Lonely traits and concomitant physiological processes: the MacArthur social neuroscience studies

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Abstract

Loneliness is a complex set of feelings encompassing reactions to unfulfilled intimate and social needs. Although transient for some individuals, loneliness can be a chronic state for others. Prior research has shown that loneliness is a major risk factor for psychological disturbances and for broad-based morbidity and mortality. We examined differences between lonely and socially embedded individuals that might explain differences in health outcomes. Satisfying social relationships were associated with more positive outlooks on life, more secure attachments and interactions with others, more autonomic activation when confronting acute psychological challenges, and more efficient restorative behaviors. Individuals who were chronically lonely were characterized by elevated mean salivary cortisol levels across the course of a day, suggesting more discharges of corticotropin-releasing hormone and elevated activation of the hypothalamic–pituitary–adrenocorticol axis. An experimental manipulation of loneliness further suggested that the way in which people construe their self in relation to others around them has powerful effects on their self concept and, possibly, on their physiology.

Introduction

Humans are social animals, so much so that a basic ‘need to belong’ has been posited (Baumeister and Leary, 1995, Gardner et al., in review, Gardner et al., in press). People form associations and connections with others from the moment they are born. The very survival of newborns depends on their attachment to and nurturance by others over an extended period of time. It should be no surprise that evolution has sculpted the human genome to be sensitive to and succoring of contact and relationships with others. For instance, caregiving and attachment have hormonal (e.g. Uvnäs-Mosberg, 1997) and neurophysiological substrates (cf. Carter et al., 1997). Communication, the bedrock of complex social interaction, is universal and ubiquitous in humans. In the rare instances in which human language is not modeled or taught, language develops nevertheless (e.g. Goldin-Meadow and Mylander, 1983, Goldin-Meadow and Mylander, 1984).

The need to belong does not stop at infancy but rather affiliation and nurturant social relationships appear to be essential for physical and for psychological well-being across the lifespan. Disruptions of social connections, whether through ridicule, separation, divorce, or bereavement, are among the most stressful events people must endure (Gardner et al., in press). Berkman and Syme (1979), for instance, operationalized social connections as marriage, contacts with friends and extended family members, church membership, and other group affiliations. They found that adults with fewer social connections suffered higher rates of mortality over the succeeding 9 years even after accounting for self-reports of physical health, socioeconomic status, smoking, alcohol consumption, obesity, race, life satisfaction, physical activity, and preventive health service usage. House et al. (1982) replicated these findings using physical examinations to assess health status. In their review of five prospective studies, House et al. (1988) concluded that social isolation was a major risk factor for morbidity and mortality from widely varying causes. This relationship was evident even after statistically controlling for known biological risk factors, social status, and baseline measures of health. The negative health consequences of social isolation were particularly strong among some of the fastest growing segments of the population: the elderly, the poor, and minorities such as African-Americans. Astonishingly, the strength of social isolation as a risk factor was comparable to smoking, high blood pressure, obesity, and sedentary lifestyles.

Social isolation and loneliness are associated with poorer mental as well as physical well-being (e.g. Perkins, 1991, Gupta and Korte, 1994, Ernst and Cacioppo, 1999). Conversely, people who report having contact with five or more intimate friends in the prior 6 months are 60% more likely to report that their lives are ‘very happy’, as compared to those who do not report such contact (Burt, 1986). People appear to be cognizant of the importance of social relationships. When asked ‘what is necessary for happiness?’ most rated relationships with friends and family as being the most important factor (Berscheid, 1985).

Although social isolation is multi-dimensional, it generally appears that the intimacy and emotional nourishment provided by at least one other individual are key to buffering the effects of the majority of stressors. In their seminal review, House et al. (1988) concluded that:

... the mere presence of, or sense of relatedness with, another organism may have relatively direct motivational, emotional, or neuroendocrinal effects that promote health either directly or in the face of stress or other health hazards but that operate independently of cognitive appraisal or behavioral coping and adaptation (p. 544).

