Victoria I. Michalowski, Denis Gerstorf, and Christiane A. Hoppmann
Aging does not occur in isolation, but often involves significant others such as spouses. Whether such dyadic associations involve gains or losses depends on a myriad of factors, including the time frame under consideration. What is beneficial in the short term may not be so in the long term, and vice versa. Similarly, what is beneficial for one partner may be costly for the other, or the couple unit over time. Daily dynamics between partners involving emotion processes, health behaviors, and collaborative cognition may accumulate over years to affect the longer-term physical and mental health outcomes of either partner or both partners across adulthood and into old age. Future research should move beyond an individual-focused approach to aging and consider the importance of and interactions among multiple time scales to better understand how, when, and why older spouses shape each other’s aging trajectories, both for better and for worse.
Matthew P. Martens
Issues associated with athletics, alcohol abuse, and drug use continue to be salient aspects of popular culture. These issues include high-profile athletes experiencing public incidents as a direct or indirect result of alcohol and/or drug use, the role that performance-enhancing drugs play in impacting outcomes across a variety of professional and amateur contests, and the public-health effects alcohol abuse and drug use can have among athletes at all competitive levels. For some substances, like alcohol abuse, certain groups of athletes may be particularly at-risk relative to peers who are not athletes. For other substances, participating in athletics may serve as a protective factor. Unique considerations are associated with understanding alcohol abuse and drug use in sport. These include performance considerations (e.g., choosing to use or not use a certain substance due to concerns about its impact on athletic ability), the cultural context of different types of sporting environments that might facilitate or inhibit alcohol and/or drug use, and various internal personality characteristics and traits that may draw one toward both athletic activity and substance use. Fortunately, there are several effective strategies for preventing and reducing alcohol abuse and drug use, some of which have been tested specifically among athlete populations. If such strategies were widely disseminated, they would have the potential to make a significant impact on problems associated with alcohol abuse and drug use in sport and athletics.
Anne Josephine Dutt, Hans-Werner Wahl, and Manfred Diehl
The term Awareness of Aging (AoA) incorporates all aspects of individuals’ perceptions, behavioral experiences, and subjective interpretations related to their process of growing older. In this regard, AoA goes beyond objective descriptions of the aging process, such as calendar age or biological age. Commonly used AoA constructs referring to the ongoing experience of the aging process encompass concepts such as subjective age, attitudes toward one’s own aging, self-perceptions of aging, and awareness of age-related change. AoA also incorporates elements that are more pre-conscious in nature, such as age stereotypes and culturally held notions about the aging process. Despite their theoretically broad common foundation, AoA constructs differ according to their specific frames of reference, such as whether and how they take into account the multidimensionality and multi-directionality of development. Examining the existing body of empirical work identifies several antecedents of AoA, such as sociodemographic “background” variables, physical health and physical functioning, cognition, psychological well-being and mental health, psychological variables (e.g., personality, anxiety), and life events. In general, more positive manifestations on these variables are accompanied by a more positive perception and evaluation of the aging process. Moreover, AoA is longitudinally linked to important developmental outcomes, such as health, cognition, subjective well-being, and mortality. Overall, the study of AoA has developed as a promising area of psychological aging research that has grown in its conceptual and empirical rigor during recent years.
Thomas M. Hess, Erica L. O'Brien, and Claire M. Growney
Blood pressure is a frequently used measure in studies of adult development and aging, serving as a biomarker for health, physiological reactivity, and task engagement. Importantly, it has helped elucidate the influence of cardiovascular health on behavioral aspects of the aging process, with research demonstrating the negative effect of chronic high blood pressure on various aspects of cognitive functioning in later life. An important implication of such research is that much of what is considered part and parcel of getting older may actually be reflective of changes in health as opposed to normative aging processes. Research has also demonstrated that situational spikes in blood pressure to emotional stressors (i.e., reactivity) also have implications for health in later life. Although research is still somewhat limited, individual differences in personal traits and living circumstances have been found to moderate the strength of reactive responses, providing promise for the identification of factors that might ameliorate the effects of age-related changes in physiology that lead to normative increases in reactivity. Finally, blood pressure has also been successfully used to assess engagement levels. In this context, recent work on aging has focused on the utility of blood pressure as a reliable indicator of both (a) the costs associated with cognitive engagement and (b) the extent to which variation in these costs might predict both between-individual and age-related normative variation in participation in cognitively demanding—but potentially beneficial—activities. This chapter elaborates on these three approaches and summarizes major research findings along with methodological and interpretational issues.
