(p. xvii) Preface
(p. xvii) Preface
Psychoneuroimmunology (PNI)—the interactions among the mind, nervous system, and immune system—is a fairly new discipline, with many of the earliest, seminal papers having been published less than 50 years ago (e.g., Solomon & Moos, 1964; Ader & Cohen, 1975). However, advances in anatomy and immunology have quickly moved the field along, and it is now widely accepted that the immune system is responsive to many of the messengers employed by the nervous system, and vice versa. This is, of course, a volume in the Oxford Library of Psychology. Therefore, the aim of the present volume is to emphasize recent advances and applications of psychology as they have influenced psychoneuroimmunology. There are six broad sections of chapters that make up the volume. The sections are: Development; Emotion; Personality and Individual Differences; Social Relationships; Ecological Approaches; and Clinical Methods and Models. From these sections, four broad themes emerge: changes in how PNI science approaches stress; expanding the number of levels of analysis; extending PNI along the life course; and a focus on inflammation.
The first theme addresses a question that may cross the reader's mind when reading the table of contents: Where is the chapter on stress? Stress is one of the earliest and most productive constructs in PNI, and I and many other budding psychoneuroimmunologists were inspired by early studies demonstrating immunological correlates of academic stress, community trauma, caregiving, bereavement, and other stressful events (Irwin, Daniels, Smith, Bloom, & Weiner, 1987; Kiecolt-Glaser, Garner, et al., 1984; Kiecolt-Glaser, Glaser, et al., 1987; McKinnon, Weisse, Reynolds, Bowles, & Baum, 1989). Stress is still a productive construct in PNI, but consistent with advances in how psychologists think about stressful events, it has become more (p. xviii) contextualized. For example, it has been some time since Finlay-Jones and Brown (1981) demonstrated the important distinction between threat and loss as they pertain to mental health, and these distinctions may also affect immunological correlates of these different kinds of stressors. Stress can also be productively characterized by its length when considering immunological correlates (Segerstrom & Miller, 2004).
However, the construct of stress was already under criticism before PNI became a discipline. Roberts (1950) famously wrote that “stress, in addition to being itself and the result of itself, is also the cause of itself” (p. 105), having pointed out that the term applies to what organisms respond to, the responses themselves, and the condition caused by these responses. In this volume, we find a more refined view of stress that focuses on specific conditions, such as lack of social status or belonging that may affect the individual (Robles and Kane, chapter 11; Uchino, Vaughn, Carlisle, & Birmingham, chapter 12; Steptoe, chapter 13; and Cole, chapter 14, this volume); on particular emotions, such as shame, that may mediate between external circumstances and immunological responses (e.g., Dickerson, chapter 5, this volume); and on the way that multimodel interventions can address the stress associated with immunologically mediated diseases such as cancer and HIV (Antoni, chapter 21, this volume).
In a related vein, we also find work that recognizes that stress—if such a construct can be pinned down—is an individual phenomenon. A group of people may experience the same event at the same time, but their individual constructions of that event may differ greatly, and these individual differences can drive differences in the immunological sequelae of the event. For example, in a cohort of first-year law students taking the same courses on the same schedule at the same law school, there were large and idiosyncratic differences between and within students in how they appraised their academic futures, and changes in these appraisals were related to changes in cell-mediated immunity (Segerstrom & Sephton, 2010). Personality psychology, having taken a hit in the late 1960s with an influential publication that threw the existence of traits into doubt (Mischel, 1968), has reemerged as an important discipline in psychology in part by work reestablishing the existence and importance of individual differences, and one section of this volume reviews how traits in both humans and nonhuman animals may influence immunity (Michael and Cavigelli, chapter 8; Cohen, Janicki-Deverts, Crittenden, and Sneed, chapter 9; Suarez, chapter 10; this volume).
