Julianne Holt-Lunstad

Loneliness and Social Isolation as Risk Factors for Mortality A Meta-Analytic Review

Actual and perceived social isolation are both associated with increased risk for early mortality. In this meta-analytic review, our objective is to establish the overall and relative magnitude of social isolation and loneliness and to examine possible moderators. We conducted a literature search of studies (January 1980 to February 2014) using MEDLINE, CINAHL, PsycINFO, Social Work Abstracts, and Google Scholar. The included studies provided quantitative data on mortality as affected by loneliness, social isolation, or living alone. Across studies in which several possible confounds were statistically controlled for, the weighted average effect sizes were as follows: social isolation odds ratio (OR) = 1.29, loneliness OR = 1.26, and living alone OR = 1.32, corresponding to an average of 29%, 26%, and 32% increased likelihood of mortality, respectively. We found no differences between measures of objective and subjective social isolation. Results remain consistent across gender, length of follow-up, and world region, but initial health status has an influence on the findings. Results also differ across participant age, with social deficits being more predictive of death in samples with an average age younger than 65 years. Overall, the influence of both objective and subjective social isolation on risk for mortality is comparable with well-established risk factors for mortality.

Is There Something Unique about Marriage? The Relative Impact of Marital Status, Relationship Quality, and Network Social Support on Ambulatory Blood Pressure and Mental Health

BackgroundHaving close social relationships and being married specifically have been reliably associated with health benefits including lower morbidity and mortality.PurposeThe purpose of this study was to examine the influence of marital status, relationship quality, and network support on measures of psychological and cardiovascular health.MethodWe examined ambulatory blood pressure (ABP) among 204 married and 99 single males and females (N = 303).ResultsWe found that both marital status and marital quality were important. Married individuals had greater satisfaction with life (SWL) and blood pressure dipping than single individuals. High marital quality was associated with lower ABP, lower stress, less depression, and higher SWL. Importantly, contrasting those who are unmarried with those in low-quality marriages, we find that single individuals had lower ABP—suggesting that single individuals fare better than their unhappily married counterparts. Likewise, having a supportive network did not moderate (i.e., buffer) the effects of being single or unhappily married.ConclusionsFindings indicate being married per se is not universally beneficial, rather, the satisfaction and support associated with such a relationship is important. However, marriage may be distinctive, as evidence further suggests that support from one’s network does not compensate for the effect of being single. These results highlight the complexities in understanding the influence of social relationships on long-term health, and they may help clarify the physiological pathways by which such associations exist.

Influence of a "Warm Touch" Support Enhancement Intervention Among Married Couples on Ambulatory Blood Pressure, Oxytocin, Alpha Amylase, and Cortisol

Objective: To investigate whether a support intervention (warm touch enhancement) influences physiological stress systems that are linked to important health outcomes. Growing evidence points to a protective effect of social and emotional support on both morbidity and mortality. Methods: In this study, 34 healthy married couples (n = 68), aged 20 to 39 years (mean = 25.2 years), were randomly assigned to a “behavior monitoring” control group or participated in a 4-week intervention study in which clinic levels of plasma oxytocin, 24-hour ambulatory blood pressure, and salivary cortisol and alpha amylase were obtained pre and post intervention, at the same time salivary oxytocin was taken at home during weeks 1 and 4. Results: Salivary oxytocin was enhanced both early and late in the intervention group and alpha amylase was reduced at post treatment in intervention group husbands and wives relative to controls. Husbands in the intervention group had significantly lower post treatment 24-hour systolic blood pressure than the control group. Conclusion: Increasing warm touch among couples has a beneficial influence on multiple stress-sensitive systems. BP = blood pressure; ABP = ambulatory blood pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; OT = oxytocin; HPA = hypothalamic-pituitary adrenocortical; SNS = sympathetic nervous system; AUC = area under the curve.

Social Support, Physiological Processes, and Health

Social relationships serve important functions in peoples everyday lives. Epidemiological research indicates that supportive relationships may also significantly protect individuals from various causes of mortality, including cardiovascular disease. An important issue is how social support influences such long-term health outcomes. In this article, we review evidence indicating that social support may influence mortality via changes in the cardiovascular, endocrine, and immune systems. These data suggest that it may be worthwhile to incorporate social-support interventions in the prevention and treatment of physical health problems.

Heterogeneity in the social networks of young and older adults: prediction of mental health and cardiovascular reactivity during acute stress.

We examined the utility of a broad framework that separated positive, negative, and ambivalent social network members. One hundred thirty-three young and older participants completed the social relationships index, measures of mental health, and a cardiovascular reactivity protocol. Results replicated prior research on the beneficial influence of positive (supportive) ties on psychological outcomes. More important, analyses also revealed that the number of ambivalent network ties predicted age-related differences in depression and sympathetic control of heart rate reactivity during stress. The statistical interactions between age and ambivalent ties on cardiovascular responses during stress were not changed when statistically controlling for other social network categories, demographic variables, and various personality factors. These data suggest that social network ambivalence was a relatively unique predictor of cardiovascular reactivity and highlight the utility of separating the variance due to positive, negative, and ambivalent network ties. Implications for the study of social relationships, physiological processes, and health outcomes are also discussed.

