Impact of Mild Cognitive Impairment on Mortality and Cause of Death in the Elderly

Article type: Research Article

Authors: Bae, Jong Bin^{a; b} | Han, Ji Won^{a; b} | Kwak, Kyung Phil^c | Kim, Bong Jo^d | Kim, Shin Gyeom^e | Kim, Jeong Lan^f | Kim, Tae Hui^g | Ryu, Seung-Ho^h | Moon, Seok Wooⁱ | Park, Joon Hyuk^j | Youn, Jong Chul^k | Lee, Dong Young^{a; l} | Lee, Dong Woo^m | Lee, Seok Bumⁿ | Lee, Jung Jaeⁿ | Jhoo, Jin Hyeong^o | Kim, Ki Woong^{a; b; p; *}

Affiliations: [a] Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea | [b] Department of Neuropsychiatry, Seoul National University Bundang Hospital, Gyeonggido, Korea | [c] Department of Psychiatry, Dongguk University Gyeongju Hospital, Gyeongju, Korea | [d] Department of Psychiatry, Gyeongsang National University, School of Medicine, Jinju, Korea | [e] Department of Neuropsychiatry, Soonchunhyang University Bucheon Hospital, Bucheon, Korea | [f] Department of Psychiatry, School of Medicine, Chungnam National University, Daejeon, Korea | [g] Department of Psychiatry, Yonsei University Wonju Severance Christian Hospital, Wonju, Korea | [h] Department of Psychiatry, School of Medicine, Konkuk University, Konkuk University Medical Center, Seoul, Korea | [i] Department of Psychiatry, School of Medicine, Konkuk University, Konkuk University Chungju Hospital, Chungju, Korea | [j] Department of Neuropsychiatry, Jeju National University Hospital, Jeju, Korea | [k] Department of Neuropsychiatry, Kyunggi Provincial Hospital for the Elderly, Korea | [l] Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Korea | [m] Department of Neuropsychiatry, Inje University Sanggye Paik Hospital, Seoul, Korea | [n] Department of Psychiatry, Dankook University Hospital, Cheonan, Korea | [o] Department of Neuropsychiatry, Kangwon National University Hospital, Chuncheon, Korea | [p] Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Korea

Correspondence: [*] Correspondence to: Ki Woong Kim, Department of Neuropsychiatry, Seoul National University Bundang Hospital, 300 Gumi-dong, Bundang-gu, Seongnam-si, Gyeonggi-do 13620, Korea. Tel.: +82 31 787 7432; Fax: +82 31 787 4058; E-mail: kwkimmd@snu.ac.kr.

Abstract: Background:Mild cognitive impairment (MCI) is a cognitive state that lies on the continuum between normal aging and dementia, and the prevalence of MCI is higher than dementia. However, the risk for mortality of people with MCI has been far less studied than that of people with dementia, and the population attributable risk percent (PAR%) of death attributable to MCI has not been estimated yet. Objective:To investigate the impact of MCI on mortality and the cause of death in the elderly, and to estimate the PAR% of deaths attributable to MCI. Methods:Data came from 7,315 elderly subjects aged ≥60 years without dementia from two cohort studies with diagnostic assessments of MCI at baseline. Deaths among participants were confirmed through the nationwide mortality database of Statistics Korea. Results:MCI increased the risk of mortality in a multivariate Cox proportional model adjusting for age, sex, education, smoking, alcohol drinking, chronic illness, depression, vascular components, and cohort (hazard ratio = 1.59, 95% confidence interval 1.30, 1.94). PAR% of death attributable to MCI was 10.7% for age 65–74 years, 16.0% for age 75–84 years, and 24.2% for age ≥85 years. In the elderly with MCI, mortality risks from cerebrovascular disease, respiratory disease, and external causes were higher than in the cognitively normal elderly. Conclusions:Our results suggest that the mortality risk of MCI in Asian countries may be comparable to that in Western countries, and MCI can contribute to the death of the elderly as much as dementia.

Keywords: Cause of death, cognitive dysfunction, death, epidemiology, neurocognitive disorders, mortality

DOI: 10.3233/JAD-171182

Journal: Journal of Alzheimer's Disease, vol. 64, no. 2, pp. 607-616, 2018