Sandi S. Wewerka

Developmental changes in hypothalamus–pituitary–adrenal activity over the transition to adolescence: Normative changes and associations with puberty

Home baseline and laboratory stressor (Trier Social Stress Test for Children) measures of salivary cortisol were obtained from 82 participants (40 girls) aged 9, 11, 13, and 15 years. Measures of pubertal development, self-reported stress, parent reports of child depressive symptoms and fearful temperament, and cardiac measures of sympathetic and parasympathetic activity were also obtained. Significant increases in the home cortisol baselines were found with age and pubertal development. Cortisol stress reactivity differed by age group with 11-year-olds and 13-year-old boys showing blunted reactivity and 9-year-olds, 13-year-old girls, and 15-year-olds showing significant cortisol reactions. Cortisol reactivity correlated marginally with sexual maturation. Measures of sympathetic activity revealed increased sympathetic modulation with age. Higher sympathetic tone was associated with more fearful temperament, whereas greater cortisol reactivity was associated with more anxious and depressed symptoms for girls. The importance of these findings for the hypothesis that puberty-associated increases in hypothalamic-pituitary-adrenal axis activity heightens the risk of psychopathology is discussed.

Moderate versus severe early life stress: Associations with stress reactivity and regulation in 10—12-year-old children

Early life stress (ELS) is expected to increase reactivity of the hypothalamic-pituitary-adrenocortical (HPA) axis; however, several recent studies have shown diminished cortisol reactivity among adults and children with ELS exposure. The goal of this study was to examine cortisol activity in 10-12-year-old internationally adopted children to determine if moderate and severe ELS have different impacts on the HPA axis. Salivary cortisol and two measures of autonomic activity were collected in response to the Trier Social Stress Test for Children (TSST-C). Three groups reflecting moderate, severe, and little ELS were studied: early adopted children who came predominantly from foster care overseas (early adopted/foster care (EA/FC), n=44), later adopted children cared for predominantly in orphanages overseas (late adopted/post-institutionalized (LA/PI), n=42) and non-adopted (NA) children reared continuously by their middle- to upper-income parents in the United States (n=38). Diminished cortisol activity was noted for the EA/FC group (moderate ELS), while the LA/PI group (severe ELS) did not differ from the NA group. Overall, few children showed cortisol elevations to the TSST-C in any group. The presence/absence of severe growth delay at adoption proved to be a critical predictive factor in cortisol activity. Regardless of growth delay, however, LA/PI children exhibited higher sympathetic tone than did NA children. These results suggest that moderate ELS is associated with diminished cortisol activity; however, marked individual differences in cortisol activity among the LA/PI children suggest that child factors modify the impact of severe ELS. Lack of effects of severe ELS even for growth delayed children may reflect the restorative effects of adoption or the generally low responsiveness of this age group to the TSST-C.

Neurodevelopmental Effects of Early Deprivation in Postinstitutionalized Children.

The neurodevelopmental sequelae of early deprivation were examined by testing (N = 132) 8- and 9-year-old children who had endured prolonged versus brief institutionalized rearing or rearing in the natal family. Behavioral tasks included measures that permit inferences about underlying neural circuitry. Children raised in institutionalized settings showed neuropsychological deficits on tests of visual memory and attention, as well as visually mediated learning and inhibitory control. Yet, these children performed at developmentally appropriate levels on similar tests where auditory processing was also involved and on tests assessing executive processes such as rule acquisition and planning. These findings suggest that specific aspects of brain-behavioral circuitry may be particularly vulnerable to postnatal experience.

Neurocognitive sequelae of infants of diabetic mothers

On the basis of animal models, it was hypothesized that infants of diabetic mothers (IDMs) would be at risk for suffering damage to the hippocampus primarily because of fetal iron deficiency, chronic hypoxia, and hypoglycemia. This, in turn, may result in impairments in recognition memory at a young age. To test this model, the memory of 6-month-old IDMs and control infants was evaluated with electrophysiological (event-related potential [ERP]) and behavioral (looking time) measures. At 12 months, the Bayley Scales of Infant Development was administered. Our ERP measures showed robust evidence consistent with memory deficits in the IDMs. In contrast, the looking time measures and the Bayley exam failed to distinguish between the groups. From these results it was concluded that the ERP, but not the behavioral, measures are able to detect, in an at-risk population, deficits in recognition memory that are thought to be mediated by damage to the hippocampus.

