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Reducing the burden of depression is a global health concern. Self-guided mobile health (mHealth) apps are one approach to address this problem. However, there is little research on self-guided mHealth apps in a global sample or on how they are used in the real world. These gaps in our knowledge must be addressed to bring the promise of mHealth apps for reducing the global burden of depression closer to reality.
The purpose of this study is to examine the naturalistic user behavior of MoodTools, a publicly available, free-to-use, self-guided mHealth app designed to improve symptoms of depression, in a global community sample.
Mobile analytics data were collected from all unique downloads of the Android version of MoodTools between March 1, 2016, and February 28, 2018. Due to the deidentification and data aggregation process, no demographic or personal identifying information was tied to individual user data. All information was stored in aggregated, anonymized data files on Google Analytics’ storage database. Google’s software development kit was used to securely capture data about the number of downloads, location of downloads, number of app sessions, frequency and duration of app sessions, time between app sessions, and user retention, allowing for examination of which app’s tools were viewed and for how long, including
MoodTools was used by 158,930 people from 198 countries, including countries where English was not the primary language and in low- and middle-income countries. After the initial download, 51.14% (n=81,277) of users returned to the app after the initial download, and retention rates decreased with each subsequent app session. The typical person used the app for 3 sessions for a total of 12 minutes over 90 days. The most frequently visited tools were
Self-guided mHealth apps could be one approach (among the many needed) to reduce the burden of depression. Observational data collected in this study show a global interest in MoodTools, including in low- and middle-income countries and countries where English is not the primary language. Future research is needed to determine whether people who use self-guided apps experience improvement in depressive symptoms, and if so, what “dosage” provides a meaningful benefit.
Mobile health (mHealth) is any medical or health practice supported by mobile devices such as smartphones [
There is a gap between how people use mHealth interventions in the real world and how researchers evaluate them. Although randomized controlled and feasibility trials find that mobile and web-based interventions are efficacious, the findings do not hold in practical settings [
There is very little ecologically valid research on the use of publicly available self-guided mHealth interventions for mental health [
There are very few studies on self-guided apps for mental health and well-being within a global sample. PTSD Coach was downloaded in 86 countries, with non-US downloads making up 12% of total downloads [
This study aims to describe how MoodTools, a publicly available, free-to-use, self-guided mental health app for depressive symptoms, is used “in the wild” among a global sample.
User retention across sessions.
Duration of MoodTools sessions.
The amount of time between downloading MoodTools and returning to the app.
MoodTools was published on Google Play for Android devices in June 2014 and on Apple App Store for iOS devices in 2015. Since its release in 2014, it has been downloaded on iOS and Android devices over 500,000 times. MoodTools is a fully automated, self-guided smartphone app for iOS (ie, iPhone and iPad) and Android devices. All content is self-contained, with the exception of external links that take the users out of the app; there is no human interaction. The app is exclusively in English. MoodTools contains 6 features called tools. The
Data were derived from mobile analytics data from all unique downloads of the Android version of MoodTools between March 1, 2016, and February 28, 2018. Mobile analytics data were not collected from the iOS app during this study period. Due to the deidentification and data aggregation process, no demographic or personal identifying information was tied to individual user data. All measures were stored in aggregated, anonymized data files on Google Analytics’ storage database.
The Google Analytics software development kit (SDK) was integrated into the Android app in March 2016. We used the SDK to securely capture aggregate usage data and retention information from March 2016 to 2018 (the maximum amount of aggregate data that can be analyzed at a time). The following information was collected:
Location: The country from which the app was installed on a user’s Android device.
Number of downloads: The number of individual users who downloaded the app.
App session: A single period of user interaction within the app. Activity that occurs within 30 minutes of each other is counted as part of the same app session. If there is no activity for 30 minutes, future activity is attributed to a new session.
Session frequency: The number of app sessions during the data collection.
Session duration: The number of minutes the app is open or used during an app session.
Session recency: The amount of elapsed time since a user’s last app session.
Total duration in app: The total amount of time spent across app sessions for an individual user.
Tools visited: The number of times a user opens the home page for each of the 6 tools within the app.
This study was approved by the Institutional Review Board at Georgia State University as Designation for Not Human Subjects Research (H21568).
Between March 1, 2016, and February 28, 2018, MoodTools on the Android platform was used by 158,930 people from 198 countries. Data were collected on the percentage of users by continent, subcontinent, and country (see
Retention was defined as the percentage of users that return to the app at any point after their initial app session. As shown in
User retention across sessions.
|
User retention, n (%) |
2 sessions | 81,277 (51.14) |
3 sessions | 51,382 (32.33) |
4 sessions | 35,282 (22.2) |
5 sessions | 25,794 (16.23) |
6 sessions | 19,787 (12.45) |
7 sessions | 15,686 (9.87) |
8 sessions | 12,762 (8.03) |
Users spent 4 minutes, on average, on each session. About one-third of sessions lasted between 0 and 10 seconds, one-third lasted between 11 seconds and 3 minutes, and the remainder lasted more than 3 minutes (
Duration of MoodTools sessions.
Session duration | Sessions, % |
0-10 s | 33.78 |
11-30 s | 9.04 |
31-60 s | 9.07 |
61-180 s | 19.14 |
180-600 s | 17.15 |
601-1800 s | 9.73 |
≥1801 s | 2.08 |
The amount of time between MoodTools app sessions.
