Objectively measured sedentary time and mental and cognitive health: Cross-sectional and longitudinal associations in The Rotterdam Study

Introduction: Based on studies using self-reported sitting time, sedentary behavior has been suggested as a risk factor for poor mental health and cognition. However, it remains unclear whether objectively measured sedentary behavior is longitudinally associated with depression, anxiety disorders or cognition. Methods: In the population-based Rotterdam Study, cross-sectional and longitudinal associations of objectively assessed sedentary time with depressive symptoms, anxiety disorders and cognition were assessed among 1841 participants (mean follow-up: 5.7 years). Participants wore a wrist actigraph for seven days between 2004 and 2007 to assess sedentary time (hours/day). Depression, anxiety disorders and cognition were assessed twice between 2004 and 2014. Depressive symptoms were continuously measured with the Centre for Epidemiologic Studies-Depression scale (CES-D) and a diagnoses of anxiety disorder (n = 147) was obtained by interview, using an adapted version of the Munich Composite International Diagnostic Interview (M-CIDI). Cognition was assessed using a test-battery. Linear regression was performed for all continuous outcomes, and logistic regression for all binary outcomes. Results: In analyses adjusted for age, sex, cohort and time awake only, 1 h/day more sedentary time was cross-sectionally associated with a 0.25 point (95% confidence interval (95%CI): 0.08, 0.41) higher CES-D score, 1.11 (95%CI: 1.01, 1.21) higher odds of anxiety disorder, and 0.03 (95%CI: 0.05, -0.01) lower global cognition score. After adjustment for confounders, these associations no longer remained. Sedentary time at baseline was not associated longitudinally with changes in depressive symptoms, anxiety disorders and cognition. Conclusions: No support was found for an association between actigraphically measured sedentary time and mental health or cognition. All observed associations were explained by confounders, in particular, disability, occupational status and smoking. The previously reported association between sitting time and mental health might reflect residual confounding, bias of subjective measures, or the social context of sedentary behavior.

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