Mindfulness-based Mobile Application to Reduce Rumination in Adolescents
Phase: NA
Conditions: Rumination, Depression, Anxiety, Self-Injurious Behavior
Sponsor: Lawrence University

 
 
 
 
Protocol for Mindfulness-based Mobile Application to Reduce 
Rumination in Adolescents 
 
PI: Lori M. Hilt, PhD., Lawrence University 
NCTNCT03900416 
01/01/2019 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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Background  
Adolescence is a vulnerable period for the development of psychopathology, with 
adolescents experiencing increases in symptoms of depression, certain types of anxiety, 
and self-injurious behavior. For example, in one epidemiological study, the lifetime 
prevalence of Major Depressive Disorder (MDD) was 1% up to age 11, but rose to 21% up 
to age 18 (Hankin et al., 1998). In another epidemiological study, rates of MDD and several 
anxiety disorders rose steadily over the teen years (Merikangas et al., 2010). Many more 
adolescents experience high levels of internalizing symptoms without meeting diagnostic 
criteria for a disorder, and these symptoms may develop into more severe mental health 
problems in adulthood (Kessler, Avenevoli, & Merikangas, 2001; Leadbeater, Thompson, & 
Gruppuso, 2012), underscoring the importance of prevention. Self-injurious behavior, in the 
form of nonsuicidal self-injury, is a prevalent phenomenon among adolescents 
(Muehlenkamp, Claes, Havertape, & Plener, 2012), and though less common, suicide is the 
second leading cause of death among adolescents (CDC, 2014). Thus, it is imperative to 
develop preventive interventions that address these mental health problems faced by 
adolescents. One way to approach these problems from a public health perspective is to 
target a transdiagnostic risk factor.  
 
Rumination has been identified as a transdiagnostic risk factor involved in the 
development of several forms of psychopathology including depression, anxiety and self-
injurious behavior (for reviews see Aldao, Nolen-Hoeksema, & Schweizer, 2010; Nolen-
Hoeksema & Watkins, 2011; Nolen-Hoeksema, Wisco, & Lyubomirsky, 2008). Rumination 
involves repetitively focusing on one’s negative emotions and brooding about their meaning 
and consequences (Nolen-Hoeksema, 1991). A meta-analysis showed that rumination is 
associated with depressive symptoms, concurrently and prospectively among adolescents 
(Rood, Roelofs, Bogels, Nolen-Hoeksema, & Schouten, 2009), and rumination also 
prospectively predicts depression diagnosis among adolescents (Abela & Hankin, 2011). 
Studies have also found that rumination concurrently and prospectively predicts anxiety 
symptoms in adolescents (e.g., McLaughlin & Nolen-Hoeksema, 2011; Muris, Roelofs, 
Meesters, & Boomsma, 2004). Finally, rumination has emerged as an important risk factor 
for both nonsuicidal self-injury (e.g., Hilt, Cha, & Nolen-Hoeksema, 2008; Barrocas, Gilleta, 
Hankin, Prinstein, & Abela, 2015) and suicidal ideation (e.g., Miranda & Nolen-Hoeksema, 
2007; Smith, Alloy, & Abramson, 2006). Given the involvement of rumination in the 
development of internalizing symptoms and self-injurious behavior, it is an important target 
for preventive interventions. 
 
Mindfulness meditation is an intervention strategy that has shown promise in 
targeting rumination. It involves focusing attention on the present moment without judgement 
(Kabat-Zinn, 2003). Rumination typically involves a perseverative focus on past events 
(Nolen-Hoeksema et al., 2008), and mindfulness may help alleviate rumination through its 
focus on the present and emphasis on detaching from mental events, rather than becoming 
caught up in them as one does while ruminating (Ma & Teasdale, 2004). Trait (i.e., habitual) 
levels of mindfulness are negatively associated with trait levels of uncontrollable rumination 
(Raes & Williams, 2010), suggesting these strategies may be antithetical. Indeed, 
mindfulness meditation interventions have resulted in decreases in distress and negative 
affect, and decreased rumination appears to be a mediator of these effects (Chiesa & 
Serretti, 2009). 
 
