Study links air pollution to reduced cognitive ability

New research suggests that even short-term exposure to polluted air, at levels generally considered “acceptable,” may impair mental ability in the elderly (Source: “Air Pollution Takes a Toll on the Brain,” New York Times, May 17).

The study of 954 men, average age 69, living in the greater Boston area found that higher levels of PM 2.5, particles of soot and other fine particulate matter with a diameter of up to 2.5 microns, were consistently associated with lower cognitive test scores. The study, in Nature Aging, adjusted for age, BMI, coronary heart disease, diabetes, alcohol consumption, smoking, high blood pressure and other factors.

Dr. Andrea A. Baccarelli, the senior author and a professor of environmental science at the Columbia Mailman School of Public Health, said that these short-term effects may be reversible. “When air pollution goes down,” he said, “the brain reboots and goes back to normal. However, if repeated, these episodes produce long-term damage to the brain.”

“Some of these particles come from natural sources — sea salt, for example, soil and pollen,” Dr. Baccarelli added. “We’ll never be completely free of them. But the ones generated by humans are much worse. The good news is that we’re at a point where we have the technology to reduce air pollution even further.”

Study finds link between neighborhood noise levels, dementia risk

Long-term exposure to noise may be linked to an increased risk for Alzheimer’s disease and other forms of dementia, a new study found (Source: “Living in Noisy Neighborhoods May Raise Your Dementia Risk,” New York Times, Oct. 28).

After controlling for education, race, smoking, alcohol consumption, neighborhood air pollution levels and other factors, researchers found that each 10 decibel increase in community noise level was associated with a 36% 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, according to the study published in the journal Alzheimer’s & Dementia.

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.