[A follow-up study on the bidirectional associations between smartphone multitasking behavior and comorbid symptoms of anxiety and depression among college students].

<b>Objective:</b> To explore the direction of the association between smartphone multitasking behavior and comorbid symptoms of anxiety and depression (CAD) among college students. <b>Methods:</b> College students from one college located in Shanxi, Chongqing, and Shenzhen were selected between October and December 2021 using a multistage random cluster sampling method, and a follow-up visit was conducted in May 2022. The Assessment of Smartphone Multitasking for Adolescents, the Patient Health Questionnaire-9 Items, and the Generalized Anxiety Disorder Questionnaire-7 Items were used to assess the smartphone multitasking behaviors and CAD of college students. Multivariate logistic regression models were used to analyze the associations between smartphone multitasking behavior and CAD. Autoregressive cross-lagged models (ARCLM) were used to analyze the bidirectional associations between smartphone multitasking behavior and CAD. <b>Results:</b> A total of 953 college students were included in this study, including 323 (33.9%) males and 630 (66.1%) females, with an age of (18.89±1.33) years. The detection rates of CAD at baseline and follow-up were 25.5% and 27.5%, respectively. The mean of the total smartphone multitasking index at baseline was 2.11±0.48. The mean of smartphone and non-media activity multitasking index was 2.00±0.55. The mean of smartphone and other media activity multitasking index was 1.92±0.67. The mean of smartphone functional use multitasking index was 2.18±0.54. The multivariate logistic regression models showed that smartphone and non-media activity multitasking index (<i>OR</i>=1.85, 95%<i>CI</i>: 1.39-2.45), smartphone and other media activity multitasking index (<i>OR</i>=1.42, 95%<i>CI</i>: 1.10-1.83), and total smartphone multitasking index (<i>OR</i>=1.66, 95%<i>CI</i>: 1.21-2.28) were positively associated with the risk of CAD among college students at baseline. The smartphone and non-media activity multitasking index (<i>OR</i>=1.74,95%<i>CI</i>: 1.30-2.32), smartphone and other media activity multitasking index (<i>OR</i>=1.37, 95%<i>CI</i>: 1.04-1.79) and total smartphone multitasking index (<i>OR</i>=1.48, 95%<i>CI</i>: 1.06-2.06) were positively associated with the risk of CAD at follow-up. There was no statistical association between smartphone functional use multitasking index at baseline and CAD. The ARCLM showed that smartphone and non-media activity multitasking index (<i>β</i>=0.974, <i>P</i>=0.029), smartphone and other media multitasking index (<i>β</i>=0.798, <i>P</i>=0.003), and the total smartphone multitasking index (<i>β</i>=1.379, <i>P</i>=0.011) at baseline could positively predict the risk of CAD at follow-up. The CAD at baseline could positively predict smartphone and other media multitasking index (<i>β</i>=0.004, <i>P</i>=0.016) and smartphone functional use multitasking index at follow-up (<i>β</i>=0.004, <i>P</i>=0.016). <b>Conclusion:</b> There is a bidirectional association between smartphone and other media activity multitasking and CAD among college students.