Risk factors and mental health comorbidities associated with subjective cognitive decline in Chinese older adults: A propensity score-matched case-control study

BACKGROUND: Subjective Cognitive Decline (SCD) is recognized as one of the earliest symptoms of Alzheimer's Disease (AD), the leading cause of dementia. However, factors influencing SCD are inconsistent across studies, with limited research on the risk associated with combinations of symptoms, particularly anxiety and depression. METHODS: This propensity score-matched case-control study analyzed data from the National Essential Public Health Service Program in Shenzhen, China. A total of 270,148 participants aged 65 and older underwent assessments in 2022. Among them, 10,471 participants with SCD were identified as the study group, matched with an equal number of controls without SCD. The match was based on age, gender, household registration, occupation, marital status, and education level. Conditional logistic regression models identified influencing factors and evaluated risks associated with various mental health symptom combinations. Parallel mediation analysis was employed to assess the mediating role of anxiety and depressive symptoms between key factors and SCD. RESULTS: The identified risk factors for SCD included diabetes (AOR: 1.12, 95 %CI: 1.04-1.21), anxiety symptoms (8.49, 6.64-10.90), depressive symptoms (8.06, 5.10-12.80), past smokers (1.20, 1.07-1.34), and occasional alcohol consumption (1.14, 1.03-1.26). Conversely, daily exercise (0.71, 0.66-0.77) and occasional exercise (0.76, 0.68-0.84) were associated with a reduced risk of SCD. Anxiety and depressive symptoms also served as mediators between exercise and SCD. The comorbidity of anxiety and depressive symptoms posed the highest risk for SCD (19.70, 10.70-36.20). CONCLUSIONS: These findings highlight the significant role of anxiety and depressive symptoms, particularly their comorbidity, in identifying individuals at high risk for SCD. Early screening and targeted interventions may help mitigate cognitive decline and promote healthy aging.