Link Between Social Isolation, Loneliness, and Cardiovascular Mortality

 Effects of Objective and Perceived Social Isolation on Cardiovascular and Brain Health: A Scientific Statement from the American Heart Association

Background

Social isolation, the relative absence or infrequency of contact with different types of social relationships, and loneliness (perceived isolation) are associated with adverse health outcomes.

Aim

To review observational and intervention research examining the impact of social isolation and loneliness on cardiovascular and brain health and discuss proposed mechanisms for the observed associations.

Methods

We conducted a systematic review of the scope of available research. Four databases were searched: PubMed, PsycInfo, Cumulative Index of Nursing and Allied Health, and Scopus.

Results

The evidence is most consistent for a direct association between social isolation, loneliness, and coronary heart disease and stroke mortality. However, data on the association between social isolation and loneliness with heart failure, dementia, and cognitive decline are scarce and less robust.

Few studies have empirically tested the mediating pathways between social isolation, loneliness, and cardiovascular and brain health outcomes using methods appropriate for explanatory analyses. In particular, the effect estimates are small and there may be unmeasured confounders of the associations.

 Research on groups that may be at higher risk or more vulnerable to the effects of social isolation is limited. We found no intervention studies that sought to reduce the adverse impact of social isolation or loneliness on cardiovascular or brain health outcomes.

Psychological factors

Psychological factors, such as depression, have also been associated with both loneliness and social isolation; however, associations with loneliness may be stronger. Data from 2 population-based studies of adults showed that loneliness (assessed by the University of California Los Angeles Loneliness Scale and the 4-item Seeman and Syme Loneliness Scale ) was significantly associated with depressive symptoms (β, 0 .33–0.44; P < 0.05) in multivariable analyzes adjusted for demographic factors, behavioral factors, and medical history. However, in these same studies, the multivariable association between social isolation and depressive symptoms was weak (β, -0.11 to -0.07; P < 0.05); Both studies used the Lubben Social Network Scale to assess social isolation.

Cross-sectional data from the Swiss Health Survey (N = 20,007) suggest that loneliness is associated with moderate and high psychological distress, depressive symptoms, and impaired self-rated health. In another study, depressive symptoms and physical activity largely explained the association between loneliness and all-cause and CVD mortality. In particular, social isolation and depressive symptoms tend to be grouped together in the prognostic literature.

A study of 292 women with established CHD found that patients with social isolation (condensed version of the Social Interaction Interview Schedule) and depressive symptoms, compared with those who had neither, were more likely to have heart disease recurrent coronary artery disease (cardiovascular death, recurrent acute myocardial infarction, or revascularization) regardless of cardiac risk factors.

Physiological Factors (Stress Response, Allostatic Load, Inflammatory)

Data on the impact of social isolation or loneliness on biomarkers of cardiovascular health are limited and may vary depending on individual biomarkers. A recent systematic review and meta-analysis examined the association between loneliness, social isolation, and inflammatory biomarkers. Although 14 studies on loneliness and 16 studies on social isolation were identified in this review, each varied in the biomarkers evaluated, limiting the robustness of the pooled estimates.

Overall, loneliness demonstrated a significant positive correlation with IL-6 (interleukin-6), but not with CRP (C-reactive protein) or fibrinogen. In contrast, social isolation demonstrated a significant positive correlation with CRP and fibrinogen, but not with IL-6. Few studies have examined the longitudinal relationship between loneliness and social isolation with cardiovascular risk biomarkers, and results have been inconsistent.

Social isolation (composite of marital status, contact with friends/family, religious affiliation, and religious/community participation) has been associated with elevated levels of CRP and CHD mortality, although individual measures within the social isolation composite were not statistically significant. . , suggesting an additive or compound effect of indicators of social integration. Several studies noted that loneliness was associated with short sleep duration and poor sleep quality among adults.

High-quality evidence from multiple systematic reviews demonstrates a negative association between social connectedness and allostatic load or body wear and tear accumulated through repeated exposure to chronic stress. Measures of allostatic load include neuroendocrine and cardiovascular biomarkers, as well as inflammatory markers. Data from a review of multiple studies clearly demonstrate that the more socially connected individuals are, the less likely they are to experience physiological manifestations of chronic stress, known as allostatic load .

