Patient and mentor language style matching as a predictor of working alliance, engagement with treatment as usual, and eating disorders symptoms over the course of an online guided self‐help intervention for anorexia nervosa.

Objective: The aim of this study was to examine the processes involved in a guided self‐help (GSH) pre‐treatment intervention (RecoveryMANTRA) for patients with anorexia nervosa (AN), by measuring the levels of patient/mentor Language Style Matching (LSM). RecoveryMANTRA was supported by student mentors or peer mentors (recovered individuals) over six weekly chat‐based sessions. We examined whether LSM during RecoveryMANTRA predicted patients'working alliance with the clinic therapist, motivation, eating disorder (ED) and general psychopathology. A further aim was to examine differences in LSM between student mentors and peer mentors. Method: 87 AN adults received RecoveryMANTRA plus treatment as usual. The LSM algorithm was used to calculate verbal attunement between patient and mentor. Participants were assessed at baseline and at the end of the intervention. Results: Both early (1st session) and late (6th session) LSM predicted higher working alliance with the clinic therapist. Moreover, late LSM predicted lower EDs symptoms at the end of the RecoveryMANTRA intervention. Patient/peer mentor dyads showed higher late verbal attunement than patient/student mentor dyads. Conclusions: These findings suggests that in the early phase of treatment relational aspects can impact on engagement with treatment. Verbal attunement in a GSH for AN is associated with working alliance and better clinical outcome. Highlights: Language Style Matching (LSM) between patients and mentors in both the early and late phase of the RecoveryMANTRA intervention predicted higher working alliance with the clinic therapist.LSM in the last phase (6th session) was associated with lower eating disorders (EDs) symptoms at the end of the RecoveryMANTRA intervention.Patients/peer mentors dyads showed higher late LSM than patients/student mentors dyads. [ABSTRACT FROM AUTHOR]