Prevalence and Progression of Subjective Cognitive Decline among Rural Chinese Older Adults: A Population-Based Study

Background: Few community-based studies have examined occurrence and progression of subjective cognitive decline (SCD).Objective: To investigate prevalence and progression of SCD among rural-dwelling Chinese elderly people.Methods: This cohort study included 2,488 cognitively unimpaired adults (age >= 65 years) who were examined at baseline (2014-2015) and followed in 2018. Demographic, epidemiological, clinical, and neuropsychological data were collected via in-person interviews and clinical examinations following a structured questionnaire. At baseline, SCD was assessed using the self-rated Ascertain Dementia 8-item Questionnaire. At follow-up, Alzheimer's disease (AD) and vascular dementia (VaD) were clinically diagnosed following the international criteria. Data were analyzed using logistic regression models.Results: The prevalence of SCDwas 40.07%. SCD at baselinewas associated with the multivariable-adjusted odds ratio (OR) of 1.51 (95% confidence interval 1.10-2.07) for incident cognitive impairment, no dementia (CIND) and 3.11 (1.64-5.93) for incident AD. Among people with SCD at baseline, the multivariable-adjusted OR of incident CIND was 0.55(0.32-0.96) for hyperlipidemia; the multivariable-adjusted OR of incident AD was 1.21 (1.14-1.30) for older age, 0.32 (0.12-0.88) for high education, 2.60 (1.11-6.08) for carrying APOE epsilon 4 allele, and 0.34 (0.13-0.86) for high social support, whereas the multivariable-adjusted OR of incident VaD was 6.30 (1.71-23.18) for obesity.Conclusion: SCD affects over 40% of rural-dwelling cognitively unimpaired older adults in China. SCD is associated with accelerated progression to CIND and AD. Older age, lack of school education, APOE epsilon 4 allele, and low social support are associated with an increased risk of progression from SCD to AD, whereas obesity is related to accelerated progression to VaD.