Long-term exposure to noise can be linked to an increased risk of Alzheimer's and other forms of dementia.
The researchers conducted regular interviews with 5,227 people aged 65 and over who were participating in a study on aging. They assessed them using standard tests for orientation, memory, and language, and tracked the average daily noise level in their neighborhood for the five years prior to the cognitive assessments. About 11 percent had Alzheimer's disease and 30 percent had mild cognitive impairments that often lead to full-blown dementia.
The noise level in residential areas varied widely between 51 and 78 decibels or between a relatively quiet suburb and an urban setting near a busy motorway. The study looks at Alzheimer's and dementia.
After checking for education, race, smoking, alcohol use, neighborhood air pollution, and other factors, they found that every 10 decibels increase in noise in the community increased the likelihood of mild cognitive impairment by 36 percent and that of 29 percent Risk was associated for Alzheimer's disease. The associations were strongest in poorer areas, which also had higher noise levels.
The reasons for the link are unknown, but lead author Jennifer Weuve, an associate professor of epidemiology at Boston University, suggested that excessive noise can cause sleep deprivation, hearing loss, increased heart rate, narrowing of blood vessels, and increased blood pressure, all with one increased risk of dementia.