Air pollution linked to age-related cognitive decline

April, 2012

A large long-running study of older women has found a dose-dependent association between air pollution and cognitive decline. A review has found a dose-dependent association between air pollution and risk of heart attack.

Data from the Nurses' Health Study Cognitive Cohort, involving 19,409 older women (70-81), has found that higher levels of long-term exposure to air pollution were associated with faster rates of cognitive decline over a four-year period.

For each 10 micrograms per cubic meter of air increase in pollutants, cognitive decline was comparable to two years of age-related decline.

Pollution exposure was estimated from geography. Cognition was tested by three telephone interviews, administered at roughly two-year intervals.

Air pollution linked to heart attack risk

Given the association between cardiovascular risk factors and cognitive decline (“What’s good for the heart is good for the brain”), it’s worth noting that a review of 34 studies has found that every main air pollutant, with the exception of ozone, was significantly associated with greater risk of heart attack. For most of the pollutants, an increase in concentration of 10 micrograms per cubic meter of air – barely noticeable – was associated with a 1-3% increase in the chance of having a heart attack in the next week.

The size of the risk is small compared with traditional risk factors such as smoking status or hypertension or diabetes, but is something that those with other cardiovascular risk factors may want to consider. There’s also growing evidence that high levels of pollution increase stroke risk.

For more about the effects of air pollution on cognition