Social Isolation & Loneliness

Social relationships are central to human well-being and are critical to the maintenance of mental and physical health (Baumeister & Leary, 1995). There are different aspects of one’s social relationships that can be assessed, including objective measures of how connected one is to others and the more subjective measure of perceived loneliness. A meta-analysis found that across studies and controlling for relevant confounds, social isolation, loneliness, and living alone were each independently associated with a greater than 25% increased likelihood of mortality (Holt-Lunstad, Smith, Baker, Harris, Stephenson, 2015). In analyses of the Health and Retirement Study data, Hughes et al. (2004) found that social isolation and loneliness were related, but the relationship was relatively modest, suggesting these are independent constructs and should both be measured.

Social Isolation: Social Network Index

Social isolation is an objective and quantifiable reflection of reduced social network size and lack of social contact. Socially isolated individuals are at increased risk for cardiovascular disease (Barth, Schneider, & von Känel, 2010), cognitive decline (Bassuck, Glass, & Berkman, 1999), and mortality (Kaplan et al., 1998). Social isolation is also associated with precursors to disease such as heightened blood pressure and peripheral inflammation (Hawkley, Thisted, Masi, Cacioppo, 2010; Louks, Berkman, Gruenewald, Seeman, 2006; Shankar, McMunn, Banks, & Steptoe, 2011).

Social isolation is often measured with Cohen’s Social Network Index measure. In a classic study linking social ties to the common cold, Cohen et al. (1997) assessed participation in 12 types of social relationships. These include relationships with a spouse, parents, parents-in-law, children, other close family members, close neighbors, friends, workmates, school-mates, fellow volunteers, members of groups with religious affiliations, and members of religious groups. One point was assigned for each type of relationship the participant indicates having, as defined by speaking to someone in that category at least once every two weeks. Number of total contacts is also captured. Results showed that people who participate in more types of social relationships have less susceptibility to the common cold. This relationship remained significant after controlling for number of contacts, indicating there is something health-protective about having a diversity of types of social relationships, not just a linear relationship between number of contacts and health. This scale can be found here:

The Berkman-Syme Social Network Index (Berkman & Syme, 1979) is a similar measure that includes subjective experiences of connection to contacts. It asks participants both frequency of contact (e.g. how many close friends do you see at least once a week) and perceived closeness (e.g. how many close friends do you have that you feel at ease with, can talk to about private matters?) This is a composite measure of four types of social connections: marital status (married vs. not); sociability (number and frequency of contacts with children, close relatives, and close friends); church group membership (yes vs. no); and membership in other community organizations (yes vs. no). This measure allows researchers to categorize individuals into four levels of social connection: from socially integrated, moderately socially integrated, or socially isolated, the latter being characterized by being unmarried, having fewer than six friends or relatives, and no membership in either church or community groups. This measure can be found here:

Loneliness: UCLA Loneliness Scale

Loneliness can be defined as the perceived lack of social companionship. It can be conceptualized as the subjective psychological component of social isolation, or the individual’s distress caused by infrequent contact or connection with their social contacts. To study loneliness, Russell, Peplau, & Ferguson (1978) developed the UCLA Loneliness Scale. The original version of this scale had 20 items and had strong validity and reliability. Hughes et al. (2004) shortened this scale to three items for epidemiological studies. These items are: How often do you feel that you lack companionship? How often do you feel left out? How often do you feeling isolated from others? Loneliness is associated with several indices of self reported and measured physical health, with higher self-reported loneliness positively associated with health outcomes such as mortality, functional limitations, and depressive symptoms (Holt-Lunstad et al., 2015; Luo, Hawkley, Waite, & Cacioppo, 2012; Shankar et al., 2017). The complete UCLA Loneliness Scale – Version 3 (Russell, 1996) can be found here:

Author and Reviewer(s)

This summary was prepared by Alexandra D. Crosswell, PhD and reviewed by the Stress Network leadership team, Teresa Seeman, PhD, and David Creswell, PhD. If you have any comments on these measures, email [email protected]. Version date: December 2017.


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