Theory of mind performance using a story comprehension task in bipolar mania compared to schizophrenia and healthy controls

Abstract

Introduction

Theory of mind (ToM) refers to the ability to understand the mental state of self and others. There is limited research into this topic in bipolar disorder (BD), with no previous study examining ToM in a BD group within a psychotic manic phase.

Methods

Twenty-eight psychotic manic BD patients were compared with 30 schizophrenia (SCZ) patients and 29 healthy controls (HC). Participants performed a ToM story comprehension task that compared ToM stories and non-ToM stories (which we relabelled non-ToM “semantic” stories). Performance was examined by answering comprehension questions.

Results

Both patient groups were equally impaired on their scores for ToM stories (scores BD = 10/24, SCZ = 9/24, HC = 14/24, p < .001). Interestingly, both patient groups showed reduced performance on non-ToM semantic stories (scores BD = 12/24, SCZ = 9/24, HC = 15/24, p < .001); SCZ showed a larger deficit. Reduced ToM performance was correlated with delusion severity in the BD group only.

Conclusions

ToM performance was impaired in BD patients experiencing psychotic symptoms. Patient performance was also impaired on the control condition (i.e., non-ToM semantic stories) supporting an additional deficit in semantic processing.

Keywords:

• Bipolar disorder
• Delusions
• Healthy controls
• Schizophrenia
• Theory of mind

Our thanks to A/Prof Philip Ward at the SRU, Liverpool Hospital, Sydney and to NISAD Schizophrenia Research Register, Australia, for assisting with the recruitment of volunteers; to Julia Coakes for assisting with subject testing; and Lucette Cysique and Catherine Boundy for data preparation. There are no conflicts of interest. SLR was funded by an International Wellcome Fellowship from The Wellcome Trust. The research was conducted at the Macquarie Centre for Cognitive Science, and the Centre funded research assistant support. Neither of the funding sources played any role in the design, data collection, analysis, interpretation of the data, or write up of the current paper; nor in the decision to submit for publication.

Notes

¹ This alpha was used as there were 40 correlations across the 10 global symptom scores and four ToM variables of interest. Bonferroni would suggest .05/40=.001.