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Angerer F, Mennel V, Grund S, Mayer A, Büscher R, Sander LB, Cuijpers P, Terhorst Y, Baumeister H, Domhardt M. Mechanisms of change in digital interventions for depression: A systematic review and meta-analysis of six mediator domains. J Affect Disord 2024; 368:615-632. [PMID: 39284530 DOI: 10.1016/j.jad.2024.09.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2024] [Revised: 08/02/2024] [Accepted: 09/10/2024] [Indexed: 09/27/2024]
Abstract
BACKGROUND While the efficacy of digital interventions for the treatment of depression is well established, comprehensive knowledge on how therapeutic changes come about is still limited. This systematic review aimed to provide an overview of research on change mechanisms in digital interventions for depression and meta-analytically evaluate indirect effects of potential mediators. METHODS The databases CENTRAL, Embase, MEDLINE, and PsycINFO were systematically searched for randomized controlled trials investigating mediators of digital interventions for adults with depression. Two reviewers independently screened studies for inclusion, assessed study quality and categorized potential mediators. Indirect effects were synthesized with a two-stage structural equation modeling approach (TSSEM). RESULTS Overall, 25 trials (8110 participants) investigating 84 potential mediators were identified, of which attentional (8 %), self-related (6 %), biophysiological (6 %), affective (5 %), socio-cultural (2 %) and motivational (1 %) variables were the scope of this study. TSSEM revealed significant mediation effects for combined self-related variables (ab = -0.098; 95 %-CI: [-0.150, -0.051]), combined biophysiological variables (ab = -0.073; 95 %-CI: [-0.119, -0.025]) and mindfulness (ab = -0.042; 95 %-CI: [-0.080, -0.015]). Meta-analytical evaluations of the other three domains were not feasible. LIMITATIONS Methodological shortcomings of the included studies, the considerable heterogeneity and the small number of investigated variables within domains limit the generalizability of the results. CONCLUSION The findings further the understanding of potential change mechanisms in digital interventions for depression and highlight recommendations for future process research, such as the consideration of temporal precedence and experimental manipulation of potential mediators, as well as the application of network approaches.
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Affiliation(s)
- Florian Angerer
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
| | - Vera Mennel
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
| | - Simon Grund
- Psychology with focus on Quantitative Methods, Universität Hamburg, Germany
| | - Axel Mayer
- Department of Psychological Methods and Evaluation, Bielefeld University, Germany
| | - Rebekka Büscher
- Medical Psychology and Medical Sociology, Faculty of Medicine, University of Freiburg, Germany; Department of Clinical, Neuro- and Developmental Psychology, Amsterdam Public Health Research Institute, Vrije Universiteit Amsterdam, the Netherlands
| | - Lasse B Sander
- Medical Psychology and Medical Sociology, Faculty of Medicine, University of Freiburg, Germany
| | - Pim Cuijpers
- Department of Clinical, Neuro- and Developmental Psychology, Amsterdam Public Health Research Institute, Vrije Universiteit Amsterdam, the Netherlands
| | - Yannik Terhorst
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
| | - Harald Baumeister
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
| | - Matthias Domhardt
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany.
