Abstract
OBJECTIVE: To investigate the temporal relationships between depressive symptoms, physical activity, and self-efficacy in individuals with stroke. DESIGN: Six-month prospective observational cohort study. SETTING: General community. PARTICIPANTS: Seventy-three individuals with stroke (42 male; 61.9±12.3 years old). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Three functional domains were the primary outcomes: physical activity was defined by average steps per day as measured by a Fitbit device; depressive symptoms and self-efficacy were measured by Patient-Reported Outcomes Measurement Information System (PROMIS) short forms. These outcome measures were collected at study enrollment and monthly thereafter for six months, resulting in a maximum of seven timepoints. RESULTS: Three separate lagged linear mixed effects models were constructed (one with each functional domain as the dependent variable). Each model included the measure of the targeted functional domain as the dependent variable, measurements from the previous month of the two other functional domains and their interaction as fixed effects, participant as a random effect, and demographics and stroke characteristics as covariates. The depressive symptoms by self-efficacy interaction was associated with future physical activity, suggesting that higher self-efficacy positively impacts the following month's physical activity only when depressive symptoms are low. Depressive symptoms were not associated with self-efficacy, steps per day, or their interaction in the prior month, indicating that the relationship between depressive symptoms and physical activity is unidirectional. Finally, depressive symptoms were associated with self-efficacy in the subsequent month. CONCLUSIONS: The longitudinal study provides evidence that 1) mitigating depressive symptoms and promoting self-efficacy may improve future physical activity; 2) addressing depressive symptoms first may lead to more effective treatment of depression, low self-efficacy, and low physical activity; and 3) treating depression may improve future self-efficacy. Together the results provide additional knowledge about the complex relationships between mobility, mood, and self-efficacy that must be carefully managed during post-stroke rehabilitation.