Association of Childhood Socioeconomic Status with Leukocyte Telomere Length Among African Americans and the Mediating Role of Behavioral and Psychosocial Factors: Results from the GENE-FORECAST Study

The interaction of socioeconomic stress and race on telomere length in children: A systematic review and meta-analysis

Rationale

Proposed mechanisms relating early life exposures to poor health suggest that biologic indicators of risk are observable in childhood. Telomere length (TL) is a biomarker of aging, psychosocial stress, and a range of environmental exposures. In adults, exposure to early life adversity, including low socioeconomic status (SES), is predictive of shorter TL. However, results in pediatric populations have been mixed. Defining the true relation between TL and SES in childhood is expected to enhance the understanding of the biological pathways through which socioeconomic factors influence health across the life span.

Objective

The aim of this meta-analysis was to systematically review and quantitatively assess the published literature to better understand how SES, race, and TL are related in pediatric populations.

Methods

Studies in the United States in any pediatric population with any measure of SES were included and identified through the following electronic databases: PubMed, EMBASE, Web of Science, Medline, Socindex, CINAHL, and Psychinfo. Analysis utilized a multi-level random-effects meta-analysis accounting for multiple effect sizes within a study.

Results

Thirty-two studies were included with a total of 78 effect sizes that were categorized into income-based, education-based, and composite indicators. Only three studies directly tested the relation between SES and TL as the primary study aim. In the full model, there was a significant relation between SES and TL (r = 0.0220 p = 0.0286). Analysis by type of SES categorization identified a significant moderating effect of income on TL (r = 0.0480, 95% CI: 0.0155 to 0.0802, p = 0.0045) but no significant effect for education or composite SES.

Conclusions

There is an overall association between SES and TL that is predominately due to the association with income-based SES measures implicating income disparities as a key target for efforts to address health inequity across the life span. Identification of associations between family income and biological changes in children that predict life-span health risk provides key data to support public health policies addressing economic inequality in families and presents a unique opportunity to assess the effect of prevention efforts at the biologic level.

Immune and Epigenetic Pathways Linking Childhood Adversity and Health Across the Lifespan

Childhood adversity is associated with a host of mental and physical health problems across the lifespan. Individuals who have experienced childhood adversity (e.g., child abuse and neglect, family conflict, poor parent/child relationships, low socioeconomic status or extreme poverty) are at a greater risk for morbidity and premature mortality than those not exposed to childhood adversity. Several mechanisms likely contribute to the relationship between childhood adversity and health across the lifespan (e.g., health behaviors, cardiovascular reactivity). In this paper, we review a large body of research within the field of psychoneuroimmunology, demonstrating the relationship between early life stress and alterations of the immune system. We first review the literature demonstrating that childhood adversity is associated with immune dysregulation across different indices, including proinflammatory cytokine production (and its impact on telomere length), illness and infection susceptibility, latent herpesvirus reactivation, and immune response to a tumor. We then summarize the growing literature on how childhood adversity may alter epigenetic processes. Finally, we propose future directions related to this work that have basic and applied implications.