Social isolation has a profound and increasingly negative impact on physical functioning in older adults

Researchers highlight the importance of incorporating strategies to reduce social isolation and promote successful aging, in the American Journal of Preventive Medicine

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Ann Arbor, May 11, 2021 - Social isolation among older adults is associated with poor health and premature mortality, but the connection between social isolation and physical functioning is poorly understood. New research generates more robust evidence about the associations between social isolation and physical functioning and how this accelerates over time, reports the American Journal of Preventive Medicine, published by Elsevier. It also highlights the importance of incorporating strategies to reduce social isolation and promote successful aging.

"Physical functioning is understood to influence the health of individuals. And social isolation is prevalent among older adults," explained lead investigator Borja del Pozo Cruz, PhD, Centre for Active and Healthy Ageing, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark. "However, the true extent of the relationship between social isolation and physical functioning was not fully understood. We needed to shed some more light on this relationship, as it plays an important role in individual aging."

As individuals age, physical functioning declines, which can result in a loss of functional independence, onset of disability, and increased mortality, with significant personal, community, and economic costs. Older adults who are socially integrated may be more likely to engage in physical activity, which would in turn elicit improvements in their physical functioning.

Social isolation is a significant problem facing the health and well-being of individuals across the life course. Individuals who are socially isolated are more likely to experience mental health problems, develop dementia, and have increased risk of premature mortality. Social isolation is particularly worrisome among older adults, with data from the United States indicating that one in four older adults is isolated or severely isolated. Given the worldwide trends in population aging, social isolation among older adults is likely to become an increasing burden in years to come.

To examine the longitudinal associations between social isolation and physical functioning, investigators used nine waves of panel data from 2011 to 2019 from the National Health and Aging Trends Study (NHATS), a large US-representative sample of adults 65 or older. This means that the results can be generalized to the US population of older adults. The study analyzed observations from 12,427 NHATS participants to measure how individual changes in social isolation were associated with individual changes in objectively assessed physical functioning. Social isolation was captured through the Social Isolation Index (SII). Physical functioning was assessed using the NHATS version of the Short Physical Performance Battery (SPPB). The analytic sample encompassed 54,860 observations, meaning that respondents were observed 4.41 times on average.

These findings add to a growing evidence base demonstrating the negative consequences of social isolation, specifically the acceleration of aging decline trajectories in physical functioning. Investigators were able to identify with a high degree of granularity how the association between social isolation and physical functioning shifts over old age and exacerbates the decline in physical functioning associated with aging. The results showed that the older individuals are, the greater the extent to which social isolation impacts their health.

A small but growing number of observational studies in the UK, Japan, and China have identified negative associations between social isolation and physical functioning in samples of older adults. The current study resonates with and complements those results. However, the robust data generated by this national rather than community-based study enable findings to be generalized to a national population.

"Physical functioning is a well-established marker of general health and it has been previously correlated with morbidity and mortality," noted Dr. del Pozo Cruz. "We demonstrate in this study that social isolation has a profound impact on the physical functioning in older adults. Mandated social contact restrictions and lockdowns due to COVID-19, coupled with more severe consequences of contagion among older adults, have likely exacerbated this trend.

Study findings suggest that public health interventions should turn their attention to the social environments in which older people are embedded, in particular for those at risk of isolation.

"Social isolation is one of the biggest challenges that societies face in the 21st century. We have to start thinking about this issue now to avoid more serious consequences down the track," added Dr. del Pozo Cruz.

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