Caffeine and Activation Theory

Effects on Health and Behavior

Barry D. Smith,Uma Gupta,B.S. Gupta

• Editorial: CRC Press
• Año: 2006
• ISBN:
  9781000654080
• Edición: 1
• Categoría: Bildung
• Categoría: Verhaltensmanagement

The virtually universal popularity of caffeine, together with concerns about its potential pathogenic effects, have made it one of the most extensively studied drugs in history. However, despite the massive scientific literature on this important substance, most reviews have either focused on limited areas of study or been produced in popular form

1 Arousal and Caffeine: Physiological, Behavioral, and Pathological Effects

Barry D. Smith, Uma Gupta, and B. S. Gupta

CONTENTS

Introduction

Organization of the Book

References

INTRODUCTION

It has long been recognized that physiological arousal is a basic and important factor in health and behavior (Smith, Osborne, Mann, Jones, & White, 2004). So important are its effects that numerous theories have focused on the arousal concept in an ongoing series of attempts to explain its origins, substrates, and consequences. In 1951, Elizabeth Duffy published her classic Psychological Review article, “The Concept of Energy Mobilization,” and later expanded on her ideas in Activation and Behavior (1962). She argued that physiological arousal, or activation, is more basic to behavior and performance than is the learning process.

Duffy was soon joined by Donald Lindsley (1957), Robert Malmo (1959), Magda Arnold (1960), and other theorists, who detailed the neurophysiological substrates of arousal and its effects on behavior and health. Another major theorist, Hans Eysenck (1967), proposed that the principal dimensions of human personality functioning—extraversion and neuroticism in his theory—are based in cortical arousal and activation. With many others, he argued that the reticular activating system and the limbic system are central to the integration of arousal functions and that arousal ultimately has an impact on and is dealt with by the cerebral cortex.

Smith has also proposed an arousal theory of personality, behavior, and health, called dual interaction theory (Smith, 1983; Smith, Davidson, & Green, 1993; Smith, Tola, & Mann, 1999; Smith et al., 2004). It differentiates between arousal traits and arousal states and between chronic and acute arousal as these affect health and behavior. The theory also proposes three basic dimensions that characterize arousal: An intensity dimension specifies a continuum that differentiates between very high and very low levels of arousal; a type dimension specifies two primary types of arousal, general and emotional, and recognizes that other types and subtypes may later be identified; and an individual differences dimension specifies multiple continua along which arousal can vary from one person to another. These include anxiety, extraversion, neuroticism, sensation seeking, and hostility, among others.

Dual interaction theory, in agreement with much of the theoretical and empirical literature, recognizes that multiple sources of and contributions to arousal. Stress, for example, has been extensively studied with regard to the increases in arousal that it produces and the adverse effects on health that it can have (Smith et al., 2004). Similarly, such widely varied mood states as anger, depression, and ecstasy can increase arousal, as can many cognitions. In addition, a substantial literature identifies and studies drugs that contribute to arousal. In particular, these include caffeine, which is arguably the single most common source of increments in arousal.

It is a common observation that caffeine is the most widely consumed drug in the world. Its multiple sources include coffee, tea, chocolate, soft drinks, energy drinks, and medications; the overall quantities in which these sources are produced and consumed are almost incalculable. More than 100 million bags of coffee beans, amounting to 6 million tons, are produced each year (International Coffee Organization [ICO], 2006). Add to this an annual production of over 3 million tons of tea (FAO, 2006) and 2.8 million tons of chocolate (Al-Ahram Weekly On-Line, 2005), along with the annual consumption of 53 gallons of soft drinks per person (Nestle, 2000), and it becomes clear that the average individual consumes a substantial amount of caffeine each year.

Heightened arousal has widespread physiological and behavioral consequences. For example, it can increase heart rate, blood pressure, and the output of adrenal corticosteroids, as well as shift EEG patterns to those associated with cortical activation. At the same time, increments in arousal are associated with elevations in anxiety, hostility, and irritability; chronically high arousal may contribute to anxiety, somatoform, and depressive disorders, among others. It is no wonder, then, that the scientific literature on caffeine is larger than that on any other drug. A search of Medline revealed 20,107 publications on caffeine, far more than the number for such drugs as marijuana and phencyclidine. With such a vast and growing literature, it is essential to review and evaluate theory and research periodically to achieve a more integrative understanding of its implications. This book provides this integration on a number of topics concerning the acute and chronic impact of caffeine consumption on health and behavior.

