Sleep quality and depression among adults co-residing with a family member with dementia: a moderated mediation analysis using propensity score matching

BACKGROUND: Dementia affects not only patients but also co-residing family members. Sleep disturbance may be an important yet underexplored pathway linking dementia co-residence to poorer mental health. AIMS: This study examined the association between co-residence with a family member with dementia and depressive symptoms among Korean adults, with a focus on the mediating and moderating role of sleep quality. METHODS: This cross-sectional secondary analysis used nationally representative data from the 2024 Korea Community Health Survey. After excluding missing data, 3066 adults co-residing with a person with dementia were matched to 7388 controls using 1:3 nearest-neighbor propensity score matching. Depressive symptoms were assessed with the Patient Health Questionnaire-9 and sleep quality with the Pittsburgh Sleep Quality Index. Multivariable regression and moderated mediation analyses with 10,000 bootstrap resamples were performed. RESULTS: Adults co-residing with a family member with dementia reported higher depressive symptoms than those who did not (3.95 ± 4.69 vs. 3.14 ± 3.88, p < .001). Poorer sleep quality was the strongest predictor of depressive symptoms (β = 0.45, p < .001). Sleep quality mediated the association between dementia co-residence and depressive symptoms (indirect effect = 0.23, 95% CI [0.13, 0.33]) and also moderated this association. CONCLUSIONS: Co-residence with a person with dementia was associated with higher depressive symptoms. Sleep quality functioned as both a mediator and a moderator, supporting the need for family-based mental health interventions that include sleep assessment and management.