###### Abstract  
We developed an mHealth application that can help alleviate the problematic use of smartphones and allied psychological symptoms. This study observed the change in patterns of users' problematic smartphone use, depression, and anxiety while using the mHealth application. We conducted this study from 9 January to 10 April 2019. The Korean Smartphone Addiction Proneness Scale for Adults, Generalized Anxiety Disorder Scale, and the Patient Health Questionnaire were measured at week 0, 8, 12. A post hoc test of Repeated Measurement Anova analysis and Linear Mixed Model analysis were used. Overall, 190 participants were allocated into two groups. Sixty-six were in the smartphone control-use group and 124 were in the problematic-use group. The study elucidated the difference between the two groups in terms of problematic smartphone use and depression and anxiety after 13 weeks of using the mHealth application. This study showed the use of the mHealth application reducing problematic smartphone use scores and negative symptoms such as anxiety and depression in the PSU group. The results can be used as the basis for similar qualitative studies to further resolve the problematic use of smartphones. p 2021 16 September 2021 1  
Excessive use of smartphones can result in compulsive behavior, which can lead to problematic smartphone use [10; 12; 13; 14]. Although excessive smartphone use is not yet classified as an addiction [15], it is defined as \"problematic\" smartphone use, with people presenting with symptoms similar to those of individuals with substance use disorder [11; 16]. Problematic smartphone use is also related to mental health [17]. Prior research shows that it can affect mental health, leading to disorders such as depression and anxiety [9; 11; 12; 13; 14; 17; 18; 19]. Therefore, there is a pressing need to manage and mitigate these problems. Continuous intervention and self-management are both important for alleviating problematic smartphone use. Among the studies on the effectiveness of interventions on smartphone use, preliminary evidence in one study showed that these interventions can reduce symptoms of anxiety [20]. Mobile health (mHealth) interventions can assist in delivering effective health care by enabling access to personalized support [21; 22]. Further, according to a recent study, it could positively affect motivation and achievement by using mobile-based devices [23]. [PERSON] et al. (2017) proposed that an application-incorporated diagnostic tool has substantial accuracy for detecting problematic smartphone use [24]. The results showed that the smartphone application can support a self-control program and help implement an intervention and diagnosis for problematic smartphone use. Therefore, we developed an mHealth application, called MindsCare, that performs an integrated intervention that can help alleviate the problematic use of smartphones and the allied psychological symptoms to assist in the treatment of the condition. The application aims to relieve problematic smartphone use. The user received personalized health care services, and it is designed to monitor smartphone usage, prevent overuse, diagnose the condition, and help in management of the condition. Problematic smartphone use and mental health symptoms are designed to be measured based on the designed intervention period through various psychological scales, and management or self-evaluation and intervention services are introduced. The objective of this study was to observe the change in patterns of users' problematic smartphone use, their level of depression and anxiety while using MindsCare during the study period, and to observe the effect of MindsCare on smartphone usage and associated mental health. We aimed to achieve several specific goals. First, we wanted to determine the difference between each groups' problematic smartphone use, anxiety, and depression with reference to time, and we achieved this by dividing the users into a smartphone usage control group and a problematic smartphone use group.