Why Loneliness Is More Than Just a Feeling

This post is by Joel Salinas, M.D., and medical student Amanda Zhao.

The COVID-19 pandemic has unfortunately forced our global community to become particularly and personally attuned to the issues of loneliness and social isolation, and it has disrupted all of our relationships and social networks. However, these issues may be even more serious than you think—our new study released this week demonstrates how loneliness can increase the risk of developing dementia.

Why should we understand loneliness?

Loneliness, defined as the subjective feeling that you are not receiving the level of social support that you want, is pervasive in American society—a survey of 950 US adults in October 2020 found that more than a third of respondents, including almost two-thirds of all young adults, felt “serious loneliness.” Other surveys estimate the prevalence of loneliness in older adults to be between 25 and 60%. However, the consequences of loneliness may extend beyond the emotional experience itself; a growing body of research has begun to document the physical and mental health repercussions of loneliness.

Loneliness isn’t just the perception of social isolation—it can kill.

One study found that loneliness and social isolation were associated with a higher risk of mortality. Higher ratings of loneliness have also been linked to higher blood pressures and greater and faster progression of coronary artery disease and heart failure. This link between loneliness and poorer heart health could be driven both by behavior (e.g., lonely people may practice less healthful behaviors) and by biology (e.g., loneliness may lead to an exaggerated stress response, leading to increased heart strain).

Other studies link loneliness to dysregulation of the body’s hormones. Lonely persons seem to have higher levels of cortisol, the body’s stress hormone, in their urine and saliva.

Loneliness also has many well-documented mental health consequences across the lifespan. A study of British children found a link between higher levels of early childhood loneliness and later-life depression; higher ratings of loneliness have been associated with lower cognitive performance in older adulthood as well as higher risk of dementia. Specifically, in our research, lower social and emotional support have been associated with less cognitive resilience and greater dementia risk, respectively. A recently published study from our lab finds that loneliness is linked with an increased 10-year risk of developing dementia, and this risk is tripled in individuals with low baseline risk of Alzheimer’s disease or other dementias.

What factors contribute to loneliness?

A recent Dutch study of more than 52,000 people spanning late adolescence to older age found that while some risk factors universally predicted loneliness across age groups (e.g., lower education, male sex, fewer financial resources, and informal caregiving roles), other risk factors are age-specific. Interestingly, in early adulthood, migration from non-Western areas was the second greatest risk factor for loneliness, which the study attributed to greater experiences of stigmatization and discrimination, leading to fewer intimate peer relationships.

Other studies also examine the prevalence of loneliness in the socially subordinated. A 2020 study of Medicare beneficiaries found that Hispanic/Latinx older adults are more likely than non-Hispanic whites to experience loneliness, and to experience the detrimental health effects from social isolation. Racial and ethnic minorities are already predisposed to poorer health outcomes for a variety of reasons; research shows that these disparities are even further compounded by loneliness. A study of low-income senior African Americans found that greater loneliness and perceived stress led to poorer physical health-related quality of life. A person’s race, ethnicity, or gender can affect their income and education, leading to differences in social network size and relationship quality, both of which contribute to their experience of loneliness.

Where does this leave us?

Loneliness is growing—and growing fast. It is a serious issue with serious mental and health repercussions. The factors that lead to loneliness are complex, varying across the lifespan and across different racial, ethnic, and demographic groups, and socially subordinated groups may be at particular risk, and as such, deserve further, dedicated intervention.

In this unpredictable pandemic world, loneliness and social isolation have unfortunately become the new normal, but we must fight against this. Reach out to your friends and family. Be a listener for someone in your life. Finding ways to safely connect with friends and family will continue to require effort, but we can, and will, get through this together.

At our lab, the UNICORN Lab, we hope to contribute to what is known about the health effects of loneliness, paying special attention to the interplay of race, ethnicity, and socioeconomic background in these effects. In particular, we are using biological markers and cutting-edge imaging techniques to learn how loneliness, and other elements of the social environment, may contribute to risk of developing Alzheimer’s disease and related dementias.