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Community mental health clinics need cost-effective, well-tolerated treatments for PTSD.

The IFS therapy-based PARTS program is promising as a cost-effective treatment for PTSD.

A follow-up trial of the IFS PARTS program has also been completed.

The IFS PARTS program shows promise for addressing PTSD, complex PTSD, depression, anxiety, and suicide risk.

Co-authored with Alexandra Comeau, Zev Schuman-Olivier, Lawrence G. Rosenberg, Hanna Soumerai Rea, and Mary Catherine Ward.

Research suggests that the complex trauma and/or other psychiatric comorbidities that often accompany post-traumatic stress disorder (PTSD) are not targeted by single-component treatments for PTSD. At the same time, community mental health care systems, which typically have limited resources and a high demand for trauma treatment and its comorbidities, are particularly in need of resource-efficient interventions.

Accordingly, the Center for Mindfulness and Compassion at the Cambridge Health Alliance did a proof-of-concept research study called Program for Alleviating and Resolving Trauma and Stress or PARTS that was published in the journal Psychological Trauma in 2024. The PARTS program was conducted in an ethnically and socioeconomically diverse community health care system. It was based on the Internal Family Systems (IFS) therapy model and offered 16 weeks of 90-minute online groups along with eight 50-minute individual IFS counseling sessions.

IFS, a non-pathologizing, destigmatizing therapy model, posits that PTSD symptomatology is protective and addresses common comorbidities like depression and anxiety as well as disturbances in self-organization, which are hallmarks of complex PTSD (C-PTSD). The PARTS program researchers hypothesized that pairing group therapy for PTSD with a limited number of individual counseling sessions could benefit both patients and the financially strapped health care systems that serve them.

IFS includes the following basic tenets:

The mind is a community of parts that come online developmentally and have different ages.

When a vulnerable part is injured by an existential or interpersonal insult (an illness, an accident, war, interpersonal shaming, rejection, physical or sexual abuse, and so on), other parts coming online feel protective and make efforts to keep that part out of sight and out of mind; therefore, IFS calls these parts exiles.

Some protectors are proactive. These inhibitory parts are called managers. They keep an eye on belonging and being included. In extremity, they can become intensely critical.

The anxiety, depression, and despair evoked by inhibitory pressures from manager parts motivate another set of protectors to react with impulsive or compulsive distractions and strategies for self-soothing that offer quick relief, including addictive processes. Since these reactive protectors will do anything to put out emotional fires, IFS calls them firefighters.

Internal conflict signals friction between protective parts over how to manage danger.

When the mind decenters from the feelings and perspectives of parts, a different and powerful resource is revealed, which IFS calls the Self. This is similar to the resource Wise Mind, which Marsha Linehan borrowed from Buddhism for dialectical behavioral therapy (DBT). From the perspective of their Self, patients can zoom in and zoom out cognitively, feel curious about intensely emotional events, and access self-compassion.

IFS therapy is internally interactive, aiming for distressed parts to develop secure internal attachments with the Self.

The completed PARTS program showed promise as a novel intervention for addressing PTSD, complex PTSD, depression, anxiety, and suicide risk, as the study demonstrated significant reductions in these symptoms. Retention rates were on par with or better than those of other evidence-based, trauma-focused treatments for PTSD, and the online, group, and individual format used 64 percent less clinician time than the individual IFS PTSD model.

This study had limitations. It had no control group, a small sample size (n = 15), and limited gender diversity, with 13 female-identified participants. Although racial diversity was in line with national census data, Black participants completed fewer post-intervention week 24 follow-ups.

PTSD has varied presentations for which we need feasible and effective treatments. This proof-of-concept study justified a randomized control trial (RCT) that explored mechanisms of change in PTSD symptomatology and the ability of the PARTS program to treat PTSD and comorbid symptoms. The RCT study, called “A randomized controlled trial of an online group-based internal family systems treatment for posttraumatic stress disorder: The Program for Alleviating and Resolving Trauma and Stress (PARTS) study,” has been completed and published in advance online form in Psychological Trauma: Theory, Research, Practice, and Policy.

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IFS Therapy Offers Several Strategies That Hold Promise for Treating PTSD

Blending and Unblending: When a part blends, we are taken over by its sensations, feelings, thoughts, and beliefs—we see through its eyes—which influences how we respond to stressful situations. When all parts unblend, we move into the aware perspective of the Self: We notice the sensations, feelings, thoughts, and beliefs of our parts, and we have the zoomed-out viewpoint necessary for assessing information (coming from outside or inside) to see choices and respond more effectively.

Interacting internally with parts: When we interact with our parts kindly, with curiosity and respect (that is, with Self-energy), they are more likely to notice us and be willing to cooperate and collaborate.

Assuming that protective parts have good intentions: We can befriend protective parts, even those engaged in extreme behavior, by assuming they mean well and asking about their intentions.

Welcoming all parts: IFS asserts that exiling wounded parts is a source of suffering, and that the radical opposite, welcoming all parts, promotes well-being.

Comeau, A., Smith, L. J., Smith, L., Soumerai Rea, H., Ward, M. C., Creedon, T. B., Sweezy, M., Rosenberg, L. G., & Schuman-Olivier, Z. (2024). Online group-based internal family systems treatment for posttraumatic stress disorder: Feasibility and acceptability of the program for alleviating and resolving trauma and stress. Psychological Trauma: Theory, Research, Practice, and Policy, 16(Suppl 3), S636–S640. https://doi.org/10.1037/tra0001688

Joss, D., Comeau, A., Chevannes, R., Parry, G., Rea, H. S., Barria, J., Bumpus, C., Rector, A., Rajan, A., Rosansky, J., Rice, F. K., Ward, M. C., Tobiasz Veltz, L., Ally, D., Rosenberg, L. G., Sweezy, M., Lovas, D., & Schuman-Olivier, Z. (2026). A randomized controlled trial of an online group-based internal family systems treatment for posttraumatic stress disorder: The Program for Alleviating and Resolving Trauma and Stress (PARTS) study. Psychological Trauma: Theory, Research, Practice, and Policy. Advance online publication. https://dx.doi.org/10.1037/tra0002089

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