Background: Depressive symptoms (DS) are highly prevalent in patients with cardiovascular diseases (CVD). Sedentary behavior is associated with DS, and together they worsen CVD health outcomes. Rural patients exhibit greater incidence of DS and physical inactivity than their urban counterparts. While females and younger adults are more likely to experience DS in general, how sedentary time (ST) interacts with age and sex on DS in rural patients with CVD has not been elucidated.

Hypothesis: Age and sex multiplicatively moderate the association of daily ST with DS in rural patients with CVD.

Methods: A total of 226 (58±12 [range 23-80] years old, 49% female) rural patients with CVD were included. The Patient Health Questionnaire-9 was used to measure DS. Patients wore the ActiGraph GT9X Link for 4 to 7 days to measure ST (minutes/day on average). We used PROCESS to test the moderated moderation model. The pick-a-point approach was used for probing a three-way interaction.

Results: We found a significant three-way interaction among daily ST (X), age (Z), and sex (W) [B=-.0016, t(218)=-3.631, p=.0004], which indicates the magnitude of the moderation by sex on the effect of daily ST on DS depended on age. Moderated moderation explained 10.1% of the variance in DS (p=.002). The pick-a-point approach indicated significant conditional interactions between ST and sex at the youngest and oldest ages (Figure). Among younger adults, there was a significantly positive association of ST with DS in females compared to males [θ_XW→Y|(Z=30)=.034; F(1;218)=8.363; p=.004], while a significantly positive association of ST with DS was found in males compared to females among older adults [θ_XW→Y|(Z=70)=-.028; F(1;218)=11.431; p=.001]. However, among middle-aged adults, the association of sedentary time with DS was not significantly moderated by sex (p=.59).

Conclusions: The findings of the study indicate a complex interaction of age and sex in the relationship of ST with DS and suggest an age- and sex-stratified intervention to improve depressive symptoms. Future research is warranted to examine factors that influence sex differences in the association of ST with DS in different age groups.