A symptom cluster-based approach to studying the association between physical activity and depressive symptoms
Background: Several studies indicate that physical activity (PA) is inversely associated with depressive symptoms across the lifespan. In most of these studies, depressive symptoms were treated as a unidimensional construct; however, depression is a multidimensional construct consisting of affective, somatic, cognitive, and behavioural symptoms. In this cross-sectional study, we examined which clusters – depressed affect, somatic symptoms, interpersonal problems, and lack of positive affect – are associated with light PA (LPA) and moderate-to-vigorous PA (MVPA) in university students. Methods: Participants were 738 undergraduate students (mean age = 19.6 years; 76.9% female) who completed an online questionnaire. Four depressive symptom cluster scores were computed from responses on the 20-item Center for Epidemiologic Studies Depression Scale, and PA scores were computed from responses on the Leisure Time Exercise Questionnaire. Results: In separate linear regression analyses (controlling for age, sex, number of exams/assignments, and target grade point average), MVPA was significantly associated with lack of positive affect (beta = -.12, p < .05), but not somatic symptoms, interpersonal problems, or negative affect. LPA was not significantly associated with any of the four depressive symptoms clusters. Conclusions: Our results suggest that the association between MVPA and overall depressive symptoms among university students may be driven primarily by the positive affect cluster. As such, researchers should seek to tease apart the positive affective symptoms of depression from the cognitive, negative affective, and interpersonal symptoms in future studies.