Karen Z. H. Li, Halina Bruce, and Rachel Downey
Research on the interplay of cognition and mobility in old age is inherently multidisciplinary, informed by findings from life span developmental psychology, kinesiology, cognitive neuroscience, and rehabilitation sciences. Early observational work revealed strong connections between sensory and sensorimotor performance with measures of intellectual functioning. Subsequent work has revealed more specific links between measures of cognitive control and gait quality. Convergent evidence for the interdependence of cognition and mobility is seen in patient studies, wherein cognitive impairment is associated with increased frequency and risk of falling. Even in cross-sectional studies involving healthy young and older adults, the effects of aging on postural control and gait are commonly exacerbated when participants perform a motor task with a concurrent cognitive load. This motor-cognitive dual-task method assumes that cognitive and motor domains compete for common capacity, and that older adults recruit more cognitive capacity than young adults to support gait and posture.
Neuroimaging techniques such as magnetic resonance imaging (MRI) have revealed associations between measures of mobility (e.g., gait velocity and postural control) and measures of brain health (e.g., gray matter volumes, cortical thickness, white matter integrity, and functional connectivity). The brain regions most often associated with aging and mobility also appear to subserve high-level cognitive functions such as executive control, attention, and working memory (e.g., dorsolateral prefrontal cortex, anterior cingulate). Portable functional neuroimaging has allowed for the examination of neural functioning during real-time walking, often in conjunction with detailed spatiotemporal measures of gait. A more recent strategy that addresses the interdependence of cognitive and motor processes in old age is cognitive remediation. Cognitive training has yielded promising improvements in balance, walking, and overall mobility status in healthy older adults, and those with age-related neurodegenerative conditions such as Parkinson’s Disease.
Alison Chasteen, Maria Iankilevitch, Jordana Schiralli, and Veronica Bergstrom
In 2016, Statistics Canada released the results of the most recent census. For the first time ever, the proportion of Canadians aged 65-plus years surpassed the proportion aged 15 and under. The increase in the proportion of older adults was viewed as further evidence of the faster rate of aging of Canada’s population. Such demographic shifts are not unique to Canada; many industrialized nations around the world are experiencing similar changes in their populations. Increases in the older adult population in many countries might produce beneficial outcomes by increasing the potential for intergenerational contact and exposure to exemplars of successful aging. Such positive intergenerational contact could counter prevailing age stereotypes and improve intergenerational relations. On the other hand, such increases in the number of older adults could be viewed as a strain and potential threat to resources shared with younger age groups. The possibility of increased intergenerational conflict makes it more important than ever before to understand how older adults are stereotyped, how those stereotypes can produce different kinds of biased behavior toward them, and what the impact of those stereotypes are on older adults themselves.
Social-cognitive age representations are complex and multifaceted. A common stereotype applied to older people is one of warmth but incompetence, often resulting in paternalistic prejudice toward them. However, such benevolent prejudice, characterized by warm overtones, can change to hostile bias if older adults are perceived to violate prescriptive norms about age-appropriate behavior. In addition to coping with age prejudice, older adults also have to deal with the deleterious effects of negative age stereotypes on their day-to-day function. Exposure to negative aging stereotypes can worsen older adults’ cognitive performance in a number of contexts. As well, age stereotypes can be incorporated into older adults’ own views of aging, also leading to poorer outcomes for them in a variety of domains. A number of interventions to counteract the effects of negative aging stereotypes appear promising, but more work remains to be done to reduce the impact of negative aging stereotypes on daily function in later life.
Shevaun D. Neupert and Jennifer A. Bellingtier
Daily diary designs allow researchers to examine processes that change together on a daily basis, often in a naturalistic setting. By studying within-person covariation between daily processes, one can more precisely establish the short-term effects and temporal ordering of concrete daily experiences. Additionally, the daily diary design reduces retrospective recall bias because participants are asked to recall events that occurred over the previous 24-hour period as opposed to a week or even a year. Therefore, a more accurate picture of individuals’ daily lives can be captured with this design. When conclusions are drawn between people about the relationship between the predictors and outcomes, the covariation that occurs within people through time is lost. In a within-person design, conclusions can be made about the simultaneous effects of within-person covariation as well as between-person differences. This is especially important when many interindividual differences (e.g., traits) may exist in within-person relationships (e.g., states).
