Mindfulness improves theory of mind in people experiencing psychosis: A pilot randomized clinical trial

Impaired Theory of Mind (ToM) ability is a core feature of psychotic disorders that challenges psychosis treatment. We aimed to explore the effect of a Mindfulness-Based Intervention (MBI) on ToM ability in a randomized clinical trial (RCT). A sample of 36 participants diagnosed with psychotic disorder were recruited from a community center and randomly allocated to Integrated Rehabilitation Treatment (IRT) or IRT+MBI. ToM skills were assessed through the Hinting Test and the Reading the Mind in the Eyes Test (RMET). IRT+MBI scored higher in RMET than IRT at posttreatment. MBI is a promising tool for improving ToM ability in psychosis.


Introduction
Impaired Theory of Mind (ToM) ability is a core feature of psychotic disorders which has a negative impact on different domains of functioning such as instrumental activities of daily life or social functioning (Thibaudeau et al., 2021). Interventions targeting ToM deficits are an ongoing challenge due its small effect (Thibaudeau et al., 2021). Mindfulness-Based Interventions (MBI) are a promising intervention due its effects improving ToM skills in the general population (Trautwein et al., 2020) and its benefits in psychosis (Böge et al., 2021;López-Navarro and Al-Halabí, 2021).
The aim of our study was to explore the effect of an MBI added to Integrated Rehabilitation Treatment (IRT) on ToM and compare it with IRT alone.

Methods
We used data from a cohort involved in a prior clinical trial (López-Navarro et al., 2020). A pilot randomized clinical trial with preand post-treatment measures was designed. The independent variable was treatment delivered, while the outcome variable was ToM performance. 36 participants diagnosed with psychotic disorder were recruited from a community rehabilitation center and randomly allocated by software to IRT or IRT+MBI. IRT entailed 26 one-hour weekly group sessions of cognitive behavior therapy for psychosis and social skills training. Each participant was interviewed once a week to adjust drug treatment -if necessary -. The IRT+MBI group involved IRT supplemented with 26 weekly group MBI sessions. The aim of MBI was to teach participants to react with acceptance to the content of the psychotic sensations instead struggling with them. Details about treatment delivery, inclusion criteria, and recruitment can be found in Lopez-Navarro et al. (2020). The study was registered with ISRCTN Registry: ISRCTN52873519.
Assessment was conducted by two clinical psychologists blinded to the treatment allocation. The instruments comprised: -A clinical record form to collect age, sex, years of education, and clinical diagnosis (psychotic disorder according to DSM criteria). -The Positive and Negative Syndrome Scale (Kay et al., 1987) was used to assess frequency and intensity of psychotic symptoms. -Executive function assessment was designed to cover the main components of the Miyake et al. (2000) (Corcoran et al., 1995) and the Reading the Mind in the Eyes Test (RMET) ( Baron-Cohen et al., 2001). Details are provided in the supplementary materials.
Data analysis involved repeated measures ANCOVA for each ToM variable, setting intervention as the independent variable. For each measure, there are seven lines of results: the four simple effects, the two main effects -Treatment and Time-, and the interaction effect between these two factors. Executive functioning baseline and post-intervention scores as covariates due to their influence on ToM in psychosis (López-Navarro, 2018). Analysis of interaction components was done via Bonferroni correction. Eta squared was used to estimate effect size. Statistical significance was set at 5%.

Results
There were no differences between treatment groups in clinical and demographic variables, executive functions, or ToM outcomes before treatment started (supplementary material, Table S1).
ANCOVA analysis of the Hinting scores showed no statistically sig-  Table 1 gives detailed data for the ANCOVA analysis. Details about covariables can be found in supplementary material (Table S2).

Discussion
Our data suggest that mindfulness plus standard rehabilitation treatment improves ToM skills related to emotion recognition, and this improvement is greater than from standard rehabilitation treatment. Add mindfulness to IRT has a larger effect on emotion recognition than on reasoning about social situations.
Our study provides the first evidence of the positive effects of an MBI on ToM performance in psychosis. Improving ToM deficits go beyond the domain of social functioning and could contribute to recovery in every sphere of functioning in schizophrenia (Thibaudeau et al., 2021). Bearing in mind the challenge of treating negative symptoms and cognitive impairment in psychosis -the main predictors of impairment of daily-life functioning-, MBI is a promising tool for improving ToM ability and related domains (Monfort-Escrig and Pena-Garijo, 2021; Strauss et al., 2021). These results could help to optimize treatment, since empirically-supported psychological interventions contribute to the field of mental health treatment (Rodríguez-Muñoz and Al-Halabí, 2020).
The study does have some limitations that should be noted: a small sample size, although enough to test the main hypothesis, and an uneven gender distribution-it remains unclear whether sex accounts for differences in treatment of psychosis (Fernández-Modamio et al., 2020). Our pilot RCT results add to the growing literature attesting for the benefits of mindfulness applied to psychosis (Böge et al., 2021;López-Navarro et al., 2015).

Declaration of Competing Interest
None