The study will examine the efficacy of an internet-based cognitive behavioural therapy (iCBT) for Inflammatory Bowel Disease (IBD) intervention to reduce stress, anxiety, and depression in individuals with IBD and comorbid clinically elevated t anxiety and/or depressive symptoms. The investigators will conduct a two-arm RCT comparing participants receiving the iCBT intervention (intervention group) and those receiving Treatment As Usual (TAU).

Inflammatory bowel disease (IBD) affects over a quarter of a million Canadians and this rate is expected to increase to 403,000 by year 2030 (Kaplan, Bernstein, Coward, Bitton, Murthy, Nguyen, Lee, Cooke-Lauder, Benchimol, 2019). The disease has a high burden for patients, with unpredictable, painful symptoms often requiring costly medications and surgery to facilitate disease remission. It is well established that individuals with IBD have significantly higher rates of anxiety and depression compared to the general population. (Bernstein, 2017; Graff, Walker, & Bernstein, 2009; Mikocka-Walus, Knowles, Keefer, Graff, 2016; Walker, Ediger, Graff, Greenfeld, Clara, Lix, Rawsthorne, Miller, Rogala, McPhail, & Bernstein, 2008).

There is growing research on psychological treatment for individuals with IBD, providing some evidence that Cognitive Behavioural Therapy (CBT) reduces psychological distress in this population (Knowles, Monshat, & Castle, 2013). Traditional CBT delivery methods involve in-person treatment, with multiple sessions over time, either one-on-one or in small groups. Development of alternate modes of effective treatment delivery is vital to enhance access and facilitate availability, particularly given limited mental health service availability. Internet-Based Cognitive Behaviour Therapy (iCBT) may be an effective alternative treatment for persons with IBD and related stress, anxiety and/or depression (McCombie, 2016) as it may mitigate the aforementioned challenges. Potential benefits of iCBT include enhanced cost effectiveness, little to no wait time to begin treatment, and increased accessibility.

Our research group developed and pilot-tested an internet-based cognitive behavioural therapy (iCBT) intervention targeting stress, anxiety and/or depression in adults with IBD. The intervention is housed on the Minddistrict online platform, the same platform used in our pilot study (HREB Ethics HS22087 (H2018:333) (Minddistrict, 2018, June, 1).The program was designed to be completed over 12 weeks. The study coordinator will be tracking participants' progress through the intervention by reviewing completion of questionnaires and modules.

The intervention includes 9 core modules and 3 optional modules. CORE Modules: 1. About the program, 2. IBD and Stress, 3. Relaxation Strategies, 4, Commitment to Living Life Fully, 5. The Brain-Gut Connection, 6. Understanding Anxiety, 7. Overcoming Avoidance, 8. Depression, 9. Behavioural Activation Optional Modules: 11. IBD and the Workplace, 12. Coping with Pain through Mindfulness, 13. Fatigue and Sleep

The next stage in extending this research is to conduct a randomized control trial (RCT) to determine the efficacy of this internet-based intervention, utilizing a control condition and ensuring adequate sample size powered to detect differences between the intervention group and Treatment as Usual (TAU).

Participants will be adults with confirmed inflammatory bowel disease, recruited from local enrollees of the IMAGINE study described earlier (IMAGINE, 2020, July, 2). They will be contacted by email to invite for participation in this study.

Participants will be randomized using a computer-generated randomization schedule which allows for allocation concealment with a ratio of 1.2 (iCBT) : 1.0 (TAU).

Inclusion Criteria:

• Participants will need to be at least 18 years of age or older, be diagnosed by a physician with IBD (Crohn's disease or Ulcerative Colitis), have anxiety and/or depression scores > 8 on the Hospital Anxiety and Depression Scale (HADS-A or HADS-D), have access to a computer, and be literate in the English language. Participants may be on psychotropic medication but dosage should be stable for at least six weeks prior to study enrollment.

Exclusion Criteria:

• Individuals who have had, within the last six months, suicidal ideation or suicidal intent, self-harming behaviour, active substance use disorder, psychotic disorder, or an eating disorder will be excluded. Presence of these behaviours and disorders will be determined through the screening process described in the next section. Individuals who are currently receiving cognitive behavioral treatment for an anxiety or mood disorder, or have participated in such treatment in the previous three months, are not eligible for this study.