Alzheimer’s Disease Linked to Air Pollution
Alzheimer’s disease has been linked to a certain type of air pollution according to researchers.
Alzheimer’s disease is often no accident. Scientific research continues to illustrate that our lifestyle, diet, and environment can significantly increase our risk of developing Alzheimer’s disease later in life. Now we find multiple recent studies confirming that air pollution significantly increases our risk of developing this devastating condition.
Certainly air pollution is a risk to the environment, as hundreds of scientists worldwide have confirmed that carbon-based air pollutants are producing increased atmospheric and oceanic temperatures in the form of greenhouse gases. But it turns out this damage to our environment is a reflection of the harm that air pollutants have upon our bodies. This includes lung diseases, allergies, cancer, and other disorders.
Air pollution and Alzheimer’s
In a 2017 study led by Professor Mafalda Cacciottolo, Ph.D. from the University of Southern California along with a number of colleagues studied 3,647 women across 48 states in the U.S.1 The women were all aged between 65 and 79 years old.
The researchers compared their long-term exposures to a certain type of air pollution. The discerning pollution type is called PM2.5. This means a particulate matter of 2.5 microns in size.
Women who lived in areas with the highest exposures of PM2.5 air pollution had significantly higher levels of cognitive decline and dementia. Cognitive decline was increased by 81 percent for higher air pollution exposure.
Higher air pollution exposures also increased the risk of dementia by 93 percent.
This was the average. Risks went up for those with, and down slightly (to 65 percent) for those without Alzheimer’s APOE genes. For those with the APOE alleles (apolipoprotein E ε4), the risk went up to nearly four times for cognitive decline (3.95 times) and nearly three times for dementia (2.95 times).
In other words, for those with a greater genetic disposition for dementia and cognitive decline, air pollution increases their risk dramatically.
The researchers also confirmed this link in animal research.
The researchers stated:
“Together, we show the contribution of particulate air pollutants to neurodegenerative changes, with potentially a greater impact on APOE ɛ4 carriers. Overall, the evidence supports the schema that airborne particulate matter accelerates neurodegenerative processes of ADRD through multiple pathways, including pro-amyloidogenic APP processing and other pathways independent of amyloid deposits.”
Other studies showing link
In 2018 Dr. Masashi Kitazawa, an environmental health professor at the University of California compiled a study of research with doctoral candidate Jason Kilian. The research analyzed the available evidence between Alzheimer’s disease and air pollution.2
The evidence from this research confirms the findings above. These found specific links between air pollution levels and Alzheimer’s disease. They wrote:
“The studies presented above represent a strong foundation for the case of particulate matter and other air pollutants as key risk factors for Alzheimer’s disease and other neurodegenerative disease etiologies. “
The results of this study were mirrored by a more recent review of research from scientists at the Hong Kong Baptist University.3 The researchers analyzed 1645 papers and 80 research studies done in 26 countries around the world.
The researchers found that long-term PM2.5 exposure had the following effects:
• 3.26 times increased risk of Alzheimer’s disease
• 70 percent increased risk of Autism
• 34 percent increased risk of Parkinson’s
• 16 percent increased risk of dementia
The researchers wrote:
“We found significant association between PM2.5 exposure and stroke, dementia, Alzheimer’s disease, Autism Spectrum Disorder, Parkinson’s disease.”
Pollution effect on children’s neurological risks
Multiple studies have now investigated to what extent pollution is affecting our children’s risk of Alzheimer’s, dementia, and neurological development in general.
A 2018 study from doctors from the Universidad del Valle de México and the Perelman School of Medicine at the University of Pennsylvania tested the cerebrospinal fluid of 507 children.4
Some of the children live in Mexico City while some live in rural areas outside the city.
The researchers found that children exposed to air pollution levels over the U.S. Environmental Protection Agency had significantly more markers in their brain that are linked to Alzheimer’s disease.
These markers include Lewy neurites and hyperphosphorylated tau (hTau) levels, which have been determined as pre-Alzheimer’s disease markers. Among toddlers with greater air pollution exposures, 84 percent exhibited hTau markers after the age of 10. Meanwhile, 68 percent had amyloid markers.
