Telomere length: population epidemiology and concordance in Australian children aged 11-12 years and their parents

Shortened Infant Telomere Length Is Associated with Attention Deficit/Hyperactivity Disorder Symptoms in Children at Age Two Years: A Birth Cohort Study

Environmental factors can accelerate telomere length (TL) attrition. Shortened TL is linked to attention deficit/hyperactivity disorder (ADHD) symptoms in school-aged children. The onset of ADHD occurs as early as preschool-age, but the TL-ADHD association in younger children is unknown. We investigated associations between infant TL and ADHD symptoms in children and assessed environmental factors as potential confounders and/or mediators of this association. Relative TL was measured by quantitative polymerase chain reaction in cord and 12-month blood in the birth cohort study, the Barwon Infant Study. Early life environmental factors collected antenatally to two years were used to measure confounding. ADHD symptoms at age two years were evaluated by the Child Behavior Checklist Attention Problems (AP) and the Attention Deficit/Hyperactivity Problems (ADHP). Associations between early life environmental factors on TL or ADHD symptoms were assessed using multivariable regression models adjusted for relevant factors. Telomere length at 12 months (TL12), but not at birth, was inversely associated with AP (β = −0.56; 95% CI (−1.13, 0.006); p = 0.05) and ADHP (β = −0.66; 95% CI (−1.11, −0.21); p = 0.004). Infant secondhand smoke exposure at one month was independently associated with shorter TL12 and also higher ADHD symptoms. Further work is needed to elucidate the mechanisms that influence TL attrition and early neurodevelopment.

Association of antidiabetic therapy with shortened telomere length in middle-aged Type 2 diabetic patients

Introduction

A wide range of antidiabetic therapies have been developed to manage diabetes and limit its lifespan but each of them have adverse long-term drug reactions. This study was performed for the investigation of the possible association of antidiabetic therapy with shortened telomere length in middle-aged Type 2 diabetic patients.

Materials and methods

The subjects in this case-control study included 100 non-diabetic patients and 300 patients with Type 2 diabetes with ages in the range of 30-50 years. The treated patients were further subdivided into diabetic patients using Doanil, those using insulin and those using both the therapies. The mean telomere length was determined using the southern-blotting technique. A logistic regression analysis was performed to predict the relationship between antidiabetic therapy and shortened telomere length.

Results

The results revealed a significant increase (P < 0.01) in the fasting blood glucose and lipid profile in non-treatment diabetic patients compared to diabetic patients with treatment, and also in diabetic patients with insulin therapy, compared to diabetic patients with Doanil or both therapies. The results showed that non-treatment diabetic patients had shorter telomere length, compared to the diabetic patients with treatment, and patients treated with insulin therapy had shorter telomere length, compared to the diabetic patients with Doanil or both therapies. The logistic regression analysis confirmed that insulin therapy was closely related to diabetic risk factors and shortened telomere length.

Conclusions

The results revealed that Doanil therapy was more effective in managing diabetic risk and limiting the shortening telomere length than insulin therapy.

The interplay between environmental exposures and COVID-19 risks in the health of children

BACKGROUND

An unusual feature of SARS-Cov-2 infection and the COVID-19 pandemic is that children are less severely affected than adults. This is especially paradoxical given the epidemiological links between poor air quality and increased COVID-19 severity in adults and that children are generally more vulnerable than adults to the adverse consequences of air pollution.

OBJECTIVES

To identify gaps in knowledge about the factors that protect children from severe SARS-Cov-2 infection even in the face of air pollution, and to develop a transdisciplinary research strategy to address these gaps.

METHODS

An international group of researchers interested in children's environmental health was invited to identify knowledge gaps and to develop research questions to close these gaps.

DISCUSSION

Key research questions identified include: what are the effects of SAR-Cov-2 infection during pregnancy on the developing fetus and child; what is the impact of age at infection and genetic susceptibility on disease severity; why do some children with COVID-19 infection develop toxic shock and Kawasaki-like symptoms; what are the impacts of toxic environmental exposures including poor air quality, chemical and metal exposures on innate immunity, especially in the respiratory epithelium; what is the possible role of a "dirty" environment in conveying protection - an example of the "hygiene hypothesis"; and what are the long term health effects of SARS-Cov-2 infection in early life.

CONCLUSION

A concerted research effort by a multidisciplinary team of scientists is needed to understand the links between environmental exposures, especially air pollution and COVID-19. We call for specific research funding to encourage basic and clinical research to understand if/why exposure to environmental factors is associated with more severe disease, why children appear to be protected, and how innate immune responses may be involved. Lessons learned about SARS-Cov-2 infection in our children will help us to understand and reduce disease severity in adults, the opposite of the usual scenario.

