Background: Shorter telomere length is associated with environmental stressors and has been
proposed to underlie health inequalities in ageing trajectories. However, the relationship
between socioeconomic position, psychosocial stress and telomere length is understudied in
childhood, when ageing trajectories may be first defined. We aimed to examine the associations
between family affluence, cortisol production and telomere length in a large cross-sectional
study of European children.
Methods: 1,160 children, aged 5 to 12 years, participating in the Human Early Life Exposome
(HELIX) project, were recruited from cohorts in the UK, France, Spain, Norway, Lithuania,
and Greece. Family material wealth was assessed using the international family affluence scale
(FAS), psychosocial stress was defined by total urinary cortisol production, and leukocyte
telomere length was measured through qPCR. Associations of FAS with cortisol production
and telomere length were analysed using sequentially adjusted multivariable linear regression.
The mediating role of cortisol production in the association between FAS and telomere length
was examined using natural effects models.
Findings: Compared to children of low FAS, children with high FAS had 4.94% (95% CI:
1.2%, 8.8%) longer telomeres after adjustment for sex, age, ethnicity and cohort. Estimates
were similar upon further adjustment for perinatal, child health, and other socioeconomic
factors. Additionally, children of medium and high FAS had significantly lower levels of
cortisol production than children of low FAS (medium FAS: -20.8%, 95% CI: -31%, -8.5%;
high FAS: -16.6% SD, 95% CI: -28%, -3.4%). However, cortisol production was not associated
with telomere length, and no significant mediation of cortisol production and other tested
mediators was found for the relationship between FAS and telomere length.
Interpretation: The impacts of economic disadvantage are biologically observable in children
and have implications for understanding health inequalities, both in child development and the
onset of later age-related disease. Given the lack of mediation by cortisol production levels, as
assessed via spot urine samples, further research should investigate alternative mechanisms
underlying the association between affluence and telomere length.
Funding: UK Research and Innovation (Grants: MR/S03532X/1, MR/Y02012X/1), European
Community (Grants: 874583, 308333)