The relationship between subjective well-being and mortality within discordant twin pairs from two independent samples

Gretchen R.B. Saunders, Irene J. Elkins, Kaare Christensen, Matt Mc Gue

Research output: Contribution to journalArticlepeer-review

Abstract

Prior research has shown robust associations between greater subjective well-being (SWB) and reduced mortality. Whether this observed association is causal in nature or due instead to confounding genetic or environmental factors affecting both SWB and mortality is not well understood. We used a combined sample of 6,802 twins drawn from two cohorts: the Longitudinal Study of Middle-Aged Danish Twins (MADT; N = 2,815, baseline age between 45 and 69 years, M = 56.8, SD = 6.4) and the Longitudinal Study of Aging Danish Twins (LSADT; N = 3,987, baseline age between 70 and 97 years, M = 76.6, SD = 4.9). The relationship between SWB, encompassing measures of life satisfaction and affect, and all-cause mortality was evaluated using survival analyses at both the individual level and within twin pairs. Twin difference analyses were completed within 1,053 monozygotic (MZ) twin pairs and 1,143 dizygotic (DZ) twin pairs to control for genetic and shared environmental confounding. As expected, the individual-level results showed that higher levels of SWB were associated with reduced mortality: affect hazard ratio (HR) = .90, 95% confidence interval (CI) [.87, .94]; life satisfaction HR = .88, 95% CI [.84, .92]. The effect of SWB on reduced mortality remained significant within both MZ and DZ pairs, suggesting that the association is independent of genetic and nonshared environmental confounding factors. These findings, which generalized across both younger (MADT) and older (LSADT) cohorts of adults, remained significant when accounting for demographic factors, physical health, and cognitive functioning.

Original languageEnglish (US)
Pages (from-to)439-447
Number of pages9
JournalPsychology and aging
Volume33
Issue number3
DOIs
StatePublished - May 2018

Bibliographical note

Funding Information:
This research was supported by National Program for Research Infrastructure 2007 Grant 09-062256 from the Danish Agency for Science Technology and Innovation to Kaare Christensen, U.S. National Institute on Aging Grant P01-AG08761 to James Vaupel, a grant from the Velux Foundations, and National Institute on Drug Abuse Grant DA038065 to Irene J. Elkins.

Funding Information:
This research was supported by National Program for Research Infrastructure 2007 Grant 09-062256 from the Danish Agency for Science Technology and Innovation to Kaare Christensen, U.S. National Institute on Aging Grant P01-AG08761 to James Vaupel, a grant from the Velux Foundations, and National Institute on Drug Abuse Grant DA038065 to Irene J. Elkins

Publisher Copyright:
© 2018 American Psychological Association.

Keywords

  • Cotwin control
  • Discordant twin design
  • Longitudinal studies
  • Mortality
  • Subjective well-being

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