Our goal here is to provide a preliminary report of an ongoing study of the psychological and physiological differences between individuals differing in social embeddedness. Although there are gripping states of loneliness that everyone experiences transiently in specific circumstances or interactions, some individuals live in the devastating clutches of loneliness even though they are not physically and socially isolated. Our target sample was college undergraduates because (a) this is an active period of dating, mate selection, and sexual activity; (b) habitual patterns of health behaviors and of interacting with others are being established; and (c) social relationships undergo an upheaval when individuals first go to college yet ample opportunities exist for making new acquaintances and friends.

Section snippets

Loneliness on college campus

We tested 2632 male and female undergraduates at the Ohio State University to determine their feelings of loneliness and their living circumstances. Loneliness was unrelated to various features of college life such as the number of roommates with whom they lived, the percent who belonged to organizations, the number of quarters of college completed, the number of hours in college in which they were enrolled, the number of quarters needed to graduate, and the number of hours they exercised

Differences in social capital

We first examined the hypothesis that individuals who were lonely simply had less social capital to offer than others. By social capital, we mean the resources they bring to a social interaction — their physical attractiveness, intelligence, height, weight, age, socioeconomic status, or scholastic achievements. Analyses revealed the groups did not differ on any of these variables.

We next examined the hypothesis that individuals who were lonely reported more traumatic life histories, were

Differences in autonomic activation

If anxiety and anger are especially powerful in lonely individuals, then they might be expected to show greater autonomic activation than embedded individuals. If, however, behavioral or emotional disengagement from the social environment is especially powerful in lonely individuals, then they might be expected to show less autonomic activation than embedded individuals. To examine this issue, participants were tested at the General Clinical Research Center at The Ohio State University

Differences in attentional control

Why might lonely individuals be more emotionally withdrawn in new social settings? Personality differences such as shyness, sociability, negativity, and fear of negative evaluation provide a partial explanation. New social settings can be overwhelming, however, and people must exert voluntary control over their attentional focus to be effective. Do lonely individuals differ in their ability to voluntarily control their attentional focus?

To explore this possibility, participants performed a

Differences in neuroendocrine activation

As noted above, a major objective in this study was to explore potential mechanisms underlying the relationship between social isolation and morbidity and mortality. Our data indicated that lonely, relative to embedded, individuals engaged in comparable or better health behaviors (e.g. cigarette smoking, alcohol consumption, drug abuse, and exercise). Autonomic reactivity to acute psychological stressors also tended to be diminished in lonely, relative to embedded, individuals. Prior research

Differences in the salubrity of sleep

The salubrity of nourishing social relationships has been documented previously, but the beneficial effects of nurturant or intimate social relationships are usually attributed to direct assistance or stress-buffering (Cohen and McKay, 1984; see Gardner et al., in press). For example, medical students undergoing exams showed stress-induced decrements in immune functioning, but this decline was particularly pronounced for the medical students who reported being lonely (Kiecolt-Glaser et al., 1984

Manipulating feelings of loneliness

Uchino et al. (1996) reviewed intervention studies that have been performed to increase social support. A meta-analysis of these studies showed that improving social support and connectedness, especially within families, had beneficial physiological effects (e.g. lowered blood pressure in hypertensives). Such findings are important because they indicate that feelings of loneliness or social embeddedness are not simply markers or epiphenomena, and that loneliness is not an invariant trait but

Conclusion

The current research underscores the centrality of social relationships to human existence and experience. For instance, lonely individuals were more anxious, angry, and negative, and less positive, optimistic, comfortable, and secure than embedded individuals, a pattern of findings that was associated with feelings of loneliness whether examined between-subjects or within-subjects. Attentional control appeared comparable in lonely and embedded individuals until voluntary attentional control

Acknowledgements

We wish to thank David Lozano and Dan Litvack of the Ohio State University Social Neuroscience Laboratory for their technical assistance, Robert Stickgold from the Harvard University Neurophysiology Lab and Bita Naouriani from the Stanford University Department of Psychiatry for their assistance in this investigation, the staff of the Ohio State University Residence Halls directed by Steve Kramer for their help, Carolyn Cheney of The Ohio State University Medical Labs for her contributions, and

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