 death in people of all ages. Research is headed toward the systematic study of these processes across generations, Dr. Cacioppo explained.
Understanding the biology of loneliness
Losing a sense of connection and community changes a person’s perception of the world. Someone experiencing chronic loneliness feels threatened and mistrustful of others, which activates a biological defense mechanism, according to Steve Cole, Ph.D., director of the Social Genomics Core Laboratory at the University of California, Los Angeles. His NIA-funded research focuses on understanding the physiological pathways of loneliness (the different ways that loneliness affects how your mind and body function) and developing social and psychological interventions to combat it.
For example, loneliness may alter the tendency of cells in the immune system to promote inflammation, which is necessary to help our bodies heal from injury, Dr. Cole said. But inflammation that lasts too long increases the risk of chronic diseases.
Loneliness acts as a fertilizer for other diseases,” Dr. Cole said. “The biology of loneliness can accelerate the buildup of plaque in arteries, help cancer cells grow and spread, and promote inflammation in the brain leading to Alzheimer’s disease. Loneliness promotes several different types of wear and tear on the body.
People who feel lonely may also have weakened immune cells that have trouble fighting off viruses, which makes them more vulnerable to some infectious diseases, he added.
NIA-supported research by Dr. Cole and others shows that having a sense of mission and purpose in life is linked to healthier immune cells. Helping others through caregiving or volunteering also helps people feel less lonely.
“Working for a social cause or purpose with others who share your values and are trusted partners puts you in contact with others and helps develop a greater sense of community,” he noted.
Researching genetic and social determinants of loneliness
In another NIA-funded study, researchers are trying to understand the differences between social isolation and loneliness and how they may influence health. They are also trying to identify potential interactions between genes and the environment of older adults affected by social isolation and loneliness.
Previous studies have estimated the heritability of loneliness between 37 percent and 55 percent using twins and family-based approaches. “Individuals who are not prone genetically to feeling lonely may, for example, suffer much less from social isolation, while others feel lonely even though they are surrounded and part of a rich social life,” according to Nancy Pedersen, Ph.D., a professor of genetic epidemiology at the Karolinska Institutet in Stockholm, Sweden. “We are also interested in understanding what role socioeconomic status plays in such associations.”
Using data from twin studies, Dr. Pedersen and researchers found that both social isolation and loneliness are independent risk factors, and that genetic risk for loneliness significantly predicted the presentation of cardiovascular, psychiatric (major depressive disorder), and metabolic traits. Family history does not strongly influence this effect.
“We need to identify people who are most prone to suffer from social isolation and loneliness and those who would benefit most from interventions,” said Dr. Pedersen. “Interventions for social isolation may look very different from interventions for those who feel lonely.”
Beyond genetics, understanding social determinants of health, and the role of social and interpersonal processes in healthy aging and longevity, is another research direction at NIH. Scientists are beginning to apply this framework to research on social isolation and loneliness.
“Future research will need to clarify the extent to which loneliness and social isolation are malleable, and if so, what are the most effective approaches? Demonstrating that we can move the needle on these risk factors is a critical first step toward developing effective interventions,” said Dr. Nielsen. Research is also needed t