Associations of plant based dietary intake and physical activity with depression symptoms in older adults aged 65 years and above in longevity areas in China

Objective: To investigate the associations of plant based dietary intake and physical activity with depression symptoms in old adults aged ≥65 years in longevity areas in China. Methods: Based on cross-sectional data from the Healthy Ageing and Biomarkers Cohort Study conducted in 2021. Information about demographic characteristics, lifestyles, and psychological characteristics of the old adults were collected. Plant based dietary index (PDI) was obtained and calculated according to the results of dietary intake frequency surveys. Physical activity status of the old adults was estimated by using Physical Activity Scale for the Elderly. Depression symptoms of the old adults were measured by using Patient Health Questionnaire-9. Logistic regression models were applied to investigate the associations of different levels of plant based dietary intake and physical activity with depression symptoms in the older adults. Results: A total of 5 464 participants aged ≥65 years were included, with a mean age of (84.3±11.4) years, the prevalence of depression symptoms was 5.5% (303). High levels of plant based dietary intake and physical activity were associated with lower risk for depression symptoms. Results of logistic regression models adjusted for confounders showed that plant based dietary intake and physical activity were negatively associated with depression symptoms of the older adults. Compared with the Q₁ group, the ORs of depression symptoms in the Q₂, Q₃, Q₄ groups were 0.85 (95%CI: 0.62-1.17), 0.83 (95%CI: 0.60-1.14), and 0.50 (95%CI:0.33-0.77), respectively, for the PDI level, and compared with the Q₁ group, the ORs of depression symptoms in the Q₂, Q₃, Q₄ groups were 0.73 (95%CI: 0.51-1.05), 0.69 (95%CI: 0.47-1.02), and 0.60 (95%CI: 0.39-0.93), respectively, for the physical activity level. No significant additive or multiplicative interaction was observed between the plant based dietary intake level and the physical activity level. Conclusion: Increased intake of plant-based dietary and physical activity in old adults are associated with reduced probability of depression symptoms.