Association Between Plant-Based Dietary Patterns and the Long-Term Trajectory of Depressive Symptoms: A 10-Year Longitudinal Study

OBJECTIVES: Previous studies have analyzed associations between plant-based dietary patterns and depressive symptoms. However, little is known about the association of plant-based dietary patterns with the long-term trajectory of depressive symptoms in older Chinese adults. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: A total of 1666 individuals aged >65 years during the period from 2008 to 2018 were included, who had complete dietary data and complete evaluations of depressive symptoms in 4 waves. METHODS: Data from the Chinese Longitudinal Health and Longevity Survey (CLHLS) were used in this study. We used the simplified Food Frequency Questionnaire at baseline to assess the overall Plant-based Diet index and unhealthy Plant-based Diet Index. Depressive symptoms were assessed by participants' responses to 5 questions. We used a group-based trajectory model to determine the trajectory of depressive symptoms and used multiple logistic regression to analyze the association of plant-based dietary patterns with the long-term trajectory of depressive symptoms in older Chinese adults. RESULTS: The study included 1666 older adults. We identified 3 trajectories of depressive symptoms. The results showed that participants with the highest quintile of Plant-based Diet index were less likely to be on a moderate depression trajectory [odds ratio (OR), 0.597; 95% CI, 0.358-0.994] or a highly progressive depression trajectory (OR, 0.344; 95% CI, 0.171-0.692) than those with the lowest quintile. In contrast, the odds of the highest unhealthy Plant-based Diet Index quintile being on a moderate depression trajectory (OR, 2.750; 95% CI, 1.555-4.863) or a highly progressive depression trajectory (OR, 6.168; 95% CI, 3.014-12.623) were increased. CONCLUSIONS AND IMPLICATIONS: Adherence to plant-based dietary patterns was associated with a lower likelihood of being on an unfavorable depressive trajectory, whereas an unhealthy plant-based diet was associated with an increased likelihood of being on an unfavorable depressive trajectory.