Associations between chronic stress and hair cortisol in children: A systematic review and meta-analysis

Objectives: This review systematically examined the associations between chronic stress and hair cortisol centration (HCC) in children, and the potential modification effects of type, measurement period and scales chronic stress, child age and sex, hair length and HCC measurement method, characteristics of study site, congruence between time periods measured for chronic stress and HCC. Methods: Pubmed, Wed of Science, and APA PsycINFO were systematically searched for articles examining association between chronic stress and HCC. Results: Thirteen studies from five countries with 1,455 participants were included in the systematic review nine studies were included in the meta-analysis. Meta-analysis revealed that chronic stress was associated HCC (pooled-r = 0.09, 95 % CI: 0.03, 0.16). Stratified analyses revealed that type, measurement time and of chronic stress, hair length and measurement method of HCC, and the congruence between time periods measured for chronic stress and HCC modified such correlations. The positive correlations between chronic and HCC were significant for studies measuring chronic stress as stressful life events, assessing chronic within the past six months, extracting HCC from 1 cm, 3 cm, or 6 cm of hair, measuring HCC by LC-MS/MS, having congruence between time periods measured for chronic stress and HCC. The potential modifying effects sex and country developmental status could not be concluded due to the limited number of studies included. Conclusions: Chronic stress was positively correlated with HCC, varying by characteristics and measurements chronic stress and HCC. HCC could be a biomarker for chronic stress among children.