Mindfulness interventions that show decreases in trait rumination typically involve 
instruction and home practice over the course of several weeks. For example, an 8-week 
Mindfulness Based Stress Reduction (MBSR; Kabat-Zinn, 1982) course that involves 
meeting for two hours once per week along with daily home practice resulted in decreased 
trait rumination in multiple studies with adult participants (e.g., Deyo, Wison, Ong, & 
Koopman, 2009; Shapiro, Brown, & Biegel, 2007). Similarly, a month-long mindfulness 
intervention with distressed college students showed decreases in trait rumination that were 
not seen in the active control condition (Jain et al., 2007). Although promising, these 
intensive interventions have not been examined for their effects on rumination with 

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adolescents. Furthermore, it is unclear how much practice is required to produce reductions 
in trait rumination. 
Recent work by the PI has shown that a brief mindfulness intervention can reduce 
state (i.e., momentary) rumination. In two laboratory studies, one with college students (Villa 
& Hilt, 2014) and one with younger adolescents (Hilt & Pollak, 2012), the PI and her 
colleagues showed that an 8-minute guided mindfulness exercise reduced state rumination 
relative to active control conditions. These studies highlight the benefit of even brief 
mindfulness interventions for adolescents, but they do not show whether occasional or 
regular use of brief mindfulness exercises would impact trait rumination and subsequent 
psychopathology.  
Because state rumination is positively associated with trait rumination (Moberly & 
Watkins, 2008), we expect that regular use of brief mindfulness exercises will allow 
adolescents to repeatedly make state adjustments that will reinforce a behavioral cycle 
leading to reductions in trait rumination and psychopathology.  
 
Overview 
The primary objective of this study is to examine whether the mindfulness mobile 
application engages adolescents and reduces rumination and subsequent psychopathology. 
We hypothesized that adolescents in the mindfulness intervention condition would 
experience a reduction in symptoms of depression, anxiety, and self-injury relative to those 
in the control group and that this would be accounted for by a reduction in the tendency to 
ruminate. We test this by using a randomized, controlled design, comparing the intervention 
group to a control group that uses the same mobile application for EMA but does not receive 
the mindfulness exercises.  
 
Aims of the study and significance 
1. To determine whether this intervention may be acceptable and engaging to 
adolescents. 
 
Participants will report on their satisfaction with the app as well as be offered the 
opportunity to continue using it during a follow up period beyond the initial 
intervention period. Their use will be tracked electronically during the 12-week, 
follow-up period as an indicator of engagement. If the app engages adolescents, it 
has the potential to be utilized with a large public health impact. 
 
2. To examine whether the intervention reduces state and/or trait rumination and 
whether this reduction accounts for a reduction in symptoms of psychopathology. 
 
Testing this putative mechanism is an important advancement that has yet to be 
examined. By comparing the intervention to a control condition, the proposed study 
will offer a more rigorous test of this research question than the previously completed 
small pilot studies. Additionally, we will use multiple informants of psychopathology 
symptoms at pre, post, and follow-up time points, strengthening our outcome 
measurement. We will also use multilevel modeling to test the effects of state 
changes in the proposed mechanism and outcomes on trait levels. If the app shows 
efficacy, it can be tested in a larger trial to determine whether it may be indicated as 
a wide-scale preventive intervention. If the app reduces rumination, a transdiagnostic 
risk factor, as hypothesized, it has the potential to prevent many deleterious mental 
health outcomes. 
 
Mobile applications are needed to address the mental health needs of adolescents. 
The majority of youth who need treatment for mental health disorders such as depression do 
not receive it, due to barriers including perceived stigma and inclination toward self-reliance 
(Gulliver, Griffiths, & Christensen, 2010). Furthermore, the cost of mental health care and 
lack of available quality care, especially for racial and ethnic-minority individuals, make the 

