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Biomedical subjects

M R Gunnar

Publications and source records attributed to M R Gunnar.

At least 19 recordsLinked to original sources
PubMed2006

Antenatal betamethasone treatment has a persisting influence on infant HPA axis regulation.

OBJECTIVE: To examine the consequences of antenatal betamethasone (AB) exposure on postnatal stress regulation. STUDY DESIGN: Fourteen AB exposed infants born at 28-30 weeks' gestation were assessed in the NICU during postnatal week 1 and at 34 weeks postconception. Nine infants born at 34 weeks gestation without AB treatment were evaluated as a postconceptional age comparison group. Salivary cortisol, heart rate, and behavior were measured at baseline and in response to a heelstick blood draw. RESULTS: Repeated measures ANOVAs revealed that both groups displayed an increase in heart rate and behavioral distress in response to the stressor. The cortisol response, however, was blunted in AB-treated infants at both assessments. CONCLUSION: AB treatment has consequences for hypothalamic-pituitary-adrenal (HPA) axis regulation that persist for at least four to six weeks after birth, indicating that studies of long-term effects are warranted.

Analysis of Variance↗
PubMed2001

Relationship functioning and home and work demands predict individual differences in diurnal cortisol patterns in women.

In 70 middle-class mothers of 2-year-old children, individual differences in mothers' morning cortisol levels, cortisol decreases across the day and average cortisol levels were predicted from demographic and medical control variables, maternal relationship functioning and home and work demands. For two days, salivary cortisol levels were measured in the morning immediately after wakeup, four times in the afternoon, and in the evening immediately prior to bedtime. Hierarchical linear modeling (HLM) growth curve analyses were used to estimate the intercept (early morning level), slope (steepness of decline in cortisol values across the day), and the average height of each mother's cortisol curve across the waking hours. HLM and multiple regression techniques were then used to predict individual differences in these parameters from the variables of interest. Time of day accounted for 72% of the variation in mothers' observed cortisol values across the day. After controlling for demographic and medical variables, positive relationship functioning was associated with higher morning cortisol levels and a steeper decline in cortisol across the day, while greater hours of maternal employment and a greater number of children in the household were associated with lower morning cortisol values and a less steep decline in cortisol levels across the day. Variables predicting higher morning values also predicted higher average cortisol levels, while variables predicting lower morning cortisol predicted lower average cortisol levels. The full model including selected control, relationship functioning and home and work demand variables accounted for 40% of the variance in mothers' morning cortisol values, 43% of the variance in cortisol slopes and 35% of the variability in mothers' average cortisol levels. This study presents the first evidence of associations between psychological variables and individual differences in the organization of cortisol levels across the waking day in normal adult women.

Adaptation, Psychological↗
PubMed2001

Low cortisol and a flattening of expected daytime rhythm: potential indices of risk in human development.

Since the work of Hans Selye, stress has been associated with increased activity of the limbic-hypothalamic-pituitary-adrenocortical (LHPA) axis. Recently, a number of studies in adults have shown that this neuroendocrine axis may be hyporesponsive in a number of stress-related states. Termed hypocortisolism, the paradoxical suppression of the LHPA axis under conditions of trauma and prolonged stress presently challenges basic concepts in stress research. Adverse conditions that produce elevated cortisol levels early in life are hypothesized to contribute to the development of hypocortisolism in adulthood. However, as reviewed in this paper, hypocortisolism also may be a common phenomenon early in human childhood. Although preliminary at this point, the ubiquity of these findings is striking. We argue that developmental studies are needed that help explicate the origins of low cortisol and to determine whether the development of hypocortisolism is, in fact, preceded by periods of frequent or chronic activation of the LHPA axis. We also argue that developmental researchers who incorporate measures of salivary cortisol into their studies of at-risk populations need to be aware of the hypocortisolism phenomenon. Lower than expected cortisol values should not necessarily be relegated to the file drawer because they contradict the central dogma that stress must be associated with elevations in cortisol. Lastly, we note that evidence of low cortisol under adverse early life conditions in humans adds to the importance of understanding the implications of hypocortisolism for health and development.