Another 2018 study, from Spain’s Barcelona Institute for Global Health5 studied 1,667 children between 7 and 11 years old from 39 schools in Barcelona. The researchers found that those children with APOEe4 gene markers for increased risk of Alzheimer’s displayed a significantly greater degree of behavior problems in areas with higher air pollution exposures.
What about wood-burning stoves?
The above studies focused on air pollution caused by traffic and other industrial sources. Does the same thing occur from wood burning stoves? Yes, actually.
Scientists from Sweden’s Umeå University studied 1,806 people from Northern Sweden.6 They found that PM2.5 exposures from wood burning stoves also produced a significantly higher risk of dementia.
Learn more about avoiding Alzheimer’s disease.
The scientists found a 55 percent increased incidence of dementia among those with exposure to wood burning stove pollution. Those who lived in areas with a lot of wood-burning stoves had a 74 percent higher risk of dementia.
This was compared to the increased incidence of dementia from traffic-based air pollution. The increased incidence of dementia in this study was 66 percent among those exposed to traffic air pollution.
So it seems that wood burning stoves are just as bad if not even a little worse than traffic air pollution when it comes to an increased risk of dementia.
Cleaner air equates to clearer thinking
The research is clearly indicating that we need to reduce our exposure to air pollution, especially the types with fine particulate matter at 2.5 microns.
Just as pollution makes our air less clear, our air pollutants are poisoning our ability to think clearly and retain our memories.
Things we can do to reduce this range from living outside of polluted areas to making personal changes in our own lifestyles. These include considering switching to an electric car or hybrid. They also include actively engaging our government and business leaders to reduce our polluting ways.
We now have the technology to largely escape carbon burning for our transportation and energy production.
There are clear ways to clean up our atmosphere without having to escape to the country. But each of us must actively embrace and make these changes. This means not only with our votes, but voting with our wallets.
Our brains and the brains of our children are depending on it.
Scientific References
1. Cacciottolo M, Wang X, Driscoll I, Woodward N, Saffari A, Reyes J, Serre ML, Vizuete W, Sioutas C, Morgan TE, Gatz M, Chui HC, Shumaker SA, Resnick SM, Espeland MA, Finch CE, Chen JC. Particulate air pollutants, APOE alleles and their contributions to cognitive impairment in older women and to amyloidogenesis in experimental models. Transl Psychiatry. 2017 Jan 31;7(1):e1022. doi: 10.1038/tp.2016.280.
2. Kilian J, Kitazawa M. The emerging risk of exposure to air pollution on cognitive decline and Alzheimer’s disease – Evidence from epidemiological and animal studies. Biomed J. 2018 Jun;41(3):141-162. doi: 10.1016/j.bj.2018.06.001.
3. Fu P, Guo X, Cheung FMH, Yung KKL. The association between PM(2.5) exposure and neurological disorders: A systematic review and meta-analysis. Sci Total Environ. 2019 Mar 10;655:1240-1248. doi: 10.1016/j.scitotenv.2018.11.218.
4. Calderón-Garcidueñas L, González-Maciel A, Reynoso-Robles R, Kulesza RJ, Mukherjee PS, Torres-Jardón R, Rönkkö T, Doty RL. Alzheimer’s disease and alpha-synuclein pathology in the olfactory bulbs of infants, children, teens and adults ≤ 40 years in Metropolitan Mexico City. APOE4 carriers at higher risk of suicide accelerate their olfactory bulb pathology. Environ Res. 2018 Oct;166:348-362. doi: 10.1016/j.envres.2018.06.027.
5. Alemany S, Vilor-Tejedor N, García-Esteban R, Bustamante M, Dadvand P, Esnaola M, Mortamais M, Forns J, van Drooge BL, Álvarez-Pedrerol M, Grimalt JO, Rivas I, Querol X, Pujol J, Sunyer J. Traffic-Related Air Pollution, APOEε4 Status, and Neurodevelopmental Outcomes among School Children Enrolled in the BREATHE Project (Catalonia, Spain). Environ Health Perspect. 2018 Aug 2;126(8):087001. doi: 10.1289/EHP2246.
6. Oudin A, Segersson D, Adolfsson R, Forsberg B. Association between air pollution from residential wood burning and dementia incidence in a longitudinal study in Northern Sweden. PLoS One. 2018 Jun 13;13(6):e0198283. doi:10.1371/journal.pone.0198283.
