Independent and joint associations of dietary diversity and physical activity on mental health among older adults in China: a cross-sectional study.

Background: The joint association of dietary diversity (DD) and physical activity (PA) on anxiety, depressive symptoms, and their comorbidity have not been extensively explored. Hence, this study focused on examining this association.

Methods: Data in this cross-sectional study was derived from the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Based on self-reported dietary diversity score (DDS) questions were used to assess DD, ranging from 0 to 8. DDS < 5 was defined as insufficient DD and DDS ≥ 5 was defined as sufficient DD. PA was based on a self-reported binary question. Anxiety was assessed using the Generalized Anxiety Disorder Scale-7 (GAD-7), and depressive symptoms were evaluated by the Center for Epidemiologic Studies Depression Scale-10 (CESD-10). The independent and joint associations of DD and PA on anxiety, depressive symptoms, and their comorbidity were examined by multivariable-adjusted binary logistic regression models.

Results: In this cross-sectional study, sufficient DD was independently associated with a decreased risk of anxiety (adjusted OR = 0.57, 95% CI = 0.50-0.65), depressive symptoms (adjusted OR = 0.69, 95% CI = 0.63-0.77), and their comorbidity (adjusted OR = 0.58, 95% CI = 0.49-0.68). Similarly, exposure to current exercise was also a significant protective factor for mental health. Importantly, co-exposure to sufficient DD and current exercise may amplify the protective effects on mental health (adjusted OR = 0.47, 95% CI = 0.38-0.57 for anxiety; adjusted OR = 0.36, 95% CI = 0.31-0.42 for depressive symptoms; adjusted OR = 0.37, 95% CI = 0.29-0.48 for their comorbidity). The robustness of these associations was demonstrated in four sensitivity analyses.

Conclusions: Our study found that sufficient DD and current exercise were associated with a decreased risk of mental health disorders. Importantly, the combination of both appeared to enhance this protective effect. Our findings promote the joint assessment of DD and PA to provide new insights into health-related behaviors for prevention strategies for mental health disorders in older adults.