Abstract

Neuropsychology of bipolar disorder

1. F.C. MURPHY, PhD

1. B.J. SAHAKIAN, PhD

+ Author Affiliations

1. Department of Psychiatry, University of Cambridge and MRC Cognition and Brain Sciences Unit, Cambridge
2. Department of Psychiatry, University of Cambridge, UK

1. Dr B. J. Sahakian, Department of Psychiatry, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. Tel: +44 (0) 1223 331209; fax: +44 (0) 1223 336968; e-mail: skw22@medschl.cam.ac.uk

Declaration of interest None.

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Abstract

Background Although the presence of wide-ranging neuropsychological deficits in individuals with major depression is well established, few studies have investigated the nature of cognitive impairment in patients with bipolar disorder.

Aims To review research of the neuropsychology of bipolar disorder, with special attention to the relationship between mood and cognitive functioning.

Method Literature review.

Results Findings generally demonstrate mania-related impairments on conventional neuropsychological tests, with direct comparisons of patients with mania and patients with depression failing to find group differences. More recent work has sought to differentiate these disorders by employing tasks with affective components. This research has demonstrated biases for processing positive and negative stimuli in patients with mania and depression, respectively.

Conclusions Future studies, employing tasks that require cognitive and emotional processing, should improve our understanding of the deficits observed in depression and mania. Neuroimaging studies of the neural regions that underlie cognitive processing of affective meaning suggest that the medial and orbitofrontal prefrontal cortex may be particularly involved.

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Patients with bipolar disorder cycle through episodes of mania, depression and euthymia, demonstrating dramatic fluctuations in energy, social behaviour, mood and cognitive functioning. The apparent links between these associated changes suggest an important role for the study of this disorder in charting a map of the relationship between mood and cognition. To date, little is known about the nature of cognitive deficits observed in patients with bipolar disorder or about how these deficits might relate to the clinical symptoms and neurobiological substrates of the disorder. In contrast to the wealth of empirical data pertaining to neuropsychological impairment in individuals suffering from major depression, few researchers have investigated cognitive functioning in patients with manic-depressive illness.

In this review, we offer a preliminary exploration of the neuropsychology of bipolar disorder and some suggestions for its future. We begin by considering cognitive functioning in each of the three phases of this illness, thus establishing broad links between affect and cognition. We address the complex issue of general v. specific cognitive deficits in patients with bipolar disorder, focusing on the comparative study of mania, depression and schizophrenia to establish distinct neuropsychological profiles, and conclude with an examination of some of the most interesting developments in recent studies of bipolar disorder and the scope for future research in this area.

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