Abstract
BACKGROUND: With the population aging and the popularization of intelligent technology, smartphones have emerged as a significant factor influencing the depressive symptoms of older adults through diversified functionalities, yet evidence remains limited. This study aims to determine the impact of the smartphone use diversity on depressive symptoms among older adults in China, and whether it varied by gender, residence, and education. METHODS: This study used data from the China Health and Retirement Longitudinal Study (CHARLS). We quantified smartphone use diversity via a composite index to measure smartphone usage capabilities among older adults. Multilevel logistic regression and propensity score matching were applied to analyze associations, with heterogeneity tests across gender, residence, and education. Additionally, latent class analysis (LCA) was conducted to identify distinct patterns of smartphone use and examine their associations with depressive symptoms. RESULTS: Higher smartphone use diversity was significantly associated with reduced depressive symptoms (OR = 0.493, 95% CI: 0.376-0.646; P < 0.001) among older adults, even after adjusting for confounders. The protective effect was stronger in males (OR = 0.482, 95% CI: 0.333-0.697, P < 0.001), urban residents (OR = 0.450, 95% CI: 0.308-0.656, P < 0.001), and those with higher education (OR = 0.488, 95% CI: 0.314-0.760, P < 0.01). Latent class analysis further revealed two distinct usage patterns: "Limited Users" and "Multi-functional Users". Compared with Limited Users, Multi-functional Users showed a significantly lower risk of depressive symptoms in both years (OR = 0.51 in 2018; OR = 0.66 in 2020). CONCLUSION: Smartphone use diversity may mitigate depressive symptoms among older adults, particularly within specific subgroups. The identification of distinct usage patterns underscores the heterogeneity in digital engagement among older adults. These findings provide empirical support for technology-enabled mental health promotion interventions targeting older adults. Therefore, integrating digital literacy programs and diverse smartphone use initiatives into public health strategies aimed at enhancing mental well-being in aging populations is essential.