Physiological stress measures in preschool children and their relationship with body composition and behavioral problems

Reading Skills, Social Competence, and Physiological Stress in the First Grade

An awareness of school-related antecedents of children’s physiological stress at the beginning of school helps educators to prevent and mitigate children’s stress, the one of the major obstacles to their well-being and academic progress. We aimed to study the effect of reading skills and social competence on first-grade students’ salivary cortisol levels in natural settings. Based on previous results of the effects of everyday situations on children’s stress according to gender, we expected that both academic and social skills would affect girls’ physiological stress more, compared to boys. Our sample consisted of 277 students (7–8 years old, 50.2% girls). We used the highest salivary cortisol level of three morning samples and a cortisol level from the middle of the school day as physiological stress indicators. Reading skills were assessed by group-administered tests and social competence by teacher ratings. We found that lower reading comprehension skills and lower disruptiveness were related to higher cortisol levels for girls but not for boys. Higher empathy and lower disruptiveness moderated the effect of better reading comprehension on higher psychological stress in the middle of the school day only for girls. By recognizing the antecedents of children’s stress and supporting their academic and social skills, children’s, especially girls’, physiological self-regulation and coping skills in the primary grades will benefit.

Human nail cortisol as a retrospective biomarker of chronic stress: A systematic review

Cortisol is the primary glucocorticoid produced by the activation of the hypothalamic pituitary adrenal (HPA) axis after a psychological or physiological stressor. The dysregulation of the HPA axis by chronic stress has been associated with psychiatric disorders. Although hair is currently the main validated source of chronic cortisol concentrations, cortisol is also bound to human nails, another keratinised matrix. Therefore, nail cortisol has the potential to be an alternative retrospective chronic measure of HPA activation. The aim of this systematic review was to assess the temporal resolution, methodological issues, HPA correlates, and target populations in nail cortisol investigations. A qualitative synthesis was performed to assess current literature exploring cortisol concentrations from human nails. A total of 18 eligible human studies extracted from Medline (PubMed and Ovid), ProQuest (PsycINFO), and Scopus found that immunoassays and mass spectrometry were the two primarily methods of analysis. However, methodological variability remained evident between studies. Nail cortisol correlated with saliva and hair in some studies and was investigated across multiple developmental periods. Finally, when applied as an outcome measure in health disorders, higher nail cortisol concentrations have been shown to be associated with acute coronary syndrome and depression. In conclusion, nail cortisol may serve as a retrospective biomarker of chronic stress; however, the ability to track how much cortisol is accumulating within nail clippings is complex and may represent a large timespan. Further, very few studies have reported effect sizes and investigated the effects of covariates, such as age, sex, ethnicity, and nail characteristics, which limits the validation of this measure. Further studies are required to validate the utility of nail cortisol as a biomarker of chronic stress across the human lifespan.

Lower activity of salivary alpha-amylase in youths with depression

Measurement of basal and stress-induced salivary alpha-amylase activity may help to understand autonomic nervous system disturbance in mental disorders. The potential sympathetic nervous system dysregulation in children and adolescent psychopathologies is mostly unknown. The present study was aimed to test the hypothesis that salivary alpha-amylase activity is higher in youths diagnosed with depression than in healthy subjects considering a part of the daily rhythm of enzyme activity and its morning to midday slope. A total of 30 children aged 15 ± 0.46 years (15 patients with depression, 4 boys, 11 girls, and 15 sex- and age-matched healthy controls) participated in the study. Two saliva samples were collected from each subject to measure activity of alpha-amylase in the morning and midday. The results of the present study revealed that the midday but not morning alpha-amylase activity was lower in patients with depression than in healthy controls. The diurnal increase in enzyme activity present in healthy subjects was absent in patients. The children and adolescents with depression exhibited flatter morning to midday slopes of alpha-amylase activity. In conclusion, the present results indicate a disturbance of alpha-amylase daily rhythm in youths with depression and motivate further studies on the relationship between sympathetic activation and mood disorders.

Autonomic Profile, Physical Activity, Body Mass Index and Academic Performance of School Students

The aim of this study was to analyze the autonomic modulation, physical activity, body mass index, and academic performance of preschool and school students by grade. Extracurricular physical activity, heart rate variability, body mass index, and objective and subjective academic performance were analyzed in 180 preschool and primary school students (7.91 ± 2.29 years). Significant lower heart rate and higher parasympathetic modulation were found in 10–12-year-old primary education students. The 8–9-year-old students obtained the worst results in English and in five of the subjective academic performance items. Students aged 10–12 years old presented the highest body composition values. No significant differences were found on the extracurricular physical activity by age. No correlation between autonomic profile, physical activity, and body composition with objective academic performance was found. Nerveless subjective academic performance perception of teachers presented a negative correlation with body composition and the parasympathetic modulation. School students presented an increased body mass index and parasympathetic modulation by age. Physical activity of all students, independently of the age, were lower than the official recommendations.