Affect↗
PubMed2001

Salivary cortisol levels in children adopted from romanian orphanages.

Six and a half years after adoption. 6- to 12-year-old children reared in Romanian orphanages for more than 8 months in their first years of life (RO. n = 18) had higher cortisol levels over the daytime hours than did early adopted (EA, < or = 4 months of age, n = 15) and Canadian born (CB, n = 27) children. The effect was marked, with 22% of the RO children exhibiting cortisol levels averaged over the day that exceeded the mean plus 2 SD of the EA and CB levels. Furthermore, the longer beyond 8 months that the RO children remained institutionalized the higher their cortisol levels. Cortisol levels for EA children did not differ in any respect from those of CB comparison children. This latter finding reduces but does not eliminate concerns that the results could be due to prenatal effects or birth family characteristics associated with orphanage placement. Neither age at cortisol sampling nor low IQ measured earlier appeared to explain the findings. Because the conditions in Romanian orphanages at the time these children were adopted were characterized by multiple risk factors, including gross privation of basic needs and exposure to infectious agents, the factor(s) that produced the increase in cortisol production cannot be determined. Nor could we determine whether these results reflected effects on the limbic-hypothalamic-pituitary-adrenal axis directly or were mediated by differences in parent-child interactions or family stress occasion by behavioral problems associated with prolonged orphanage care in this sample.

Adoption↗
PubMed2000

Cortisol and vagal tone responses to competitive challenge in preschoolers: associations with temperament.

Sixty-one 3- to 5-year-old nursery school children participated in a study of tempera ment and stress responses to competition. Each child individually participated in a competition against a familiar adult experimenter to determine who would win enough games to receive a prize. After initially winning three games (Win Period), the children lost the next three games (Lose Period), before winning the final games and receiving the prize. Salivary cortisol, vagal tone, affect and turn-taking behavior were measured in response to the competition and examined in relation to child temperament using a teacher-report version of the Child Behavior Questionnaire. Behavioral measures indicated that the procedures were emotionally engaging and the threat of losing was aversive. Surgency (extroversion) was positively correlated with positive affect during Win periods and tense/angry affect during the Lose period of the competition. Vagal tone decreased as the children began to play against the adult and children who were more tense/angry while losing showed additional suppression of vagal tone when they began to lose the competition. Most of the children did not show a cortisol response to the competition; however, the 15% who increased cortisol (responses >1 SD of classroom baselines) were described by teachers as more surgent and lower in effortful control. All but one of these children who increased in cortisol was male. Cortisol responsive children also displayed higher levels of tense/angry affect during the Lose period. Surgent, extroverted children appear to be vulnerable to competition stress.

Adult↗
PubMed2000

Quality of care and temperament determine changes in cortisol concentrations over the day for young children in childcare.

The current study investigated whether patterns of cortisol production in preschool-aged children in group care were influenced by characteristics such as group size, adult:child ratio, separation from family/parents, and quality of attention and stimulation from the childcare provider. Data were obtained from preschoolers attending home-based childcare. Cortisol levels were sampled at home and at childcare. Parents and teachers assessed the child's temperament (CBQ, TBQ). At childcare, the children were observed using the Observational Ratings of the Caregiving Environment (ORCE). Childcare characteristics were independent of family or child characteristics. In home-based childcare, children's cortisol patterns over the day correlated significantly with the amount of attention and stimulation provided by the childcare provider. Using a median split on the quality index measure of focused attention/stimulation, children in settings that were above the median exhibited no change in cortisol from home to childcare, while those in settings below the median exhibited a reversal of the typical pattern of cortisol production from morning to afternoon. At home these children exhibited the expected decrease in cortisol from morning to afternoon. Patterns of cortisol production at childcare were also correlated with child temperament with larger increases from morning to afternoon for more emotionally negative children and those with less self-control. Finally, cortisol production in home-based childcare was compared to data from children in center-based childcare and children not enrolled in full-day childcare.

Attention↗
PubMed2000

International adoption of institutionally reared children: research and policy.

