Social isolation among older adults linked to having fewer teeth

"Our study suggests that maintaining and improving social connections may benefit the oral health of older adults," said Xiang Qi, a PhD student at NYU Meyers and the study's first author. "The findings align with previous studies demonstrating that structural indicators of social disconnection can have powerful effects on indicators of health and well-being."

Social isolation and loneliness in older adults are major public health concerns around the world and are risk factors for heart disease, mental health disorders, cognitive decline, and premature death. In some countries, including the United States and China, up to one in three older adults are lonely, according to the World Health Organization. The COVID-19 pandemic has exacerbated these issues among older adults, as many in-person interactions have been interrupted to protect older adults from infection.

Social isolation and loneliness are related but different. Social isolation is an objective measure defined as having few social relationships or infrequent social contact with others, while loneliness is the feeling created by a lack of social connection.

"While social isolation and loneliness often go hand in hand, it's possible to live alone and be socially isolated but to not feel lonely, or to be surrounded by people but still feel lonely," said Bei Wu, Dean's Professor in Global Health at NYU Meyers and the study's senior author.

Older adults are also at risk for another health concern: losing teeth. In China, older adults aged 65 to 74 have fewer than 23 teeth on average (adults typically have 32 teeth, or 28 if wisdom teeth have been removed) and 4.5% of this age group has lost all of their teeth. Gum disease, smoking, lack of access to dental care, and chronic illnesses like diabetes and heart disease increase the risks of tooth loss. Missing teeth can have a significant impact on one's quality of life, affecting nutrition, speech, and self-esteem.

To understand the relationship between social isolation, loneliness, and tooth loss in older adults in China, the researchers used the Chinese Longitudinal Healthy Longevity Survey to analyze data from 4,268 adults aged 65 and up. The participants completed surveys at three different timepoints (2011-12, 2014, and 2018), which captured measures of social isolation and loneliness, how many teeth people had and lost over the 7-year study, and other factors. More than a quarter (27.5%) of the study participants were socially isolated, and 26.5% reported feeling lonely.

The researchers found that higher levels of social isolation were associated with having fewer teeth and losing teeth more quickly over time, even when controlling for other factors such as oral hygiene, health status, smoking and drinking, and loneliness. Older adults who were socially isolated had, on average, 2.1 fewer natural teeth and 1.4 times the rate of losing their teeth than those with stronger social ties.

"Socially isolated older adults tend to be less engaged in social and health-promoting behaviors like physical activity, which could have a negative impact on their overall functioning and oral hygiene, as well as increase their risk for systemic inflammation," said Wu. "This functional impairment seems to be a major pathway linking social isolation to tooth loss."

Surprisingly, loneliness was not associated with the number of remaining teeth, nor with the rate of tooth loss.

"While social isolation can result in a lack of support that can affect health behaviors, for older adults who feel lonely, it's possible that their social networks are still in place and can help them to keep up healthy behaviors," said Qi.

The findings -- which are relevant to countries beyond China, given that social isolation and tooth loss are global issues -- highlight the importance of developing interventions to reduce social isolation. Programs could aim to foster intergenerational support within families and improve older adults' peer and social connections within their local communities.

Additional study authors include Yaolin Pei of NYU Meyers, Katherine Wang of Duke University, and Shuyu Han of Fudan University in China. The research was supported by the National Institute on Aging (1R56AG067619) and the National Institute of Dental and Craniofacial Research (U01DE027512).