Social Isolation and Loneliness Increase the Risk of Dying From a Heart Attack or Stroke, as Well as Developing Dementia

New research led by Florida State University College of Medicine has quantified the link between loneliness and dementia by analyzing data from more than 600,000 people around the world – the largest study of its kind. The meta-analysis of 21 longitudinal studies found that experiencing loneliness increased the risk of developing dementia by 31%. The research results were published in Nature Mental Health.

How Loneliness and Cognitive Impairment are Linked

These results are not surprising, as there is a growing body of evidence linking loneliness to poor health outcomes,” said assistant professor Martina Luchetti, who led the study. Dementia is a spectrum with neuropathological changes that begin decades before the clinical onset. It is important to further investigate the link between loneliness and various cognitive outcomes or symptoms in this spectrum. Loneliness – dissatisfaction with social relationships – can impact cognitive performance and daily living. The analysis found loneliness to be a major risk factor for cognitive impairment, regardless of age or gender. It also linked loneliness to specific causes of dementia, such as Alzheimer’s disease, and cognitive impairment that can occur before a diagnosis. The team’s work was advanced by the World Health Organization and the U.S. Surgeon General, who declared loneliness a public health crisis in the wake of the COVID-19 pandemic and associated social restrictions.

It is important to understand why and under what circumstances loneliness increases the risk of dementia in old age. Although the data for the study included subjects from around the world, most were collected from people in more affluent cultures in the Western Hemisphere. Future research should include more data from other countries, Luchetti said. Dementia cases are increasing in low-income countries. Future studies need to collect more data from these countries to assess the impact of loneliness in different national and cultural contexts. The results of the meta-analysis provide information that can be used to guide future prevention and intervention efforts. Now that there is solid evidence of a link, the researchers say it is crucial to identify the causes of loneliness in order to prevent or manage it and promote the well-being and cognitive health of older adults.

Cardiovascular Health and Loneliness

Social isolation and loneliness don’t just affect the brain. In fact, they are also associated with a roughly 30% increased risk of heart attack or stroke or death from either of these conditions, according to a new scientific statement from the American Heart Association published in the Journal of the American Heart Association, a peer-reviewed, open-access journal of the American Heart Association. The statement also highlights the lack of data on interventions that could improve the cardiovascular health of people who are socially isolated or lonely.

“Over four decades of research have unequivocally demonstrated that social isolation and loneliness are associated with adverse health outcomes,” said Crystal Wiley Cené, M.D., M.P.H., FAHA, chair of the scientific statement working group and professor of clinical medicine and chief administrative officer for health equity, diversity and inclusion at the University of California San Diego Health. The risk of social isolation increases with age due to life events such as widowhood and retirement. Nearly one-quarter of adults aged 65 and older are socially isolated, and the prevalence of loneliness is even higher, with estimates ranging from 22% to 47%. However, younger adults also suffer from social isolation and loneliness. A survey by Harvard University’s Making Caring Common project describes “Generation Z” (adults aged 18 to 22) as the loneliest generation. The increasing isolation and loneliness of younger adults can be traced to their increased use of social media and less involvement in meaningful in-person activities.

Relationship Between Social Isolation and Heart and Brain Health

The data also suggest that social isolation and loneliness may have increased during the COVID-19 pandemic, particularly among young adults aged 18 to 25, older adults, women, and those with lower incomes. Social isolation is defined as having infrequent face-to-face contact with people for social relationships, such as family, friends, or members of the same community or religious group. Loneliness means feeling alone or having fewer connections with others than one would like. The writing group reviewed research on social isolation published through July 2021 to examine the association between social isolation and heart and brain health. They found that

• Social isolation and loneliness are common but underrecognized contributors to cardiovascular and brain health.
• Lack of social ties is associated with increased risk of premature death from all causes, especially in men.
• Isolation and loneliness are associated with increased inflammatory markers, and individuals who were less socially connected were more likely to show physiological symptoms of chronic stress.
• When assessing risk factors for social isolation, the relationship between social isolation and its risk factors goes both ways: depression can lead to social isolation, and social isolation can increase the likelihood of developing depression.
• Social isolation in childhood is associated with increased cardiovascular risk factors in adulthood, such as obesity, high blood pressure and elevated blood sugar levels.

Socio-economic factors, including transportation, housing, dissatisfaction with family relationships, the pandemic and natural disasters, are also factors that influence social ties. There is strong evidence, according to the researchers, that social isolation and loneliness are associated with increased risk of poorer heart and brain health in general; however, data on the association with specific outcomes such as heart failure, dementia and cognitive impairment is scant. The strongest evidence is for an association between social isolation, loneliness and death from cardiovascular disease and stroke, with a 29% increased risk of heart attack and/or death from cardiovascular disease and a 32% increased risk of stroke and death from stroke. Social isolation and loneliness are also associated with a poorer prognosis in individuals who already suffer from coronary heart disease or a stroke.

During a six-year follow-up study, people with heart disease who were socially isolated had a two- to three-fold increased risk of death. Socially isolated adults who have three or fewer social contacts per month may have a 40% increased risk of recurrent stroke or heart attack. Furthermore, five-year heart failure survival rates were lower (60%) among people who were socially isolated and those who were both socially isolated and clinically depressed (62%) than among people who had more social connections and were not depressed (79%). Social isolation and loneliness are also associated with behaviors that negatively impact cardiovascular and brain health, such as lower self-reported physical activity, less fruit and vegetable consumption, and more sedentary behavior. Several large studies have found a significant association between loneliness and a higher likelihood of smoking.

Further Research Needed

According to the researchers, 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 groups. Doctors should ask their patients about the frequency of their social activities and whether they are satisfied with the level of their interactions with friends and family. They should then be prepared to refer people who are socially isolated or lonely – especially those with a history of heart disease or stroke – to community agencies 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. The review highlights research conducted with older adults that aims to reduce 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, show promise for reducing isolation and loneliness. The review did not identify any research that aimed to reduce social isolation with the specific goal of improving cardiovascular health.

It is unclear whether what matters most for cardiovascular and brain health is actually being isolated (social isolation) or feeling isolated (loneliness), as few studies have examined both in the same sample. According to the researchers, further research is needed to explore the links between social isolation, loneliness, coronary heart disease, stroke, dementia and cognitive impairment, and to better understand the mechanisms by which social isolation and loneliness affect cardiovascular and brain health outcomes.