Mediating role of homebound status between depressive symptoms and cognitive impairment among community-dwelling older adults in the USA: a cross-sectional analysis of a cohort study

Objective Depressive symptoms are known modifiable factors of cognitive impairment in older adults. However, the pathway through which depressive symptoms lead to cognitive impairment is not well understood. This study aimed to investigate whether homebound status (defined as usually unable to leave home unassisted) mediates the association between depressive symptoms and cognitive impairment in community-dwelling older adults in the USA. Design A secondary analysis of cross-sectional data. Setting(s) Communities in the USA. Participants Community-dwelling older adults (N=7537) from the 2011 National Health and Aging Trends Study, a nationally representative survey of Medicare Beneficiaries in the USA. Main outcome measures Participants' cognitive impairment status was classified using a composite measure. Depressive symptoms were assessed using Patient Health Questionnaire-2. Homebound status was determined by the frequency, difficulty and needing help in getting outdoors. We used logistic regression and the Paramed command in STATA to analyse whether homebound mediated the association between depressive symptoms and cognitive impairment. Results Participants were on average, 77.7 years old, female (58.3%) and non-Hispanic white (68.1%). About 26% of the participants were classified as having cognitive impairment, 16% reported depressive symptoms and 25% were homebound. Depressive symptoms (adjusted OR, 1.60; 95% CI 1.36 to 1.89) and homebound status (adjusted OR, 1.58; 95% CI 1.34 to 1.86) were independently associated with cognitive impairment. Homebound significantly mediated 12.5% of the total effect between depressive symptoms and cognitive impairment, with significant indirect effect (OR, 1.07; 95% CI 1.04 to 1.10), direct effect (OR, 1.61; 95% CI 1.36 to 1.91) and total effect (OR, 1.72; 95% CI 1.46 to 2.03). Conclusions This study supports a mediating role of homebound status in the relationship between depressive symptoms and cognitive impairment. Interventions to promote outdoor mobility should be studied for their ability to delay cognitive impairment for older adults with depressive symptoms.