Long-term exposure to noise may be linked to an increased risk for Alzheimer’s disease and other forms of dementia.
Researchers did periodic interviews with 5,227 people 65 and older participating in a study on aging. They assessed them with standard tests of orientation, memory and language, and tracked average daytime noise levels in their neighborhoods for the five years preceding the cognitive assessments. About 11 percent had Alzheimer’s disease, and 30 percent had mild cognitive impairment, which often progresses to full-blown dementia.
Residential noise levels varied widely, from 51 to 78 decibels, or from the level of a relatively quiet suburban neighborhood to that of an urban setting near a busy highway. The study is in Alzheimer’s & Dementia.
After controlling for education, race, smoking, alcohol consumption, neighborhood air pollution levels and other factors, they found that each 10 decibel increase in community noise level was associated with a 36 percent higher likelihood of mild cognitive impairment, and a 29 percent increased risk for Alzheimer’s disease. The associations were strongest in poorer neighborhoods, which also had higher noise levels.
The reasons for the connection are unknown, but the 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, constriction of the blood vessels and elevated blood pressure, all of which are associated with an increased risk for dementia.