Cognitive functions in bipolar affective disorder and schizophrenia: Comparison
Article first published online: 29 SEP 2008
© 2008 The Authors. Journal compilation © 2008 Japanese Society of Psychiatry and Neurology
Psychiatry and Clinical Neurosciences
Volume 62, Issue 5, pages 515–525, October 2008
How to Cite
Pradhan, B. K., Chakrabarti, S., Nehra, R. and Mankotia, A. (2008), Cognitive functions in bipolar affective disorder and schizophrenia: Comparison. Psychiatry and Clinical Neurosciences, 62: 515–525. doi: 10.1111/j.1440-1819.2008.01844.x
- Issue published online: 29 SEP 2008
- Article first published online: 29 SEP 2008
- Received 24 August 2007; revised 2 May 2008; accepted 19 June 2008.
- bipolar disorder;
- cognitive functions;
Aims: Earlier comparisons of cognitive impairment among patients with bipolar disorder and schizophrenia have found a largely similar profile of deficits, but results have varied between studies. This prompted the current attempt at another such comparison.
Methods: Executive functions, memory, IQ, attention–concentration and perceptuomotor function were assessed in 48 bipolar disorder patients with operationally defined euthymia, and compared with 32 schizophrenia patients in remission, and 23 normal controls. Comparisons were re-attempted after controlling for years of schooling and residual affective symptoms.
Results: Uncontrolled comparisons indicated that, compared to controls, both bipolar disorder and schizophrenia patients were significantly impaired on different tests of executive function, memory, IQ and perceptuomotor functions. Controlling for years of schooling and residual affective symptoms, however, served to remove most of the differences between patients and controls, apart from some aspects of executive function in schizophrenia and memory impairment in both schizophrenia and bipolar disorder. Patients with schizophrenia consistently performed worse than patients with bipolar disorder, but none of the differences between schizophrenia and bipolar disorder were significant.
Conclusions: Patients with bipolar disorder exhibit cognitive difficulties that are very similar to schizophrenia in terms of their profile, although patients with schizophrenia may have more severe and widespread impairments. The resemblance in cognitive profiles has important implications for the etiology and treatment of both disorders.