Evaluation of Self-help Books for Depression

The goal of this study is to compare the efficacy of acceptance and commitment therapy (ACT) and cognitive behavioral therapy (CBT) for depression in a bibliotherapy format and assess hypothesized mechanisms of change in depression symptomatology, quality of life, and functioning.

This study will test the following hypotheses:

1. CBT and ACT will both result in decreased depression, distress, and self-stigma associated with depression. Life satisfaction and values progress will increase in both conditions.
2. CBT will result in greater use of reappraisal than ACT.
3. ACT will results in greater use of defusion and decreased psychological inflexibility than CBT.
4. Changes in experiential avoidance and defusion will predict changes in depression in the ACT condition.
5. Changes in reappraisal will predict changes in depression in the CBT condition.
6. Participants who are given their choice of treatment will show better adherence and satisfaction in the intervention.

The investigators aim to recruit 150 participants for this RCT (50 per treatment condition). This will provided adequate power (0.80) to detect differences between groups of medium effect size (d=0.50). Note that detailed eligibility criteria are listed in the "Eligibility" section. Participants will be recruited via SONA, flyers, online postings, classroom announcements, and through the USU CBS lab website.

All study procedures will be completed online, on a computer/mobile phone. After completing informed consent online through Qualtrics, participants will complete an online baseline survey. Participants will then be randomized to one of three groups: a CBT book, an ACT book, or a choice between the two books. Participants will be asked not to access other self-help books during the study duration. A link will be provided to access the book online along with a 10-week suggested reading schedule. Participants will be asked to complete a midtreatment survey 5 weeks after the beginning of treatment, and a posttreatment survey 10 weeks after the beginning of treatment. A follow-up survey will be sent to participants 3 months after the posttreatment survey. In addition to psychological measures, these surveys will also ask about adherence and use of strategies taught in the book. Researcher contact will involve reminders to complete assessments and weekly reminders of the suggested reading schedule.

Participants assigned to the CBT condition will receive a link to access The Cognitive Behavioral Workbook for Depression (Knaus, 2008), based on a psychosocial treatment that has shown effectiveness in reducing depression symptoms (Jiménez, 2012). The primary treatment components in this book are psychoeducation (introducing the cognitive behavioral model of depression), self-assessment worksheets (e.g. identifying depressive thought patterns, separating sensations from appraisals), cognitive restructuring, using metacognition/logic, and avoiding perfectionism.

Participants assigned to the ACT condition will receive a link to access The Mindfulness and Acceptance Workbook for Depression (Strosahl \& Robinson, 2008), based on a modern cognitive behavioral therapy that combines acceptance and mindfulness methods with values and behavior change methods (Hayes, Strosahl \& Wilson, 2011). The primary treatment components in this book are psychoeducation (introducing the ACT model of depression), values and goals, mindfulness, acceptance, defusion, committed action, and "rewriting" inflexible life stories.

An additional subset of study participants will be given their choice of the two self-help books described above after completing the baseline assessment. Participants who are randomized to receive their choice of book will be provided a brief description of the contents of each book before making a decision.

Eligibility Criteria:
Inclusion Criteria:

* Age 18 or older
* Enrolled at Utah State University
* Have not participated in other self-help studies run by the USU CBS Lab
* Interested in using self-help book for depression
* Elevated depressive symptoms as determined by scoring a 10 or higher on the depression subscale of the Depression, Anxiety, and Stress Scale (DASS-21)

Exclusion Criteria:

* Below the age of 18
* Not a student at Utah State University
* Have participated in other self-help studies run by the USU CBS Lab
* Not interested in using self-help book for depression
* No elevated depressive symptoms as determined by scoring lower than 10 on the depression subscale of the Depression, Anxiety, and Stress Scale (DASS-21)