Examining the factors that moderate progression from subjective cognitive decline to objective cognitive decline: A 4‐year longitudinal study

Abstract Background Subjective cognitive decline (SCD) in older adults has been identified as a risk factor for dementia, although the literature is inconsistent, and the factors that contribute to this inconsistency are not fully understood. We focused on the protective factors for dementia risk and aimed to determine whether SCD has more protective factors for dementia risk and whether they reduce the association with future objective cognitive decline (OCD) from a 4‐year longitudinal study. Method We included 4,363 older adults (age: 71.7±5.3 [mean ± standard deviation] years; 2,239 women) from the National Center for Geriatrics and Gerontology–Study of Geriatric Syndromes. SCD, OCD, and protective factors such as lifestyle and activity for dementia risk were assessed using a face‐to‐face interviews and objective cognitive assessment tools. Participants were categorized into cognitive status: normal cognition (neither SCD nor OCD), SCD only, OCD only, and SCD and OCD (both SCD and OCD) groups. Four years later, participants were classified as having or not having mild cognitive impairment or global cognitive impairment. Binomial logistic regression analysis was performed with follow‐up on the cognitive status and at the baseline cognitive status groups as the dependent and independent variables, respectively. Result Potential confounding factors‐adjusted odds ratios for SCD only, OCD only, and SCD and OCD groups for developing OCD at follow‐up were 1.08 (95% CI, 0.80‐1.45; p = 0.608), 4.00 (95% CI, 2.64‐6.07; p<0.001), and 3.12 (95% CI, 2.22‐4.37; p<0.001), respectively. The SCD only group had more protective factors for dementia risk than the OCD only group. Conclusion Community‐dwelling elderlies with SCD had more protective factors for dementia risk at the baseline and a lower association with OCD in the 4‐year follow‐up. Our results suggest that the presence of protective factors for dementia risk may be a contributing factor to the inconsistent literature on the SCD outcomes.