What We Know: The Tantalizing Potential

ETIOLOGY, PART I

John Cacioppo

The University of Chicago

Dr. Cacioppo began his presentation on the concepts of social isolation and loneliness by pointing out what has been learned since Francis Crick articulated his central dogma of molecular biology some 30 years ago. Crick maintained that social and environmental influences on health were largely those codified in the DNA we’ve inherited from our ancestors of millennia past. These molecules direct the production of proteins in our bodies, which, among other things, underlie our behavior and sense of well-being.

But over the past few decades, Dr. Cacioppo said, we have learned that different environmental contexts produce different molecular-level reactions. The social environment not only operates in terms of genetic constitutions sculpted over thousands of years ago but also can affect the genetic processes of transcription and translation in the individual.

In a study conducted at Ohio State University, Dr. William Malarkey, Dr. Cacioppo, and colleagues showed that the amounts of growth hormone produced by B and T cells in the body were diminished in individuals who’d been exposed to chronic social stressors. The most likely means by



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What We Know: The Tantalizing Potential ETIOLOGY, PART I John Cacioppo The University of Chicago Dr. Cacioppo began his presentation on the concepts of social isolation and loneliness by pointing out what has been learned since Francis Crick articulated his central dogma of molecular biology some 30 years ago. Crick maintained that social and environmental influences on health were largely those codified in the DNA we’ve inherited from our ancestors of millennia past. These molecules direct the production of proteins in our bodies, which, among other things, underlie our behavior and sense of well-being. But over the past few decades, Dr. Cacioppo said, we have learned that different environmental contexts produce different molecular-level reactions. The social environment not only operates in terms of genetic constitutions sculpted over thousands of years ago but also can affect the genetic processes of transcription and translation in the individual. In a study conducted at Ohio State University, Dr. William Malarkey, Dr. Cacioppo, and colleagues showed that the amounts of growth hormone produced by B and T cells in the body were diminished in individuals who’d been exposed to chronic social stressors. The most likely means by

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FIGURE A Mechanisms that contribute to individual differences in loneliness. which this was achieved, the authors posited, was through the down-regulatory influences of catecholamines and corticosteroids on lymphocytes. One major factor responsible for chronic stress, as well as broad-based morbidity and mortality, is social isolation, though the mechanism by which it produces these adverse health effects has not been specified. In a series of studies of individual differences in loneliness—or the perception that one is socially isolated from others and bereft of meaningful human contact—the researchers tested various mechanisms that could contribute to this relationship (see Figure A). They studied over 2,600 young adults at Ohio State University and Stanford University because, developmentally speaking, they were selecting partners and establishing lifetime health habits. More recently, they have studied older adults whose physiological resilience could be expected to be diminished. Dr. Cacioppo said that when we look at the psychological profiles of lonely individuals they “tend to be shy and possess poor social skills; report higher levels of stress, anxiety, and hostility; distrust other individuals and feel as if they are contributing more than their share to their relationships; be characterized by higher negative affectivity, pessimism, and negative reactivity; and respond to stressors less through active coping and seeking social support and more through withdrawal.” In general, this profile is evident in personality and social inventories and in momentary reports using an experience sampling methodology to assess subjects’ status during their normal daily life.

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Although genetic studies of loneliness are rare, the extant data suggest that at least half the variance is attributable to environmental factors, Dr. Cacioppo said. It was not the case, for instance, that lonely individuals were characterized by lower levels of “social capital”: lonely and nonlonely individuals did not differ in height, weight, body mass index, intelligence, physical attractiveness, family wealth, or any other sociodemographic variable they examined. Additional evidence for the importance of environmental influences was provided by Dr. Cacioppo and Stanford’s Dr. David Spiegel in a study in which they used hypnosis to manipulate the feelings of loneliness in a sample of adults at Stanford. They found that when these participants were led to feel lonely, they were characterized by the same psychological profile as the lonely individuals tested at Ohio State; when the Stanford participants were led to feel socially connected (not at all lonely), they were characterized by the same psychological profile as the socially connected individuals tested at Ohio State. Poor health behaviors contribute to broad-based morbidity and mortality, so the health behaviors of lonely and nonlonely individuals were compared. Though results consistently show no differences, lonely individuals do report higher levels of stress, dysphoria, and anxiety. Individuals who are socially disconnected may be exposed to more stressors (direct effects), and when exposed to a stressor they may have less assistance to help them deal with it (stress buffering). Dr. Cacioppo and colleagues found additional evidence not only that lonely individuals were more stressed by daily hassles and events, but that restorative activities were less salubrious for the lonely than the nonlonely. The quintessential restorative behavior is sleep. But in a sleep monitoring study, he said, “we found that lonely days invaded the nights. Lonely individuals showed poor sleep efficiency and more time awake after sleep onset,” which cause the fatigue that one feels the next day. In both young and older adults, lonely individuals reported poorer sleep and more fatigue during the day than nonlonely adults. Sleep disruptions, of course, can affect health. This was shown by Evan Carter and colleagues at the University of Chicago in a study published in The Lancet 2 years ago. After causing people to incur a sleep debt by depriving them of a great deal of sleep, the researchers found metabolic, neural, and hormonal effects that mimic those of aging. Another important health-related parameter is blood pressure, which becomes elevated acutely, say, when giving a speech and becomes elevated

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chronically in many American adults as a function of age. Interestingly, the basal levels and stress-related elevations in blood pressure were found to be comparable for the lonely and nonlonely young adults, Dr. Cacioppo said, but important differences were found in the underlying cardiovascular activity. Lonely young adults were characterized by higher total peripheral resistance (the resistance to blood flow in the cardiovascular system), with normal blood pressures achieved through lower cardiac output than nonlonely adults. The same differences were found in the laboratory and in ambulatory recordings during the course of their normal day. We wondered if, as in other systems that are chronically stressed over many years, we would start to see blood pressure rise in those individuals who had long been lonely, Dr. Cacioppo said. The answer appears to be yes. In a preliminary study of older adults, lonely participants were characterized by age-related increases in blood pressure, whereas the nonlonely older adults were spared this trend (see Figure B). Humans are social animals who benefit psychologically and physically from a sense of contact, FIGURE B Systolic blood pressure of lonely and nonlonely individuals.