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need for new and readily available modes of service, such as mobile mental health care 
interventions, of tantamount importance (Kazdin & Blase, 2011). Although many mindfulness 
mobile applications have been developed, almost none have been subject to rigorous 
empirical investigation (Mani, Kavanaugh, Hider, & Stoyanov, 2015). One randomized, 
controlled study using a self-selected group of adults showed promise, with those using a 
mindfulness application 10 minutes per day for 10 days showing a modest reduction in 
depressive symptoms (Howells, Ivtzan, & Eiroa-Orosa, 2016). The proposed study has the 
potential to serve as a proof of concept that could help inform intervention researchers, 
clinicians, parents, and educators about the effectiveness of mobile mindfulness exercises 
for adolescents. This study also has the potential to inform the broader field of mobile mental 
health. Many mobile mental health applications collect ecological momentary assessment 
(EMA) data and subsequently recommend customized interventions. However, it is unclear 
whether the effects are due to the specific mental health intervention, the EMA process or 
both. By comparing the intervention to a control condition that receives EMA only, I will be 
able to parse these effects while offering a strong test of Aim 1 (efficacy of the intervention). 
In sum, the proposed study addresses the important need of transdiagnostic 
preventive interventions. Risk for developing psychopathology increases during 
adolescence, and successful preventive measures can reduce the lifetime burden of 
psychopathology. For example, preventing a first episode of depression is of great import, 
given the findings that a first episode results in scars that make future episodes more likely 
(Rohde, Lewinsohn, & Seeley, 1994; Kendler, Thornton, & Gardner, 2000). The proposed 
study targets rumination, a transdiagnostic risk factor, using a mindfulness intervention that 
will be delivered in a format that has the potential for a large public health impact. 
Furthermore, undergraduate students will be involved in all aspects of the research (i.e., 
recruitment, scheduling, data collection, analysis, interpretation and presentation), thereby 
enhancing research training opportunities at the PI’s undergraduate-only institution. 
 
Sample 
We will recruit 150 adolescent girls and boys, ages 12-15. This age range was 
chosen to capture the developmental period directly preceding increased rates of depression 
(Hankin et al., 1998), providing an opportune window for prevention. Participants will be 
recruited through a recruitment letter mailed to students enrolled in grades 7-10 at a large, 
local, public school district with over 5000 students in our target age range. In order to 
maximize the potential of targeting the proposed mechanism, we will only enroll adolescents 
who report at least moderate baseline levels of trait rumination. This will be accomplished 
through a 2-question phone screen. Once parents verbally consent and the child has 
verbally assented, we will ask them to respond to two questions from the Children’s 
Response Style Questionnaire (CRSQ; Abela, Brozina, & Haigh, 2002) that assess 
brooding, a particularly maladaptive aspect of rumination (Treynor, Gozalez, & Nolen-
Hoeksema, 2003). The aggregate of these two questions are highly correlated with the full 
rumination subscale from the CRSQ (r = .79, p < .01) and have been associated with 
depressive symptoms and NSSI in previous work by the PI (Hilt et al., 2008). Adolescents 
who meet the screening criteria (age 12-15, score of 2 or higher on the brooding questions, 
and physically and cognitively able to use a mobile application) will be invited to participate 
in the study. Once they provide written consent and assent, they will be randomly assigned 
to a condition: EMA only or EMA + Mindfulness at a 1:1 ratio (i.e., ~ 75 participants per 
condition). 
 
Procedure 
Participants and a parent or guardian will come to the laboratory to provide written 
assent and consent, complete baseline questionnaires, and get the mobile application and 
instructions. The lab visit will last approximately 40 minutes. We will put the application on 
participants’ own mobile devices (android or iOS platform) if they have them and loan mobile 
devices (android phones without calling services) to participants who do not have their own. 
The active intervention period will last three weeks, during which time participants will be 

5 
 
 
asked to use the application at least three times per day. Undergraduate research assistants 
(RAs) masked to condition will monitor daily use via the database where responses are 
logged. Midway through each week of the active intervention period, RAs will send reminder 
messages for motivation and encouragement. A small bonus ($5 per week) will be offered to 
participants for protocol compliance (i.e., using the app 21 times that week). The weekly 
emails will let participants know whether they were on track to receive the bonus or 
encourage them to use the app more regularly. At the end of three weeks (i.e., post), 
participants will be notified to complete questionnaires online. At this time, participants still 
have the opportunity to use the mobile application, but they will not be reminded to use it so 
that we can monitor self-motivated use. All use will be monitored electronically through a 
database that tracks responses with time stamps. After six weeks, participants will again be 
notified to complete questionnaires online (follow-up 1). Finally, after an additional six weeks 
(approximately 3 months after post), participants will be notified to complete questionnaires 
online (follow-up 2) and return borrowed phones if applicable (via drop-off, pick up or mail). 
The total time that participants’ use is monitored will be 15 weeks (i.e., 3 weeks for the active 
intervention period and 12 weeks of follow up). See Figure 1 for depiction of timeline. 
 