Social Relationships and Ambulatory Blood Pressure: Structural and Qualitative Predictors of Cardiovascular Function During Everyday Social Interactions

Healthy normotensive men and women (N = 102) underwent a 3-day ambulatory blood pressure (BP) assessment in which a BP reading was taken 5 min into each social interaction. After each interaction, participants completed a diary that included structural categorization of the relationship and ratings of the quality of the relationship with the interaction partner. Random regression analyses revealed that interactions with family members and spouses were associated with lower ambulatory BP. Interactions with ambivalent network members (characterized by both positive and negative feelings) were associated with the highest ambulatory systolic BP, an effect that was independent of the familial effects on BP. Although there were psychological correlates associated with both structural and functional aspects of relationships, no evidence was found that these mediated the primary findings involving ambulatory BP. These data highlight the influence of both structural and qualitative aspects of relationships on ambulatory BP and possibly health.

On the importance of relationship quality: The impact of ambivalence in friendships on cardiovascular functioning

Background: Social relationships are reliably related to rates of morbidity and mortality. One pathway by which social relationships may influence health is via the impact of relationship quality on cardiovascular reactivity during social interactions.Purpose and Method: This study examined the effects of the quality of a friendship on cardiovascular reactivity when speaking about positive or negative life events with an ambivalent or supportive friend. To examine this, 107 healthy male and female adults (and their same-sex friend) were recruited.Results: Results revealed that participants exhibited the greatest levels of systolic blood pressure reactivity when discussing a negative event with an ambivalent friend compared to a supportive friend. We also found higher resting levels of heart rate and lower respiratory sinus arrhythmia among those who brought in ambivalent friends than those who brought in supportive friends.Conclusion: Individuals may not be able to fully relax in the presence of ambivalent friends and may not benefit from support during stress. This research may help clarify the health-related consequences of differing types of social relationships.

Aging and cardiovascular reactivity to stress: longitudinal evidence for changes in stress reactivity.

Although age differences in cardiovascular function are well documented, little research has provided longitudinal evidence for age-related changes in cardiovascular reactivity to stress. In this study, the authors report such data from a follow-up of their prior work (B. N. Uchino, D. Uno, J. Holt-Lunstad, & J. B. Flinders, 1999) with participants between the ages of 30 to 70 (n=108, mean follow-up=10 months, range=7 to 16 months). Results revealed longitudinal evidence for an age-related increase in systolic blood-pressure reactivity and parasympathetic withdrawal to acute stress. The implications of these findings are discussed in light of the increased cardiovascular disease risk with age, as well as the links between aging, emotions, and physiology.

Maternal Defense Breast Feeding Increases Aggression by Reducing Stress

Mothers in numerous species exhibit heightened aggression in defense of their young. This shift typically coincides with the duration of lactation in nonhuman mammals, which suggests that human mothers may display similarly accentuated aggressiveness while breast feeding. Here we report the first behavioral evidence for heightened aggression in lactating humans. Breast-feeding mothers inflicted louder and longer punitive sound bursts on unduly aggressive confederates than did formula-feeding mothers or women who had never been pregnant. Maternal aggression in other mammals is thought to be facilitated by the buffering effect of lactation on stress responses. Consistent with the animal literature, our results showed that while lactating women were aggressing, they exhibited lower systolic blood pressure than did formula-feeding or never-pregnant women while they were aggressing. Mediation analyses indicated that reduced arousal during lactation may disinhibit female aggression. Together, our results highlight the contributions of breast feeding to both protecting infants and buffering maternal stress.

Diurnal cortisol variation is associated with nocturnal blood pressure dipping.

Objective: To investigate if diurnal cortisol variation is associated with nocturnal blood pressure (BP) dipping. Methods: In this study, 302 healthy adults (51% female; average age 31 years) underwent 24-hour ambulatory BP assessment with BP measured randomly approximately every 20 minutes during waking hours and every hour during sleep. Salivary cortisol was obtained at five time points. Cortisol and BP have natural diurnal variations and disruptions in these diurnal variations are related to pathological conditions, such as greater risk for cardiovascular disease. A lack of a drop in cortisol from day to night and a lack of a drop in BP from waking to sleeping have both been associated with negative outcomes. It is not known, however, if diurnal variations in cortisol and BP are related, or if changes in cortisol from day to night influence BP dipping. Results: Diurnal cortisol variation was a significant predictor of BP dipping. Controlling for gender, body mass index, age, phase of menstrual cycle, sleep quality, morning cortisol, and daytime measures of the relevant cardiovascular assessments did not significantly affect the results. Cortisol variation was found to have a stronger relationship with BP dipping than any of the covariates measured. Conclusion: Decreased diurnal variation in cortisol is associated with decreased diurnal variation in BP. Future studies could benefit from examining how these two variables interact in predicting disease outcomes. BP = blood pressure; SBP = systolic blood pressure; DBP = diastolic blood pressure; SES = socioeconomic status; HPA = hypothalamic-pituitary adrenalcortical; BMI = body mass index; AUC = area under the curve.