Not just anyone: Living situation is indirectly associated with cognitive impairment via depressive symptoms

OBJECTIVES: Socially isolated individuals are at a greater risk of cognitive decline. We examined whether this relationship is dependent on the type of household living situation, living alone or living with others (spouse/partner or relative/friend), and the indirect effects of depression. METHODS: We evaluated 10,545 cognitively normal (CN, mean age = 71.6) and 9334 individuals with mild cognitive impairment (MCI, mean age = 72.9) cross-sectional data from the National Alzheimer's Coordinating Center. Participants' living situation was classified as living alone, living with spouse/partner, or living with a relative/friend. Cognitive function and depression were assessed by a neuropsychological battery and the Geriatric Depression Scale respectively. Cross-sectional mediation was tested using regression-based path analyses. RESULTS: In CN individuals, living with a spouse/partner was associated with higher cognitive performance compared to all other living situations, while living with a relative/friend was associated with the worst cognitive performance. This difference was most evident in females. MCI individuals living with a relative/friend also had lower cognitive performance even when compared to individuals living alone. Greater depressive symptoms among those living with a relative/friend mediated this difference, accounting for 7% and 10% of the effect in CN and MCI respectively. DISCUSSION: Our findings suggest that living situations may entail social dynamics that elicit psychological stresses and impact cognitive aging. While living with a spouse/partner may provide cognitive resilience through social support, living alone may be more beneficial for cognitive preservation than living with a relative/friend due to lower depressive symptoms, particularly for CN females and individuals with MCI.