Daily diary research can take many forms. Diary research can be conducted with printed paper questionnaires, divided into daily booklets where participants mail back each daily booklet at the end of the day or entire study period. Previous studies have called participants on the telephone to respond to interview questions each day for a series of consecutive days, allowing for quantitative as well as qualitative data collection. Online surveys that can be completed on a computer or mobile device allow the researcher to know the specific day and time that the survey was completed while minimizing direct involvement with the collection of each daily survey. There are many opportunities for lifespan developmental researchers to adopt daily diary designs across a variety of implementation platforms to address questions of important daily processes. The benefits and drawbacks of each method along with suggestions for future work are discussed, noting issues of particular importance for aging and lifespan development.
Carolyn M. Aldwin and Ritwik Nath
Erythocyte sedimentation rate (ESR) is one of the oldest measures of inflammation. It is used extensively in clinical medicine and has shown some utility in biomedical research. It is a nonspecific inflammation assay, and although it is less sensitive than more modern measures such as C-reactive protein, it is a useful measure in chronic illnesses.
In general, ESR increases with age and appears to be a biomarker of aging in general. It predicts both cardiovascular disease (CVD) and cancer and is elevated in autoimmune disorders such as rheumatoid arthritis. Further, it predicts mortality both in the general population and in those with chronic illnesses such as CVD and cancer, independent of other indicators of illness severity.
Interestingly, ESR is not associated with anxiety or general measures of distress but is consistently associated with measures of depression and suicidal ideation. Further, the effect of depressive symptoms on mortality appears to be mediated through increases in ESR.
Studies of the relationship between stress and ESR have been less consistent, primarily because early studies were largely cross-sectional and in small samples. Studies using more modern, longitudinal analyses in larger samples may show more consistent results, especially if multilevel modeling was used that examined within-person changes in ESR in response to stress. Given that other large, longitudinal studies, such as the Baltimore Longitudinal Study on Aging, the Rotterdam Study, The Reykjavik Cohort Study, and Women’s Healthy Ageing Study have included ESR in their biomedical assays, it should be possible to analyze existing data to examine how psychosocial factors influence inflamm-aging in humans.
Christiane A. Hoppmann, Theresa Pauly, Victoria I. Michalowski, and Urs M. Nater
Everyday salivary cortisol is a popular biomarker that is uniquely suited to address key lifespan developmental questions. Specifically, it can be used to shed light on the time-varying situational characteristics that elicit acute stress responses as individuals navigate their everyday lives across the adult lifespan (intraindividual variability). It is also well suited to identify more stable personal characteristics that shape the way that individuals appraise and approach the stressors they encounter across different life phases (interindividual differences). And it is a useful tool to disentangle the mechanisms governing the complex interplay between situational and person-level processes involving multiple systems (gain-loss dynamics). Applications of this biomarker in areas of functioning that are core to lifespan developmental research include emotional experiences, social contextual factors, and cognition. Methodological considerations need to involve careful thought regarding sampling frames, potential confounding variables, and data screening procedures that are tailored to the research question at hand.
There is no doubt that exercise, a vital health-promoting activity, regardless of health status, produces numerous well-established physical, functional, and mental health benefits. Many people, however, do not adhere to medical recommendations to exercise consistently, especially if they have chronic illnesses. Put forth to explain this conundrum are numerous potential explanatory factors. Among these are mental health correlates such as anxiety, fear, fatigue, pain, motivation, and depression, as well as various self-efficacy perceptions related to exercise behaviors, which may be important factors to identify and intervene upon in the context of promoting adherence to physical activity recommendations along with efforts to reduce the cumulative health and economic burden of exercise non-adherence among the chronically ill and those at risk for chronic illnesses.
Benjamin Gardner and Amanda L. Rebar
This is an advance summary of a forthcoming article in the Oxford Research Encyclopedia of Psychology. Please check back later for the full article.
Within psychology, the term habit is most often used to refer to a process whereby situations prompt action automatically, through activation of mental situation-action associations acquired through prior performances. Unlike consciously intended behavior, which proceeds via a cognitively effortful reflective processing system, behavior that is directed by habit is regulated by an impulsive processing system, and so can be elicited with minimal cognitive effort, awareness, control, or intention. The habit formation process involves a gradual transferral of action initiation from the conscious attentional or motivational processes involved in reflective processing, to external cuing mechanisms characteristic of impulsive processing. Behavior thus becomes detached from motivational or volitional control, freeing finite cognitive resources for unfamiliar or otherwise more demanding tasks. Upon encountering associated situations, habitual tendencies dominate action regulation, and alternative actions become less readily accessible.
