Social cognitive endophenotypes in bipolar disorder and schizophrenia?

  • Dr Melissa Green, Black Dog Institute, University of New South Wales., Australia
  • Ms Amy Sparks, School of Psychiatry & Black Dog Institute, University of New South Wales., Australia
  • Ms Bianca Lino, Black Dog Institute, University of New South Wales., Australia
  • Professor Skye McDonald, University of New South Wales., Australia
  • Professor Philip Mitchell, Black Dog Institute and University of New South Wales., Australia

Objective: Evidence for common genetic susceptibility to bipolar disorder (BD) and schizophrenia (SCZ) implicates shared cognitive endophenotypes. Proposed candidates include executive and social cognitive processes, which may not be mutually exclusive. In this study we (a) compared the performance of BD and SCZ patients on simple and complex social cognitive tasks, and (b) examined relationships between social cognition and executive function in each group.

Methods: Nineteen BD, 19 SCZ, and 17 healthy controls (HCs) completed the Ekman (60-faces) facial emotion perception test, and The Awareness of Social Inference Test (TASIT) to assess affect perception and mental state inferences (MSI) from dynamic social exchanges. The Intra/Extradimensional Set Shift (IED) task from the CANTAB was used to measure executive functions.

Results: SCZ (but not BD) patients showed impaired basic emotion perception from static and dynamic stimuli. In addition, impaired MSI in SCZ was evident in all social exchanges involving sarcasm, while impaired MSI in BD was limited to complex social exchanges involving paradoxical sarcasm. On the IED, SCZ were less likely to complete ED shift stages than BD patients. Increased IED errors were associated with impaired MSI for social exchanges involving paradoxical sarcasm in both BD and SCZ.

Conclusion: Deficits in social cognition are more extensive in SCZ compared to BD. Only SCZ show basic emotion recognition deficits, while both groups show impaired MSI during complex social exchanges. Executive dysfunction contributes to social cognitive deficits in both SCZ and BD, and may thus represent a better candidate for shared genetic association.