School of Public Health in Ann Arbor.

The researchers suspect that the correlation between increased noise and a higher risk of cognitive impairment may be due to several factors. In rats that were exposed to prolonged noise exposure, a 2015 study found an accelerated development of beta-amyloid, a protein that researchers consider to play a major role in Alzheimer’s disease.

Previously studies have shown how noise exposure can cause adverse health effects ranging from elevated blood pressure to sleep disturbance. There is evidence that dementia risk can be increased by both vascular health and inadequate rest.

The new study’s authors hope that if research continues to demonstrate that exposure to noise in the U.S. leads to the risk of dementia, it will be possible to convince policymakers to change policies to reduce noise levels.

There is a lot at stake: Alzheimer’s disease is a public health issue in the United States alone with an estimated 5.8 million people over 65 years of age living with the disease. Scientists expect the figure to jump to 13.8 million by 2050.

“Although noise has not received a great deal of attention in the U.S. to date, there is a public health opportunity here, as there are interventions that can reduce exposures both at the individual and population level.”

– Sara Adar