1. Any father loss, or loss of father by death, separation and/or divorce, or incarceration was associated with a significant reduction in telomere length at 9 years of age, and these effects were at least partly mediated by change in income after father loss.
2. In moderation analysis, male sex at 0-5 years of age and more reactive serotonergic and dopaminergic genetic profiles appeared to strengthen the association between father loss and reduction in telomere length.
Evidence Rating: 2 (Good)
Study Rundown: Existing research suggests a positive association between social stressors and morbidity and mortality. Recent studies have suggested that shortening of the ends of chromosomes, also known as telomeres, may serve as a biomarker for chronic lifetime stress. Telomeres serve as protective caps to chromosome ends that prevent senescence. Most research in this field focuses on adults, and has shown reductions in adult telomere length with factors such as mental illness, poverty, poor sleep quality, smoking and stress. In this study, researchers examined whether there is an association between type of father loss and child telomere length and if this potential association is mediated by change in income and/or moderated by child’s sex, race/ethnicity and dopaminergic and serotonergic genetic profiles. Study results showed that any type father loss – separation and/or divorce, incarceration and/or death – was significantly associated with reduced telomere length (TL). Specifically, death of a father had the highest and most significant reduction in TL. Overall, income change after father loss only accounted for approximately half of the observed reduction in TL. With regards to moderation analysis, male gender between the ages of 0-5 years had a significantly greater reduction in TL after father loss. More reactive dopaminergic and serotonergic profiles were also associated with greater reduction in TL after father loss. Race/ethnicity showed no significant results for moderation analysis. This study suggests that telomere length in children may be responsive to social stressors. The authors advocate for future research on TL and maternal parenting, paternal parenting before and/or after loss and epigenetic modification of telomerase activity. This study represents a new model for understanding pediatric stress, and suggests individual genetic architecture may play a role in physiologic response to social stressors.
Relevant Reading: Social disadvantage, genetic sensitivity and children’s telomere length
In-Depth [retrospective cohort]: In this retrospective cohort study, researchers used data from the Fragile Families and Child Wellbeing Study, a cohort of children (n = 2420) born between 1998 and 2000 from 20 large American cities. The cohort included an oversample of low income families. Interviews were conducted with parents 2 days after birth, and then at 1, 3, 5, and 9 years. Salivary DNA samples were taken from children at 9 years of age. Any father loss before 9 years of life was associated with a 14% reduction in TL (p < 0.01). With regards to type of father loss, separation and/or divorce, incarceration and death were associated with a 6% (p = 0.05), 10% (p = 0.01) and 16% (p = 0.005) reduction in TL, respectively. Mediation of father loss with income as a mediating factor in TL length showed that income change accounted for 53%, 95%, 30%, and 25% of TL reduction after any father loss, separation and/or divorce, incarceration and death, respectively. Moderation analysis was performed for sex, race/ethnicity and genetic profile for serotonergic and dopaminergic reactivity. With regard to sex, between the ages of 0-5, males had a significantly greater reduction in TL than females (17% vs. 13% reduction, p < 0.05), but this effect was not true for loss between 5-9 years, or for overall loss. When studying the neurotransmitter-related genes, alleles coded as sensitizing – or alleles thought to confer greater risk of telomere shortening from external stress based on existing gene-environment literature – were summed and divided into terciles, with the highest being the most sensitizing. In the serotonergic pathway, the third tercile was associated with an overall 17% TL reduction (p = 0.006) compared to the first and second terciles. Similarly, for the dopaminergic pathway, the third tercile was associated with an overall 15% TL reduction (p = 0.01) compared to the first and second terciles. There was no significant moderation by race/ethnicity.
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