Short review: Air pollution, noise and lack of greenness as risk factors for Alzheimer's disease- epidemiologic and experimental evidence.

The number of patients with Alzheimer's disease (AD) is likely to triple in a few decades as the world's population ages. Given the high personal and societal burden of this disease, it is imperative to identify its risk factors. The etiology of AD is still not fully understood, but environmental factors have emerged as plausible important risk factors on the population-level. In this short review, the author summarizes literature on air pollution, noise and (lack of) greenness as risk factors for AD. In conclusion, a link between air pollution and AD is supported by experimental studies as well as epidemiological studies, although a multi-exposure approach is lacking in most epidemiological studies. Although evidence is much more limited regarding noise and (lack of) greenness as risk factors for AD, future epidemiological studies should have a multi-exposure approach in order to separate potential effects of air pollution, noise and lack of greenness. Given the heavy toll of AD on individuals and society, as well as the ubiquitous nature of environmental factors, a link between environmental stressors and AD deserves special attention.