By virtue of these characteristics, habit theory proposes that habit strength will predict the likelihood of enactment of habitual behavior, and that strong habitual tendencies will dominate over motivational tendencies. Evidence of these effects, albeit predominantly observational and correlational, has been found for many everyday socially significant and health-relevant behaviors, such as physical activity, healthy eating, alcohol consumption, TV viewing, and travel mode choice. Such findings have stimulated interest in habit formation as a behavior change mechanism—commentators have argued that adding habit formation components into behavior change interventions should sustain what are otherwise typically only short-term effects, by shielding new behaviors against potential motivational lapses. Habit-based interventions differ from non-habit-based interventions in that they include elements that promote context-dependent repetition, with the explicit aim of developing situation-action associations, and thus, situationally cued automatic behavioral responses. A wealth of habit-based behavior change interventions have been studied in clinical trials and have mostly shown positive effects on behavior. However, due to the methodological limitations of these trials, the longevity of such effects, and the unique impact on behavior of habit-focused components are not yet known. As an intervention strategy, habit formation has been shown to be acceptable to intervention recipients, who report that, through repetition, behaviors gradually become routinized and “second nature.” Whether habit formation interventions truly offer a route to long-lasting behavior change, however, remains unclear.
Philip Sayegh, David J. Moore, and Pariya Fazeli Wheeler
Since the first cluster of people with HIV was identified in 1981, significant biomedical advances, most notably the development of antiretroviral therapy (ART), have led to considerably increased life expectancy as well as a reduction in the morbidity and mortality associated with HIV/AIDS. As a result, HIV/AIDS is no longer considered a terminal illness, but rather a chronic illness, and many persons living with HIV/AIDS are beginning to enter or have already reached later life. In fact, Americans ages 50 years and older comprise approximately half of all individuals with HIV/AIDS and represent the most rapidly growing subpopulation of persons living with HIV/AIDS in the United States.
Despite significant advances in HIV/AIDS treatment and prognosis, older adults living with HIV (OALH) face a number of unique challenges and circumstances that can lead to exacerbated symptoms and poorer outcomes, despite demonstrating generally better ART adherence than their younger counterparts. These detrimental outcomes are due to both chronological aging and cohort effects as well as social and behavioral factors and long-term ART use. For instance, neurocognitive deficits and neuropsychiatric symptoms, including depression, anxiety, apathy, and fatigue, are often observed among OALH, which can result in feelings of loneliness, social isolation, and reduced social support. Taken together, these factors can lead to elevated levels of problems with everyday functioning (e.g., activities of daily living) among OALH. In addition, sociocultural factors such as race/ethnicity, ageism, sexism, homophobia, transphobia, geographic region, socioeconomic status and financial well-being, systemic barriers and disparities, and cultural values and beliefs play an influential role in determining outcomes.
Notwithstanding the challenges associated with living with HIV/AIDS in later life, many persons living with HIV/AIDS are aging successfully. HIV/AIDS survivor and community mobilization efforts, as well as integrated care models, have resulted in some significant improvements in overall HIV/AIDS patient care. In addition, interventions aimed at improving successful aging outcomes among OALH are being developed in an attempt to effectively reduce the psychological and physical morbidity associated with HIV disease.
Amy E. Richardson and Elizabeth Broadbent
Cognitions about illness have been identified as contributors to health-related behavior, psychological well-being, and overall health. Several different theories have been developed to explain how cognitions may exert their impact on health outcomes. This article includes three theories: the Health Belief Model (HBM), the Theory of Planned Behavior (TPB), and the Common Sense Model (CSM), with the primary focus on the CSM. The HBM posits that cognitions regarding susceptibility to a health threat, the severity of the threat, and the benefits and costs associated with behavior, will determine whether or not a behavior is performed. In the TPB, behavior is thought to be a consequence of intention to act, which is shaped by attitudes regarding a behavior, subjective norms, and perceived behavioral control. The Common Sense Model (CSM) proposes that individuals form cognitive representations of illness (known as illness perceptions) as well as emotional representations, which are key determinants of coping behaviors to manage the illness. Coping behaviors are theorized to have direct relationships with physical and psychological health outcomes. Cognitive representations encompass perceptions regarding the consequences posed by the illness, its timeline, personal ability to control the illness, whether the illness can be cured or controlled by treatment, and the identity of the illness (including its label and symptoms). Emotional representations reflect feelings such as fear, anger, and depression about the illness. The development of illness representations is influenced by a number of factors, including personal experience, the nature of physical symptoms, personality traits, and the social and cultural context. Illness cognitions can vary considerably between patients and health care professionals. There are a number of methods to assess illness-related cognitions, and increasing evidence that modifying negative or inaccurate cognitions can improve health outcomes.
