Network cultivation, diurnal cortisol and biological ageing: The rejuvenation hypothesis

A stronger motivation to cultivate social ties in older adults (ages range from 62 to 86 years) has been associated with a cortisol profile similar to that observed in undergraduate students, who are decades younger. We have shown the cultivation of social networks buffers against increases in diurnal cortisol common in old age. Cortisol is crucial for the response to stress and the process of ageing, and a recent study has demonstrated that a lower cortisol level is associated with longevity. We link the findings of social network cultivation and cortisol profile to the processes of biological ageing through DNA telomere length. Telomeres are repeated DNA sequences that cap and protect the ends of chromosomes, and telomere length is considered a potential biomarker for biological age because it is closely related to the cellular process of ageing and chronic stress and is inversely related to chronological age. Studies examining biological ageing have shown an association between an altered cortisol profile and telomere length dynamics. Together, these findings on social networks, cortisol profiles and telomere length suggest that seniors who are motivated to maintain social ties are biologically younger. We therefore propose the 'rejuvenation hypothesis', which posits that seniors with a stronger motivation for social network cultivation are biologically younger, as measured by cortisol levels and telomere length, than their peers who are less motivated to pursue social relationships. This idea suggests a new perspective and potentially fruitful direction for geriatric research. The focus on social network cultivation adds an important psychosocial dimension to rejuvenation therapies that so far have been dominated by biomedical approaches. The rejuvenation hypothesis also has important implications for social policy by supporting the viability of promoting network cultivation among the elderly to facilitate healthy ageing.