Stress and working memory in children and adolescents: Insights from a multisystem approach.

Despite considerable research with adults suggesting that acute stress negatively affects working memory (WM), a core cognitive function, few studies have assessed these effects in youths. Studies that have been conducted have produced null findings, although these studies did not measure stress via multiple systems (e.g., hypothalamic-pituitary-adrenal [HPA] axis and sympathetic nervous system [SNS]) or include wide developmental age ranges. In the current study, we examined the links between acute stress and WM in 8- to 15-year-olds. Youths completed the Trier Social Stress Test-Modified, during which repeated saliva samples were collected to measure responses of the HPA axis (cortisol) and SNS (salivary alpha-amylase). Immediately afterward, youths completed the n-back task, an established measure of WM. Accuracy and false alarm (FA) scores were computed to explore whether associations between arousal and WM differed when WM versus only the inhibitory control facet of WM processes were considered. Relations varied as a function of age, physiological system, and type of WM process. Accuracy improved and FA scores deceased as age and SNS reactivity increased, particularly in combination. Moreover, when arousal was higher according to only one physiological system (HPA axis or SNS), FA scores were lower, but when arousal was driven by both systems or low in both systems, FA scores were higher. Together, results highlight the need for more complex investigations of stress and WM across development that take into account system-specific responses and multiple facets of WM.

Stress and emotional valence effects on children's versus adolescents' true and false memory.

Despite considerable interest in understanding how stress influences memory accuracy and errors, particularly in children, methodological limitations have made it difficult to examine the effects of stress independent of the effects of the emotional valence of to-be-remembered information in developmental populations. In this study, we manipulated stress levels in 7-8- and 12-14-year-olds and then exposed them to negative, neutral, and positive word lists. Shortly afterward, we tested their recognition memory for the words and false memory for non-presented but related words. Adolescents in the high-stress condition were more accurate than those in the low-stress condition, while children's accuracy did not differ across stress conditions. Also, among adolescents, accuracy and errors were higher for the negative than positive words, while in children, word valence was unrelated to accuracy. Finally, increases in children's and adolescents' cortisol responses, especially in the high-stress condition, were related to greater accuracy but not false memories and only for positive emotional words. Findings suggest that stress at encoding, as well as the emotional content of to-be-remembered information, may influence memory in different ways across development, highlighting the need for greater complexity in existing models of true and false memory formation.

Effects of stress on memory in children and adolescents: testing causal connections.

Although a sizeable body of research has examined children's memory for stressful prior experiences, relatively few studies have experimentally manipulated stress during a to-be-remembered event to draw causal inferences about the effects of stress, especially across wide age ranges. We exposed children and adolescents to a more or a less arousing version of the Trier Social Stress Test-Modified (TSST-M), a widely used laboratory stress task. Two weeks later, we tested their memory for what happened. Interviewers behaved in a supportive or non-supportive manner. In adolescents, those who completed the high-arousal TSST-M provided fewer correct responses to recognition questions and fewer incorrect responses to misleading questions for which any answer would have been incorrect, compared to those who completed the lower-arousal TSST-M. Thus, arousal seemed to have reduced the adolescents' willingness to answer questions rather than having influenced their memory per se. In children, across TSST-M conditions, greater physiological arousal during the TSST-M predicted enhanced recall. Finally, interviewer support reduced the amount of factual information provided in free recall but increased correct responses to misleading questions. Results highlight the complex ways in which event stress and interviewer demeanour shape recounting of prior experiences across development.

The role of cortisol reactivity in children's and adults' memory of a prior stressful experience.

The purpose of this study was to identify whether cortisol reactivity to a stressful laboratory event was related to children's memory of that event and to determine whether this relation was comparable to that observed in adults. Nine- to 12-year-olds and young adults completed an impromptu speech and math task during which repeated cortisol samples and self-reported stress ratings were collected. Two weeks later, participants' memory for the tasks was examined. Greater cortisol reactivity was associated with enhanced memory, most prominently in children. Self-reported stress was unrelated to memory. Findings reveal that an important mechanism underlying the association between emotion and memory in adults, namely activation of the hypothalamic pituitary adrenal axis, appears to operate similarly in late childhood. Findings also demonstrate that positive associations between cortisol reactivity and memory are evident when the event that actually elicited that reactivity serves as the to-be-remembered event.

