Association between depressive status and mild cognitive impairment in middle-aged and elderly Chinese adults from CHARLS study.

Background: The potential association between depressive status and the risk of mild cognitive impairment (MCI) remains unclear, especially in the absence of prospective evidence. This study aims to elucidate the impact of either depression score or depression on the risk of MCI using longitudinal data from the China Health and Retirement Longitudinal Study (CHARLS).

Methods: This prospective study included 5,766 participants from CHARLS followed from 2011 to 2015. We calculated the baseline depression score using the 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) and the cognitive status score after 3 years of follow-up through four dimensions: orientation, memory, calculation, and draw. We collected baseline sociological characteristics and health-related factors as covariates, using multivariate-adjusted logistics regression models (odds ratios (OR) and 95% confidence intervals (CI)) and restricted cubic splines (RCS) to estimate the effect of depressive status on MCI risk.

Results: We observed 724 new cases of MCI at follow-up. Logistics regression analysis showed that participants with depression had a 58% higher risk of developing MCI than those without depression (OR = 1.58, 95%CI: 1.35-1.85), and the positive association persisted after adjusting for covariates such as sociological characteristics of the population and health-related factors (OR = 1.24, 95%CI: 1.04-1.48). We also observed a dose-response relationship between depression score and MCI risk, with participants with 11~20 and 21~30 scores having a progressively higher risk of MCI compared to participants with depression score of 0~10 (p for trend < 0.05), and a 3% increase in MCI risk for each 1-point increase in depression scores (OR = 1.03, 95%CI: 1.01-1.04). RCS analysis also showed a nonlinear association between depression score and MCI risk (p for non-linearity = 0.001), with MCI risk increasing with increasing depression score. In addition, stratified analyses based on sex, age, marital status, residence, BMI, nighttime sleep, smoking status, alcohol drinking status, baseline serological indicators, and comorbidities showed no interaction (p for interaction > 0.05) other than serum total cholesterol levels (p for interaction = 0.008).

Conclusions: Among middle-aged and elderly adults from CHARLS, depression is an independent risk factor for MCI, indicating that individuals with more severe depression symptoms are more likely to suffer from MCI. Early depression screening based on CESD-10 may help identify individuals at high risk of MCI, and early intervention may reduce the incidence of MCI and Alzheimer's disease, thereby reducing the social care burden of an ageing population.