Assessment of prenatal stress-related cortisol exposure: focus on cortisol accumulation in hair and nails

Prenatal stress adversely affects offspring development. Although cortisol is hypothesized to be a key mediator of stress-induced developmental deficits, determining the amount of fetal cortisol exposure produced by maternal stress has proved challenging. Current approaches, such as measuring cortisol concentrations in maternal plasma, saliva, or urine, amniotic fluid, fetal plasma, or cord blood, all have significant limitations for assessing cumulative fetal cortisol exposure over time. A recently emerging approach is to measure cortisol concentrations in maternal hair and/or newborn hair or nail samples. Maternal hair cortisol potentially shows long-term production across each trimester of pregnancy, whereas neonatal hair or nail cortisol is thought to reflect mainly third trimester hormone accumulation. This review first describes fetal adrenocortical development, placental cortisol metabolism, and the various sources of fetal cortisol exposure across pregnancy. We then summarize the results obtained from "classical" methods of assessing prenatal cortisol exposure prior to the advent of hair and nail cortisol measurement. Lastly, we discuss the initial development and validation of the hair cortisol methodology, its subsequent application to studies of chronic stress, and recent findings regarding maternal and neonatal hair or nail cortisol concentrations in relation to prenatal stress and other variables of interest.

Fingernail cortisol - State of research and future directions

The extraction of cortisol from fingernails represents a recent advancement in the retrospective, long-term assessment of hypothalamic-pituitaryadrenal (HPA) axis activity: Fingernail cortisol has the potential to overcome some of the major disadvantages of established HPA axis markers. However, the introduction of any novel methodology also raises certain caveats. This review provides a comprehensive summary of the current state of research on fingernail cortisol. It identifies a number of strengths of his novel methodology (e.g., its high feasibility), while also pointing out open questions which currently challenge the interpretability of fingernail findings, in particular regarding the time period of cortisol secretion reflected in fingernail samples, as well as regarding potential determinants or confounders of fingernail cortisol (e.g. sociodemographic, lifestyle, or health characteristics). Clarification of these issues in the context of further methodological studies is necessary to validate the use of fingernail cortisol as a retrospective marker of HPA axis activity.

Innovations in biological assessments of chronic stress through hair and nail cortisol: Conceptual, developmental, and methodological issues

Much of the existing research on biological mechanisms underlying the stress experience has focused largely on moment-to-moment stress, rather than on chronic stress, an arguably more powerful predictor of long-term outcomes. Recent methodological innovations have paved the way for new lines of research on chronic stress, with promising implications for developmental researchers and for those who study health and adversity. In particular, there are increasing studies that have focused on chronic stress assessments by relying on cortisol derived from hair and nails as a biomarker for chronic stress. In this paper, we provide an overview of their use, describe how hair and nail cortisol ought to be conceptualized differently across the lifespan, how developmental factors may impact its interpretation, and the circumstances under which its use may be more methodologically sensible. The purpose of this review is to provoke further discussion and encourage careful research designs that utilize hair and nail cortisol for understanding the effects of chronic stress exposure from the early developmental period, across adverse contexts, and in association with psychological and physical health outcomes.

Intensive longitudinal modelling predicts diurnal activity of salivary alpha-amylase

Salivary alpha-amylase (sAA) activity has been widely used in psychological and medical research as a surrogate marker of sympathetic nervous system activation, though its utility remains controversial. The aim of this work was to compare alternative intensive longitudinal models of sAA data: (a) a traditional model, where sAA is a function of hour (hr) and hr squared (sAA_j,t= f(hr, hr²), and (b) an autoregressive model, where values of sAA are a function of previous values (sAA_j,t= f(sAA_j,t-1, sAA_j,t-2, …, sAA_j,t-p). Nineteen normal subjects (9 males and 10 females) participated in the experiments and measurements were performed every hr between 9:00 and 21:00 hr. Thus, a total of 13 measurements were obtained per participant. The Napierian logarithm of the enzymatic activity of sAA was analysed. Data showed that a second-order autoregressive (AR(2)) model was more parsimonious and fitted better than the traditional multilevel quadratic model. Therefore, sAA follows a process whereby, to forecast its value at any given time, sAA values one and two hr prior to that time (sAA _j,t= f(SAA_j,t-1, SAA_j,t-2) are most predictive, thus indicating that sAA has its own inertia, with a “memory” of the two previous hr. These novel findings highlight the relevance of intensive longitudinal models in physiological data analysis and have considerable implications for physiological and biobehavioural research involving sAA measurements and other stress-related biomarkers.