This article summarizes the research on the developmental outcomes of postinstitutionalized children and discusses the implications for social policy. Postinstitutionalized children often reach their adoptive families with varying degrees of physical growth retardation, cognitive delays, and socioemotional problems. Many children demonstrate remarkable recovery following adoption. Unfortunately, some of the children continue to display significant problems that require professional intervention. It appears that the children's recovery may be influenced by their early experiences with their birth family and in institutional care, and there is suggestive evidence that postadoption experiences also play a role. These findings indicate that preadoption and postadoption services may support the outcome of postinstitutionalized children.

Adoption↗
PubMed2000

Preventive intervention for maltreated preschool children: impact on children's behavior, neuroendocrine activity, and foster parent functioning.

OBJECTIVE: This article describes the results of a pilot study that evaluated the effectiveness of the Early Intervention Foster Care (EIFC) program in the period immediately following a child's placement in a new foster home. METHOD: Data were collected from an EIFC group, a regular foster care group, and a community comparison group-each with 10 participants-via questionnaires for children and their caretakers and salivary cortisol sampling. RESULTS: EIFC foster parents adopted and maintained positive parenting strategies, EIFC children's behavioral adjustment improved, and changes occurred in several salivary cortisol measures. Moreover, regular foster care children exhibited decrements in functioning in several areas over the same time period. CONCLUSIONS: Results are discussed with regard to how such research fits into a larger program of prevention research for high-risk preschool children.

Black or African American↗
PubMed2000

Cortisol and social stressors in children with fragile X: a pilot study.

Evidence of neuroendocrine dysfunction, behavioral features of social anxiety and avoidance, and neuroanatomical abnormalities suggest that abnormal hypothalamic-pituitary-adrenal (HPA) function may be a component of the fragile X (fra X) syndrome. In this preliminary study, salivary cortisol levels of males (n = 8, mean age = 13.5 yr) and females (n = 7, mean age = 13.9 yr) with the fra X full mutation were studied for 3 days. Day 1 was an experimental day, during which subjects experienced a Social Stressor task midmorning. Days 2 and 3 were routine days, during which the subjects were engaged in their typical activities. Saliva samples were collected before breakfast, lunch, dinner, and bedtime. On the experimental day, the prelunch sample collection occurred 30 and 90 minutes after the Social Stressor task. Compared with children's norms, the combined group of males and females with fra X had significantly higher cortisol levels in the prelunch and the prebedtime samples for the routine days. Comparisons between the two fra X groups for the experimental day revealed similar diurnal patterns for cortisol level. However, compared with females with fra X, males with fra X had significantly higher cortisol levels at two points during the day: 30 minutes after the social stressor and at bedtime. These preliminary data suggest that individuals with fra X have abnormal HPA function. Understanding the relations among HPA dysfunction, abnormalities in brain structure and/or function, and maladaptive behavior and cognition in fra X could inform the design of early interventions using pharmacological or environmental measures designed to normalize neuroendocrine function.

Adolescent↗
PubMed1999

The start of a new school year: individual differences in salivary cortisol response in relation to child temperament.

Noon and evening salivary cortisol levels were examined in 70 elementary school children during the 1st week of a new school year. Samples were obtained on the 1st and 5th days of school and on weekend days. Delta cortisol scores were created to measure the change in children's levels on initial school days relative to weekend days. Temperament was assessed using Rothbart's Child Behavior Questionnaire, a parent report instrument. The three dimensions of surgency or extroversion, negative affectivity, and effortful control were examined. Positive correlations were obtained with Day 1 delta cortisol for negative affectivity and Day 5 delta cortisol for surgency. Contrary to the expectation that internalizing aspects of temperament (shyness, fearfulness) would be associated with larger increases in cortisol to the novelty and challenge of a new school year, these data indicate that larger increases in cortisol were observed in more extroverted children.

Arousal↗
PubMed1999

Cortisol levels of young children in full-day childcare centers: relations with age and temperament.

