Cognitive dysfunction: cause or consequence of bipolar disorder?

Chamberlain, Samuel R. and Sahakian, Barbara J. (2005) Cognitive dysfunction: cause or consequence of bipolar disorder? In, Bipolar Disorder: The Upswing in Research and Treatment. CRC Press, pp. 145-156. (doi:10.1201/b13932).

Abstract

Bipolar disorder is characterized by cycling between depression, euthymia and mania. The argument that alterations or dysfunctions in cognition are a core phenomenon comes from evidence on several levels. Cognitive dysfunction is central to the diagnosis of depressive and manic episodes using the Diagnostic and Statistical Manual IV (DSM–XIV). Distractibility and poor decision-making are included in the diagnostic criteria for manic episodes, and diminished ability to concentrate and indecisiveness are included in the criteria for depression. Another tier of evidence comes from psychological models, in which abnormalities in cognition are often held to be important. In Beck’s Cognitive Model,1 aberrant cognitive schema develop during childhood and are activated in later years by stressful and unpleasant life events (Figure 16.1). The activation of these aberrant schema leads to systematic errors in logic, and the well-known triad of negative belief directed at self, world and future. Cognitive therapies developed from these psychological models2 aim to correct dysfunctional attitudes and negative automatic thoughts. From a top-level perspective, the emotional states of people with mania and depression form two extremes of an affective spectrum (Figure 16.2). The emotional status of a given individual can vary on this spectrum in response to life events: towards dysphoria in response to relationship break-up, or towards euphoria when celebrating achievements. However, the extreme emotional states of people with mania or depression differ in that the moods are disproportionate and cause gross impairments in social functioning. Indeed, the deficits in social functioning, and behaviour of bipolar patients more broadly, are in themselves suggestive of cognitive dysfunction. Collectively, whether one examines affective disorder from the perspective of overt syndromic behaviour, DSM-IV diagnosis, or psychological models, cognitive dysfunction is central to our understanding. The development of advanced neurocognitive testing coupled with functional neuroimaging has in recent years facilitated the reliable investigation of specific cognitive profiles between patient groups.

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Contributors

Author: Samuel R. Chamberlain

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