No differences in visual theory of mind abilities between euthymic bipolar patients and healthy controls

Haag et al. Int J Bipolar Disord (2016) 4:20 DOI 10.1186/s40345-016-0061-5 Open Access RESEARCH No differences in visual theory of mind abilities between euthymic bipolar patients and healthy controls Silvia Haag1*, Paula Haffner1, Esther Quinlivan1, Martin Brüne2 and Thomas Stamm1 Abstract Background: Research on theory of mind (ToM) abilities in patients with bipolar disorder has yielded conflicting results. Meta-analyses point to a stable moderate impairment in remitted patients, but factors such as subsyndromal symptoms, illness severity, and deficits in basic neurocognitive functions might act as confounders. Also, differences in deficits depending on task area (cognitive or affective) or task modality (visual or verbal) have been observed. This study aimed to test the hypothesis that euthymic bipolar patients would perform more poorly than healthy subjects on visual cognitive and visual affective ToM tasks. Furthermore, we aimed to explore the relationship between ToM performance and basic neurocognitive functions, subsyndromal symptom severity, and illness burden. Twenty-nine clinically stable outpatients with bipolar disorder and 29 healthy comparison subjects completed a measure of visual cognitive ToM (Mental State Attribution Task, MSAT), a measure of visual affective ToM (Reading the Mind in the Eyes Test, RMET), and a battery of tests assessing neurocognitive functioning (attention, verbal memory, executive functions, and intelligence). Results: Patients did not differ significantly from healthy controls for the ToM tasks or any of the neurocognitive measures, suggesting a high level of neurocognitive functioning in the bipolar group. On average, patients were slower than controls to complete the ToM tasks. Within the bipolar group, ToM performance was moderately correlated with attention, verbal memory and reasoning abilities. Performance on the RMET was positively correlated with clinician-rated depressive symptoms with a small effect. Number of years of illness was weakly and negatively correlated with performance on the MSAT. Overall, no moderate or strong correlations were found between ToM performance, subsyndromal depressive or manic symptoms, illness duration, and number of depressive or (hypo)manic episodes. Moderate correlations between ToM performance and age were found for patients but nor for controls. Conclusions: Our findings suggest preserved visual cognitive and affective ToM abilities in euthymic bipolar patients characterized by a high level of neurocognitive functioning. Keywords: Bipolar disorder, Euthymia, Theory of mind, Social cognition, Neurocognitive functioning Background Theory of mind (ToM) is an aspect of social cognition that describes the ability to understand the feelings, thoughts and intentions of oneself and of others (Brüne 2008). The term was originally introduced in 1978 by Premack and Woodruff (1978) in an article that discussed *Correspondence: 1 Department of Psychiatry and Psychotherapy, Charité University Hospital, Charitéplatz 1, 10117 Berlin, Germany Full list of author information is available at the end of the article the ability of chimpanzees to infer mental states that are not directly observable (for example, intentions, knowledge or beliefs) and that can serve to predict the behavior of others. The article sparked a wave of research on ToM that has been increasing ever since. As Schaafsma et al. (2015) point out, the original definition of ToM referred to a variety of processes which led to heterogeneity in the scientific methods approaching ToM. Thus, as research on the topic is growing, attempts to clarify the construct are advancing. © 2016 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Haag et al. Int J Bipolar Disord (2016) 4:20 In psychological terms, ToM has recently been described as dual-process schemes that distinguish either between mental state reasoning (social-cognitive processes) and mental state decoding (social-perceptual processes) (Samamé et al. 2012) or between cognitive and affective ToM (Shamay-Tsoory et al. 2007). The identification of particular ToM processes is directly related to the interpretation of different tasks designed to measure ToM abilities. Tasks that request subjects to understand the beliefs or false beliefs of other persons to detect hidden intentions, indirect meaning, or inappropriate social communication are assumed to account for cognitive ToM or mental state reasoning. On the other hand, tasks that demand of subjects to infer the feelings or affective mental states of others are regarded as measures to assess affective ToM and also mental state decoding abilities if visual information such as facial expressions needs to be decoded. These dual-process schemes are supported by evidence from imaging studies that have reported taskspecific differences in brain activation patterns (Kalbe et al. 2010; Schurz et al. 2014; Shamay-Tsoory and Aharon-Peretz 2007). The ability to understand the mental or affective states of others has been found to be impaired in some developmental and mental disorders. ToM deficits have consistently been observed in patients with autism spectrum disorders (Frith 2012) and schizophrenia (Savla et al. 2013). Bipolar disorder (BD) is often discussed in relation to schizophrenia and much research is done comparing the two conditions. In BD, ToM deficits have been less consistently shown than in schizophrenia (Mitchell and Young 2016). Studies on ToM in BD vary widely in how ToM has been operationalized, hence rendering the collective findings difficult to interpret. This may be related to possible moderating variables such as subsyndromal symptom severity, indicators of illness burden, and basic neurocognitive functions not always being taken into account. Indeed, the association between these factors and ToM abilities has, to date, not been explicitly clarified. Recently, two task-specific meta-analyses were conducted to synthesize the heterogeneous results yielded so far in this field. A meta-analysis by Samamé et al. (2015) reported small-to-medium effect sizes for tasks measuring cognitive ToM and small effect sizes for tasks measuring affective ToM in favor of healthy controls (HCs) versus euthymic bipolar patients (eBPs). Based on a slightly extended data pool, Bora et al. (2016) specifically investigated the relationship between ToM deficits and mood state. Pooling all studies irrespective of task modality or content, they found stable moderate effects in strictly euthymic BD samples, as well as in subsyndromal samples, favoring HCs. In acute BD samples, a strong Page (...truncated)