Social relationships and health: is feeling positive, negative, or both (ambivalent) about your social ties related to telomeres?

The quality and quantity of one’s social relationships are reliably related to physical health outcomes (Berkman, Glass, Brissette, & Seeman, 2000; DeVogli, Chandola, & Marmot, 2007; House, Landis, & Umberson, 1988; Uchino, 2004). For instance, Holt-Lunstad, Smith, & Layton (2010) conducted a meta-analysis of 148 studies comprised of over 308,000 participants. They found evidence that social support was related to about a 50% lower risk for future mortality (Holt-Lunstad et al., 2010). These links were not moderated by standard control variables and appeared consistent across different causes of death. These data suggest that the quality of one's social relationships may play a general role across major diseases. Research examining links between relationships and health-relevant physiological pathways is consistent with the above epidemiological links. Low social support and high social negativity are related to greater cardiovascular reactivity during acute stress and elevated ambulatory blood pressure (ABP) during daily life (Gerin, Pieper, Levy, & Pickering, 1992; Ewart, Taylor, Kraemer, & Agras, 1991; Steptoe, Lundwall, & Cropley, 2000). Importantly, both cardiovascular reactivity and ABP are linked to the development of future cardiovascular problems (Chida & Steptoe, 2010; Pickering, Shimbo, & Haas, 2006). Social support and social negativity have also been linked to immune-mediated processes that have implications for infectious and malignant diseases (Graham et al., 2009). However, very little work has examined general biological mechanisms that can link these disease-specific biological pathways with epidemiological studies that tend to focus on all-cause mortality. Recent research on cellular processes related to biological aging provides a framework for examining more general associations (Blackburn, 2000). Telomeres are repetitive structures at the end of chromosomes that help to promote its stability (Dahse, Fiedler, & Ernst, 1997; Saretzki & von Zglinicki, 2002). However, with each successive replication of the cell, telomeres shorten and when a critical threshold is met the result is cellular senescence. This mechanism serves several critical genomic purposes, including the prevention of chromosomal fusions and unregulated cellular activity (Chan & Blackburn, 2003). Importantly, Cawthon and colleagues (2003) found that shorter telomere length was associated with a three times greater mortality risk for heart disease and an eight times greater mortality risk from infectious diseases up to 20 years later. Thus, one aim of this study was to provide a test of links between relationships and a general biological index of cellular aging (i.e., telomeres). A second and major aim of our study was to examine this question in the context of a comprehensive model on the health effects of relationships (Uchino, Holt-Lunstad, Uno, & Flinders, 2001, see Figure 1). Although a relatively small body of research has linked telomeres to psychosocial processes (e.g., Epel et al., 2004; Kiecolt-Glaser et al., 2011), no study that we are aware of has examined it in the context of both positivity and negativity in relationship functioning. Relationship positivity refers broadly to interpersonal processes that facilitate successful relationship maintenance and growth such as helpful support and guidance (Uchino, 2004). In comparison, relationship negativity refers to interactions that involve conflict, insensitivity, and interference that are generally detrimental to relationships (Brooks & Dunkel Schetter, 2011). Importantly, most of the prior literature on social relationships and health has examined these dimensions of relationships separately. However, positive and negative aspects of relationships are separable dimensions and hence can be uncoupled (e.g., just positive) or co-occur (both positive and negative, Uchino et al., 2001). We have argued that social network members can be classified as either being socially supportive (i.e., high positivity/low negativity), aversive (i.e., low positivity/high negativity), or indifferent (i.e., low in both positivity/negativity). A unique aspect of Figure 1 made salient by our framework is represented in the high positivity / high negativity cell and represents a network member who is a source of both positivity and negativity (ambivalence). For instance, conflict with close family members in which socialization processes or past supportive interactions dictate a positive relationship might result in strong perceptions of ambivalence in these relationships. Figure 1 A general framework for examining positive and negative aspects of relationships on health. Our prior work is consistent with the possibility that despite the positivity in such ambivalent ties, they appear to be related to worse health outcomes. We have argued that such ambivalent ties are harmful because they tend to be unpredictable and hence associated with increased interpersonal stress (Uchino, Holt-Lunstad, Uno, Campo, & Reblin, 2007). Consistent with this reasoning, such ambivalent ties are related to increased cardiovascular reactivity (Holt-Lunstad et al., 2007; Reblin, Uchino, & Smith, 2010) and higher ABP during daily life (Holt-Lunstad, Uchino, & Smith, Cerny, & Nealey-Moore, 2003). Moreover, individuals who are sources of ambivalence tend to make-up close to half of important social network members so there is ample opportunity for such ties to broadly influence health-relevant outcomes (Campo et al., 2009). In the present study, we thus predicted that the number of ambivalent network ties would be related to shorter telomeres. Consistent with the health benefits of support, we also predicted that the number of supportive ties would be related to longer telomeres. Aversive and indifferent ties were not predicted to be linked to telomeres given their low prevalence and / or limited influence (Campo et al., 2009). We also examined if any of these links were independent of other psychosocial factors previously associated with telomere length (e.g., perceived stress; Epel et al., 2004). A related aim of this study was to examine the moderation of these predicted associations via the demographic factors of age and gender. Age is of interest because it has implications for the processes underlying any associations. Consistent with an age-related difference in disease risk, age is related to shorter telomeres (Frenck, Blackburn, & Shannon, 1998; Iwama et al., 1997). Thus, if age moderates these links, it suggests a developmental process by which over time these ties cumulatively impact on cellular aging. Alternatively, it could indicate that older adults are more sensitive or influenced by these relationship processes (Kiecolt-Glaser & Glaser, 2001). However, the lack of moderation via age suggests that these processes have an impact on cellular aging regardless of the stage of the lifespan. A second potentially important moderator is gender. In an early review of relationships and mortality, Shumaker and Hill (1989) argued that women are more likely to be negatively influenced by being socially integrated because it can result in greater role strain or conflict. The self-esteem of women also appears to be more contingent on satisfactory relationships due to self-representations that overlap with close others (Cambron, Acitelli, & Pettit, 2009). As a result, women may be more reactive to conflict in close relationships compared to men (Beals & Rook, 2006; Kiecolt-Glaser & Newton, 2001). It would thus follow that links between relationship processes and cellular aging might be stronger in women compared to men.