Alone in the Crowd: The Structure and Spread of Loneliness in a Large Social Network

The discrepancy between an individual's loneliness and the number of connections in a social network is well documented, yet little is known about the placement of loneliness within, or the spread of loneliness through, social networks. The authors use network linkage data from the population-based Framingham Heart Study to trace the topography of loneliness in people's social networks and the path through which loneliness spreads through these networks. Results indicated that loneliness occurs in clusters, extends up to 3 degrees of separation, is disproportionately represented at the periphery of social networks, and spreads through a contagious process. The spread of loneliness was found to be stronger than the spread of perceived social connections, stronger for friends than family members, and stronger for women than for men. The results advance understanding of the broad social forces that drive loneliness and suggest that efforts to reduce loneliness in society may benefit by aggressively targeting the people in the periphery to help repair their social networks and to create a protective barrier against loneliness that can keep the whole network from unraveling. Human social isolation is recognized as a problem of vast importance. Social species do not fare well when forced to live solitary lives. increases the activation of the sympatho-adrenomedullary response to an acute immobili-zation or cold stressor in rats (Dronjak, Gavrilovic, Filipovic, & Radojcic, 2004); decreases the expression of genes regulating glucocorticoid response in the frontal cortex of piglets (Poletto, Steibel, Siegford, & Zanella, 2006); decreases open field activity, increases basal cortisol concentrations, and decreases lymphocyte proliferation to mitogens in pigs (Kanitz, Tuchscherer, Puppe, Tuchscherer, & Stabenow, 2004); increases the 24-hr urinary catecholamines levels and evidence of oxidative stress in the aortic arch of the Watanabe heritable hyperlipidemic rabbit (Nation et al., 2008); increases the morning rises in cortisol in squirrel monkeys (Lyons, Ha, & Levine, 1995); and profoundly disrupts psychosex-ual development in rhesus monkeys (Harlow et al., 1965). Humans, born to the longest period of abject dependency of any species and dependent on conspecifics across the lifespan to survive and prosper, do not fare well, either, whether they are living solitary lives or whether they simply perceive that they live in isolation. The average person spends about 80% of waking hours in the company of others, and the time with others is preferred to Humans are an irrepressibly meaning-making species, and a large literature has developed showing that perceived social …