Cognitive Dysfunction in Bipolar Disorder: A Guide for Clinicians
Bipolar disorders are common, chronic, and recurrent. Functional recovery generally lags behind symptomatic improvement. The effects on occupational functioning are often enduring, with a 40% lower likelihood of being gainfully employed than the general population of those with disabilities. Both transient and enduring cognitive impairments contribute to the gap between education and the significantly lower workplace accomplishments of persons with bipolar disorders. This timely book, edited by two leaders in clinical and laboratory studies of cognition in bipolar disorder, provides practical information to aid clinicians in application of current knowledge of the forms of cognitive dysfunction in bipolar disorders. Lucid discussions of the key concepts in cognitive assessments are included in the chapters. For many of the concepts (e.g.,working memory), a key to understanding how they operate is to recognize that they incorporate two or more fundamental tasks. For working memory, this means initial storage of information followed by some type of mental operation on the information.
Recognition of cognitive dysfunction during major episodes of bipolar disorder is generally adequate. Although performance in persons who recover from episodes generally improves in areas of impulsivity, risk taking, and decision making, certain problems in attention and executive function continue to adversely affect functional capabilities. This persistence of cognitive difficulties has been more difficult for researchers to study and clinicians to recognize, since it requires study of individuals over time. The much greater challenge of studying this aspect of cognitive function contributes to some diverging opinions, which are aired in this book, regarding the degree and specifics of features that improve as clinical state improves.
The authors of the several chapters take the reader in hand to distinguish between deficits that largely remit during euthymia (impulsivity, risk taking) and those that, at least to some degree, persist during euthymia (attention and executive function). The discussions emphasize the clinical rather than the strictly laboratory presentations of these functions.
Luke Clark and Guy Goodwin's chapter is notably helpful to clinicians in anticipating what is likely to persist in good times and bad versus what clears with symptom control. A useful chapter on the implications of cognitive deficits for learning and behavioral change through psychotherapy also reminds the reader that cognitive-behavioral therapy entails learning to think in a more structured way, not just having a nice chat. Cognitive function can also be impaired as a result of anxiety and fearfulness, which are common in all clinical states of bipolar disorder. To date, this important driver of some cognitive impairment has not been studied systematically. This important topic is addressed within the limits of current evidence.
Chapters on the effects of psychotropic medications on cognition in bipolar disorder are less successful, in part because most data are opportunistic, uncontrolled, or based on information from patients with other illnesses. Perhaps the most intriguing information comes from a series of well-conducted studies in humans and animals indicating neurotrophic effects of both lithium and valproate. The inference I take from these studies is not just that the drugs may have some of their benefits on these systems but that targeting drug development toward the neural systems, which collectively form what we refer to as neuroprotective, may be one important pathway to improve the treatments we can apply to benefit our patients. Even at present, these findings indicate that all of the actions of at least some available psychotropic drugs are not limited to neurotransmitter systems.
Most chapters end with a "take-home-points" page that is invariably useful. Clark and Goodwin offer: "When manic, patients with bipolar disorder show impulsive responding, impaired decision making, poor judgment when gauging probabilities, and difficulty moderating risk-taking behavior. These deficits largely remit during euthymia" (p. 41). Gin Mahli, Catherine Cahill, and Philip Mitchell state: "Anxiety symptoms can directly impair cognitive function and must be considered when assessing reasons for cognitive deficits. Treatment of comorbid anxiety features may also help to improve apparent cognitive problems that might otherwise be misattributed to other aspects of psychopathology" (p. 105). Both succinctly describe evidence-based problems that clinicians confront, and both provide recommendations that clinicians can apply in their management of patients. That is about as good as it can get.
