1. Staticstics Korea population status and prospects in the world and Korea in 2019. http://kostat.go.kr/portal/korea/kor_nw/1/2/6/index.board?bmode=read&bSeq=&aSeq=377226&pageNo=1&rowNum=10&navCount=10&currPg=&searchInfo=&sTarget=title&sTxt= (accessed January 10).
2. Health insurance review & assessment service 2018 health insurance statistical yearbook. http://www.hira.or.kr/bbsDummy.do?pgmid=HIRAA020045020000&brdScnBltNo=4&brdBltNo=2311 (accessed January 10).
3. Pathology of neurodegenerative diseases;Dugger;Cold Spring Harb Perspect Biol,2017
4. Serotonergic system, cognition, and BPSD in Alzheimer's disease;Chakraborty;Neurosci Lett,2019
5. Olfactory dysfunction as a predictor of neurodegenerative disease;Albers;Curr Neurol Neurosci Rep,2006