1. United Nations, D. of E. and S. A. P. D. (2020). World population ageing 2019 (ST/ESA/SER.A/444). Retrieved from https://www.un.org/development/desa/pd/sites/www.un.org.development.desa.pd/files/files/documents/2020/Jan/un_2019_worldpopulationageing_report.pdf.
2. Milken Institute School of Public Health at The George Washington University. (2018, April 6). The growing cost of aging in America Part 1: An aging population and rising health care costs. Retrieved from https://onlinepublichealth.gwu.edu/resources/cost-of-aging-healthcare/.
3. Vespa, J., Armstrong, D. M., & Medina, L. (2020, February). Demographic turning points for the United States: Population projections for 2020 to 2060. United States Census Bureau. Retrieved from https://www.census.gov/library/publications/2020/demo/p25-1144.html.
4. de Nardi, M., French, E., Jones, J. B., & McCauley, J. (2015, June). Medical spending of the elderly. National Bureau of Economic Research. Retrieved from https://www.nber.org/bah/2015no2/medical-spending-elderly#:~:text=Medical%20spending%20by%20the%20elderly,percent%20of%20all%20 medical%20spending.
5. Gitler, A. D., Dhillon, P., & Shorter, J. (2017). Neurodegenerative disease: Models, mechanisms, and a new hope. Disease Models & Mechanisms, 10(5). https://doi.org/10.1242/dmm.030205.