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Jackson HM, Batterham PJ, Calear AL, Ohan JL, Farrer LM. Skill Enactment Among University Students Using a Brief Video-Based Mental Health Intervention: Mixed Methods Study Within a Randomized Controlled Trial. JMIR Ment Health 2024; 11:e53794. [PMID: 39167783 PMCID: PMC11375386 DOI: 10.2196/53794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 03/05/2024] [Accepted: 06/21/2024] [Indexed: 08/23/2024] Open
Abstract
BACKGROUND Mental health problems are common among university students, yet many students do not seek professional help. Digital mental health interventions can increase students' access to support and have been shown to be effective in preventing and treating mental health problems. However, little is known about the extent to which students implement therapeutic skills from these programs in everyday life (ie, skill enactment) or about the impact of skill enactment on outcomes. OBJECTIVE This study aims to assess the effects of a low-intensity video-based intervention, Uni Virtual Clinic Lite (UVC-Lite), in improving skill enactment relative to an attention-control program (primary aim) and examine whether skill enactment influences symptoms of depression and anxiety (secondary aim). The study also qualitatively explored participants' experiences of, and motivations for, engaging with the therapeutic techniques. METHODS We analyzed data from a randomized controlled trial testing the effectiveness of UVC-Lite for symptoms of depression and anxiety among university students with mild to moderate levels of psychological distress. Participants were recruited from universities across Australia and randomly assigned to 6 weeks of self-guided use of UVC-Lite (243/487, 49.9%) or an attention-control program (244/487, 50.1%). Quantitative data on skill enactment, depression, and anxiety were collected through baseline, postintervention, and 3- and 6-month follow-up surveys. Qualitative data were obtained from 29 intervention-group participants through open-ended questions during postintervention surveys (n=17, 59%) and semistructured interviews (n=12, 41%) after the intervention period concluded. RESULTS Mixed model repeated measures ANOVA demonstrated that the intervention did not significantly improve skill enactment (F3,215.36=0.50; P=.68). Skill enactment was also not found to influence change in symptoms of depression (F3,241.10=1.69; P=.17) or anxiety (F3,233.71=1.11; P=.35). However, higher levels of skill enactment were associated with lower symptom levels among both intervention and control group participants across time points (depression: F1,541.87=134.61; P<.001; anxiety: F1,535.11=73.08; P<.001). Inductive content analysis confirmed low levels of skill enactment among intervention group participants. Participants were motivated to use techniques and skills that were perceived to be personally relevant, easily integrated into daily life, and that were novel or had worked for them in the past. CONCLUSIONS The intervention did not improve skill enactment or mental health among students with mild to moderate psychological distress. Low adherence impacted our ability to draw robust conclusions regarding the intervention's impact on outcomes. Factors influencing skill enactment differed across individuals, suggesting that it may be necessary to tailor therapeutic skills and engagement strategies to the individual user. Theoretically informed research involving collaboration with end users is needed to understand the processes underlying skill enactment in digital mental health interventions. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry ACTRN12621000375853; https://tinyurl.com/7b9ar54r.
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Affiliation(s)
- Hayley M Jackson
- Centre for Mental Health Research, National Centre for Epidemiology and Population Health, The Australian National University, Acton ACT, Australia
| | - Philip J Batterham
- Centre for Mental Health Research, National Centre for Epidemiology and Population Health, The Australian National University, Acton ACT, Australia
| | - Alison L Calear
- Centre for Mental Health Research, National Centre for Epidemiology and Population Health, The Australian National University, Acton ACT, Australia
| | - Jeneva L Ohan
- School of Psychological Science, University of Western Australia, Perth, Australia
- Telethon Kids Institute, Nedlands, Australia
| | - Louise M Farrer
- Centre for Mental Health Research, National Centre for Epidemiology and Population Health, The Australian National University, Acton ACT, Australia
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Axelsson E, Santoft F, Särnholm J, Ljótsson B. Brief scales for the measurement of target variables and processes of change in cognitive behaviour therapy for major depression, panic disorder and social anxiety disorder. Behav Cogn Psychother 2024; 52:376-393. [PMID: 37986585 DOI: 10.1017/s1352465823000541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
BACKGROUND The measurement of process variables derived from cognitive behavioural theory can aid treatment development and support the clinician in following treatment progress. Self-report process measures are ideally brief, which reduces the burden on patients and facilitates the implementation of repeated measurements. AIMS To develop 13 brief versions (3-6 items) of existing cognitive behavioural process scales for three common mental disorders: major depression, panic disorder, and social anxiety disorder. METHOD Using data from a real-world teaching clinic offering internet-delivered cognitive behavior therapy (n=370), we drafted brief process scales and then validated these scales in later cohorts (n=293). RESULTS In the validation data, change in the brief process scales significantly mediated change in the corresponding domain outcomes, with standardized coefficient point estimates in the range of -0.53 to -0.21. Correlations with the original process scales were substantial (r=.83-.96), internal consistency was mostly adequate (α=0.65-0.86), and change scores were moderate to large (|d|=0.51-1.18). For depression, the brief Behavioral Activation for Depression Scale-Activation subscale was especially promising. For panic disorder, the brief Agoraphobic Cognitions Questionnaire-Physical Consequences subscale was especially promising. For social anxiety disorder, the Social Cognitions Questionnaire, the Social Probability and Cost Questionnaire, and the Social Behavior Questionnaire-Avoidance and Impression Management subscales were all promising. CONCLUSIONS Several brief process scales showed promise as measures of treatment processes in cognitive behaviour therapy. There is a need for replication and further evaluation using experimental designs, in other clinical settings, and preferably in larger samples.
