A Seattle-based study found that people living in an area with air pollution levels of PM2.5 have a 16% increase in risk of dementia
A team at the University of Washington found that a small increase in the levels of fine particle pollution (PM2.5 or particulate matter 2.5 micrometres or smaller) averaged over a decade at specific addresses in the Seattle area was associated with a greater risk of dementia for people living at those addresses.
‘Similar association for Alzheimer’s-type dementia’
“We found that an increase of 1 microgram per cubic meter of exposure corresponded to a 16% greater hazard of all-cause dementia. There was a similar association for Alzheimer’s-type dementia,” said lead author Rachel Shaffer, who conducted the research as a doctoral student in the UW Department of Environmental & Occupational Health Sciences.
Dr Eric Larson, ACT’s founding principal investigator and a senior investigator at KPWHRI, said: “The ACT Study is committed to advancing dementia research by sharing its data and resources, and we’re grateful to the ACT volunteers who have devoted years of their lives to supporting our efforts, including their enthusiastic participation in this important research on air pollution.”
Looking into the past of 72 year old dementia patients
Once a patient with dementia was identified, researchers compared the average pollution exposure of each participant leading up to the age at which the dementia patient was diagnosed.
For example, if a person was diagnosed with dementia at 72 years old, the researchers compared the pollution exposure of other participants over the decade prior to when each one reached 72.
In this analysis, the researchers also had to account for the different years in which these individuals were enrolled in the study, since air pollution has dropped dramatically in the decades since the ACT study began.
‘Dementia develops over a long period of time’
“We know dementia develops over a long period of time. It takes years – even decades – for these pathologies to develop in the brain, and so we needed to look at exposures that covered that extended period,” said Shaffer.
“We had the ability to estimate exposures for 40 years in this region. That is unprecedented in this research area and a unique aspect of our study.
“Over an entire population, a large number of people are exposed. So, even a small change in relative risk ends up being important on a population scale. There are some things that individuals can do, such as mask-wearing, which is becoming more normalized now because of COVID. But it is not fair to put the burden on individuals alone.
“These data can support further policy action on the local and national level to control sources of particulate air pollution.”