Social isolation, loneliness may drive risk for fatal or nonfatal MI, stroke
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Social isolation and loneliness are common and underrecognized determinants of CV and brain health, and more research is needed to understand causal pathways and interventions, according to a new scientific statement.
“Over 4 decades of research has clearly demonstrated that social isolation and loneliness are both associated with adverse health outcomes,” Crystal W. Cene, MD, MPH, FAHA, professor of clinical medicine and chief administrative officer for health equity, diversity and inclusion at the University of California San Diego Health and chair of the writing group for the American Heart Association scientific statement, said in a press release. “Given the prevalence of social disconnectedness across the U.S., the public health impact is quite significant.”
Social isolation is defined as the objective state of having few or infrequent social contacts, whereas loneliness is perceived isolation that is distressing for the individual, the statement notes. The two terms, while related, are distinct, have different pathways and unique downstream effects on health.
“Individuals can lead a relatively isolated life and not feel lonely; conversely, individuals with many social contacts may still experience loneliness,” the researchers wrote. “Both social isolation and loneliness denote some degree of social disconnection.”
Data on some outcomes ‘less robust’
In a systematic scoping review, Cene and colleagues reviewed observational and intervention research examining the impact of social isolation and loneliness on CV and brain health, discussing proposed mechanisms for observed associations.
The researchers found that evidence is most consistent for a direct association between social isolation, loneliness, and CHD and stroke mortality. However, data on the association between social isolation and loneliness with HF, dementia and cognitive impairment are sparse and less robust.
“Even where associations were found, after adjusting for factors that are presumed to be on the causal pathway, the effect sizes are on the order of 1 to 1.5, which is comparable to recognized psychosocial factors, including depression and anxiety,” the researchers wrote.
The evidence is most consistent for an association among social isolation, loneliness and death from heart disease and stroke, with a 29% increase in risk for MI and/or CV death and a 32% increased risk for stroke and stroke death, according to the researchers.
“Social isolation and loneliness are also associated with worse prognosis in individuals who already have coronary heart disease or stroke,” Cené said in the release.
The researchers found that socially isolated adults with three or fewer social contacts per month may have a 40% increased risk for recurrent stroke or MI, as well as lower 5-year HF survival rate compared with those who have more social contacts.
More data needed on diverse groups
The statement also notes that the effects may be underestimated because of underrepresentation or loss to follow-up in longitudinal studies of individuals and groups who may be at higher risk for both social isolation and CVD, such as people from underrepresented racial and ethnic groups; those with multiple chronic conditions and those with lower levels of education, income, wealth or social status, such as immigrants or incarcerated people.
The researchers also noted that it is unclear whether social isolation or loneliness matters most for CV and brain health, as few studies examined both in the same sample.
“More research is needed to examine the associations among social isolation, loneliness, coronary heart disease, stroke, dementia and cognitive impairment, and to better understand the mechanisms by which social isolation and loneliness influence cardiovascular and brain health outcomes,” Cene said in the release.
Researchers also did not find any intervention studies that sought to reduce the adverse impact of social isolation or loneliness on CV or brain health outcomes.
“Overall, findings suggest an increased risk of worse outcomes among individuals with prevalent CHD and stroke in those who are also socially isolated or lonely; however, these studies do not suggest causality, and associations may be mediated by other factors that need to be further tested in intervention trials,” the researchers wrote.
The statement follows recent research suggesting that social isolation and loneliness increases CV risk. As Healio previously reported, social isolation and loneliness are independently associated with an 11% to 16% higher risk for CVD among older women, with overall CVD risk was highest for women who had high social isolation and high loneliness.
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