Subjective Cognitive Decline in Brazilian Adults: Prevalence and Associated Social, Lifestyle, and Health-related Factors: a Nationally Representative Cross-Sectional Analysis from the ELSI-Brazil Cohort

Background/Objectives: Subjective cognitive decline (SCD) is an early stage of dementia, although its risk factors remain unclear. We estimated prevalence of SCD and its associated dementia risk factors in Brazilian adults. Methods: Cross-sectional study based on data from the second wave (2019-2021) of The Brazilian Longitudinal Study of Aging (ELSI-Brazil), on a nationally representative sample of adults aged ≥50 years. Prevalence of SCD was estimated, defined as self-reported cognitive decline without objective impairment or dementia diagnosis, and adjusted odds ratios (OR) with 95% confidence intervals (CI) were estimated through logistic regression models. Results: Of 6,631 participants, 57.5% were women, 54.4% individuals of non-white race, with a mean age of 65.1 years (standard deviation: ±9.70). SCD prevalence was 19.7% (95%CI 18.6-20.9) for a total of 1,346 individuals. Significant higher odds of SCD emerged with increasing age (OR=1.57; 95%CI: 1.19-2.09 for the oldest ages; p-value for trend <0.01), non-white race (OR=1.53; 95%CI:1.30-1.79), lower education (OR=2.79; 95%CI: 2.02-3.85 for the lowest compared to the highest level, p for trend <0.01), lower income (OR=1.58; 95%CI:1.14-2.21 for the lowest compared to the highest level; p for trend <0.01), loneliness (OR=1.35; 95%CI:1.15-1.59), and sedentary lifestyle (OR=1.33; 95%CI: 1.13-1.59). SCD was also associated with multimorbidity (OR=1.40; 95%CI:1.06-1.84 for 3+ compared to none chronic diseases), diabetes (OR=1.25; 95% CI: 1.02-1.53), visual loss (OR=1.31; 95% CI:1.11-1.56), hearing loss (OR=2.29; 95% CI:1.93-2.71), and depressive symptoms (OR=1.30; 95%CI:1.05-1.60). Conclusions: Our findings highlight the need for strategies to address early cognitive decline and reduce health inequalities in vulnerable populations.