Stephanie J. Wilson, Alex Woody, and Janice K. Kiecolt-Glaser
Inflammatory markers provide invaluable tools for studying health and disease across the lifespan. Inflammation is central to the immune system’s response to infection and wounding; it also can increase in response to psychosocial stress. In addition, depression and physical symptoms such as pain and poor sleep can promote inflammation and, because these factors fuel each other, all contribute synergistically to rising inflammation. With increasing age, persistent exposure to pathogens and stress can induce a chronic proinflammatory state, a process known as inflamm-aging.
Inflammation’s relevance spans the life course, from childhood to adulthood to death. Infection-related inflammation and stress in childhood, and even maternal stress during pregnancy, may presage heightened inflammation and poor health in adulthood. In turn, chronically heightened inflammation in adulthood can foreshadow frailty, functional decline, and the onset of inflammatory diseases in older age.
The most commonly measured inflammatory markers include C-reactive protein (CRP) and proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). These biomarkers are typically measured in serum or plasma through blood draw, which capture current circulating levels of inflammation. Dried blood spots offer a newer, sometimes less expensive collection method but can capture only a limited subset of markers. Due to its notable confounds, salivary sampling cannot be recommended.
Inflammatory markers can be added to a wide range of lifespan developmental designs. Incorporating even a single inflammatory assessment to an existing longitudinal study can allow researchers to examine how developmental profiles and inflammatory status are linked, but repeated assessments must be used to draw conclusions about the associations’ temporal order and developmental changes. Although the various inflammatory indices can fluctuate from day to day, ecological momentary assessment and longitudinal burst studies have not yet incorporated daily inflammation measurement; this represents a promising avenue for future research.
In conclusion, mounting evidence suggests that inflammation affects health and disease across the lifespan and can help to capture how stress “gets under the skin.” Incorporating inflammatory biomarkers into developmental studies stands to enhance our understanding of both inflammation and lifespan development.
This article aims to provide a narrative overview on injury prevention in sport and performance psychology. Research and applied interest in psychological injury prevention in sport and performance psychology has risen in popularity over the past few decades. To date, existing theoretical models, pure and applied research, and practice-based evidence has focused on conceptualizing and examining psychological injury occurrence and prevention through stress-injury mechanisms, and predominantly in sport injury settings. However, given the inherited similarities across the different performance domains however, it is the authors’ belief that existing injury prevention knowledge can be transferable beyond sport but should be done with caution. A range of cognitive-affective-behavioral strategies such as goal setting, imagery, relaxation strategies, self-talk, and social support have been found beneficial in reducing injuries, particularly when used systematically (a) prior to injury occurrence as part of performance enhancement program and/or as a specific injury prevention measure, (b) during injury rehabilitation, and (c) as part of a return-to-activity process to minimize the risk of secondary injuries and reinjuries. Existing theoretical and empirical evidence also indicates that using cognitive-affective-behavioral strategies for injury prevention are effective when used as part of a wider, multi-modal intervention. Equally, such interventions may also need to address possible behavioral modifications required in sleep, rest, and recovery. Considering the existing empirical and anecdotal evidence to date, this paper argues that injury prevention efforts in sport and performance psychology should be cyclical, biopsychosocial, and person-centered in nature. In short, injury prevention should be underpinned by recognition of the interplay between personal (both physical and psychological), environmental, and contextual characteristics, and how they affect the persons’ cognitive-affective-behavioral processes before, during, and after injury occurrence, at different phases of rehabilitation, and during the return to activity or retirement from activity process. Moreover, these holistic injury prevention efforts should be underpinned by a philosophy that injury prevention is inherently intertwined with performance enhancement, with the focus being on the individual and their overall well-being.