 
 
 
Figure 1. Overview of participant activities and compensation. 
 
Questionnaires 
At each time point (baseline, post, follow-up 1, follow-up 2), internalizing symptoms 
will be assessed using multiple informants (adolescent and parent). Additionally, 
adolescents will self-report on their self-injurious thoughts and behaviors, trait rumination, 
and trait mindfulness. Finally, parent-reported demographics will be obtained at baseline, 
and adolescent satisfaction with the application will be obtained at post. Questionnaires will 
take adolescents approximately 30 minutes to complete and less than 10 minutes for 
parents. Questionnaires will be completed online using Qualtrics (a survey software platform 
with secure data storage) except for the demographics form which will be completed on 
paper to avoid storing any identifying data on the server.  
Internalizing symptoms. Depression will be assessed using the gold-standard, self-
report Children’s Depression Inventory (CDI; Kovacs, 1992). This 27-item questionnaire 
assesses behavioral, cognitive, and physical symptoms of depression and has high reliability 
and validity (α=.88). Anxiety will be assessed using the Multidimensional Anxiety Scale for 
Children (MASC; March, Parker, Sullivan, Stallings, & Connors, 1997), a 39-item reliable 
and valid index of anxiety in youth (α=.88). It yields a total score along with subscales for 
physical symptoms of anxiety, harm avoidance, social anxiety, and separation anxiety. 
Parent-reported internalizing symptoms will be assessed using the 5-item, internalizing 
subscale from the Pediatric Symptom Checklist (PSC; Jellinek & Murphy, 1988), a widely-
used 35-item measure of psychopathology in youth with sound psychometric properties. All 
of these questionnaires have shown change in response to interventions in previous 
research. 

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Self-injury. Thoughts and behaviors related to suicide and NSSI will be assessed 
with the self-report form of the Self-injurious Thoughts and Behavior Interview (SITBI; Nock, 
Homberg, Photos, & Michel, 2007), a highly reliable and valid assessment tool used with 
adolescents. 
Rumination. Trait rumination will be assessed with the rumination subscale from the 
CRSQ (Abela, Brozina, & Haigh, 2002). This 13-item subscale has demonstrated good 
reliability and validity (α=.88). 
Mindfulness. Trait mindfulness will be assessed with the modified Five Facet 
Mindfulness Questionnaire (FFMQ; Baer, Smith, Hopkins, Krietemeyer, & Toney, 2006). 
This 39-item, self-report questionnaire measures five facets of mindfulness including: 
observing, describing, acting with awareness, non-judging of inner experience, and non-
reactivity to inner experience. The factor structure and construct validity have been 
demonstrated, and it has high internal consistency (α=.80). 
Demographics. Parents will report on child birth date, sex, race, ethnicity, family 
socioeconomic status (SES; i.e., occupation, income, family size), and living situation. 
Adolescents will also report on gender, race, and ethnicity. 
Satisfaction. Adolescents will answer several questions about the mobile application 
regarding ease of use and acceptability. 
 
Mobile Application and EMA 
There are two versions of the mobile application, depending on the condition: EMA or 
EMA + Mindfulness. Participants will be randomized using a true randomization procedure 
(i.e., rolling die with even or odd number determining their condition). The first time they use 
the mobile application (i.e., during the lab visit), participants enter a unique identification 
number. Thus, all responses will be logged electronically based on the identification number. 
Participants are also prompted to enter their wake time and bed time. The application uses 
this information to time the three daily notifications. Adolescents will be told to respond as 
soon as possible after receiving a notification, but instructed not to use the phone if they 
were in a situation where it is not permitted. When accessing the application, adolescents 
will respond to 10 EMA questions assessing the following: 
Time and place. Participants are asked whether they are thinking about the past, 
present, future; whether they are alone or with others and where they are located (e.g., 
school, home, other). These questions were adapted from a large EMA study (Killingsworth 
& Gilbert, 2010). 
State rumination. Participants will respond to two questions regarding focus on 
emotions and focus on problems using a sliding scale from 0 to 100 for each. These 
questions were adapted from a previous EMA study on rumination (Moberly & Watkins, 
2008) and have been used to assess state rumination in other work (e.g., Hilt & Pollak, 
2012; Hilt, Sladek, Doane, & Stroud, 2017).  
State mood. Using sliding scales ranging from 0 to 100, participants indicate how 
happy, sad, calm, and anxious they currently feel.  
State mindfulness. Participants rate their degree of focusing on bodily sensation 
using a 0 to 100 scale.  
 