Continuous reference intervals for leukocyte telomere length in children: the method matters

OBJECTIVES

Children with very short telomeres commonly develop bone marrow failure and other severe diseases. Identifying the individuals with short telomeres can improve outcome of bone marrow transplantation, with accurate diagnosis requiring the use of age-matched reference intervals (RIs). This study aimed to establish RIs for telomere length (TL) in children using three commonly used methods for TL measurement.

METHODS

Healthy children aged 30 days to 18 years were recruited for assessment using age as a continuous variable. Venous blood samples were collected and leukocyte TL was measured using terminal restriction fragment (TRF) analysis, quantitative PCR (QPCR) and flow cytometry with fluorescence in situ hybridization (Flow-FISH). Fractional polynomial model and quantile regression were performed to generate continuous RIs. Factors that might contribute to variation in TL, such as gender, were also examined.

RESULTS

A total of 212 samples were analyzed. Continuous RIs are presented as functions of age. TRF analysis and QPCR showed significant negative correlation between TL and age (r=-0.28 and r=-0.38, p<0.001). In contrast, Flow-FISH showed no change in TL with age (r=-0.08, p=0.23). Gender did not have significant influence on TL in children.

CONCLUSIONS

This study provides three options to assess TL in children by establishing method-specific continuous RIs. Choosing which method to use will depend on several factors such as amount and type of sample available and required sensitivity to age-related change.

The metabolic syndrome in pregnancy and its association with child telomere length

AIMS/HYPOTHESIS

The aim of this study was to determine whether presence of the metabolic syndrome in pregnancy associates with child telomere length or child anthropometry (weight, BMI) and BP, measured at 10 years of age.

METHODS

The Screening for Pregnancy Endpoints study (SCOPE) was a multicentre, international prospective cohort of nulliparous pregnant women recruited from Australia, New Zealand, Ireland and the UK (N = 5628). The current analysis is a 10 year follow-up of SCOPE pregnant women and their children, from the Australian cohort. Clinical data collected at 14-16 weeks' gestation during the SCOPE study were used to diagnose the metabolic syndrome using IDF criteria. Telomere length, a biomarker of ageing, was assessed by quantitative PCR from children's saliva collected at 10 years of age.

RESULTS

In women who completed follow-up (n = 255), 20% had the metabolic syndrome in pregnancy. After adjusting for a range of confounders, children of mothers who had the metabolic syndrome in pregnancy had 14% shorter telomeres than children of mothers without the metabolic syndrome in pregnancy (mean difference -0.36 [95% CI -0.74, 0.01]). Height- and weight-for-age, and BMI z scores were similar in children of mothers who did and did not have the metabolic syndrome during pregnancy.

CONCLUSIONS/INTERPRETATION

Children of mothers who had the metabolic syndrome in pregnancy have shorter telomeres, a biomarker of accelerated ageing. These findings warrant further studies in larger cohorts of children, as well as investigations into whether telomere length measured in cord blood associates with telomere length in childhood.

Objectively measured sleep and telomere length in a population-based cohort of children and midlife adults

STUDY OBJECTIVES

Poor sleep patterns in older adults are associated with chromosomal telomere shortening, a marker of cellular senescence. However, studies have relied on self-reported sleep characteristics, with few data for younger individuals. We investigated whether sleep measured via actigraphy was cross-sectionally associated with telomere length in children and midlife adults.

METHODS

A population-based sample of 1874 11-12 year olds and midlife adults (mean age 44 years, SD 5.1) had biological and physical assessments at centers across Australia in 2015-2016. Sleep characteristics, including duration, onset, offset, day-to-day variability, and efficiency, were derived from actigraphy. Relative telomere length (T/S ratio) was measured by quantitative polymerase chain reaction on genomic DNA from peripheral blood. Multivariable regression models estimated associations, adjusting for prespecified confounders.

RESULTS

Both sleep and telomere data were available for 728 children and 1070 adults. Mean (SD) T/S ratio was 1.09 (0.55) in children and 0.81 (0.38) in adults. T/S ratio was not predicted by sleep duration (β 0.04, 95% confidence interval [CI] -0.02 to 0.09, p = .16, children; β -0.004, 95% CI -0.03 to 0.02, p = .70, adults) or most other sleep metrics. The only exception was a weak association between later sleep timing (the midpoint of sleep onset and offset) and longer telomeres in adults (β 0.03, 95% CI 0.01 to 0.06, p = .01).

CONCLUSIONS

Objective sleep characteristics show no convincing associations with telomere length in two largely healthy populations up to at least midlife. Sleep-telomere associations may be a late-life occurrence or may present only with a trigger such as presence of other morbidities.

