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I’m Iris (she/her) and I’m a Clinical Psychologist at Grenadier. I completed my PhD in Psychology from Toronto Metropolitan University in 2022. I’ve received prior training at St. Michael’s Hospital, the Anxiety Treatment and Research Centre at St. Joseph’s Healthcare Hamilton, the Women’s Inpatient Unit at the Centre for Addiction and Mental Health, the Centre for MindBody Health, CBT Associates, as well as various clinical research trials. 


I work collaboratively with individuals and couples by drawing on their capacity for growth to help them gain greater self-understanding and meet their desired goals. I believe therapy should offer a supportive, non-judgmental space where clients can explore their inner worlds. My therapeutic approach is grounded in cognitive behavioural therapy and other evidence-based methods such as mindfulness-based interventions, self-compassion, and emotion-focused therapy. My practice is anti-oppressive, LGBTQ+ affirmative, and trauma-informed.


In addition to my role at Grenadier, I currently work as a psychologist and post-doctoral fellow at Remedy, which is a private practice that also conducts clinical research. I’m passionate about innovating psychotherapies to increase their effectiveness and I’m involved in various clinical trials examining the effects of MDMA-facilitated therapy for PTSD. 


  • Doctorate of Philosophy (PhD) in Clinical Psychology, Toronto Metropolitan University (Toronto, ON)


Thomas, F. C., Loskot, T., Mutschler, C.,  Burdo, J., Lagdamen, J.,  Sijercic, I., Liebman, R. E., Lane, J. E. M., Finley, E., Monson, C. M., Wiltsey-Stirman, S. (2023). Initiating Cognitive Processing Therapy (CPT) in community settings: A qualitative investigation of therapist decision making. Administration and Policy in Mental Health, 50, 137-150.


Sijercic, I., Liebman, R. E., Ip, J., Whitfield, K. M., Ennis, N., Sumantry, D., Sippel, L. M., Fredman, S. J., & Monson, C. M. (2022). A systematic review and meta-analysis of individual and couple therapies for posttraumatic stress disorder: Clinical and intimate relationship outcomes. Journal of Anxiety Disorders, 91, 102613. 10.1016/j.janxdis.2022.102613.

Keefe, J. R., Hernandez, S., Johanek, C., Landy, M. S. H., Sijercic, I., Shnaider, P., Wagner, A. C., Lane, J. E. M., Monson, C. M., & Stirman, S. W. (2021). Competence in delivering cognitive processing therapy and the therapeutic alliance both predict PTSD symptom outcomes. Behavior Therapy.

Ennis, N., Sijercic, I., & Monson, C. M. (2020). Trauma-focused cognitive-behavioral therapies for posttraumatic stress disorder under ongoing threat: A systematic review. Clinical Psychology Review, 88, 102049.

Sijercic, I., Liebman, R. E., Stirman, S. W., & Monson, C. M. (2021). The effect of therapeutic alliance on dropout in Cognitive Processing Therapy for PTSD. Journal of Traumatic Stress, 34(4), 819-828. 

Johnson, C., Holmes, S., Suvak, M., Song, J., Shields, N., Lane., J. E. M., Sijercic, I., Cohen, Z. D., Stirman, S. W., & Monson, C. M. (2021). The effect of PTSD symptom change on suicidal ideation in a combined military and civilian sample engaged in cognitive processing therapy. Behavior Therapy, 52(3), 774-784.

Ennis, N., Sijercic, I., Wanklyn, S. G., & Monson, C. M. (2021). Assessing posttraumatic stress disorder with close others’ collateral reports: Convergence with self- and clinician-reports. Journal of Family Psychology, 35, 258-263.

Sijercic, I., Whitfield, K. M., Cassin, S. E., & Antony, M. M. (2020). A systematic review of cognitive-behavioral therapy for pharmacotherapy treatment-resistant obsessive-compulsive disorder. Journal of Obsessive-Compulsive and Related Disorders, 26, 100532.

Liebman, R. E., Whitfield, K. M., Sijercic, I., Ennis, N., & Monson, C. M. (2020). Harnessing the healing power of relationships in trauma recovery: A review of Cognitive-Behavioral Conjoint Therapy for PTSD. Current Treatment Options in Psychiatry, 7, 203-220.

Larsen, S. E., Mackintosh, M. A., La Bash H., Evans, W. R., Suvak, M. K., Shields, N., Sijercic, I., Monson, C. M., & Stirman, S. W. (2020). Temporary PTSD symptom increases among individuals receiving CPT in a hybrid effectiveness-implementation trial: Potential predictors and association with overall symptom change trajectory. Psychological Trauma: Theory, Research, Practice, and Policy 14(5), 853-861.

Cassin, S. E., Sijercic I., & Montemarano, V. (2020). Psychosocial interventions for food addiction: A systematic review. Current Addiction Reports, 7, 9-19.

David, L. A., Sijercic, I., & Cassin, S. E. (2020). Pre- and post-operative psychosocial interventions for bariatric surgery patients: A systematic review. Obesity Reviews, 1(4), 1-23.

Lord, K. A., Suvak, M. K., Holmes, S., Shields, N., Lane, J. E. M., Sijercic, I., Wagner, A. C., Stirman, S. W., & Monson, C. M. (2020). Bidirectional relationships between posttraumatic stress disorder (PTSD) and social functioning during cognitive processing therapy. Behavior Therapy, 51(3), 447-460.

Sijercic, I., Ennis, N., & Monson, C. M. (2020). A systematic review of cognitive and behavioral treatments for individuals with psoriasis. Journal of Dermatological Treatment, 31(6), 1-8. 

​Sijercic, I., Lane, J. E. M., Gutner, C. A., Monson, C. M., & Stirman, S. W. (2020). The association between clinician and perceived organizational factors with early fidelity to cognitive processing therapy for posttraumatic stress disorder in a randomized controlled implementation trial. Administration and Policy in Mental Health and Mental Health Services Research, 47(1), 8-18.

Holmes, S., Johnson, C. M., Suvak, M. K., Sijercic, I., Monson, C. M., & Stirman, S. W. (2019). Examining patterns of dose response for clients who do and do not complete cognitive processing therapy. Journal of Anxiety Disorders, 68, 102120.

Ennis, N., Sijercic, I., & Monson, C. M. (2018). A systematic review of internet-delivered early interventions for individuals exposed to traumatic events. Journal of Medical Internet Research, 20, e280.

Monson, C. M., Shields, N., Suvak, M. K., Lane, J. E. M., Shnaider, S., Landy, M. S. H., Wagner, A. C., Sijercic, I., Masina, T., Wanklyn, S. G., & Stirman, S. W. (2018). A randomized controlled effectiveness trial of training strategies in cognitive processing therapy for posttraumatic stress disorder: Impact on patient outcomes. Behaviour Research and Therapy, 110, 31-40.

Shnaider, P., Sijercic, I., Wanklyn, S. G., Suvak, M. K., & Monson, C. M. (2017). The role of social support in cognitive-behavioral conjoint therapy for posttraumatic stress disorder. Behavior Therapy, 48(3), 285-294.

Sijercic, I., Button, M. L., Westra, H. A., & Hara, K. M. (2016). The interpersonal context of client motivational language in cognitive-behavioral therapy. Psychotherapy, 53(1), 13-21.


  • College of Psychologists of Ontario

  • Ontario Psychological Association

  • Association of Behavioral and Cognitive Therapies (ABCT)

  • International Society for Traumatic Stress Studies (ISTSS)  

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