Internet accessibility and incident depressive symptoms in middle aged and older adults in China: A national longitudinal cohort study.

Background: With the rapid development of the Internet over the past ten years, its widespread applications and accessibility may cause dynamic changes in the association between internet use and depressive symptoms.

Objective: We aim to explore the association between internet accessibility (including broadband connection, internet use, frequency, and devices for internet use), as well as its changes, and the risk of incident depressive symptoms for middle aged and older adults based on a cohort study.

Methods: 8772 participants with three repeat waves of follow-up (average 6.04 years) were included. Cox proportional hazards regressions were used to explore risk effects. Hazard ratios (HRs) and 95 % Confidence Intervals [CI] were presented.

Results: Incidence density for depressive symptoms was 53.89 for every 1000 person-years. The rate of internet usage by middle aged and older adults in China increased evidently from 2012 to 2018 (16.39 % vs 77.41 %). Broadband internet connection (BIC) (HR = 0.80, 95%CI: 0.71, 0.90) and moderate frequency of internet use (IU) (HR = 0.30, 95%CI: 0.10, 0.92) were associated with decreased risk of depressive symptoms. Participants who changed from no internet accessibility to internet accessibility were associated with a lower risk of depressive symptoms (BIC: HR = 0.46, 95%CI: 0.41, 0.51; IU: HR = 0.42, 95%CI: 0.34, 0.51). Using large screen devices (HR = 0.64, 95%CI: 0.45, 0.91) for internet access, instead of phones, was associated with lower risk of depressive symptoms.

Conclusions: Older adults should be encouraged to use the Internet; online time, frequency, and devices for internet use should be considered simultaneously.