Dorothée Out

Focus on Methodology: Salivary bioscience and research on adolescence: An integrated perspective

The characterization of the salivary proteome and advances in biotechnology create an opportunity for developmental scientists to measure multi-level components of biological systems in oral fluids and identify relationships with developmental processes and behavioral and social forces. The implications for developmental science are profound because from a single oral fluid specimen, information can be obtained about a broad array of biological systems and the genetic polymorphisms related to their function. The purpose of this review is to provide a conceptual and tactical roadmap for investigators interested in integrating these measurement tools into research on adolescent health and development.

Oxytocin receptor gene and depressive symptoms associated with physiological reactivity to infant crying

Both the oxytocin receptor (OXTR) gene and depressive symptoms have been associated with parenting behaviour. The OXTR GG genotype has been suggested to be related to more sensitive parenting, whereas depressive symptoms may affect sensitivity negatively. We examined the role of OXTR and the influence of depressive symptoms in explaining differences in physiological reactivity to infant crying. Heart rate responses of 40 healthy females without children (age 19-47 years, randomly selected half of twin pairs) were measured during the presentation of three episodes of infant cry sounds. Participants with the presumably more efficient variant of the oxytonergic system gene (OXTR GG) had more pronounced physiological reactivity to repeated cry sounds, except when they showed more symptoms of depression. Results were replicated in the second half of the twin sample. This is the first study to suggest effects of OXTR genotype on physiological reactivity to infant crying. Depressive symptoms may however suppress the effect of the OXTR GG genotype.

Assessing salivary C-reactive protein: longitudinal associations with systemic inflammation and cardiovascular disease risk in women exposed to intimate partner violence.

This study evaluated individual differences in levels of C-reactive protein (CRP) measured in saliva, cross-sectionally and prospectively, in relation to systemic inflammation and risk for cardiovascular disease (CVD). Plasma and saliva samples, later assayed for CRP, were collected multiple times from an ethnically diverse group of women seeking help from domestic violence crisis shelters-agencies (N=107; mean age at study start=34 years). Plasma and saliva CRP levels were moderately associated cross-sectionally and across two years. There were indications that saliva CRP levels were, on average, higher in the morning than evening. Higher levels of saliva and plasma CRP were associated with a higher body mass index, but did not differ between women who did and did not smoke. Salivary CRP reliably discriminated between high and low levels of plasma CRP, using a clinically relevant cutoff point of 3mg/L, recommended by the American Heart Association. Results build upon an emerging literature suggesting that under specific conditions levels of CRP in saliva may reflect low-grade inflammation and have the potential to serve as a screen for CVD risk status.

The role of disconnected and extremely insensitive parenting in the development of disorganized attachment: validation of a new measure

Early adverse caregiving experiences constitute an important risk factor for the development of disorganized attachment in infancy, especially extreme insensitivity and frightening behavior associated with an unresolved loss or trauma. Using existing measures for frightening parenting and disrupted communication, we developed a new measure assessing Disconnected and extremely Insensitive Parenting (DIP), in order to investigate the unique contribution of disconnected and extremely insensitive parenting behaviors to infant disorganization. Maternal behavior was assessed during a laboratory session in a low-risk sample of 202 mothers and their infants. Construct and discriminant validity of the DIP was established for both types of parental behavior. Disconnected parental behavior predicted infant disorganization but not organized attachment security, whereas extreme insensitivity was marginally related to organized attachment insecurity in boys but not to attachment disorganization.

Disentangling sources of individual differences in diurnal salivary α-amylase: reliability, stability and sensitivity to context.

In the present study, we employ a longitudinal design and a generalizability framework to examine the sources of variance in the diurnal rhythm of salivary α-amylase (sAA). The sample consisted of 122 first-year law students (55% male, mean age=23.9 years), who collected five saliva samples on each of three consecutive days at each of five data collection waves. In total, over 6900 saliva samples were collected, which allowed us to examine the properties of diurnal variation in sAA in great detail. Systematic individual differences accounted for 15-29% of the variability in the awakening response and diurnal slope, and for 61-65% of the variation in overall daily levels (i.e., diurnal mean, area under the curve with respect to ground [AUCg]). Although less than 1% of the variation was due to differences between waves and between days, the generalizability analyses revealed that between 16% and 17% of the variance in the diurnal mean, slope and AUCg is due to person by wave interactions, indicating that individuals vary in their biological sensitivity to environmental influences. In sum, this study documents sufficient stability and variation in diurnal sAA to warrant future studies on the origins and consequences of alterations in the diurnal rhythm of sAA worthwhile, and proposes guidelines on obtaining reliable measures.

