Psychological Medicine



Original Article

Bipolar I and bipolar II disorder: cognition and emotion processing


MARY SUMMERS a1c1, KYRIAKI PAPADOPOULOU a2, STEFANIA BRUNO a1, LISA CIPOLOTTI a2a3 and MARIA A. RON a1
a1 NMR Research Unit, Institute of Neurology, University College London, London, UK
a2 Department of Neuropsychology, National Hospital for Neurology and Neurosurgery, London, UK
a3 Department of Psychology, University of Palermo, Italy

Article author query
summers m   [PubMed][Google Scholar] 
papadopoulou k   [PubMed][Google Scholar] 
bruno s   [PubMed][Google Scholar] 
cipolotti l   [PubMed][Google Scholar] 
ron ma   [PubMed][Google Scholar] 

Abstract

Background. Cognitive impairment may be part of the endophenotype of bipolar disorder (BP), but little is known about patterns and severity of impairment in BP subgroups and their relation to depression. The same applies to deficits in emotion processing known to be present in BP.

Method. To explore the relationship between depression and impairment in cognition and emotion processing and the differences between BP subgroups, we assessed 36 (25 BP I and 11 BP II) patients using a cognitive battery and a facial emotion recognition task.

Results. BP patients were impaired compared to published norms on memory, naming and executive measures (Binomial Single Proportion tests, p<0·05). Cognitive performance was largely unrelated to depression ratings. Surprise recognition was the only emotion processing impairment in BP patients compared to controls (patients' recognition score 75% v. controls' 89%, p=0·024). Patients with higher depression ratings were more impaired in recognizing expressions of anger (t23=2·21, p=0·037). BP II patients were more impaired than BP I patients in IQ, memory and executive measures (Mann–Whitney tests, p<0·05). Depression severity or exposure to medication or electroconvulsive therapy (ECT) did not explain these differences.

Conclusions. We confirm cognitive impairment and an isolated facial emotion processing deficit in BP patients and suggest that these deficits are largely unrelated to depressive symptoms. Our study also provides evidence that cognitive deficits are more severe and pervasive in BP II patients, suggesting that recurrent depressive episodes, rather than mania, may have a more detrimental and lasting effect on cognition.

(Published Online August 29 2006)


Correspondence:
c1 NMR Research Unit, Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK. (Email: m.summers@ion.ucl.ac.uk)


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