Mindfulness Intervention 
In the EMA + Mindfulness condition, participants have a 67% chance of receiving a 
mindfulness exercise, unless their sad or anxious mood rating is 90 or above, in which case 
their chance is 85%. This graded strategy was chosen so that participants would not be able 
to easily figure out the mood rating that results in an exercise and so that participants would 
have a greater chance of receiving an exercise when they most needed it. 
If an exercise is assigned, participants are prompted to enter how much time they 
have to engage in an activity (from 0-15 minutes). There are three 1-minute exercises 
(written instructions for focusing on the breath, sounds, or physical sensations); six 3-5 
minute exercises (guided audio focusing on breathing, sounds, or body scan); and five 10-12 
minute exercises (guided audio focusing on breath, body scan, or mountain metaphor). 

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Participants who indicate having less than 5 minutes receive one of the 1-minute exercises, 
those who indicate having at least 5 minutes receive either a 1-minute or a 3-5 minute 
exercise, and those who indicate having at least 12 minutes receive any exercise. Exercises 
are randomly assigned based on these parameters. The guided audio exercises were 
chosen based on those freely available that represent the type of mindfulness exercises 
typically found in MBSR courses, appeared accessible for adolescents, featured a variety of 
voices, and performed well in pilot testing. Following each mindfulness exercise, participants 
were prompted with the same EMA questions plus an additional question asking how helpful 
the activity was, rated on a 0-100 sliding scale.  
 
Data Handling and Record Keeping 
All data (EMA, questionnaire) will be stored electronically and password protected 
using only an ID number (i.e., without identifying information). The PI will maintain a 
password protected document linking ID numbers to participant names. A paper copy of 
information that includes identifying information will be stored in a locked file cabinet in a 
locked room in a folder labeled with an ID number.  
The PI will put several actions in place to assure quality of data collected in the 
study. The PI will oversee recruitment and enrollment and assure that enrollment targets are 
met. The PI will be in close contact with the research associate who managed recruitment 
and enrollment and updates will be monitored weekly. The PI will also oversee data 
collection and management to insure its validity and integrity. Only key project personnel will 
have access to the data. Any personnel doing data analysis will work with a copy of the data 
to avoid any changes being made to original data files. The PI will assure that the 
dissemination plan is followed. Finally, all project staff, including the PI will complete a Good 
Clinical Practice training course (e.g., https://gcp.nidatraining.org/).  
 
Assessment of Safety  
Questionnaires assessing self-injury (including suicidal thoughts and behaviors) will 
be collected from adolescents at four time points (baseline, post-intervention, and three 
follow-up periods). Participants who indicate suicidal ideation (by responding to an item on 
the Children’s Depression Inventory indicating that they want to kill themselves, i.e., scoring 
a 3 on item 9) or serious self-injurious behavior (by responding affirmatively to questions on 
the Self-injurious Thoughts and Behaviors inventory indicating having a suicide plan or 
attempt in the past year/week/since the last assessment) will be contacted by the PI, a 
licensed clinical psychologist with extensive experience doing research and treatment for 
self-injury. The PI will assess risk by talking with the participant and determine whether 
contact with a mental health professional is warranted. If necessary, the PI will talk with the 
adolescent’s parent to determine whether the participant is currently in treatment, and if so, 
will advise the parent and adolescent to make contact with their mental health professional. 
If a participant requests confidentiality regarding serious self-injurious behavior, we will 
remind them that this is one of the exceptions to confidentiality because we are seriously 
concerned for their safety. Every effort will be made to allow the adolescent some control in 
how the information is presented to the parent (i.e., the adolescent tells the parent or the PI 
tells the parent), but serious concerns will be communicated with parents, regardless, for 
safety. For participants not currently under the care of a mental health professional, we will 
provide a list of local mental health resources and help the family with the referral. We will 
re-contact families to monitor the participants and determine whether contact with a mental 
health professional has been made. For participants deemed in imminent risk of suicide, we 
will inform the parent and advise them to transport the subject to an emergency room or call 
911 for assistance with transportation.  
Participants will report on their daily mood during the active intervention period (three 
weeks) and during the optional follow up periods (6 months). In order to monitor and address 
any potential distress or dissatisfaction during the active intervention period, we will invite 
participants to contact us with concerns. During our twice-weekly emails to motivate 

