Emulating physical activity interventions on depressive symptoms using observational data from the NutriNet-Brasil cohort

Background: While randomized controlled trials have demonstrated the short-term benefits of physical activity, particularly during leisure-time, on depressive symptoms, uncertainties persist regarding long-term interventions and the necessary dose in different domains.

Purpose: Applying the principles of target trial emulation, our objective was to estimate the effect of sustained physical activity interventions on the 2-year risk of depressive symptoms among adults.

Methods: We used the NutriNet-Brasil cohort, including 15,558 adults (12,036 women, 46.0±12.9) without depressive symptoms, as well as with complete data on baseline and pre-baseline potential confounders. Physical activity was assessed using the global physical activity questionnaire. Depressive symptoms were assessed using the Patient Health Questionnaire. We estimated the 2-year risk of developing depressive symptoms from baseline to the end of follow-up, incomplete follow-up or incident depressive symptoms, whichever comes first. We adjusted for pre-baseline, baseline and time-varying potential confounders, using parametric g-formula, to estimate the 2-year risk of depressive symptoms under different physical activity intervention strategies (i.e., domains and durations), comparing them to the natural course.

Results: Compared to the estimated 30.7%(95%CI:27.1; 34.3) risk of depressive symptoms under the natural course, the 2-year risk of depressive symptoms was reduced by 0.4 percentage points (pp) (-0.7;-0.1) for ≥75min/wk, 1.2pp(-1.9;-0.4) for ≥ 150min/wk, and 2.2pp(-3.5;-0.8) for ≥300min/wk. Considering leisure-time physical activity, the risk was reduced in 1.5pp(-2.1;-1.1) for practicing any leisure-time physical activity, 3.2pp(-4.2;-2.3) for ≥75min/week, and 4.6pp(-6.1;-3.2) for ≥150min/week. However, emulated interventions on transport physical activity showed no association with a reduced risk of developing depressive symptoms.

Conclusions: Adults experience a lower incidence of depressive symptoms with long-term sustained physical activity interventions, even with lower doses.

Practical implications: Long-term strategies aimed at preventing incident depressive symptoms should prioritize leisure-time physical activity, particularly targeting individuals who do not engage in any leisure-time physical activity.

Funding: São Paulo Research Foundation (process: 2019/24124-7).