ORGANIZATION OF THE BOOK

We begin the first section of the book on caffeine basics with a chapter by Barry Smith, Thomas White, and Rachel Shapiro that provides detailed information concerning major sources of caffeine, including coffee, tea, chocolate, soft drinks, energy drinks, and medications. For the principal sources, the chapter provides brief histories and discusses production and consumption. In chapter 3, Astrid Nehlig details caffeine physiology. This chapter deals with the biochemical impact of the drug, including adenosine receptor inhibition, release of intracellular calcium, and inhibition of cyclic nucleotide phosphodiesterases. Nehlig also discusses the neurophysiological effects of caffeine and their downstream consequences in locomotor activity, sleep, behavior, and pathology.

Section II of the book deals with one of the major concerns about caffeine: its potentially adverse effects on the cardiovascular system. The four central issues in this section all revolve around the arousal effects of the drug and their possible cardiovascular consequences. One major theme in this literature is concerned with the potentially adverse effects of acute caffeine intake on heart function. Another addresses the contribution of chronic caffeine consumption to coronary heart disease (CHD) and myocardial infarction (MI). A third assesses the role of the drug in hypertension, and a final chapter examines its effects on serum lipid profile.

In chapter 4, Barry Smith and Katherine Aldridge address cardiac effects of acute caffeine intake, including its effects on heart rate and rhythm; this literature has yielded some surprising findings. Chapter 5, by Barry Smith, Radha Gholkar, Mark Mann, and Nancy Toward, provides a detailed analysis of the CHD literature. It begins with a review of the major factors known to contribute to CHD and then investigates the role of caffeine in relation to other causal factors.

In chapter 6, Jack James makes the point that chronic caffeine consumption is a risk factor for hypertension. Pointing out that numerous epidemiological studies have been conducted, he provides careful, in-depth review and analysis of this sizable scientific literature to support his conclusions regarding the caffeine–blood pressure relationship. In chapter 7, the final chapter in this section, Ming Wei and Harvey Schwertner review the numerous epidemiological studies and clinical trials that have addressed the effect of coffee and caffeine consumption on serum lipids. They consider and evaluate discrepancies among studies and also discuss the important observation that various coffee brewing methods affect serum lipids differently.

Section III deals with the effects of caffeine as they relate to the menstrual cycle and reproduction. In chapter 8, Hoa Vo, Barry Smith, and Solmaz Elmi deal with the relationship between caffeine and the menstrual cycle, as well as effects of the drug in women with premenstrual syndrome (PMS). Vo provides an overview of the physiology and psychology of the menstrual cycle and shows how caffeine pharmacokinetics are affected by changing menstrual physiology, as well as how caffeine affects menstrual function. She then reviews the scientific literature concerned with the possible role of caffeine in PMS.

In the second chapter in this section (chapter 9), Kate Northstone and Jean Golding address another important question concerning caffeine effects: Does this widely consumed drug reduce fertility? They point out that fertility levels in the population have been decreasing for a number of years and address the possible detrimental effects of caffeine on fertility. This chapter provides an in-depth scientific analysis of all prospective and retrospective studies of the caffeine–fertility relationship, taking into consideration sample sizes, power, and likely confounds.

Section IV deals with the effects of caffeine on mood state, cognition, and performance. Hendrik Smit and Peter Rogers review the literature on mood state effects in chapter 10 and discuss the impact of caffeine intake and caffeine deprivation on affect. Their review points out the potentially important effects of differing individual sensitivities to caffeine, time of day at which the drug is consumed, and age. They also provide a detailed methodological analysis of relevant studies and suggest the need to employ modified methods in the effort to understand the caffeine–mood relationship further.