Salivary cortisol responses to a psychosocial laboratory stressor and later verbal recall of the stressor: The role of trait and state rumination.

This study investigated whether trait rumination predicts greater increases in salivary cortisol concentration and delayed recovery in response to a standardized, acute laboratory psychosocial stressor (modified Trier Social Stress Test). It also tested whether trait and state rumination predict reactivation of the cortisol response during later verbal recall of the stressor. Fifty-nine undergraduates (31 females; 28 males) completed the stress protocol and returned 2 weeks later for a surprise interview about the first session, conducted in either a supportive or unsupportive context. Participants completed a measure of trait rumination and reported negative thoughts about the stressor in the 2 weeks between sessions (state rumination). Trait rumination was associated with greater reactivity of salivary cortisol level and delayed recovery from the stressor, F(1,310) = 6.77, p < 0.001. It also predicted greater cortisol reactivity when recalling the stressor, but only for males in the unsupportive interview context, F(2,119) = 7.53, p < 0.001. This effect was heightened for males who also scored high on state rumination, F(2,119) = 7.53, p < 0.001. Rumination was not associated with cortisol responses to the interviews in females. The findings indicate that rumination may play a role in prolonging cortisol stress responses through delayed recovery and reactivation and that rumination disposition and the context of stressor recall are important in understanding the rumination-cortisol response association.

Children's and adults' salivary alpha-amylase responses to a laboratory stressor and to verbal recall of the stressor.

Salivary alpha-amylase (sAA), an enzyme produced by the salivary glands, increases in response to physical and psychosocial stressors in adults. Whether similar increases are evident among children, though, is less clear, and there is a lack of studies directly comparing children's and adults' sAA responses to an identical stressor. In this study, 24 children (9-12 years; 12 female) and 26 adults (18-23 years; 16 female) were exposed to an identical psychosocial laboratory stressor and a recall interview regarding that stressor after a 2-week delay. Saliva was collected before and 1, 10, 20, and 30 min after the stressor/recall interview. Among adults, concentrations of sAA increased on both study days, but similar increases were not detected among children. Findings suggest developmental differences in sAA reactivity, and underscore the need to characterize the confluence of elements that will reliably elicit sAA responses to mild stress in youth.

Can facial type be used to predict changes in hyoid bone position with age? A perspective based on longitudinal data.

INTRODUCTION: Low positioning of the hyoid bone is associated with the unique human ability of speech, but it might also predispose the airway to collapse. The low position of the hyoid bone has been studied in adults with sleep apnea. However, information on age-related changes in hyoid bone position in the general adult population is sparse. METHODS: We used pairs of lateral cephalometric radiographs taken 15 years apart to assess vertical changes over time in hyoid position in 163 normal white men (ages, 30-72 years). RESULTS AND CONCLUSIONS: Significant changes in hyoid bone position were independent of age or obesity but were related to facial type, as classified by the steepness of the lower margin of the mandible. Changes in hyoid position over time were significant in dolichofacial subjects but not in brachyfacial subjects. This finding might be particularly important because a low hyoid bone with a brachial face appears to be a morphologic characteristic of nonobese patients with severe obstructive sleep apnea.

Experimental manipulation of the Trier Social Stress Test-Modified (TSST-M) to vary arousal across development.

Reliable laboratory protocols manipulating the intensity of biobehavioral arousal for children are uncommon, and those available have minimal converging evidence of their efficacy in manipulating arousal across multiple biological systems. This report presents two studies of the efficacy of the modified Trier Social Stress Test (TSST-M). In Study 1, sixty-three 7-15-year olds, and 19 young adults (18-25 yrs) completed the TSST-M. Comparable reactivity across age groups was observed for salivary cortisol, salivary alpha-amylase (sAA), pre-ejection period (PEP) and respiratory sinus arrhythmia (RSA), whereas self-reported stress was higher in adults compared to children. In Study 2, eighty-four 7-8-year olds and eighty-six 12-15-year olds were randomly assigned to a standard or low-stress TSST-M condition. Cortisol and self-reported stress responses were higher in the standard compared to the low-stress condition. In contrast, sAA and PEP were higher in the low-stress condition and RSA responses were comparable between the two TSST-M conditions. In addition, age group differences emerged in Study 2, though never in conjunction with the TSST-M manipulation. To test, refine, and advance theory about the implications of stress for child development, laboratory tasks that manipulate and enable assessment of biobehavioral arousal in children are needed.