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Affiliation(s)
- Erland Axelsson
- Division of Family Medicine and Primary Care, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
- Liljeholmen University Primary Health Care Center, Region Stockholm, Stockholm, Sweden
- Academic Primary Health Care Center, Region Stockholm, Stockholm, Sweden
| | - Fredrik Santoft
- Center for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Josefin Särnholm
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Brjánn Ljótsson
- Division of Psychology, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Reinosa Segovia FA, Benuto LT. A Systematic Review of Ethnoracial Participation in Randomized Clinical Trials of Behavioral Activation. Behav Ther 2022; 53:927-943. [PMID: 35987549 DOI: 10.1016/j.beth.2022.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 02/18/2022] [Accepted: 03/25/2022] [Indexed: 11/27/2022]
Abstract
As of the last available NIH report, people of color (POC) constituted 28.1% of enrollment across all U.S. domestic clinical trials. The literature on prevalence rates of depression among POC is mixed. While the prevalence rates of depression may vary across POC, it remains unknown to what degree POC have been included in outcome clinical trials of depression since NIH's mandates for inclusion of minorities in clinical outcome research. Following PRISMA guidelines, the present review identified randomized controlled trials of behavioral activation from 1989 to 2021 using the following search engines: PsycINFO, EMBASE, and Cochrane Central Register of Controlled Trials. We reviewed 5,247 articles and included 28 articles that met full inclusion criteria (n = 5,169 participants). Across studies included in this review, 70% were non-Latinx White, 14.1% were African American, 8.9% were Latinx, 0.5% were Asian, 2.9% were other, and 3.7% were unknown. Results indicated an increase in representation of ethnoracial inclusion rates across time and that recruitment method was not associated with adequate inclusion of POC. However, the university setting was associated with inadequate representation of POC.
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Weitzel EC, Pabst A, Luppa M, Kersting A, König HH, Löbner M, Riedel-Heller SG. Are self-managed online interventions for depression effective in improving behavioral activation? A secondary analysis of a cluster-randomized controlled trial. J Affect Disord 2022; 308:413-420. [PMID: 35460734 DOI: 10.1016/j.jad.2022.04.090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 04/06/2022] [Accepted: 04/13/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND Online interventions can effectively improve depressive symptoms. They often include behavioral activation (BA) techniques, but research on the effects on behavioral activation is scarce. This study aims to examine short- and long-term effects of online interventions on behavioral activation in routine care. METHODS This study is a secondary analysis of a pragmatic cluster-randomized controlled trial (@ktiv) with a sample of N = 647 GP patients with mild to moderate depression. The intervention group (IG) received treatment-as-usual (TAU) and adjunct access to an online intervention; the control group (CG) received TAU. BA was assessed in terms of the frequency and enjoyment of pleasant activities at baseline, after six weeks and after six months. Intention-to-treat analyses were performed via multilevel mixed linear regression. RESULTS The frequency of pleasant activities was significantly higher in the IG than in the CG six months after baseline (t(1406) = 2.25, p = .024). The enjoyment of pleasant activities was significantly higher in the IG than in the CG both six weeks (t(1405) = 2.11, p = .035) and six months after baseline (t(1405) = 3.44, p = .001). Initial depressive symptoms significantly moderated the treatment effect on the enjoyment but not the frequency of pleasant activities. LIMITATIONS BA measures have not been validated in a clinical context. CONCLUSIONS GP patients with mild to moderate depressive symptoms profited from access to an online adjunct intervention in terms of improved behavioral activation. The findings emphasize the usefulness of online interventions as supportive options in mental health care.