In chapter 11, Lorenzo Stafford, Jennifer Rusted, and Martin Yeomans detail the literature concerned with effects of caffeine and its deprivation on cognitive functioning and performance. They review the substantial body of research on psychomotor performance involving such tasks as tapping and pursuit rotor, as well as the cognitive literature, which examines effects of caffeine on attention and memory. Finally, they point to a number of factors affecting study outcomes, including drug dosage, placebo effects, arousal threshold, and fatigue.

In chapter 12, Uma Gupta and B. S. Gupta review scientific research dealing with effects of caffeine on multicomponent task performance. They point out that human performance is affected by multiple factors, including basal arousal, caffeine dosage, and habituation, as well as task complexity and such personality traits as extraversion. The authors then report two experiments involving performance on a letter-transformation task. In the first, participants received one of four caffeine doses or placebo; the second employed the highest dose of the drug and examined its effect on three individual processing components of the task.

The remaining two brief sections deal with psychopathology (section V) and the potentially beneficial effects of green and black tea (section VI). In chapter 13, Iulian Iancu, Ahikam Olmer, and Rael Strous review literature on “caffeinism” and, more generally, the impact of caffeine on psychopathology. They detail what is known about caffeinism as a diagnostic entity and analyze the scientific literature on physiology of caffeine intoxication, its clinical features, and available treatments. They also consider the role of caffeine in other pathologies, including anxiety disorders, depression, eating disorders, restless-legs syndrome, and suicide.

Chapter 14, by Ray Cooper, Talash Likimani, Dorothy Morré, and James Morré, addresses the scientific literature on green and black teas. The authors discuss the effects of caffeine in tea and also hypothesized health benefits studied in recent years. They consider the possible role of polyphenols—particularly catechins—in preventing some cancers, such as colon and bladder, and the interaction of caffeine with the polyphenols as it may affect cancer prevention. Also considered is the literature on caffeine and polyphenols in weight loss and exercise endurance.

Section VII ends the book with a broad overview of the literature on arousal and caffeine in chapter 15 by Barry Smith, Uma Gupta, and B. S. Gupta. There, the health effects of the drug and its impact on behavior are considered.

REFERENCES

Al-Ahram Weekly On-Line. (2005). Death by chocolate. Retrieved on 2/20/2006 weekly. ahram.org.eg/2005/743/pe2.htm.

Arnold, M. B. (1960). Emotion and personality. New York: Columbia University Press.

Duffy, E. (1951). The concept of energy mobilization. Psychology Review, 58, 30–40.

Duffy, E. (1962). Activation and behavior. New York: John Wiley & Sons.

Eysenck, H. J. (1967). Biological basis of personality. Springfield, IL: Charles C Thomas.

FAO. (2006a). Retrieved February 17, 2006, from http://www.fao.org/DOCREP/003/X6939E/X6939e02.htm.

International Coffee Organization. (2006). About coffee: Caffeine contents. Retrieved on 2/17/2006, from http://www.ico.org/caffeine.asp.

Lindsley, D. B. (1957). Psychophysiology and motivation. In M. R. Jones (Ed.), Nebraska symposium on motivation, 1957. Lincoln: University of Nebraska Press.

Malmo, R. B. (1959). Activation: A neurophysiological dimension. Psychological Review, 66, 267–386.

Nestle, M. (2000). Soft drink pouring rights: Marketing empty calories. In Public Health Reports. Oxford University Press.

Smith, B. D. (1983). Extraversion and electrodermal activity: Arousability and the inverted-U. Personality and Individual Differences, 4, 437–440.

Smith, B. D., Davidson, R. R., & Green, R. L. (1993). Effects of caffeine on physiology and performance: Further tests of a biobehavioral model. Physiological Behavior, 54...

Índice

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Table of Contents
• Chapter 1 Arousal and Caffeine: Physiological, Behavioral, and Pathological Effects
• SECTION I Caffeine: The Drug
• SECTION II Cardiovascular Effects
• SECTION III Menstrual and Reproductive Effects
• SECTION IV Mood and Performance and Psychopathology
• SECTION V Green and Black Teas
• SECTION VI Integration and Conclusion
• Index