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participants, we will tell them that they should contact us if they are having any difficulties or 
feeling upset so that we can talk with them by phone and intervene as needed (e.g., conduct 
a suicide safety assessment as described above). 
In all cases, we will document conversations and interactions with subjects and any 
health professionals they ask us to contact on their behalf. We will also report any adverse 
events or unanticipated problems to the appropriate party (e.g., IRB). Because of the low 
risk involved in the proposed study, the PI will be responsible for carrying out this data and 
safety monitoring plan. 
 
Adverse Event 
We do not anticipate any risks, as no serious adverse events have been reported in 
the literature with respect to brief mindfulness interventions. Potential serious adverse 
events would include hospitalization and suicide attempt. To protect participants against 
foreseeable risks, participants who indicate serious suicidal concerns will be excluded from 
or withdrawn from the study until these concerns are resolved. Potential adverse events may 
include increases in suicidal thoughts or behaviors, breach of confidentiality, upsetting 
experiences, distress or dissatisfaction as the result of assessment or use of the app. We 
will ask both participants and their parents about any adverse events that may have 
occurred during the active intervention period (e.g., upsetting experiences, distress or 
dissatisfaction as the result of assessment or use of the app). Adverse and serious adverse 
events will be reported to the appropriate individuals (see section below).   
 
Written informed consent and assent will be obtained by trained research assistants 
(RAs) during the laboratory visit to Lawrence University at the beginning of the study. The 
RA will bring the parent and adolescent into a private room and read the assent form to the 
adolescent. The RA will ask the parent and adolescent separately if they have any questions 
about the study and answer them. If the parent signs the written consent form, then the RA 
will say to the adolescent, “Would you like to be in the study and complete the activities? If 
you say yes, this means you have read this paper or had it read to you and want to be in the 
study. If you say no, that means you do not want to be in the study. You can say yes or no. 
Being in the study is your choice. No one will be mad or upset if you do not say yes, sign this 
paper, or even change your mind later.” If the adolescent indicates a definite “yes”, the RA 
will obtain their signature and certify the assent procedure was followed. 
 
To project against a potential breach of confidentiality, the EMA data are stored on a 
secure, password protected website, without any identifying information. The questionnaire 
data are also stored on a secure, password protected website, without any identifying 
information. Data collected during the first lab visit are obtained in separate, private rooms 
for each parent and child. Family background and contact information (i.e., identifying 
information) will be collected on paper and stored in a locked file cabinet in a locked room 
only accessible to study staff. No information collected from the adolescent participants will 
be shared with parents unless there are serious concerns about the child’s safety (i.e., 
suicide concerns or child abuse). Participants and project staff will communicate via phone, 
email, and text regarding scheduling and completing study materials, but no data or 
sensitive information will be shared.  
 
The trial will be stopped should findings suggest that the intervention is resulting in 
mean suicide and/or self-injury levels to increase to a level of clinical concern (e.g., ideation 
with a plan, attempts, or completions). 
 
 
Statistical Analysis Plan 
General Analytic Strategies. The number of participants recruited and retained will 
be documented, and comparisons will be made on all study variables between those who 
complete and those who drop out of the study in order to inform external validity. 
Compliance and intervention dose will be assessed with time-stamped electronic records 
generated through the app. All data will be inspected for normality and transformations will 

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Figure 2. Conceptual indirect effect model. Note that 
moderators (e.g., sex) may also be included. 
be applied as needed. Missing questionnaire data will handled using multiple imputation if 
data are missing completely at random (Enders, 2013).  
Specific Aim 1. There are multiple ways to assess participants’ engagement to 
determine the acceptability of the intervention. The first two involve examining how much 
adolescents use the mobile application. We will examine compliance during the 3-week 
intervention period by comparing the amount of application use (as recorded electronically) 
in the intervention group to the control group. We will also examine use during the follow-up 
periods (12 weeks), when it is optional. Both of these usage questions can be answered with 
t-tests comparing use between groups.  
 
