Testing Interventions for Borderline Personality Disorder.

Borderline personality disorder (BPD) is a life-threatening, costly public health crisis affecting \~1-3% of North Americans, with 10% dying by suicide and annual healthcare costs of \~$63k (Canadian Dollars)/patient. Further, people with BPD's intimate relationships are highly disrupted, and their partners report elevated mental health problems but little access to treatment. Existing BPD treatments are resource-heavy, inaccessible, and 47% of people with BPD do not respond to them. These treatments also neglect relationship problems and intimate partner's mental health concerns, even though they are thought to play a key role in BPD maintenance. BPD interventions may produce stronger, quicker, and more durable outcomes if they incorporated partners to target both the emotional and relationship core of BPD. Moreover, incorporating partners into interventions may improve relationship outcomes and partner mental health without added resource investments. Accordingly, members of our team developed Sage. Named after a plant that thrives in relationship with its ecosystem, Sage is a brief, 12-session conjoint intervention for people with BPD and their intimate partners that targets BPD, relationship conflict, and partner mental health. Our recent uncontrolled trial provides preliminary support for its efficacy. As a next step in testing Sage, it is critical to utilize a Randomized Controlled Trial (RCT) design to identify if Sage is more efficacious than standard care that these couples typically receive; supportive individual psychotherapy (SIP) for people with BPD and their partners. The investigators propose to conduct the first RCT of Sage for couples wherein one member has BPD. The study will examine if Sage is more efficacious than SIP in improving BPD symptoms (primary outcome), as well as relationship conflict and partner mental health (secondary outcomes), as well as a range of other outcomes, from pre- to post-intervention, and post-intervention to follow-up. It will also investigate factors that influence treatment response, BPD severity, and related problems. Up to 152 couples wherein one member has BPD will be randomized to receive Sage or SIP. Gold-standard measures of primary, secondary, and exploratory outcomes will be administered at baseline, mid-intervention, post-intervention, and a one-month, three- month, and six-month follow-up.