Cortisol levels of 70 children, aged 39-106 months, were sampled at home and at their full-day childcare centers at two times of day, mid-morning and mid-afternoon. Parents and teachers completed questionnaires assessing child temperament (negative affectivity, surgency or extroversion, and effortful control) and aggressive behavior. The results replicated a previous study showing increases in cortisol levels over the day at childcare for preschool-aged children, while home levels followed the expected circadian decrease in cortisol from morning to afternoon for most children regardless of age. At childcare, 3- and 4-year olds were more likely to show elevations in cortisol by mid-afternoon than were older children. Controlling statistically for age, shyness for boys, and poor self-control and aggression for both sexes were associated with increases in cortisol over the day at childcare. The results suggest that younger children and those with more immature social skills may frequently experience elevations in cortisol as the day progresses in group care contexts.

Aggression↗
PubMed1998

Familiar and novel contexts yield different associations between cortisol and behavior among 2-year-old children.

We examined 10:30 a.m. salivary cortisol levels in twenty-four 2-year-old children at home, and then at several points during transition into preschool: Week 1, Weeks 6-9, and the 1st week following a month-long holiday break. Cortisol levels did not increase when the children first started school as compared to either home or later school levels. Cortisol levels were correlated across similar, but not across dissimilar, psychosocial contexts. Home levels were correlated wit more shy, anxious, internalizing behavior while the response to starting school was correlated with more assertive, angry, and aggressive behavior. Behavior was assessed using parent temperament reports, teacher reports, and observational measures. We conclude that HPA activity as indexed by salivary cortisol measures is differentially associated with behavior in familiar and novel contexts. Consistent with our prior work, shy/anxious behavior is not significantly associated with elevations in cortisol when young children enter new social situations.

Child Behavior Disorders↗
PubMed1998

Social behavior correlates of cortisol activity in child care: gender differences and time-of-day effects.

The relations between social behavior and daily patterns of a stress-sensitive hormone production were examined in preschool children (N = 75) attending center-based child care. Three behavioral dimensions, shy/anxious/internalizing, angry/aggressive/externalizing, and social competence, were assessed by teacher report and classroom observation, and their relations with 2 measures of cortisol activity, median (or typical) levels and reactivity (quartile range score between second and third quartile values) were explored. Cortisol-behavior relations differed by gender: significant associations were found for boys but not for girls. Specifically, for boys externalizing behavior was positively associated with cortisol reactivity, while internalizing behavior was negatively associated with median cortisol. Time of day of cortisol measurement affected the results. Surprisingly, median cortisol levels rose from morning to afternoon, a pattern opposite to that of the typical circadian rhythm of cortisol. This rise in cortisol over the day was positively correlated with internalizing behavior for boys. The methodological and theoretical implications of these findings for the study of the development of hormone-behavior relations are discussed.

Child Behavior↗
PubMed1998

Assessing salivary cortisol in studies of child development.

In a series of studies, we evaluated the susceptibility of radioimmunoassays (RIA) for saliva cortisol to interference effects caused by oral stimulants used to facilitate saliva collection in studies with children. When added directly to saliva samples, oral stimulants (drink mix crystals) artificially inflated estimated cortisol concentrations. The magnitude of the interference effect was concentration-dependent and more pronounced for some stimulants and RIA procedures than for others. Analysis of samples collected using oral stimulants from child and adult participants confirmed stimulant interference as an extraneous source of variability in measured saliva cortisol. Associations between serum and saliva cortisol and between saliva cortisol and "behavioral" variables were attenuated by stimulant interference. A survey of six large child studies estimated interference effects, indexed by low sample pH, to be present in 14.7% of the 1,148 total saliva samples, or 2%-54% (M = 22%) of samples within each study. Recommendations to minimize the impact of stimulant interference in studies involving salivary cortisol in the context of child health and development are outlined.

Beverages↗
PubMed1997

Temperament, social competence, and adrenocortical activity in preschoolers.

