Social isolation increases risk for death, dementia in older adults

Key takeaways:

• Increased social isolation over 4 years was tied to increased risks for death, dementia and disability.
• Decreased social isolation lowered mortality risk in those not socially isolated at baseline.

Increased social isolation may be linked to greater risks for several adverse health outcomes in older adults, according to a study published in JAMA Network Open.

Previous research reported that social isolation and loneliness were associated with an increased risk for all-cause and cardiovascular disease-related mortality.

“The dynamic nature of mental health undergoes constant change,” Chen Lyu, MS, PhD, an associate research scientist at NYU Langone Medical Center, and colleagues wrote. “However, much of the existing research on social isolation relies on cross-sectional measurements, overlooking the association between changes in social isolation and subsequent health outcomes.”

In the current analysis, the researchers assessed associations between changes in social isolation and multiple health outcomes — including death, CVD, dementia, stroke and disability — within a sample of 13,649 respondents aged 50 years or older from the 2006 to 2020 Health and Retirement Study waves.

Study investigators measured isolation at baseline and changes in isolation using the Steptoe 5-item Social Isolation Index (SII).

“We defined each respondent’s baseline assessment as the year of their initial SII measurement, with the second SII measurement occurring 4 years after baseline,” Lyu and colleagues noted.

Changes in isolation were divided into three groups, with respondents categorized as having:

• increased isolation if their second SII measurement score increased by 1 unit or more;
• stable isolation if their second SII measurement score remained unchanged; and
• decreased isolation if their second SII measurement score decreased by 1 unit or more.

Lyu and colleagues found that among respondents socially isolated at baseline, those with increased isolation had higher mortality (incidence rate [IR] = 68.19 per 1,000 person-years; 95% CI, 60.89-76.36) than those who were stable (IR = 44.02; 95% CI, 40.47-47.88) or had decreased isolation (IR = 37.77; 95% CI, 34.73-41.09).

Compared with those who had stable isolation, researchers reported associations between increased isolation higher risk for mortality (adjusted HR = 1.29; 95% CI, 1.09-1.51), disability (aHR = 1.35; 95% CI, 1.09-1.67) and dementia (aHR = 1.4; 95% CI, 1.02-1.93).

These associations occurred regardless of the participant’s isolation status at baseline.

Further analysis showed an association between decreased isolation and lower risk for mortality (aHR = 0.73; 95% CI, 0.61-0.87) among those not socially isolated at baseline.

Lyu and colleagues wrote that there are several possible biological and psychological mechanisms behind the findings.

They pointed out that social isolation “can activate the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system, leading to behavioral alteration, such as physical inactivity, smoking, and disrupted sleep.”

They added social isolation can also result in decreased engagement in social activities, changes in dietary patterns, decreased physical activity and increased depression, anxiety and stress, “all of which can exacerbate its negative impact on health.”

Researchers identified multiple study limitations, including an inability to determine causality due to the study’s design and potential underestimation of outcome events.

Ultimately, the findings “suggest a need for interventions aimed at averting increases in isolation among older adults as a means to mitigate its adverse outcomes regarding mortality, as well as physical and cognitive function decline,” Lyu and colleagues concluded.