The other two ways of measuring acceptability are more direct. Participants will 
complete a satisfaction questionnaire during the post-assessment, and we will compare 
scores on these questions between groups using t-tests. Finally, participants in the 
intervention condition will answer a question after each mindfulness exercise regarding how 
helpful it was using a 0-100 scale ranging from not at all helpful to extremely helpful. Scores 
on this question can be averaged and examined separately for each type of mindfulness 
exercise to see if they fall above the benchmark of 50, indicating that adolescents find them 
helpful in the moment. With all statistical analyses, we will use best current practices 
regarding correction for multiple tests.  
 
Specific Aim 2. Testing of the hypothesis that the intervention will reduce symptoms 
through the mediating effect of reduced rumination will be accomplished by capitalizing on 
both trait-level questionnaire data and state-level EMA data. Using trait-level data, an 
indirect effect model will be tested to examine the effect of condition (EMA-only vs. EMA + 
Mindfulness) on each outcome (depressive symptoms, anxiety symptoms, parent-reported 
internalizing symptoms, and self-injury) through the indirect effect of rumination (see Figure 
2). These analyses will be accomplished using the PROCESS macro (Hayes, 2013) for 
SPSS (IBM Corp.) which relies on bootstrapping to generate bias corrected confidence 
intervals. This approach is particularly well-suited for testing mediation models with relatively 
small sample sizes. It also allows for the addition of covariates and/or moderators if inclusion 
of them are warranted. For example, if there are sex differences in rumination and/or 
symptoms, as is likely based on previous research (e.g., Hilt, McLaughlin, & Nolen-
Hoeksema, 2010), sex can be covaried or tested as a moderator of effects (Exploratory 
Aim) using methods described by Preacher, Rucker, and Hayes (2007). Dose can also be 
examined as a covariate, to test whether variability in use of the mobile application affects 
outcomes. These indirect effects models will be tested at each time period (post, follow-up 1, 
and follow-up 2). If the hypothesis is supported for  
 
 
 
 
 
 
the post-intervention time period, it will be helpful to see if effects are maintained at 6 and 12 
weeks. If the hypothesis is not supported at the post-intervention period, it will be possible to 
examine delayed effects at the follow-up time points. For example, the intervention could 
reduce rumination first and have a delayed effect on symptoms.  

10 
 
 
The primary hypothesis can also be examined on a finer-grain time scale using state-
level EMA data to test whether a mindfulness exercise results in reduced negative mood 
immediately or at subsequent time points relative to each person’s average level of mood. 
Relatedly, we can examine whether mindfulness exercises reduce state rumination 
compared to one’s average level of state rumination and if so, test mediation. Similar to the 
trait-level models, covariates (i.e., between-person factors such as sex, SES, and 
race/ethnicity) may be included if warranted. These multilevel models will be estimated in 
Mplus (Muthén & Muthén, 1998-2015) using maximum likelihood estimation with robust 
standard errors to account for the nested nature of the data. This approach will allow for the 
examination of between- and within-person variation in outcomes and is consistent with 
current recommendations for handling missing data (Baraldi & Enders, 2010).  
Although rumination is the proposed mediator, we can also test an alternative 
mechanism, i.e., changes in mindfulness (Exploratory Aim). Another mindfulness 
intervention found that changes in state mindfulness predicted changes in trait mindfulness 
(Kiken, Garland, Bluth, Palsson, & Gaylord, 2015). Furthermore, there appears to be an 
inverse relationship between trait mindfulness and depressive symptoms (e.g., Way, 
Creswell, Eisenberger, & Liberman, 2010). Thus, it is possible that the intervention will 
improve symptoms by increasing mindfulness, reducing rumination, or both. Both trait- and 
state-level mindfulness can be included as mediators in the above-mentioned models 
(Preacher & Hayes, 2008). 
 
 
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