Stuart Linke and Elizabeth Murray
Alcohol-use disorders are widespread and associated with a greatly increased risk of health-related and societal harms. The majority of harms associated with consumption are experienced by those who drink above recommended guidelines, rather than those who are alcohol dependent. Brief interventions and treatments based on screening questionnaires and feedback have been developed for this group, which are effective tools for reducing consumption in primary care and in other settings. Most people who drink excessively do not receive help to reduce the risks associated with excessive consumption. Digital versions of brief and extended interventions have the potential to reach populations that might derive benefit from them. Digital interventions utilize the same principles as do traditional face-to-face versions, but they have the advantages of availability, confidentiality, flexibility, low marginal costs, and treatment integrity. The evidence for the feasibility, acceptability, costs, and effectiveness of digital interventions is encouraging, and the evidence for effectiveness is particularly strong in studies of student populations. There are, however, a number of unresolved questions. It is not clear which components of interventions are required to maximize effectiveness, whether digital versions are enhanced by the addition of personal contact from a facilitator or a health professional, or how to increase take up of the offer of a digital intervention and reduce attrition from a program. These questions are common to many online behavior-change interventions and there are opportunities for cross-disciplinary learning between psychologists, health professionals, computer scientists, and e-health researchers.
Markus Wettstein, Hans-Werner Wahl, and Michael Schwenk
When referring to life space, researchers usually mean the area in which individuals move in their everyday lives. Life space can be measured based on different approaches, by means of self-reports (i.e., questionnaires or diaries) or by more recent approaches of technology-based objective assessment (e.g., via Global Positioning System [GPS] devices or smartphones). Life space is an important indicator of older adults’ out-of-home mobility and is meaningfully associated with autonomy, well-being, and quality of life. Substantial relationships between life space and socio-demographic indicators, health, and cognitive abilities have been reported in previous research. Future research on life space in old age will benefit from a more comprehensive and stronger interdisciplinary perspective, from taking into account different time scales (i.e., short- and long-term variability), and from considering life space as a multidimensional measure that can be best assessed based on multi-method approaches with multiple indicators.
Loneliness or perceived social isolation is a subjective experience relating to dissatisfaction with one’s social relationships. Most research has focused on the experience of loneliness in old age, but levels of loneliness are also known to be high among teenagers and young adults. While poor health may be associated with increased feelings of loneliness, there is now considerable evidence on the role of loneliness as a risk factor for poor mental and physical health. Studies show that loneliness is associated with an increased risk of developing dementia and chronic diseases, and also with a higher rate of mortality. Risky health behaviors, a poor cardiovascular profile and compromised immune functioning have all been proposed as potential pathways through which loneliness may affect health. However, much still remains to be understood about these mechanisms.
Ildiko Tombor and Susan Michie
People’s behavior influences health, for example, in the prevention, early detection, and treatment of disease, the management of illness, and the optimization of healthcare professionals’ behaviors. Behaviors are part of a system of behaviors within and between people in that any one behavior is influenced by others. Methods for changing behavior may be aimed at individuals, organizations, communities, and/or populations and at changing different influences on behavior, e.g., motivation, capability, and the environment. A framework that encapsulates these influences is the Behavior Change Wheel, which links an understanding of behavior in its context with methods to change behavior. Within this framework, methods are conceptualized at three levels: policies that represent high-level societal and organizational decisions, interventions that are more direct methods to change behavior, and behavior change techniques that are the smallest components that on their own have the potential to change behavior. In order to provide intervention designers with a systematic method to select the policies, interventions, and/or techniques relevant for their context, a set of criteria can be used to help select intervention methods that are likely to be implemented and effective. One such set is the “APEASE” criteria: affordability, practicability, effectiveness, acceptability, safety, and equity.
Sarah E. Hampson
Although the belief that personality is linked to health goes back at least to Greek and Roman times, the scientific study of these links began in earnest only during the last century. The field of psychosomatic medicine, which grew out of psychoanalysis, accepted that the body and the mind were closely connected. By the end of the 20th century, the widespread adoption of the five-factor model of personality and the availability of reliable and valid measures of personality traits transformed the study of personality and health. Of the five broad domains of personality (extraversion, agreeableness, conscientiousness, emotional stability, and intellect/openness), the most consistent findings in relation to health have been obtained for conscientiousness (i.e., hard-working, reliable, self-controlled). People who are more conscientious have better health and live longer lives than those who are less conscientious. These advantages are partly explained by the better health behaviors, good social relationships, and less stress that tend to characterize those who are more conscientious. The causal relation between personality and health may run in both directions; that is, personality influences health, and health influences personality. In addition to disease diagnoses and longevity, changes on biomarkers such as inflammation, cortisol activity, and cellular aging are increasingly used to chart health in relation to personality traits and to test explanatory models. Recognizing that both personality and health change over the life course has promoted longitudinal studies and a life-span approach to the study of personality and health.