Background & Objective: Multiple sclerosis (MS) is an inflammatory, demyelinating, and neurodegenerative disorder of the central nervous system, characterized by myelin sheath degradation and axonal damage in the brain and spinal cord. Its clinical course ranges from relapsing-remitting forms to progressive variants. Beyond its physical consequences, MS has profound psychological impacts, affecting patients’ quality of life and exposing them to anxiety, depression, perceived stress, and rumination, thereby compromising their ability to adapt to the illness. Emotion regulation, as a fundamental construct of mental health, plays a critical role in managing emotional experiences and mitigating psychological distress. Adaptation to the disease is a multidimensional process encompassing cognitive, emotional, and behavioral efforts to accept limitations while maintaining a sense of meaning, control, and functional engagement in life. Metacognitive therapy (MCT), a third-wave cognitive-behavioral approach, targets maladaptive metacognitive beliefs, reduces rumination, and trains patients in cognitive distancing, thereby holding potential to enhance emotion regulation and improve adaptation to the disease in individuals with chronic conditions. Considering the high prevalence of emotional dysregulation in MS and the paucity of systematic studies in this context, the present study aimed to investigate the effectiveness of MCT on emotion regulation and adaptation to the disease in women with MS.

Methods: This semi-experimental study employed a pre-test–post-test design with a control group and a three-month follow-up period. The study population consisted of all female patients with multiple sclerosis (MS) who attended the MS clinic at Naft Hospital, Tehran, Iran, during 2024, and whose diagnoses had been confirmed by a neurologist. Thirty participants meeting inclusion criteria were selected through purposive sampling and randomly assigned to an experimental group (n=15; receiving MCT) or a control group (n=15; no intervention). Inclusion criteria included female sex, age 24–45 years, confirmed MS diagnosis, disease duration under five years, basic literacy, absence of severe comorbid physical or psychiatric disorders, and informed consent. The experimental group received eight weekly 60‑minute sessions of metacognitive therapy, while the control group received no intervention. Data were collected using the Difficulties in Emotion Regulation Scale (Gross & John, 2003) and the Adjustment to Multiple Sclerosis Scale (Besharat, 2004) at three time points. Repeated-measures analysis of variance (ANOVA) and Bonferroni post-hoc tests were conducted using SPSS v25, with significance set at p<0.05.

Results: The group effect on cognitive reappraisal (η²=0.26), expressive suppression (η²=0.38), and illness adaptation (η²=0.31) was significant (p<0.001). Moreover, the main effect of time was significant for cognitive reappraisal (η²=0.86), expressive suppression (η²=0.76), and illness adaptation (η²=0.83) (p<0.001). The interaction effect of time and group was also significant for cognitive reappraisal (η²=0.79), expressive suppression (η²=0.69), and illness adaptation (η²=0.83) (p<0.001). In the experimental group, the mean differences between pretest and posttest as well as between pretest and follow-up were significant for all three variables (p<0.001); however, the mean differences between posttest and follow-up were not significant for any of the studied variables (p>0.05). In the control group, none of the pairwise comparisons between assessment stages for the studied variables were significant

Conclusion: The study demonstrates that metacognitive therapy significantly improves cognitive reappraisal, reduces expressive suppression, and enhances adaptation to the disease in women with MS. These benefits are sustained over time, supporting MCT as an effective intervention to strengthen emotion regulation and promote adaptive coping in patients with MS.