Theory of mind disturbances in borderline personality disorder: A meta-analysis

Highlights

• In general, BPD patients have ToM deficits.

• BPD patients are impaired in cognitive ToM and in reasoning, but not in decoding mental states.

• BPD patients’ affective ToM performance is largely task dependent.

• The Faux Pas Task is the most sensitive task to detect ToM deficits in BPD.

• Comorbid anxiety disorders can enhance overall and affective ToM in BPD.

Abstract

Impairments of theory of mind (ToM) are widely accepted underlying factors of disturbed relatedness in borderline personality disorder (BPD). The aim of this meta-analysis a was to assess the weighted mean effect sizes of ToM performances in BPD compared to healthy controls (HC), and to investigate the effect of demographic variables and comorbidities on the variability of effect sizes across the studies. Seventeen studies involving 585 BPD patients and 501 HC were selected after literature search. Effect sizes for overall ToM, mental state decoding and reasoning, cognitive and affective ToM, and for task types were calculated. BPD patients significantly underperformed HC in overall ToM, mental state reasoning, and cognitive ToM, but had no deficits in mental state decoding. Affective ToM performance was largely task dependent in BPD. Comorbid anxiety disorders had a positive moderating effect on overall and affective ToM in BPD. Our results support the notion that BPD patients’ have specific ToM impairments. Further research is necessary to evaluate the role of confounding factors, especially those of clinical comorbidities, neurocognitive functions, and adverse childhood life events. Complex ToM tasks with high contextual demands seem to be the most appropriate tests to assess ToM in patients with BPD.

Introduction

Borderline personality disorder (BPD) is a phenomenologically heterogeneous disorder characterized by affective, cognitive, behavioral, and interpersonal (i.e. disturbed relatedness) symptom areas (APA, 2013). It is widely accepted that BPD patients’ unstable relational style is of central importance (Gunderson, 2007), and other symptoms, such as impulsivity, self-harm, anger or emotional instability are consequences of, or triggered by the social, interpersonal context (Hepp et al., 2017, Brodsky et al., 2006; Kehrer and Linehan, 1996). Clinical research paid increasing attention to BPD patients’ social dysfunctions during the past decades, and a growing body of data indicates that BPD patients have social cognitive deficits (Daros et al., 2013; reviewed by Roepke et al., 2013, Herpertz and Bertsch, 2014.). Theory of mind (ToM), (or mentalizing) is one of the essential components of social cognition. ToM is the ability to attribute mental states (i.e. beliefs, desires) to self and others, and to understand and predict their behaviors, intentions, and wishes (Baron-Cohen, 1995).

Hence, ToM is a multidimensional construct involving several dimensions. Sabbagh (2004) identified two processes of ToM: (1) detecting and discriminating cues in the immediate social environment, i.e. the ability to decode the mental states of others; and (2) making inferences about those cues, i.e. the ability to reason about the mental states of others. An additional distinction can be made between components of ToM: one component is involved in understanding others’ intentions and beliefs (cognitive or ‘cold’ ToM), whereas the other one processes other people's feelings and emotions (affective, or ‘hot’ ToM). The findings of the functional brain imaging studies sustain the separate neurological underpinnings of ToM decoding and reasoning, as well as those of cognitive and affective ToM (Shamay-Tsoory et al., 2006, Sabbagh, 2004). During the past years, increasing attention has been paid to the disassociations of processes and components of ToM in specific clinical populations. Several studies found intact or enhanced mental state decoding abilities together with a dissociation between decoding and reasoning abilities in BPD samples (Preißler et al., 2010, Baez et al., 2015; Zabizadeh et al., 2017). Harari et al. (2010) found a dissociation between cognitive and affective ToM in patients with BPD, but this dissociation was not replicated in later studies (Baez et al., 2015; Petersen et al., 2016). Recently, two studies using different ToM tasks in the same sample reported a decoupling of mental state decoding and reasoning abilities, as well as that of affective and cognitive ToM in BPD (Baez et al., 2015, Zabihzadeh et al., 2017).

Clinical studies report common comorbidities in the BPD populations: e.g. 41–83% for major depressive disorder (MDD), 10–20% for bipolarity, 64–66% for substance misuse, 46–56% for post-traumatic stress disorder (PTSD), 23–47% for social phobia, 16–25% for obsessive-compulsive disorder, 31–48% for panic disorder, and 29–53% for any eating disorder (Lieb et al., 2004, Zanarini et al., 1998). Among these, MDD and PTSD have been found to negatively influence ToM performance in BPD patients (e.g. Unoka et al., 2015, Zabihzadeh et al., 2017, Nazarov et al., 2014).

Until now, several studies have investigated ToM in BPD, but the results were controversial. Discrepant findings on ToM deficits in BPD might be caused by the low sample sizes, the variability of the ToM processes and components assessed, as well as the heterogeneity of the clinical samples mainly due to the co-morbidities. To resolve controversies, we conducted a quantitative meta-analysis (MA) of the existing data on ToM in BPD. So far, two meta-analyses of social cognition in BPD have been published. Daros et al. (2013) reviewed and meta-analyzed data on facial emotion recognition in BPD – involving 10 primary studies, while Richmann and Unoka (2015) aggregated and meta-analyzed ToM results of 5 studies. However, the latter publication comprised only studies using the Reading the Mind in the Eyes Test (RMET, Baron-Cohen et al., 2001) to assess ToM in BPD.

We outlined the following meta-analysis questions: Can overall ToM deficits be detected in BPD patients compared to healthy control subjects in a large, pooled sample derived from several studies? If so, how can we characterize BPD patients’ ToM deficits within the various dimensions and subcomponents of ToM? Do demographic and clinical variables have an impact on ToM capacities of BPD patients? Does task type have an impact on the ToM results? Are there tasks particularly sensitive to assess BPD patients’ ToM abnormalities?