**10. Methods**

Article research was performed using Pubmed database and key words such as Alzheimer's disease, environmental factors, and genes were used for database search of articles published from 1975 to 2016. Articles relevant for the review were selected based on different criteria such as topics of interests, scientific rigor, and reproducibility of results.

## **Acknowledgements**

This work was supported in whole or in part by funding from Alzheimer Association (NIRP14-304720), Department of Veteran Affairs RR&D SPiRE (1I21RX001558-01A1), and NIH R01 (1R01AG048923-01) for DC.