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Affiliation(s)
- E C Weitzel
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany.
| | - A Pabst
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
| | - M Luppa
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
| | - A Kersting
- Clinic of Psychosomatic Medicine and Psychotherapy, University of Leipzig, Leipzig, Germany
| | - H H König
- Department of Health Economics and Health Services Research, Hamburg Centre for Health Economics, University Medical Centre Hamburg-Eppendorf, University of Hamburg, Hamburg, Germany
| | - M Löbner
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
| | - S G Riedel-Heller
- Institute of Social Medicine, Occupational Health and Public Health (ISAP), Medical Faculty, University of Leipzig, Philipp-Rosenthal-Str. 55, 04103 Leipzig, Germany
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Sanford BT, Ciarrochi J, Hofmann SG, Chin F, Gates KM, Hayes SC. Toward empirical process-based case conceptualization: An idionomic network examination of the process-based assessment tool. JOURNAL OF CONTEXTUAL BEHAVIORAL SCIENCE 2022. [DOI: 10.1016/j.jcbs.2022.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Temporal and specific pathways of change in cognitive behavioral therapy (CBT) and interpersonal psychotherapy (IPT) for depression. Behav Res Ther 2021; 151:104010. [DOI: 10.1016/j.brat.2021.104010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 11/18/2021] [Accepted: 11/22/2021] [Indexed: 12/19/2022]
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Baggett KM, Davis B, Sheeber L, Miller K, Leve C, Mosley EA, Landry SH, Feil EG. Optimizing Social-Emotional-Communication Development in Infants of Mothers With Depression: Protocol for a Randomized Controlled Trial of a Mobile Intervention Targeting Depression and Responsive Parenting. JMIR Res Protoc 2021; 10:e31072. [PMID: 34406122 PMCID: PMC8411326 DOI: 10.2196/31072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 06/23/2021] [Accepted: 06/24/2021] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Postpartum depression interferes with maternal engagement in interventions that are effective in improving infant social-emotional and social-communication outcomes. There is an absence of integrated interventions with demonstrated effectiveness in both reducing maternal depression and promoting parent-mediated practices that optimize infant social-emotional and social-communication competencies. Interventions targeting maternal depression are often separate from parent-mediated interventions. To address the life course needs of depressed mothers and their infants, we need brief, accessible, and integrated interventions that target both maternal depression and specific parent practices shown to improve infant social-emotional and social-communication trajectories. OBJECTIVE The aim of this study is to evaluate the efficacy of a mobile internet intervention, Mom and Baby Net, with remote coaching to improve maternal mood and promote parent practices that optimize infant social-emotional and social-communication development. METHODS This is a two-arm, randomized controlled intent-to-treat trial. Primary outcomes include maternal depression symptoms and observed parent and infant behaviors. Outcomes are measured via direct observational assessments and standardized questionnaires. The sample is being recruited from the urban core of a large southern city in the United States. Study enrollment was initiated in 2017 and concluded in 2020. Participants are biological mothers with elevated depression symptoms, aged 18 years or older, and who have custody of an infant less than 12 months of age. Exclusion criteria at the time of screening include maternal homelessness or shelter residence, inpatient mental health or substance abuse treatment, or maternal or infant treatment of a major mental or physical illness that would hinder meaningful study participation. RESULTS The start date of this grant-funded randomized controlled trial (RCT) was September 1, 2016. Data collection is ongoing. Following the institutional review board (IRB)-approved pilot work, the RCT was approved by the IRB on November 17, 2017. Recruitment was initiated immediately following IRB approval. Between February 15, 2018, and March 11, 2021, we successfully recruited a sample of 184 women and their infants into the RCT. The sample is predominantly African American and socioeconomically disadvantaged. CONCLUSIONS Data collection is scheduled to be concluded in March 2022. We anticipate that relative to the attention control condition, which is focused on education around maternal depression and infant developmental milestones with matching technology and coaching structure, mothers in the Mom and Baby Net intervention will experience greater reductions in depression and gains in sensitive and responsive parent practices and that their infants will demonstrate greater gains in social-emotional and social-communication behavior. TRIAL REGISTRATION ClinicalTrials.gov NCT03464630; https://clinicaltrials.gov/ct2/show/NCT03464630. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) DERR1-10.2196/31072.
