Understanding Caffeine: A Biobehavioral Analysis

Caffeine is without a doubt the most widely used drug in the world today, consumed daily in coffee and tea, in many soft drinks, in cocoa and chocolate, and in a variety of over-the-counter and prescription medicines. Recent estimates suggest that at least 80% of the entire world’s population consumes caffeine on a regular, if not daily, basis. 1 Moreover, the popularity of caffeine in the United States appears to be growing, as demonstrated by the explosive increase in the number of specialty coffee and tea shops and by the development and marketing of a variety of new caffeinecontaining products including spring water, fruit juice, and most recently chewing gum. The ubiquity and popularity of caffeine give it a special place in popular culture. However, despite nearly 400 years of widespread use and more than 50 years of scientific and medical research, many questions remain unanswered, including the basic questions of why people enjoy caffeine so much and whether the long-term consumption of this drug has an impact on health and disease. In Understanding Caffeine , James attempts to promote a better public understanding of the drug and its effects and to correct some of the common misconceptions we have about caffeine. Jack James is one of the world’s leading authorities on the health effects of caffeine, and in this book he provides a comprehensive yet concise summary of a vast scientific and medical literature. The book presents a potentially controversial message that everyone interested in health education should hear and consider carefully. Contrary to general public opinion, which considers caffeine to be a socially accepted drug with beneficial stimulant effects and no significant hazards, James advances as his theme the proposition that caffeine is a drug of abuse that is best avoided because chronic consumers realize few if any benefits from it and suffer a variety of detrimental effects on their health and well-being. James presents the necessary background information for his arguments in several introductory chapters. He provides a brief account of the history of caffeine use and describes current patterns of consumption. James also reviews the pharmacology and toxicology of caffeine, describing how the drug travels through the body, the mechanism through which it works, and the broad range of acute effects it has on physiology both at the doses most normally ingested and at the high doses that produce acute symptoms of toxicity. He makes an important point that habitual consumers may experience quite different effects, as their bodies accommodate to the continued presence of the drug. These changes also lead to the development of a physical dependence on caffeine and a pattern of unpleasant drug withdrawal symptoms when drug use is abruptly suspended. James develops his argument that caffeine offers little benefit to the habitual consumers in a chapter on the psychopharmacology of caffeine that reviews the decades of research on how caffeine affects psychological processes including cognition and mood. Although it has long been held that caffeine enhances cognitive processes, leading to improved alertness, a faster flow of thought, and a boost in performance, 2 James’s review of the scientific literature reaches a much less favorable conclusion. He details the contradictions and inconsistencies among the many studies that have been conducted to date and points out how methodological fallibility has severely constrained the conclusions that can be drawn from them. In James’s view, the psychological effects of caffeine are subtle and sporadic at best. Moreover, James argues that caffeine does not enhance either mood or cognitive function in the habitual consumer. As James describes it, the apparent benefits that a coffee drinker experiences each morning (e.g., improved alertness and a more positive mood after drinking a cup or two of coffee) are simply the restoration of functions that were impaired because he or she was deprived of caffeine overnight and is suffering the symptoms of caffeine withdrawal. This intriguing argument illustrates the difficulties inherent in studying the effects of any drug in