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alliance, and community with others. When bereft of these feelings, everyday events appear more daunting, others appear more threatening, activities become more hopeless, and the nights become less restorative. Over time, such a mindset takes its toll on the body. ETIOLOGY, PART II Robert J. Sampson The University of Chicago Dr. Sampson began his presentation—on the association of health-related outcomes, especially lethal violence, with social context—by stating his thesis: we need to treat neighborhood and community contexts as important units of analysis in their own right, which in turn calls for new strategies that look well beyond the traditional approach of focusing largely on the individual. “Understanding the pathways to healthy and unhealthy communities,” he said, “may provide opportunities for preventive intervention at lower costs than traditional strategies.” While there has been a long history in this country of differentiation across neighborhoods, Dr. Sampson observed, this pattern appears not to be receding but is in fact expanding. Recent research shows that the spatial separation of economic groups has increased and also that segregation by race/ethnicity remains very high and in some cases has increased as well. This intersection of socioeconomic context with race/ethnicity has hit African Americans and other minority groups especially hard. Regardless of individual or family differences, these groups disproportionately tend to live in areas of concentrated poverty. Dr. Sampson noted that neighborhood inequality is definitely linked with well-being or the lack of it. “For at least a hundred years,” he said, “research has shown that violence and other health-related outcomes are correlated especially with concentrated disadvantage. For example, research in the early 1920s showed that a number of health outcomes—not just crime and delinquency but things such as low birth weight, tuberculosis, physical abuse, and other factors detrimental to the well-being of individuals—were concentrated in certain areas and that these areas were disproportionately disadvantaged.” This general empirical finding continues to the present day, Dr. Sampson said, as illustrated by “ecological co-morbidity,” or the spatial

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clustering of homicide, infant mortality, low birth weight, and other adverse health conditions. The implication, he said, is that there are “hot spots” of poor health outcomes. For example, in a map he displayed of Chicago’s distribution of homicides—literally, pinpoints of homicide events—from 1990 to 1996, there was distinct spatial clustering in particular neighborhoods (see Figure A). A similar map of the city that showed the distribution of another health outcome—low birth weight—revealed a very similar pattern (see Figure B). “If I didn’t label these,” he noted, “you’d probably have a hard time distinguishing between the two maps.” FIGURE A(left) Homicide distribution in Chicago neighborhoods, 1990-1996. FIGURE B(right) Low birth weight distribution in Chicago Neighborhoods, 1990-1996.

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Might this just be the result of vulnerable individuals being left behind in poor neighborhoods? Or perhaps of poor, unhealthy individuals migrating to certain communities? That is probably part of the story, Dr. Sampson said, but not the whole story. Neighborhood characteristics correlate with degrees of well-being even after individual attributes and risky behaviors are adjusted. What are the underlying mechanisms? This is a very difficult issue to address, he said, but in a new generation of studies researchers are trying to systematically measure and elucidate neighborhood processes such as trust, social networks, informal social control, and the density and capacity of organizations—in other words, social structural features of the environment. Dr. Sampson and colleagues are involved in one such interdisciplinary study, the Project on Human Development in Chicago Neighborhoods, that started in 1995. “It is essentially a ‘life course,’ or developmental, study not just of delinquent and violent behavior,” he said, “but of achievement and various aspects of youth growing up. How are they doing well and how are they doing poorly? And how do outcomes—violence, for example— correlate with variations in neighborhood context?” The study has focused on the “collective efficacy” of community members in achieving a common good, and it has looked at two features in particular: informal social control (the willingness and ability of adults in the neighborhood to be involved with local organizations and also to monitor and supervise the activities of children) and working trust among neighbors (not tight-knit social bonds, but rather a linkage of trust with shared expectations for action). Basically, Dr. Sampson said, the project’s research has shown that areas with higher degrees of collective efficacy have significantly lower rates of violence, all else being equal, and that this effect is observed regardless of the socioeconomic status of the community. “However, I’m not here just to tell you that local collective features of neighborhoods matter,” Dr. Sampson said. The social context of the larger urban environment also plays an important role that researchers often over-look. “Specifically, spatial proximity to disadvantage turns out to be one of the strongest predictors of homicide and some other health outcomes, regardless of the resources, racial composition, and socioeconomic status of individual neighborhoods.” He illustrated the concept of spatial vulnerability to risk with another map of Chicago (see Figure C). In addition to a clear connection between

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FIGURE C Spatial typology of collective efficacy (CE) with homicide “hot” and “cold” spots. neighborhoods of low collective efficacy with hot spots and neighborhoods of high collective efficacy with cold spots, the map also revealed a different kind of risk: neighborhoods with high collective efficacy that are in close proximity to high-risk areas have very high homicide rates themselves. Conversely, “spatially advantaged” neighborhoods (which border low-risk areas) have low risks of homicide even when they are low in collective efficacy. “So even though I would like to argue that neighborhood effects matter,” Dr. Sampson said, “it is not just the neighborhoods but actually the embeddedness within the larger metropolitan context” that also matters.