Predictors of children's cortisol activation during the transition to kindergarten.

The purpose of the present study was to identify predictors of children's cortisol responses after the transition to kindergarten. Morning salivary cortisol was measured in 50 children 1 week before and 1 week after they began kindergarten. Children who experienced a greater degree of change between their preschool and kindergarten routines and who had infrequent preschool experiences exhibited the largest increases in morning cortisols after kindergarten entry. Children whose parents indicated that they would have an easier, rather than more difficult, time adapting to kindergarten also tended to be more reactive in their morning cortisol levels after kindergarten entry. Results provide new insight into experiential and individual-difference factors that predict children's physiological reactivity and self-regulation during times of transition and potential stress.

Hypothalamic pituitary adrenal axis and sympathetic activation: joint predictors of memory in children, adolescents, and adults.

Although the links between physiological arousal and adults' memory for emotional information are well understood, little is known about these links across development or when memory is examined for the actual event that induced arousal. In the current study, we examined the associations between physiological arousal and memory in children, adolescents, and young adults. Participants completed a laboratory stressor, the Trier Social Stress Test-Modified (TSST-M) during which salivary cortisol, pre-ejection period (PEP), and self-reported distress were measured. Two weeks later, participants completed a surprise memory test about what occurred during the TSST-M. Larger cortisol responses predicted enhanced memory, especially among individuals who also exhibited a PEP response the TSST-M. These associations did not vary with age. Results have implications for understanding how coordinated physiological responses may influence memory for salient, personal experiences across development.

Children's and adults' salivary cortisol responses to an identical psychosocial laboratory stressor.

Many studies have investigated hypothalamus-pituitary-adrenal (HPA) axis responses to psychosocial stress in adults. In children, much less is known about HPA axis reactivity, and a sizable number of studies has not detected a significant cortisol response. Moreover, there is a lack of studies comparing adults' and children's responses to identical stressors. The aim of the present study was to modify an existing laboratory stressor to serve as a potent stressor in children and to allow for direct comparison between children's and adults' stress responses. Thirty children, ages 9-12 (14 female), and 31 young adults, ages 18-25 (17 female), were exposed to the modified protocol (TSST-M). A significant increase in salivary cortisol was observed in response to the TSST-M, F(2.5,125.4)=19.65, p<.001, eta(2)=.28, and overall, no differences were found between children's and adults' responses, F(2.5,125.4)=.31, n.s. Children and adults also showed similar changes in negative and positive affect, both F<1.18, n.s. and reported a similar amount of distress during the TSST-M, F(1,57)=.97, n.s. Children did, however, exhibit a significantly greater number of behaviors indicative of distress, F(1,50)=6.59, p=.01, eta(2)=.12. This study provides preliminary evidence that the TSST-M is a useful laboratory procedure to induce significant cortisol responses in children. It also suggests comparable responses in cortisol and self-reported affect in young adults and children.

Physiological reactivity, social support, and memory in early childhood.

The interactive effects of physiological reactivity and social support on children's memory were examined. Four- to 6-year-olds completed a laboratory protocol during which autonomic responses and salivary cortisol were measured. Memory was assessed shortly afterward and 2 weeks later. During the second interview, children were questioned by a supportive or nonsupportive interviewer. Few significant relations emerged between reactivity and children's short-term memory. Following a 2-week delay, cortisol reactivity was associated with poorer memory and autonomic reactivity was associated with increased accuracy among children questioned in a supportive manner but decreased accuracy among children questioned in a nonsupportive manner. Results question traditional conceptualizations of reactivity as a risk factor and instead suggest that reactivity may only confer risk in certain environmental contexts.