Telomere length and lung function in a population-based cohort of children and mid-life adults

OBJECTIVE

Telomere length is associated with poorer lung health in older adults, possibly from cumulative risk factor exposure, but data are lacking in pediatric and population-based cohorts. We examined associations of telomere length with lung function in children and mid-life adults.

METHODS

Data were drawn from a population-based cross-sectional study of 11 to 12 year-olds and mid-life adults. Lung function was assessed by spirometric FEV₁ , FVC, FEV ₁ /FVC ratio, and MMEF _25-75 . Telomere length was measured by quantitative polymerase chain reaction from blood and expressed as the amount of telomeric genomic DNA to the beta-globin gene (T/S ratio). Associations of telomere length with spirometric parameters were tested by linear and logistic regression models, adjusting for potential confounders of sex, age, body mass index, socioeconomic position, physical activity, inflammation, asthma, pubertal status, and smoking.

RESULTS

Mean T/S ratio was 1.09 (n = 1206; SD 0.55) in children and 0.81 (n = 1343; SD 0.38) in adults. In adults, for every additional unit in T/S ratio, FEV ₁ /FVC and MMEF _25-75 z-scores were higher (β 0.21 [95% confidence interval, CI; 0.06-0.36] and 0.23 [95% CI; 0.08-0.38], respectively), and the likelihood of being in the lowest quartile for FEV ₁ /FVC and MMEF _25-75 z-scores was lower (odds ratios 0.59 [95% CI, 0.39-0.89] and 0.64 [95% CI, 0.41-0.99], respectively). No evidence of association was seen for adult FEV ₁ or FVC, or any childhood spirometric index after adjustments.

CONCLUSION

Shorter telomere length showed moderate associations with poorer airflow parameters, but not vital capacity (lung volume) in mid-life adults. However, there was no convincing evidence of associations in children.

Population health bio-phenotypes in 11-12 year old children and their midlife parents: Growing Up in Australia's Child Health CheckPoint

In an ambitious undertaking, Growing Up in Australia's Child Health CheckPoint streamlined and implemented wide-ranging population phenotypes and biosamples relevant to non-communicable diseases in nearly 1900 parent-child dyads throughout Australia at child aged 11-12 years. This BMJ Open Special Issue describes the methodology, epidemiology and parent-child concordance of 14 of these phenotypes, spanning cardiovascular, respiratory, bone, kidney, hearing and language, body composition, metabolic profiles, telomere length, sleep, physical activity, snack choice and health-related quality of life. The Special Issue also includes a cohort summary and study methodology paper.

Child Health CheckPoint: cohort summary and methodology of a physical health and biospecimen module for the Longitudinal Study of Australian Children

OBJECTIVES

'Growing Up in Australia: The Longitudinal Study of Australian Children' (LSAC) is Australia's only nationally representative children's longitudinal study, focusing on social, economic, physical and cultural impacts on health, learning, social and cognitive development. LSAC's first decade collected wide-ranging repeated psychosocial and administrative data; here, we describe the Child Health CheckPoint, LSAC's dedicated biophysical module.

DESIGN, SETTING AND PARTICIPANTS

LSAC recruited a cross-sequential sample of 5107 infants aged 0-1 year and a sample of 4983 children aged 4-5 years in 2004, since completing seven biennial visits. CheckPoint was a cross-sectional wave that travelled Australia in 2015-2016 to reach LSAC's younger cohort at ages 11-12 years between LSAC waves 6 and 7. Parent-child pairs participated in comprehensive assessments at 15 Assessment Centres nationwide or, if unable to attend, a shorter home visit.

MEASURES

CheckPoint's intergenerational, multidimensional measures were prioritised to show meaningful variation within normal ranges and capture non-communicable disease (NCD) phenotype precursors. These included anthropometry, physical activity, fitness, time use, vision, hearing, and cardiovascular, respiratory and bone health. Biospecimens included blood, saliva, buccal swabs (also from second parent), urine, hair and toenails. The epidemiology and parent-child concordance of many measures are described in separate papers.

RESULTS

1874 (54% of eligible) parent-child pairs and 1051 second parents participated. Participants' geographical distribution mirrored the broader Australian population; however, mean socioeconomic position and parental education were higher and fewer reported non-English-speaking or Indigenous backgrounds. Application of survey weights partially mitigates that the achieved sample is less population representative than previous waves of LSAC due to non-random attrition. Completeness was uniformly high for phenotypic data (>92% of eligible), biospecimens (74%-97%) and consent (genetic analyses 98%, accessing neonatal blood spots 97%, sharing 96%).

CONCLUSIONS

CheckPoint enriches LSAC to study how NCDs develop at the molecular and phenotypic levels before overt disease emerges, and clarify the underlying dimensionality of health in childhood and mid-adulthood.