Days between app sessions | App sessions, n (%) |
<1 day | 134,987 (37.16) |
1 day | 41,653 (11.47) |
2 days | 24,187 (6.66) |
3 days | 17,256 (4.74%) |
4 days | 13,365 (3.68%) |
5 days | 10,972 (3.02) |
6 days | 9820 (2.70) |
7 days | 8184 (2.25) |
8-14 days | 35,334 (9.73) |
15-30 days | 31,306 (8.62) |
31-60 days | 20,017 (5.51) |
61-120 days | 12,174 (3.35) |
121-364 days | 4041 (1.11) |
We examined how often users visited each of the 6 tools (Thought Diary, Test, Information, Activities, Videos, and Safety Plan). Visiting a tool was operationalized as opening the home page screen for that tool. The Thought Diary tool and Test tool were tied for the most frequently visited tools, each making up 24.32% (n=393,487) of all home page screens viewed across all app sessions for all users (N=1,618,277 total screen views;
Home page views by tool.
Tool name | Total screen views (N=1,618,277), n (%) | Average screen views per app session | Average time on home page screen(s) |
Thought Diary | 393,549 (24.32) | 2.24 | 12.25 |
Test | 393,487 (24.32) | 2.00 | 5.71 |
Activities | 331,961 (20.51) | 2.35 | 10.08 |
Safety Plan | 236,449 (14.61) | 2.32 | 14.20 |
Videos | 138,164 (8.54) | 1.40 | 5.76 |
Information | 124,667 (7.70) | 1.23 | 11.34 |
MoodTools was downloaded in 198 countries, suggesting that there is global interest in a free-to-use self-guided smartphone app for depression. It is worth noting that the developers of MoodTools had done no marketing campaigns and that, even though the app is presented exclusively in English, there have been downloads in countries where English is not the primary language. Users from low- and middle-income countries downloaded the app as well. Despite widespread interest, self-guided mental health apps will not make an impact on the global burden of depression if they are not effective. A review of evidence-based apps for anxiety and depression showed that a large majority (74%) were free to download, but only 3% had research to justify claims of effectiveness [
A key challenge for mHealth interventions for depression is to engage and retain users, given the low motivation and behavioral avoidance associated with the condition. Just over half of MoodTools users (n=81,277, 51.14%) returned to the app after the initial download, which is comparable to IntelliCare (about 50%) and PTSD Coach (61.1%) [
It is important to determine how much app use is needed for meaningful improvement in symptoms. Research indicates that there is a relationship between app use and clinically meaningful benefit [
The dose achieved by typical MoodTools users was 3 app sessions (averaging 4 minutes per session), for a total of 12 minutes over 90 days, which can be compared to PTSD Coach users, who initiated 6.3 app sessions (averaging 47 seconds per session) for a total of 5 minutes before discontinuing its use [
Unlike mental health professionals, everyday users of mental health apps are not trained to use the science of psychopathology to relieve symptoms. It is critical to identify what users of self-guided mental health apps naturally gravitate to, and the results are encouraging. The most frequently visited tools for MoodTools users were Thought Diary (thought record) and Test (mood self-monitoring). These results are consistent with research on naturalistic user behavior of other smartphone apps, despite differences in layout and psychological problems targeted. The most-visited areas of PTSD Coach were Self-Assessment (symptom tracking) and Manage Symptoms (coping skills) [
This study of naturalistic user behavior has several notable limitations. First, this study only included users from the Android platform of MoodTools and differences between those who use Android and iOS devices may influence user behavior. iOS users are more likely than Android users to be female, more educated, belong to a higher income group, and have more technical knowledge [
The number of areas for future research on self-guided mHealth apps for reducing depression is seemingly infinite. It is critical to improve our understanding of what happens immediately following the download of the app. Consistent with research on other apps, half of all MoodTools users did not return to the app after their first app session. Research is needed to understand how to maintain users’ engagement from the very first app session and to identify users most at risk for discontinuing use. Additionally, it may be helpful to sort users into low- and high-use comparison groups, as was done in the Wysa study [
The scope and impact of depression worldwide is breathtaking. Results show a global interest in a publicly available, free-to-use mHealth app designed to improve depressive symptoms, including in low- and middle-income countries and in countries where English is not the primary language. About half of MoodTools users returned to the app after their initial app session. About one-third of all sessions lasted between 0 and 10 seconds, one-third lasted between 11 seconds and 3 minutes, and the remaining third lasted 3 minutes or longer. The average MoodTools user used the app for 3 sessions for a total of 12 minutes over 90 days. Users tend to spend most time using tools designed for self-monitoring of symptoms and for targeting a core mechanism of depressive psychopathology and negative cognitions. Observational data from this study show that self-guided mental health apps could be one among the many approaches needed to reduce the global burden of depression; however, research is needed to determine whether app engagement can lead to symptom improvement.
MoodTools users by continent, subcontinent, and country.
mobile health
Patient Health Questionnaire
software development kit
user version of the Mobile Application Rating Scale
LS is the cocreator of MoodTools and one of the owners of Inquiry Health LLC, which publishes MoodTools. PLA has no conflicts of interest to declare.