Written by Afif Showkat, MSPH, BA

Brain health is shaped not only by our bodies and lifestyles, but also by the environments we live in. Environmental toxins like pollution, chemicals, and heavy metals can enter the body and affect how the brain grows, functions, and ages.

Dementia is the name for a group of symptoms that include memory problems and trouble thinking. The most common type of dementia is Alzheimer’s disease. Risk increases with age, but it is not a normal part of aging. Over time, exposure to environmental toxins can increase the risk for conditions like Alzheimer’s and other forms of cognitive decline.

What Are Environmental Toxins?

Environmental toxins are harmful substances in the air, water, soil, and food. Sources include mining, industry, agriculture, vehicle emissions, and wildfire smoke. Common examples include fine particle air pollution (also known as PM2.5), heavy metals (lead, arsenic, mercury, cadmium, and manganese), pesticides, and industrial chemicals. 

Many Tribal communities experience higher exposure due to contaminated lands, abandoned mines, industrial waste, and limited cleanup resources.¹

How Do Toxins Affect Brain Health?

Toxins enter the body when breathing polluted air, drinking contaminated water, eating contaminated fish or wildlife, or coming into contact with polluted soil. Some reach the brain directly; others cause chronic inflammation and long-term cell damage.² Over time, this may increase the risk of memory loss and dementia. Exposure increases risk but does not guarantee that someone will develop the disease.³

What Have Researchers Learned About This Topic?

How Can I Protect Myself and My Community?

 _________

Sources 
1. Cade R, Yu D, Knoble C, Whyte K, Lal P, Borgerson C. Environmental justice in Indigenous communities: the disproportionate effects of environmental contamination. ScienceDirect. 2025;10:101348. https://doi.org/10.1016/j.sftr.2025.101348

2. Kotha SV, Kuo G, Kammula SV, et al. The epidemiological and toxicological intersection of air pollution and dementia. Reviews of Environmental Contamination and Toxicology. 2025. Volume 263. https://doi.org/10.1007/s44169-025-00092-6

3. Risk factors for Alzheimer’s disease. Alzheimer’s Association. Accessed February 3, 2026. https://www.alz.org/alzheimers-dementia/what-is-alzheimers/risk-factors 

4. Air pollution linked to dementia cases. National Institutes of Health. September 5, 2023. Accessed January 28, 2026. https://www.nih.gov/news-events/nih-research-matters/air-pollution-linked-dementia-cases

5. Zhao YL, Qu Y, Ou YN, Zhang YR, Tan L, Yu JT. Environmental factors and risks of cognitive impairment and dementia: A systematic review and meta-analysis. Ageing Research Reviews. 2021;72:101504. https://doi.org/10.1016/j.arr.2021.101504

6. Newell ME, Aravindan A, Babbrah A, Halden RU. Epigenetic biomarkers driven by environmental toxins associated with Alzheimer’s disease, Parkinson’s Disease, and Amyotrophic Lateral Sclerosis in the United States: a systematic review. Toxics. 2025;13(2):114. https://doi.org/10.3390/toxics13020114

7. Ahmed G, Rahaman S, Perez E, Khan KM. Associations of environmental exposure to arsenic, manganese, lead, and cadmium with Alzheimer’s disease: a review of recent evidence from mechanistic studies. J. Xenobiot. 2025;15(2):47. https://doi.org/10.3390/jox15020047

8. Mercury exposure widespread among Yanomami tribe in Amazon, report finds. Associated Press. April 4, 2024. Accessed January 2026. https://apnews.com/article/amazon-mercury-gold-mining-yanomami-brazil-indigenous-8809d4f22c84dd6e81bb7a1f5f3ba9f6

9. Elonheimo HM, Andersen HR, Katsonouri A, Tolonen H. Environmental substances associated with Alzheimer’s disease—a scoping review. Int J Environ Res Public Health. 2021;18(22):11839. https://doi.org/10.3390/ijerph182211839

10.    Dementia. Mayo Clinic. June 7, 2025. Accessed February 3, 2026. https://www.mayoclinic.org/diseases-conditions/dementia/symptoms-causes/syc-20352013