Recent research within the Proceedings of the National Academy of Sciences used a prospective cohort study to research the contribution of loneliness to excess deaths and mortality risk amongst middle-aged and older individuals residing in the USA. Their findings indicate a significantly higher risk of mortality for individuals who reported feeling lonely during three or more survey rounds.

Study: Association of cumulative loneliness with all-cause mortality amongst middle-aged and older adults in the USA, 1996 to 2019. Image Credit: sasirin pamai / Shutterstock

Background

A survey conducted in 2018 estimated that 27% of individuals between the ages of fifty and 80 felt isolated from others; in 2020, this proportion had greater than doubled to 56%, clearly exacerbated by the coronavirus pandemic. As of early 2023, it remained at pre-pandemic levels, at 34%.

Loneliness, which researchers have described because the gap between desired and actual social connection, can increase emotional stress, blood pressure, and the danger of heart disease while accelerating cognitive decline. Quite a few studies have also quantified the correlation between social isolation and mortality, including one which showed that lonely individuals have an increased risk of dying inside 30 days of nonelective surgery. Nevertheless, these studies measured loneliness at a single point or during a brief period.

This approach risks conflating intermittent loneliness, which may very well be followed by helpful coping strategies, with prolonged isolation resulting in chronic health conditions and associated mortality. Accounting for the dynamic and time-varying nature of loneliness and considering its cumulative impact is a very important step toward quantifying its long-term consequences and designing effective policies to alleviate them.

Concerning the study

The Health and Retirement Study (HRS) has followed a representative sample of Americans since 1992 through a longitudinal panel design, conducting surveys once every two years. During each survey round, participants were asked in the event that they felt lonely.

For this study, researchers restricted the HRS dataset to observations from 1996-2004 to measure the experience of loneliness and the period 2004-2019 to measure mortality. They included individuals who were no less than 50 years old in 1996 and were still alive in 2004 and excluded those with incomplete data on reported loneliness.

Cumulative loneliness was categorized as never, once, twice, thrice, or more. Deaths were confirmed by the next-of-kin and validated through the National Death Index. Potential confounding variables were included as controls, including sociodemographic characteristics like age, gender, race/ethnicity, marital status, education, employment, and household wealth.

Researchers also used data on how many individuals lived within the respondents’ households, what number of close friends and relatives lived of their neighborhoods, and the way often they socialized with neighbors to calculate an index of objective social isolation. They controlled for health-related aspects similar to depression, obesity, and comorbidity.

Considering these aspects, the adjusted association between cumulative loneliness and mortality was investigated by calculating a hazard ratio (HR) obtained from fitting an age-stratified Cox proportional hazards regression model.

Findings

The evaluation included 9032 participants with 93,684 observations in the shape of person-years between 2004 and 2019. In the beginning of the study, participants were 63.99 years old on average; 62.51 were women. They were followed for a median time of 10.37 years.

Younger people were less more likely to experience loneliness than their older counterparts, while women were more more likely to report feeling lonely than men. Being married, non-Hispanic White, employed with pay, and wealthy were also aspects related to lower loneliness. While 61.05% of respondents reported never feeling lonely, 11.84% were lonely during three or more survey rounds.

Researchers identified 106 excess deaths amongst those that felt lonely during one survey wave. Similarly, they noted 202 more deaths per 10,000 person-years than expected amongst those that reported two periods of loneliness and 288 for individuals who reported three or more. By way of mortality risk, those that reported loneliness three or more times were at 1.16 times higher risk of mortality throughout the study than those that had never been lonely. These findings were strengthened through robustness checks to rule out the opportunity of reverse causation and knowledge bias.

Conclusions

This study is among the many first to focus on the contribution of cumulative loneliness to mortality in middle-aged and older people, further establishing a dose-response association between the frequency of loneliness and mortality risk. Strengthening social networks, animal therapy, and physical activity are all promising interventions to minimize social isolation.

Addressing this public health issue and meaningfully improving the standard of life for a lot of could increase life expectancies and reduce excess deaths. Nevertheless, further investigation is required to substantiate these ends in other settings and populations.