The aim of this study is to evaluate the efficacy of the Family Connections Transdiagnostic (FC-T) program in relatives of individuals with psychological disorders associated with emotional dysregulation through a randomized controlled trial.

Emotional dysregulation (ED) is a core transdiagnostic process characterized by heightened emotional sensitivity, intense emotional responses, and difficulties returning to baseline emotional states. It is present across a wide range of psychological disorders, including eating disorders (EDs), Cluster B personality disorders (PD), and disruptive, impulse-control, and conduct disorders. These conditions are associated with significant impairments in social functioning and are often accompanied by psychological symptoms such as depression, anxiety, interpersonal difficulties, and reduced quality of life. In addition, maladaptive strategies to cope with emotional distress (e.g., self-harm, impulsivity, aggression, binge eating) contribute to the maintenance and severity of these disorders.

Families of individuals with psychological disorders characterized by ED experience a high burden of illness and frequently report elevated levels of psychological distress, including anxiety and depression, as well as impairments in their own quality of life. Despite their key role as primary caregivers, family members often lack the necessary skills to effectively manage emotional crises and daily challenges, which may contribute to dysfunctional family dynamics and increased conflict. Although some intervention programs have been developed for caregivers of specific disorders, there is currently a lack of transdiagnostic treatments specifically designed for relatives of individuals with ED.

A skills training program called "Family Connections" (FC) was developed by Hoffman and Fruzzetti's group for relatives of individuals with borderline personality disorder (BPD). It is a program consisting of 12 weekly two-hour sessions delivered in a group format. It is divided into six modules that include psychoeducation about the disorder and its impact on family functioning, as well as skills adapted from Dialectical Behavior Therapy, such as mindfulness, emotion regulation, validation, radical acceptance, and problem management, among others. In addition, all modules include practical exercises, video examples, and homework assignments. Previous studies have shown that this program leads to significant reductions in caregiver burden, perceived distress, depression, and anxiety, as well as improvements in coping strategies and family functioning.

The present study aims to develop and evaluate a transdiagnostic adaptation of the program (Family Connections Transdiagnostic; FC-T), designed to be applied to relatives of individuals with psychological disorders characterized by emotional dysregulation, regardless of specific diagnosis. The psychoeducational modules will be adapted to address ED as a common underlying mechanism, while maintaining the core skills training components of the original program.

The aims of this study are the following: (a) to adapt and test, in the Spanish population, the modules of the FC-T intervention protocol for relatives of patients with psychological disorders characterized by ED; (b) to test the efficacy of FC-T in reducing caregiver burden and clinical symptomatology and improving family relationships and quality of life; (c) to test its efficiency, understood as the acceptance of the intervention program by participants and clinicians, and to demonstrate its feasibility; and (d) to carry out an effective dissemination of this protocol.

This paper presents the study protocol. The study design consists of a two-arm randomized controlled trial with two conditions: Family Connections Transdiagnostic (FC-T) or Treatment as usual optimized (TAU-O). Participants will be family members of patients diagnosed, according to the 5th version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), with eating disorders, Cluster B personality disorders, or disruptive, impulse-control, and conduct disorders. The caregivers' primary outcome measures will be the Burden Assessment Scale (BAS) and a Family-Patient Critical Incident Record. Secondary outcomes will include measures of family functioning, clinical symptomatology, coping strategies, and quality of life. Patient-related outcomes will include measures of emotional dysregulation and impulsivity. Participants will be assessed at pre-treatment, post-treatment, and twelve-month follow-up. The intention-to-treat principle will be used when analyzing data, using mixed-effects models with full information and maximum likelihood estimation.

Inclusion Criteria:

• • Being 18 years of age or older.

  • Being a family member (e.g., parent, partner, sibling, or other close relative) of a patient diagnosed, according to the 5th version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), with a psychological disorder characterized by emotional dysregulation (e.g., eating disorders, Cluster B personality disorders, or disruptive, impulse-control, and conduct disorders).
  • The patient must currently be receiving treatment in a participating clinical center.
  • Having sufficient knowledge and understanding of the Spanish language to complete the assessments and participate in the intervention.
  • Providing written informed consent to participate in the study.

Exclusion Criteria:

• • Presence of any severe mental disorder or condition in the family member that may interfere with participation in the intervention (e.g., psychotic disorders, schizophrenia, severe cognitive impairment, or intellectual disability).

  • Current substance dependence that may hinder participation in the study.
  • Severe clinical instability in the patient that prevents the family member from participating in the intervention (as judged by clinicians).

Individual participant data will be available after de-identification.

The data will be available immediately after publication

The data will be available to anyone who wishes and justify to access them

Double-blind