The relations among temperament, social competence, and levels of a stress-sensitive hormone (salivary cortisol) were examined in two studies of preschoolers children (Study 1, N = 29; Study 2, N = 46). In both studies, we sampled cortisol daily for the initial weeks of school year (Group Formation period) and for several weeks later in the year (Familiar Group period). For each child, we examined two measures of cortisol activity (separately for each period) based on the distribution of cortisol levels across days: (a) median cortisol (50th percentile) and (b) cortisol reactivity (the difference between the 75th and 50th percentile). Median cortisol was modestly stable across periods, but cortisol reactivity was not. Children who showed high cortisol reactivity (75th minus 50th percentile > or = 0.10 micrograms/dl) during the Group Formation period but low-to-normal cortisol reactivity during the Familiar Group period were outgoing, competent, and well liked by their peers. In contrast, children who changed from low/normal to high cortisol reactivity and those who maintained high cortisol reactivity from the Group Formation to Familiar Group period were affectively negative and solitary. Children who showed high median cortisol during the Familiar Group period or over both periods scored lower on a measure of attentional and inhibitory control. Together, these results suggest that relations among temperament, social competence, and neuroendocrine reactivity reflect both individual and contextual differences.

Affect↗
PubMed1997

Beyond dorsal penile nerve block: a more humane circumcision.

OBJECTIVE: To explore techniques that can be utilized in addition to the dorsal penile nerve block (DPNB) to further reduce the neonate's stress and pain from routine circumcision, and thus make the procedure more humane. SETTING: Level 1 nursery at a community hospital. SUBJECTS: Eighty healthy, term, newborn male infants scheduled for routine neonatal circumcision. STUDY DESIGN: Prospective and randomized; double blind and placebo controlled for the study solutions. METHODS: Four statistically similar groups of 20 were studied. The control group included infants circumcised using: a) a rigid plastic restraint board; b) standard DPNB; and c) a pacifier dipped in water to comfort the infant. Each study group differed from the controls in one variable including: 1) using a specially designed, physiologic circumcision restraint chair; 2) pH buffering of lidocaine hydrochloride used for DPNB; and 3) offering a pacifier dipped in a 24% sucrose solution during the DPNB and circumcision. Behavioral observations were recorded and compared for each group starting before the injection of lidocaine hydrochloride and continuing through the completion of the circumcision. Plasma for cortisol levels were collected 30 minutes after the circumcision. RESULTS: Neonates circumcised on the new restraint chair showed a significant decrease in distress scores (>50%) compared with the control group on the rigid molded-plastic restraint. The pacifier dipped in sucrose had a distress-reducing effect during both the post-DPNB injection and circumcision periods. The infants who were injected with the buffered lidocaine showed no differences in distress from the controls. The plasma cortisol levels were not significantly affected by any additional technique and were comparable to the levels previously reported. CONCLUSIONS: When neonatal circumcisions are performed routinely, they should be done as humanely as possible. This study demonstrates that, when used in conjunction with DPNB, a pacifier dipped in 24% sucrose and a more comfortable, padded, and physiologic restraint can be useful in decreasing distress and pain.

Circumcision, Male↗
PubMed1996

Stress reactivity and attachment security.

Seventy-three 18-month-olds were tested in the Ainsworth Strange Situation. These children were a subset of 83 infants tested at 2, 4, 6, and 15 months during their well-baby examinations with inoculations. Salivary cortisol, behavioral distress, and maternal responsiveness measures obtained during these clinic visits were examined in relation to attachment classifications. In addition, parental report measures of the children's social fearfulness in the 2nd year of life were used to classify the children into high-fearful versus average- to low-fearful groups. In the 2nd year, the combination of high fearfulness and insecure versus secure attachment was associated with higher cortisol responses to both the clinic exam-inoculation situation and the Strange Situation. Thus, attachment security moderates the physiological consequences of fearful, inhibited temperament. Regarding the 2-, 4-, and 6-month data, later attachment security was related to greater maternal responsiveness and lower cortisol baselines. Neither cortisol nor behavioral reactivity to the inoculations predicted later attachment classifications. There was some suggestion, however, that at their 2-month checkup, infants who would later be classified as insecurely attached exhibited larger dissociations between the magnitude of their behavioral and hormonal response to the inoculations. Greater differences between internal (hormonal) and external (crying) responses were also negatively correlated with maternal responsiveness and positively correlated with pretest cortisol levels during these early months of life.

Crying↗