Incorporating Salivary Biomarkers Into Nursing Research: An Overview and Review of Best Practices

Analytes and biomarkers present in saliva may provide insight into individual differences in environmental chemical exposures, variation in reproductive hormones, therapeutic and illegal substance use, changes in stress-related physiology, and the immunologic footprints of infectious disease. The wealth of information provided by salivary analytes has the potential to enrich biobehavioral nursing research by enabling researchers to measure these individual differences in the clinic as well as in patients’ and participants’ everyday social worlds. In this article, the authors provide a roadmap for researchers new to this area who would like to learn more about integrating salivary biospecimens into the next generation of health research. In addition, the authors highlight best practices and strategies to avoid common pitfalls for researchers already engaged in this field.

Beating the brain about abuse: Empirical and meta-analytic studies of the association between maltreatment and hippocampal volume across childhood and adolescence

We present new empirical data and meta-analytic evidence for the association of childhood maltreatment with reduced hippocampal volume. In Study 1, we examined the effects of maltreatment experiences reported during the Adult Attachment Interview on hippocampal volume in female twin pairs. We found that reduced hippocampal volume was related to childhood maltreatment. In addition, individuals who reported having experienced maltreatment at older ages had larger reductions in hippocampal volume compared to individuals who reported maltreatment in early childhood. In Study 2, we present the results of a meta-analysis of 49 studies (including 2,720 participants) examining hippocampal volume in relation to experiences of child maltreatment, and test the moderating role of the timing of the maltreatment, the severity of maltreatment, and the time after exposure to maltreatment. The results of the meta-analysis confirmed that experiences of childhood maltreatment are associated with a reduction in hippocampal volume and that the effects of maltreatment are more pronounced when the maltreatment occurs in middle childhood compared to early childhood or adolescence.

In defence of situational morality: genetic, dispositional and situational determinants of children's donating to charity

In this paper we argue that moral behaviour is largely situation‐specific. Genetic make‐up, neurobiological factors, attachment security and rearing experiences have only limited influence on individual differences in moral performance. Moral behaviour does not develop in a linear and cumulative fashion and individual morality is not stable across time and situations. To illustrate our position we present two studies on children’s willingness to donate their money to a charity (UNICEF) as a prime example of pro‐social behaviour. In two samples of seven‐year‐old children we found no evidence for a role of attachment, temperament or parenting. Using a twin design we did not find any evidence for a genetic component either. The most striking finding in both studies was that very few children were inclined to donate any money after viewing a promotional UNICEF film about children suffering from poverty. Only after gentle probing by an experimenter were most children willing to donate some of their money. The situation appeared to be a much more powerful determinant of donating behaviour than any other factor. These findings are discussed in the broader context of evidence for situational canalisation of moral behaviour. We conclude that moral competence may be a universal human characteristic, but that it takes a situation with specific demand‐characteristics to translate this competence into actual prosocial performance.

Salivary Cytokines in Healthy Adolescent Girls: Intercorrelations, Stability, and Associations with Serum Cytokines, Age and Pubertal Stage

Theoretically, the measurement of cytokines in saliva may have utility for studies of brain, behavior, and immunity in youth. Cytokines in saliva and serum were analyzed across three annual assessments in healthy adolescent girls (N = 114, 11-17 years at enrollment). Samples were assayed for GM-CSF, IFNγ, IL-1β, IL-2, IL-6, IL-8, IL-10, IL-12p70, TNFα, adiponectin, and cotinine. Results revealed: (1) cytokine levels, except IFNγ and IL-10, were detectable in saliva, and salivary levels, except IL-8 and IL-1β, were lower than serum levels; (2) salivary cytokine levels were lower in older girls and positively associated with adiponectin; (3) compared to serum levels, the correlations between salivary cytokines were higher, but salivary cytokines were less stable across years; and (4) except for IL-1β, there were no significant serum-saliva associations. Variation in basal salivary cytokine levels in healthy adolescent girls reflect compartmentalized activity of the oral mucosal immune system, rather than systemic cytokine activity.

Cortisol awakening response in adolescents with acute sexual abuse related posttraumatic stress disorder

Little is known regarding changes in the hypothalamic‐pituitary‐adrenal axis (HPA axis) of adolescent girls with and without posttraumatic stress disorder (PTSD) who have recently experienced sexual abuse. Therefore, in this pilot study, we utilized non‐stressed home saliva collection three times a day for three days to assess the levels, diurnal variation and awakening response of cortisol in recently sexually abused adolescent girls.