Socioeconomic status and quality of social connections are important moderators of this association. Meanwhile, individual studies suggest that marital status (an indicator of social isolation), specifically being widowed or single, may be independently associated with coronary artery calcium scores.

In summary, studies explicitly testing mediating pathways between social isolation, loneliness, and CVD are scarce and equivocal. Most studies do not use path analysis or causal mediation methods that are more appropriate than standard regression techniques for examining explanatory paths. This gap is important because it is not possible to control for confounding of the exposure-mediator association as well as the outcome-exposure directly using standard regression-based mediation analyses. Of the studies we reviewed, one study found, using standard regression techniques, that unhealthy behaviors and comorbidities mediate 21% of the association between social isolation and mortality.

Furthermore, some of the potential mediators, such as health behaviors and depression, could also be confounders, and there may be unmeasured confounders that are associated with both the exposure and the outcome. These unmeasured confounders could lead to a spurious association between social isolation or loneliness and our outcomes of interest.

Conclusions

Social isolation and loneliness are common, but underrecognized, determinants of cardiovascular health and brain health. Overall, the findings suggest a higher risk of worse outcomes among people with prevalent CHD and stroke in those who are also socially isolated or alone; However, these studies do not suggest causality, and the associations may be mediated by other factors that need to be further tested in intervention trials.

Data on the association of social isolation and loneliness with incident cardiovascular disease, heart failure, dementia, and cognitive impairment are scarce and mixed. No published interventions have been tested to mitigate the adverse impact of social isolation and loneliness on cardiovascular and brain health, making it difficult to identify implications for future clinical practice. Although the Institute of Medicine recommended that data on social isolation and loneliness be included in electronic health records, this practice is still evolving and is not widely adopted.

Comments

Social isolation and loneliness are associated with a 30% increase in the risk of suffering a heart attack or stroke, or dying from any of these causes, according to a new scientific statement from the American Heart Association published in the Journal of the American Heart Association , an open access, peer-reviewed journal. The statement also notes the lack of data about interventions that can improve cardiovascular health in socially isolated or lonely people.

“More than four decades of research has clearly shown that both social isolation and loneliness are associated with adverse health outcomes,” said Crystal Wiley Cené, MD, MPH, FAHA, chair of the scientific statement writing group and professor of clinical medicine and administrative director of health equity, diversity and inclusion at the University of California, San Diego Health. “Given the prevalence of social disconnection across the US, the impact on public health is quite significant.”

The risk of social isolation increases with age due to life factors such as widowhood and retirement. Nearly a quarter of American adults aged 65 and older are socially isolated and the prevalence of loneliness is even higher, with estimates of 22% to 47%. However, younger adults also experience social isolation and loneliness. A survey by Harvard University’s Making Caring Common project describes “Generation Z” (adults between the ages of 18 and 22 today) as the loneliest generation. The increase in isolation and loneliness among younger adults can be attributed to increased use of social media and decreased participation in meaningful in-person activities.

Data also indicates that social isolation and loneliness may have increased during the COVID-19 pandemic, particularly among young adults ages 18 to 25, older adults, women, and low-income people.

• Social isolation is defined as having infrequent face-to-face contact with people in terms of social relationships, such as with family, friends, or members of the same community or religious group.
   
• Loneliness occurs when you feel like you are alone or have less connection with other people than you would like . “Although social isolation and the feeling of loneliness are related, they are not the same ,” explains Cené. “People can lead a relatively isolated life and not feel lonely, and, conversely, people with many social contacts can still experience loneliness.”

The writing group reviewed social isolation research published through July 2021 to examine the relationship between social isolation and cardiovascular and brain health. This is what they discovered:

Social isolation and loneliness are common, yet underrecognized, determinants of cardiovascular and brain health.

Lack of social connection is associated with a higher risk of premature death from all causes, especially among men.

Isolation and loneliness are associated with elevated inflammatory markers, and individuals who were less socially connected were more likely to experience physiological symptoms of chronic stress.

In assessing risk factors for social isolation, the relationship between social isolation and its risk factors goes in both directions: depression can lead to social isolation, and social isolation can increase the likelihood of depression.

