Inhaling dementia: Environmental toxins, Alzheimer’s disease, and Parkinson’s disease

The olfactory system allows for a direct connection between the environment and the brain. Consistent evidence shows that exposure to inhaled environmental toxins increases risk of dementia, such as what is observed in Alzheimer’s disease (AD) and Parkinson’s disease (PD). As dementia critically impacts several aspects of the self, caregivers, society, and the economy, the author stresses the need for this information to be more visible in scientific literature, books, and other media perused by social scientists. In this brief review, the author summarizes general olfactory processes, describes evidence underscoring the invasion of the brain by toxins, outlines the neuropathology of structures in dementia that underly olfaction, and discusses additional considerations, such as COVID-19 and wildfire pollution.