Air Pollution: A Neglected Risk Factor for Dementia in Latin America and the Caribbean.

Nathália Villa Dos Santos,Laís Fajersztajn,Victor Yuji Yariwake,Karina do Valle Marques,Mariana Matera Veras

doi:10.3389/fneur.2021.684524

Abstract

The risk of dementia and Alzheimer's disease in Latin America and the Caribbean (LAC) rises with increasing age and polluted air. Currently, at least 172 million people breathe unhealthy levels of air pollution in LAC countries. Several cohort studies have indicated that air pollution increases the risk of developing dementia and neurodegenerative diseases, but the mechanisms underlying the association are still not clear. Air pollution causes and aggravates five established risk factors for dementia (obesity, hypertension, stroke, diabetes mellitus, and heart diseases) and is linked to three other risk factors (physical inactivity, cognitive inactivity, and depression). Some of these risk factors could be mediating the association between air pollution and dementia. Reducing the risks for dementia is crucial and urgently needed in LAC countries. There is room for improving air quality in many urban areas in the LAC region and other low- and middle-income countries (LMICs), a routealready explored by many urban areas in developing regions. Moreover, reducing air pollution has proved to improve health outcomes before. In this article, we propose that despite the ongoing and valid scientific discussion, if air pollution can or cannot directly affect the brain and cause or aggravate dementia, we are ready to consider air pollution as a potentially modifiable risk factor for dementia in LAC and possibly in other LMICs. We suggest that controlling and reducing current air pollution levels in LAC and other LMIC regions now could strongly contribute.

Highlights

Despite the ongoing and valid scientific discussion about whether air pollution can or cannot directly affect the brain, and cause or aggravate dementia, in this article, we propose that we are ready to consider air pollution as a modifiable risk factor for dementia in Latin America and the Caribbean (LAC), and in other low- and middle-income countries (LMICs)
It is characterized by increased levels of systemic inflammatory mediators that cross the blood–brain barrier (BBB) and metabolic mediators released by adipose tissue and the pancreas that play additional important roles in mediating central nervous system inflammation and neuronal regulation [92], and leading to activation of microglia and astrocytes, inducing the release of cytokines and oxidants
A better air quality in the region could reduce their risk of developing dementia

Summary

INTRODUCTION

Despite the ongoing and valid scientific discussion about whether air pollution can or cannot directly affect the brain, and cause or aggravate dementia, in this article, we propose that we are ready to consider air pollution as a modifiable risk factor for dementia in Latin America and the Caribbean (LAC), and in other low- and middle-income countries (LMICs). The obesity–diabetes–dementia connection occurs through inflammation and oxidative stress in the brain, caused by systemic inflammation It is characterized by increased levels of systemic inflammatory mediators (cytokines) that cross the blood–brain barrier (BBB) and metabolic mediators released by adipose tissue and the pancreas (leptin, insulin, and amylin) that play additional important roles in mediating central nervous system inflammation and neuronal regulation [92], and leading to activation of microglia and astrocytes, inducing the release of cytokines and oxidants. This inflammatory microenvironment causes neuronal dysfunction or death and creates a neurodegenerative cascade. In patients with apolipoprotein E4, it can significantly accelerate olfactory decline, attention, and short-term memory contributing to neurodegeneration and the progress of Alzheimer’s disease [80, 104, 105]

DISCUSSION

Findings

DATA AVAILABILITY STATEMENT