Social isolation during childhood is associated with an increase in cardiovascular risk factors in adulthood, such as obesity, high blood pressure and increased blood glucose levels.

Socio-environmental factors , such as transportation, housing, dissatisfaction with family relationships, the pandemic, and natural disasters, are also factors that affect social connections.

“There is strong evidence linking social isolation and loneliness with an increased risk of worse overall heart and brain health; however, data on the association with certain outcomes, such as heart failure, dementia, and cognitive decline, are scarce,” Cené said.

The evidence is more consistent regarding the relationship between social isolation, loneliness and death from heart disease and stroke, with a 29% increase in the risk of myocardial infarction or death from heart disease and a 32% increase % in the risk of stroke and stroke death. “Social isolation and loneliness are also associated with a worse prognosis in people who already have coronary heart disease or stroke,” Cené added.

People with heart disease who were socially isolated had a two- to threefold increase in death during a six-year follow-up study. Socially isolated adults, with three or fewer social contacts per month, may have a 40% increased risk of suffering a stroke or recurrent myocardial infarction.

Additionally, 5-year heart failure survival rates were lower (60%) for people who were socially isolated and for people who are both socially isolated and clinically depressed ( 62%), compared to those who have more social contacts and are not depressed (79%).

Social isolation and loneliness are also associated with behaviors that negatively affect cardiovascular and brain health, such as lower levels of self-reported physical activity, less fruit and vegetable consumption, and more sedentary time. Several large studies found significant associations between loneliness and an increased likelihood of smoking.

“There is an urgent need to develop, implement and evaluate programs and strategies to reduce the negative effects of social isolation and loneliness on cardiovascular and brain health, especially for at-risk populations,” Cené said. “Physicians should ask patients about the frequency of their social activity and whether they are satisfied with their level of interaction with friends and family. “Then, they should be prepared to refer socially isolated or lonely people, especially those with a history of heart disease or stroke, to community resources to help them connect with others.”

Some populations are more vulnerable to social isolation and loneliness, and more research is needed to understand how social isolation affects cardiovascular and brain health in these groups, including children and young adults, people from underrepresented racial and ethnic groups , lesbian, gay, bisexual, transgender, and queer (LGBTQ) people, people with physical disabilities, people with hearing or vision impairments, people living in rural areas and in communities with few resources, people with limited access to technology and Internet service, recent immigrants, and incarcerated people.

The review highlights research among older adults with the aim of reducing social isolation and loneliness. These studies found that fitness programs and recreational activities in senior centers, as well as interventions that address negative self-esteem and other negative thoughts, have shown promise in reducing isolation and loneliness.

The review did not identify any research aimed at reducing social isolation with the specific aim of improving cardiovascular health.

“It is not clear whether actually being isolated (social isolation) or feeling isolated (loneliness) is most important for cardiovascular and brain health, because only a few studies have examined both in the same sample,” Cené said. “More research is needed to examine the relationships between social isolation, loneliness, coronary heart disease, stroke, dementia, and cognitive decline, and to better understand the mechanisms by which social isolation and loneliness influence cardiovascular and brain health outcomes.

The voluntary writing group prepared this scientific statement on behalf of the Social Determinants of Health Committee of the Council on Epidemiology and Prevention and the Council on Quality of Care and Outcomes Research; the Prevention Science Committee of the Council on Epidemiology and Prevention and the Council on Quality of Care and Outcomes Research; the Prevention Science Committee of the Council on Epidemiology and Prevention and the Council on Cardiovascular and Stroke Nursing; the Council on Arteriosclerosis, Thrombosis and Vascular Biology; and the Stroke Council of the American Heart Association.

Co-authors are Vice President Theresa M. Beckie, Ph.D., FAHA; Mario Sims, Ph.D., FAHA; Shakira F. Suglia, Sc.D., MS, FAHA; Brooke Aggarwal, Ed.D., MS, FAHA; Nathalie Moise, MD; Monik C. Jiménez, SM, Sc.D., FAHA; Bamba Gaye, Ph.D.; and Louise D. McCullough, MD, Ph.D.