Age-Related Cognitive Decline and Prevalence of Mild Cognitive Impairment in the Iwaki Health Promotion Project

Article type: Research Article

Authors: Nakahata, Naoko^{a; b} | Nakamura, Takumi^{b; c} | Kawarabayashi, Takeshi^{b; c; d} | Seino, Yusuke^e | Ichii, Sadanobu^b | Ikeda, Yoshio^c | Amari, Masakuni^d | Takatama, Masamitsu^d | Murashita, Koichi^f | Ihara, Kazunari^b | Itoh, Ken^g | Nakaji, Shigeyuki^b | Shoji, Mikio^{b; c; d; *}

Affiliations: [a] Department of Rehabilitation Sciences, Division of Speech-Language-Hearing Therapy, School of Health Sciences, Hirosaki University of Health and Welfare, Hirosaki, Aomori, Japan | [b] Department of Social Medicine, Hirosaki University Graduate School of Medicine, Hirosaki, Japan | [c] Department of Neurology, Gunma University Hospital, Maebashi, Japan | [d] Department of Neurology, Dementia Research Center, Geriatrics Research Institute and Hospital, Maebashi, Japan | [e] Department of Neurology, Hirosaki National Hospital, Hirosaki, Japan | [f] Center of Innovation Research Initiatives Organization, Hirosaki University, Hirosaki, Aomori, Japan | [g] Department of Stress Response Science, Hirosaki University Graduate School of Medicine, Hirosaki, Japan

Correspondence: [*] Correspondence to: Mikio Shoji, MD, PhD, Department of Neurology, Dementia Research Center, Geriatrics Research Institute and Hospital, 3-26-8 Ootomo-machi, Maebashi, 371-0847 Japan. Tel.: 81 27 253 3311; Fax: 81 27 252 7575; E-mail: m-shoji@ronenbyo.or.jp.

Abstract: Background: The Iwaki Health Promotion Project (IHPP) is a community-based study for the prevention of lifestyle-related diseases and improvement of quality of life. Objective: Between 2014 and 2017, a total of 4,442 Iwaki town residents from 19 to 93 years of age participated in annual surveys to clarify the natural course of age-related cognitive decline and mild cognitive impairment (MCI). Methods: Modified OLD and SED-11Q questionnaires, MMSE, Logical Memory II, educational history, and APOE genotypes were examined at the first screening. MCI and dementia were diagnosed at the second examination by detailed neurological examination, CDR, and MRI, and followed for 3 years. Spline regression analyses based on a linear mixed model was adopted for statistical analysis. Results: MMSE scores declined with age from 55 to 64 years. There was also interaction between levels of education and ages. At the second examination, 56 MCI and 5 dementia patients were identified. None of the MCI cases progressed to dementia during the 3 years. During follow-up examinations, 13 cases showed improved MMSE scores (0.95 point/year), 5 remained stable, and 7 deteriorated (–0.83 point/year). Five cases showed improved CDR-SOB scores (–0.28 point/year), 9 remained stable, and 6 deteriorated (0.3 point/year). Conclusion: IHPP revealed that age- and education-related cognitive decline began and advanced from 55 years of age. The prevalence of MCI and dementia was estimated to be 5.9%in the Iwaki town cohort over 60 yeas of age. About 30%of MCI cases showed progression of cognitive decline.

Keywords: Age-related cognitive decline, APOE ɛ4, dementia, education, Iwaki Health Promotion Project, mild cognitive impairment

DOI: 10.3233/JAD-210699

Journal: Journal of Alzheimer's Disease, vol. 84, no. 3, pp. 1233-1245, 2021