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Epigenetic DNA methylation is not associated with natural variation in caregiver-infant physical contact time in a cross-sectional sample of human toddlers

University of British Columbia

Background: Early infant experience has been associated with long term epigenetic modifications of gene expression and subsequent health outcomes. We questioned whether daily physical contact time shared between an infant and their caregiver as an early experience was associated with prolonged variations in the epigenetic patterns of toddlers. Methods: We performed a second look analysis of a self-reported 3-day diary kept by 1,055 caregivers of their behaviours and interactions with their infants at 5 weeks of age. We measured the average daily physical contact time shared between the infant and caregiver and compared this across the sample. We defined high and low caregiver-infant contact groups as the upper and lower 16th percentiles. We conducted a descriptive analysis of the associated caregiver and infant behaviours with high and low contact caregiving. We then collected epithelial buccal cells from a subsample of the now 3-5 year old toddlers of the high and low caregiver-infant pairs. We collected samples for 98 toddlers (59 high contact infants, 39 low contact infants). We determined DNA methylation patterns in all toddlers using the Infinium Illumina Methylation Assay and then compared the degree of methylation at 434580 CpG sites. In addition, we compared methylation status of five genes associated with stress response pathways. Results: Average daily caregiver-infant contact time followed a normal distribution over a large range. The mean physical contact time between caregiver-infant dyads was (± SD) 9h7m (± 2h 52m). High and low contact caregiver-infant contact pairs were defined as those who shared ≥12h 22m/day and those who shared ≤6h14m/day of physical contact respectively. There were no significant associations between the methylation patterns of the epithelial buccal cells of the toddlers and the differences in physical contact time at 5 weeks of age. There were no significant associations between the methylation status and physical contact time when controlling for gender. No differences were associated with the 5 candidate genes. Interpretation: A difference in caregiver-infant physical contact time of at least 6hrs/day at 5 weeks of age was not associated with individual differences in epigenetic methylation patterns in the epithelial buccal cells of toddlers at 3-5 years of age.

Text

2012-04-20

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/42157

Experimental Medicine

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/