Book Review
Fatigue as a Window to the Brain
N Engl J Med 2006; 354:427-428January 26, 2006
- Article
Fatigue as a Window to the Brain
(Issues in Clinical and Cognitive Neuropsychology.) Edited by John DeLuca. 336 pp. Cambridge, Mass., MIT Press, 2005. $55. ISBN: 0-262-04227-4Subjective health complaints are common in all societies, and pain and fatigue are among the most frequent. Pain is a valid ticket to receiving health care. Although pain has been extensively researched and pain clinics are numerous, fatigue is still controversial. Scientific studies of fatigue are scarce, and fatigue clinics are nonexistent in most places. This multiauthored book offers an excellent overview of the current knowledge of fatigue and the neural mechanisms involved in it, as well as an interesting chapter on the psychiatric diagnosis and treatment of fatigue by Edward Shorter, a professor of the history of medicine at the University of Toronto.
Acute fatigue due to extensive physical or mental work is a normal phenomenon, and the treatment of choice is rest. Pathologic fatigue remains after rest and can block normal social life and work life. Even though everyone has experienced fatigue, it is difficult to define and measure. Central fatigue — mental or cognitive fatigue, manifested as a subjective lack of mental energy, lack of motivation, or negative affect — is differentiated from peripheral (physical or muscular) fatigue. Three chapters are devoted to defining fatigue and the methods used to measure it: questionnaires, interviews, and performance tests.
Several chapters describe fatigue associated with well-defined diseases such as multiple sclerosis, stroke, traumatic brain injury, other neurologic conditions, HIV infection, cardiovascular disease, systemic lupus erythematosus, cancer, depression, and sleeping disorders. In many of these conditions, fatigue is a typical and prominent finding, sometimes associated with markers of disease activity (such as cytokines and complement activity) but often just as strongly related to psychological factors (such as focusing on and expecting the worst possible outcomes or avoiding normal, daily activities because of fear). Self-reported fatigue is often poorly correlated with the results of tests of physical performance.
In the book, special attention is devoted to chronic fatigue syndrome, which in Britain is called myalgic encephalomyelitis. Chronic fatigue syndrome is a complex illness characterized by debilitating fatigue as well as by symptoms of rheumatologic, infectious, and neuropsychiatric diseases. The prognosis of chronic fatigue syndrome is as dubious as the illness itself. Findings from magnetic resonance imaging studies of the brain show hypersensitivity of white matter, particularly in patients with chronic fatigue syndrome but without coexisting psychiatric conditions. Some patients have abnormalities of the hypothalamic–pituitary–adrenal axis, often in the opposite direction from those observed in patients with clinical depression.
The interplay among biologic, psychological, and social factors in fatigue is described in detail in many chapters. For example, in the excellent chapter titled “Heart Disease, Cardiovascular Functioning, and Fatigue,” the consistent relationship between symptoms of depression and coronary heart disease is emphasized. Interleukins (a group of proinflammatory cytokines) can initiate behavior related to sickness (such as feeling sick and staying in bed). Cytokine-induced fatigue may also play an independent role in heart disease, partly as a risk factor but also as a symptom of heart disease.
I found this book enlightening and loaded with updates from recent research. All physicians treating patients with fatigue should read it. The conceptualization and treatment of chronic fatigue require knowledge and understanding. Contrary to much of the schism and dualism in public and scientific debate about fatigue, this book offers a balanced point of view. It has the potential to bridge the gap between patients' organizations and health professionals who proclaim that fatigue is “anything but psychiatry” and their colleagues who believe that fatigue is all in patients' heads.
Ingvard Wilhelmsen, M.D., Ph.D.
University of Bergen, 5009 Bergen, Norway
ingvard.wilhelmsen@med. uib. no