Explicit memory performance in infants of diabetic mothers at 1 year of age

The aim of the present research was to investigate the impact of abnormal fetal environment on explicit memory performance. Based on animal models, it was hypothesized that infants of diabetic mothers (IDMs) experience perturbations in memory performance due to exposure to multiple neurologic risk factors including: chronic hypoxia, hyperglycemia/reactive hypoglycemia, and iron deficiency. Memory performance, as measured by the elicited/deferred imitation paradigm, was compared between 13 IDMs (seven females, six males; mean age 365 days, SD 11) and 16 typically developing children (seven females, nine males; mean age 379 days, SD 9). The IDM group was characterized by shorter gestational age (mean 38w, SD 2), greater standardized birthweight scores (mean 3797g, SD 947), and lower iron stores (mean ferritin concentration 87C microg/L, SD 68) in comparison with the control group (mean gestational age: 40w, SD 1; mean birthweight: 3639g, SD 348; mean newborn ferritin concentration 140 microg/L, SD 46). After statistically controlling for both gestational age and global cognitive abilities, IDMs demonstrated a deficit in the ability to recall multi-step event sequences after a delay was imposed. These findings highlight the importance of the prenatal environment on subsequent mnemonic behavior and suggest a connection between metabolic abnormalities during the prenatal period, development of memory, circuitry, and behavioral mnemonic performance.

If memory serves, will language? Later verbal accessibility of early memories

Of major interest to those concerned with early mnemonic process and function is the question of whether early memories likely encoded without the benefit of language later are accessible to verbal report. In the context of a controlled laboratory study, we examined this question in children who were 16 and 20 months at the time of exposure to specific target events and who subsequently were tested for their memories of the events after a delay of either 6 or 12 months (at 22-32 months) and then again at 3 years. At the first delayed-recall test, children evidenced memory both nonverbally and verbally. Nonverbal mnemonic expression was related to age at the time of test; verbal mnemonic expression was related to verbal fluency at the time of test. At the second delayed-recall test, children evidenced continued accessibility of their early memories. Verbal mnemonic expression was related to previous mnemonic expression, both nonverbal and verbal, each of which contributed unique variance. The relevance of these findings on memory for controlled laboratory events for issues of memory for traumatic experiences is discussed.

Auditory Brain Maturation and Recognition Memory in Newborn Infants of Diabetic Mothers 1237

Infants of diabetic mothers (IDMs) are at increased risk for cognitive impairments, possibly due to alterations in fetal brain growth and development. The purpose of this longitudinal study is to evaluate the neural bases of cognitive impairments in IDMs. In this first phase, we evaluated neonatal brain function in 21 IDMs studied at term and compared with 22 full term healthy control infants using event-related potentials (ERPs). The ERP technique is an electrophysiologic method which can be used to study regional brain maturation and cognitive function.

Electrophysiological Assessment of Recognition Memory in 6-Month-Old Infants of Diabetic Mothers and Growth Retarded Infants ♦ 1304

Electrophysiological Assessment of Recognition Memory in 6-Month-Old Infants of Diabetic Mothers and Growth Retarded Infants ♦ 1304

Appendix A: Event Sequences Used

Presented here are descriptions of the three-step and four-step event sequences used in the present research. Materials necessary to produce the event sequences are included in parentheses.

Appendix B: Potential Effects on Children's Performance of Features of the Research Design

In addition to the variables of interest in this research (namely, age, delay, sequence type, mode of experience, and verbal reminders), childrens performance may have been affected by a number of features of the research design. This Appendix is a report of the results of analyses of three potential influences on the childrens performance. First, we examined the possibility that the particular experimenter who conducted the session might have affected the childrens performance. Second, we examined the possibility that conclusions regarding childrens recall of the event sequences were qualified by specific event sequence effects. Third, we examined the possibility that differences in the lengths of the child-controlled response periods might account for the patterns of effects observed. Although in each case some effects obtained, in no case did the findings present substantive qualifications to the major patterns described in the body of the text.