Of course, traits are not the only individual differences of importance. The past two decades have also seen a rise in affective science: the study of the nature, structure, regulation, and physiology of emotion and mood. Affective science reintroduced the “hot” brain back into the “cool” climate created by the cognitive revolution of the 1960s and the rise of social cognition in the 1970s and 1980s. It also re-ignited a useful debate about whether emotions should be considered distinct from each other or whether they could be usefully arrayed along a smaller number of dimensions. One clear result of this debate that is reflected in this volume is that positive affect is not just the absence of negative affect but may be a separate, orthogonal dimension of experience from negative affect, with its own biological correlates (see Friedman, chapter 3; Pressman and Black, chapter 6, this volume) and that emotion regulation is an important area of study in its own right (Booth, chapter 7, this volume).
Levels of analysis
The study of individual differences interpolates the study of the person between the shared environment and the cell, and this observation provides a segue to the second theme: levels of analysis. In fact, rather than being limited to the more established study of people within groups, organs within people, and cells within organs, the chapters in this volume analyze nearly the whole hierarchy of living systems, from genes and molecules to large social structures (e.g., Cole, chapter 14, this volume). In fact, one section of this volume deals directly with how high-level organization, ecology, coordinates the low-level organizations—organs, cells, and molecules—to align the organism best with the demands of its (p. xix) environment (Adamo, chapter 15; Weil and Nelson, chapter 16; Aubert, chapter 17; this volume). This section on ecological approaches to psychoneuroimmunology also provides an alternative perspective on stress—in some cases, the immunological sequelae of stress may appear maladaptive, but in fact may be secondary to adaptive shifts in the energetic priorities of the organism. This perspective has mainly been applied to animal models of energy, stress, and immunity, as reflected in these chapters, but there is clear relevance to human models as well (Segerstrom, 2010; Straub, Cutolo, Buttgereit, & Pongratz, 2010).
The life course
In addition to expanding the dimensions of PNI along levels of analysis, recent work has also been expanding along the life course, the third theme. In the lifespan development section of this volume, authors make the case that the very earliest and latest stages of life are critical for PNI effects, whether those effects relate to pregnancy outcomes, fetal programming, or protection against the deleterious effects of aging on immunity (Cousson-Read, chapter 1; Coe, chapter 2; Friedman, chapter 3; Effros, chapter 4; this volume). In fact, death rates in developed countries such as the United States are curvilinear, with death rates highest under 1 year of age and remaining lower thereafter until age 55 (Centers for Disease Control, 2010a). This U-shaped pattern is also seen in the death rates due to specific infectious causes, including septicemia, meningitis, influenza, and pneumonia (Centers for Disease Control, 2010b), indicating the importance of prenatal and early influences on the developing immune system as well as of immune senescence.
Of course, clinically relevant situations arise all through the lifespan, and even immunological changes present in midlife can increase risk for disease in later life. One final theme that has emerged in the past decade in PNI and is to be found in abundance in this volume is a focus on inflammation. Inflammation contributes to a number of pathologies that develop both acutely and across the lifespan. For example, atherosclerosis is now commonly considered an inflammatory disease (Ross, 1999), and with signs of the disease beginning to develop in late childhood and adolescence (McGill et al., 2000), it is also a lifespan disease. Inflammation increases with age (Friedman, chapter 3; Effros, chapter 4; this volume), is critical to pathologies such as arthritis, autoimmune disease, and neuroinflammation (Kavelaars, Garza Carbajal, and Heijnen, chapter 20, this volume), and also contributes to poorer outcomes in cancer (Lutgendorf, Costanzo, and Sood, chapter 19, this volume). In addition to its effects on peripheral pathologies, inflammation also acts on the brain to affect psychological states, including motivation (Aubert, chapter 17, this volume) and fatigue (Jain, Bower, and Irwin, chapter 18, this volume).
The chapters in this volume illustrate the best of PNI: cutting-edge models of how the outer and inner worlds interact with each other, and the amazing complexity of both of those worlds.