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Affiliation(s)
| | - Betsy Davis
- Oregon Research Institute, Eugene, OR, United States
| | - Lisa Sheeber
- Oregon Research Institute, Eugene, OR, United States
| | - Katy Miller
- Georgia State University, Atlanta, GA, United States
| | - Craig Leve
- Oregon Research Institute, Eugene, OR, United States
| | | | - Susan H Landry
- University of Texas Health Sciences Center, Houston, TX, United States
| | - Edward G Feil
- Oregon Research Institute, Eugene, OR, United States
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Domhardt M, Steubl L, Boettcher J, Buntrock C, Karyotaki E, Ebert DD, Cuijpers P, Baumeister H. Mediators and mechanisms of change in internet- and mobile-based interventions for depression: A systematic review. Clin Psychol Rev 2020; 83:101953. [PMID: 33422841 DOI: 10.1016/j.cpr.2020.101953] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/09/2020] [Accepted: 11/23/2020] [Indexed: 01/05/2023]
Abstract
The efficacy of Internet- and mobile-based interventions (IMIs) for depression in adults is well established. Yet, comprehensive knowledge on the mediators responsible for therapeutic change in these interventions is pending. Therefore, we conducted the first systematic review on mediators in IMIs for depression, investigating mechanisms of change in interventions with different theoretical backgrounds and delivery modes (PROSPERO CRD42019130301). Two independent reviewers screened references from five databases (i.e., Cochrane Library, Embase, MEDLINE/PubMed, PsycINFO and ICTRP), selected studies for inclusion and extracted data from eligible studies. We included 26 RCTs on mediators in IMIs for depression (6820 participants), rated their risk of bias and adherence to methodological quality criteria for psychotherapy process research. Primary studies examined 64 mediators, with cognitive variables (e.g., perceived control, rumination or interpretation bias) being the largest group of both examined (m = 28) and significant mediators (m = 22); followed by a range of other mediators, including mindfulness, acceptance and behavioral activation. Our findings might contribute to the empirically-informed advancement of interventions and mental health care practices, enabling optimized treatment outcomes for patients with depression. Furthermore, we discuss implications for future research and provide methodological recommendations for forthcoming mediation studies with more pertinent designs, allowing for inferences with higher causal specificity.
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Affiliation(s)
- Matthias Domhardt
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany.
| | - Lena Steubl
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
| | - Johanna Boettcher
- Department of Clinical Psychology and Psychotherapy, Psychologische Hochschule Berlin, Germany
| | - Claudia Buntrock
- Department of Clinical Psychology and Psychotherapy, Friedrich-Alexander University Erlangen-Nuremberg, Germany
| | - Eirini Karyotaki
- Department of Clinical, Neuro and Developmental Psychology, Vrije Universiteit Amsterdam, the Netherlands; Department of Global Health and Social Medicine, Harvard Medical School, United States
| | - David D Ebert
- Department of Clinical, Neuro and Developmental Psychology, Vrije Universiteit Amsterdam, the Netherlands
| | - Pim Cuijpers
- Department of Clinical, Neuro and Developmental Psychology, Vrije Universiteit Amsterdam, the Netherlands; Public Health Research Institute, Vrije Universiteit Amsterdam, the Netherlands
| | - Harald Baumeister
- Department of Clinical Psychology and Psychotherapy, Ulm University, Germany
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Depression prevention in digital cognitive behavioral therapy for insomnia: Is rumination a mediator? J Affect Disord 2020; 273:434-441. [PMID: 32560938 DOI: 10.1016/j.jad.2020.03.184] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 03/24/2020] [Accepted: 03/30/2020] [Indexed: 11/23/2022]
Abstract
Background There has been growing support for digital Cognitive Behavioral Therapy (dCBT-I) as a scalable intervention that both reduces insomnia and prevents depression. However, the mechanisms by which dCBT-I reduces and prevents depression is less clear. Methods This was a randomized controlled trial with two parallel arms: dCBT-I (N=358), or online sleep education as the control condition (N=300). Outcome variables were measured at pre-treatment, post-treatment, and one-year follow-up, and included the Insomnia Severity Index (ISI), the Quick Inventory of Depressive Symptomatology (QIDS-SR16), and the Perseverative Thinking Questionnaire (PTQ). The analyses tested change in PTQ scores as a mediator for post-treatment insomnia, post-treatment depression, and incident depression at one-year follow-up. Results Reductions in rumination (PTQ) were significantly larger in the dCBT-I condition compared to control. Results also showed that reductions in rumination significantly mediated the improvement in post-treatment insomnia severity (proportional effect = 11%) and post-treatment depression severity (proportional effect = 19%) associated with the dCBT-I condition. Finally, reductions in rumination also significantly mediated the prevention of clinically significant depression via dCBT-I (proportional effect = 42%). Limitations Depression was measured with a validated self-report instrument instead of clinical interviews. Durability of results beyond one-year follow-up should also be tested in future research. Conclusions Results provide evidence that rumination is an important mechanism in how dCBT-I reduces and prevents depression.
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