To add another horrible link to air pollution, welcome dementia! Already known to be a risk factor for heart disease/stroke and respiratory disease, air pollution is now being tied to dementia as well, according to new research published in BMJ Open. Though the new research is only an observational study and cannot outrightly establish cause, the numbers are quite convincing. Take a look.
The researchers behind the study focused on the area of Greater London to determine the connection between ambient air quality and new dementia diagnoses. Using data from the Clinical Practice Research Datalink (CPRD), which goes back to 1987, the team of scientists analyzed almost 131,000 patients. These patients, aged 50 to 79 in 2004, had not been previously diagnosed with dementia and lived in varying residential areas within the London orbital M25 motorway.
This part is key, because based on peoples’ residencies, the researchers were able to estimate how much air pollution each individual would likely be exposed to on a yearly basis. The types of air pollution that they estimated for individuals’ exposure included nitrogen dioxide (NO2), fine particulate matter (PM2.5), and ozone (O3), among others.
The researchers tracked these patients’ health over 7 years, or, in some cases, until a diagnosis of dementia, death, or deregistration from the practice. During the time, they found that 2181 patients (1.7%) were diagnosed with dementia (which includes Alzheimer's disease).
The link here comes with the discovery that in a significant number of cases, dementia diagnoses were associated with ambient levels of NO2 and PM2.5 – i.e. air pollution. In fact, people who lived in residencies where NO2 levels were in the top fifth had a 40% higher chance of a dementia diagnosis than those who lived in areas with NO2 levels in the bottom fifth. That’s pretty significant if you ask me.
Nevertheless, the researchers are hesitant to extrapolate meaning beyond the limited scope of this study. Though seven years sounds like a long time, many longer-term studies would be needed in many different places in order to establish cause between air pollution and dementia. So, for the time being, just try to breathe some fresh air.