Objective: We estimate the causal effect of social connectedness (i.e., the frequencies of meeting with friends, relatives, or neighbors) on cognitive function (the Korean version of Mini-Mental State Exam) among Korean older adults. Methods: We used longitudinal panel data collected before and during the coronavirus disease-2019 (COVID-19) to set up the fixed (FE) or random effect (RE) models. To overcome omitted variable bias or reverse causality, we used COVID-19 pandemic period as an instrumental variable to estimate the causal effect of social connectedness on cognitive function. Results: Social distancing measures during the COVID-19 period decreased social interaction. The results showed that an increase in the frequency of social interaction led an increase in cognitive scores. Specifically, an increase of one unit in the frequency of meeting familiar people increased cognitive scores by 0.1470 and 0.5035 in the RE and FE models, respectively. Conclusion Social distancing policies due to the global pandemic may have increased the risk of social isolation and cognitive decline among older adults. The government and local communities need to increase their effort to develop way to connect adults through the remainder of the pandemic and beyond.

Objective: This study investigates the longitudinal effects of changes in the associations between two distinct aspects of social connections—i.e., social connectedness and loneliness—on depressive symptoms among community-dwelling Korean adults. This study also examines whether these associations vary across three age groups (45–64, 65–74, and 75 or above). Methods: Using data from the Korean Longitudinal Study of Ageing collected between 2014 and 2020 (n=3,642 individuals), fixed effects models were used to examine the age-specific associations between the two distinct aspects of social connections and depressive symptoms (Center for Epidemiologic Studies-Depression Scale) while, accounting for time-invariant individual heterogeneity. Social connectedness is measured by asking the frequency of interactions with friends, relatives, or neighbors. Results: The findings indicate that the impact of loneliness on depressive symptoms outweighs that of social disconnectedness. Notably, this study unveils age-specific patterns concerning the impact of the coronavirus disease-2019 pandemic on depressive symptoms and changes in the association between loneliness and depressive symptoms. Specifically, middle-aged individuals reported higher levels of depressive symptoms and loneliness along with a heightened impact of loneliness on depressive symptoms, despite maintaining stable social connections. Conversely, the oldest adults experienced reductions in both depressive symptoms and loneliness, despite a significant decrease in socializing. Conclusion These findings shed light on the differential effects of loneliness on depressive symptoms within distinct age groups before and during the pandemic. The implications of these findings are discussed with a focus on informing the development of targeted policy interventions tailored to the specific needs of different age groups.