Association between PHQ-9-measured depressive symptoms and a positive AD8 screen among older adults during the COVID-19 pandemic: a large cross-sectional study in China

Background The association between depressive symptoms and possible cognitive impairment among older adults during the COVID-19 pandemic warrants further investigation. This cross-sectional study examined the association between depressive symptoms measured using the PHQ-9 and a positive AD8 screen among older adults in China, including whether the association departed from linearity. Methods In this cross-sectional study, participants aged 60 years or older were recruited through quota sampling in 120 cities selected using a non-probability approach across China. The PHQ-9 scale was used to assess depressive symptoms, and the AD8 was used to screen for possible cognitive impairment or possible dementia. Logistic regression, restricted cubic spline regression analyses, and subgroup analyses were conducted to examine the association between depressive symptoms and a positive AD8 screen. Results Among 1,026 participants, 483 (47.1%) screened positive on the AD8. The fully adjusted logistic regression analysis revealed a significant association between PHQ-9 scores and a positive AD8 screen (OR, 95% CI: 1.34, 1.05–1.71, per 1 SD increase). The restricted cubic spline analysis indicated a nonlinear association between depressive symptoms and a positive AD8 screen ( P for overall < 0.001; P for nonlinear < 0.001). Exploratory subgroup analyses suggested differences in the association between depressive symptoms and a positive AD8 screen by living-alone status and chronic illness. Conclusion This cross-sectional study identified a nonlinear association between depressive symptoms measured using the PHQ-9 and a positive AD8 screen among older adults during the COVID-19 pandemic. These findings suggest that depressive symptoms may help identify older adults who could benefit from further cognitive assessment and closer clinical attention.