Acute psychosocial stress and children's memory

Moderate-to-vigorous physical activity and reactivity to acute psychosocial stress in preadolescent children

OBJECTIVES

High reactivity to psychosocial stress during childhood increases the risk of future psychological and physiological disorders. The main objective of this study was to investigate associations between children's moderate-to-vigorous physical activity (MVPA) and physiological and psychological reactions to acute psychosocial stress.

DESIGN

Randomized cross-over study comparing two groups.

METHODS

After a 7-day accelerometer-based measurement of MVPA, 110 children aged 10-13 years (48 female) were categorized into a low (<30 min/d) or a high MVPA group (>60 min/d). On separate laboratory appointments, participants completed the Trier Social Stress Test for Children (TSST-C) and a non-stressful control task in randomized order. Stress reactivity was assessed from saliva cortisol, heart rate variability and self-reported anxiety.

RESULTS

In repeated measures analyses of variance, main effects of condition indicated higher stress reactivity in the TSST-C compared to control for cortisol and anxiety, with more pronounced effects in girls compared to boys. Differences in heart rate variability disappeared after controlling for confounding variables. No interactions with MVPA were found. A main effect of MVPA indicated generally lower cortisol reactivity in the high compared to the low MVPA group.

CONCLUSIONS

The TSST-C is suitable for induction of psychosocial stress in the laboratory, but sex-specific differences have to be considered. Children who met the WHO recommendations for MVPA exhibited generally lower endocrine reactivity to both laboratory tasks combined, underlining the potential role of regular physical activity in the regulation of the stress response in early developmental stages. Further studies are necessary to ascertain causal associations.

Who benefits most from a prenatal HEPA filter air cleaner intervention on childhood cognitive development? The UGAAR randomized controlled trial

BACKGROUND

Air pollution exposure during pregnancy affects children's brain function. Maternal stress and nutrition, socioeconomic status, and the child's sex may modify this relationship.

OBJECTIVE

To identify characteristics of children with the largest increases in full-scale IQ (FSIQ) after their mothers used HEPA filter air cleaners during pregnancy.

METHODS

In this randomized controlled trial we randomly assigned women to receive 1-2 air cleaners or no air cleaners during pregnancy. We analyzed maternal hair samples for cortisol and dehydroepiandrosterone (DHEA). When the children were 48 months old, we measured FSIQ with the Wechsler Preschool and Primary Scale of Intelligence. We evaluated ten potential modifiers of the intervention-FSIQ relationship using interaction terms in separate regression models. To account for correlations between modifiers, we also used a single regression model containing main effects and intervention x modifier terms for all potential modifiers.

RESULTS

Among 242 mother-child dyads with complete data, the intervention was associated with a 2.3-point increase (95% CI: -1.5, 6.0 points) in mean FSIQ. The intervention improved mean FSIQ among children of mothers in the bottom (5.4 points; 95% CI: -0.8, 11.5) and top (6.1 points; 95% CI: 0.5, 11.8) cortisol tertiles, but not among those whose mothers were in the middle tertile. The largest between-group difference in the intervention's effect was a 7.5-point (95% CI: -0.7, 15.7) larger increase in mean FSIQ among children whose mothers did not take vitamins than among children whose mothers did take vitamins (interaction p-value = 0.07). We also observed larger benefits among children whose mothers did not complete university, and those with lower hair DHEA concentrations, hair cortisol concentrations outside the middle tertile, or more perceived stress.

CONCLUSION

The benefits of reducing air pollution during pregnancy on brain development may be greatest for children whose mothers who do not take vitamins, experience more stress, or have less education.

A New Perspective on Assessing Cognition in Children through Estimating Shared Intentionality

This theoretical article aims to create a conceptual framework for future research on digital methods for assessing cognition in children through estimating shared intentionality, different from assessing through behavioral markers. It shows the new assessing paradigm based directly on the evaluation of parent-child interaction exchanges (protoconversation), allowing early monitoring of children’s developmental trajectories. This literature analysis attempts to understand how cognition is related to emotions in interpersonal dynamics and whether assessing these dynamics shows cognitive abilities in children. The first part discusses infants’ unexpected achievements, observing the literature about children’s development. The analysis supposes that due to the caregiver’s help under emotional arousal, newborns’ intentionality could appear even before it is possible for children’s intention to occur. The emotional bond evokes intentionality in neonates. Therefore, they can manifest unexpected achievements while performing them with caregivers. This outcome shows an appearance of protoconversation in adult-children dyads through shared intentionality. The article presents experimental data of other studies that extend our knowledge about human cognition by showing an increase of coordinated neuronal activities and the acquisition of new knowledge by subjects in the absence of sensory cues. This highlights the contribution of interpersonal interaction to gain cognition, discussed already by Vygotsky. The current theoretical study hypothesizes that if shared intentionality promotes cognition from the onset, this interaction modality can also facilitate cognition in older children. Therefore in the second step, the current article analyzes empirical data of recent studies that reported meaningful interaction in mother-infant dyads without sensory cues. It discusses whether an unbiased digital assessment of the interaction ability of children is possible before the age when the typical developmental trajectory implies verbal communication. The article develops knowledge for a digital assessment that can measure the extent of children’s ability to acquire knowledge through protoconversation. This specific assessment can signalize the lack of communication ability in children even when the typical trajectory of peers’ development does not imply verbal communication.

Increased cortisol levels caused by acute resistance physical exercise impair memory and learning ability

Acute physical exercise works as an activator of the responses of the human organism to stress. This is based on the activation of the hypothalamic-pituitary-adrenal (HPA) axis, affecting physical, physiological and psychological levels. This study aimed to analyse the effects of a single bout of high-intensity resistance exercise on cognitive-behavioural responses: visuo-spatial path learning and memory, as well as physiological responses (salivary cortisol levels). Nineteen healthy male military-trained powerlifting subjects were tested in a within-subject design on two experimental days with an interval of 48 h. The stress and cognitive variables were measured by cortisol levels and Ruff-Light trail-learning test (RULIT) test scores, respectively. The results showed the immediate influence of acute exercise on cortisol, with significantly higher cortisol levels found in subjects after completion of the acute resistance exercise. In addition, this study found a significant deterioration of memory and learning ability after a dose of intense resistance exercise. In conclusion, the study highlights the relative effects of resistance exercise on cortisol and cognitive performance depending on the intensity and type of the exercise, the moment of measurement and the cerebral areas implicated.

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.

Association of salivary alpha-amylase and salivary flow rate with working memory functioning in healthy children

The aim of this study was to examine the association between auditory and visual working memory (WM) performance and salivary alpha-amylase (sAA) and salivary flow rate (SFR) in a sample of 63 children (38 boys). WM was assessed by means of WISC-V subtests: four auditory subtests (Digit Span and Letter-Number Sequencing) and one visual subtest (Picture Span). SAA activity, output, and SFR were measured at baseline (10 min prior to testing), one minute prior to testing, one minute after the end of the auditory WM subtests and one minute after the end of the visual WM subtest. Our statistical analyses showed an association among SAA activity, output and SFR levels and the number of recalled digits in the last attempt score in Letter-Number Sequencing subtest. Specifically, our results showed that working performance in this task was associated with a concurrent decrease in SFR (r(63) = -0.423, p < .05). This salivary measure was the best predictor of this specific index of working memory performance (β = -0.423, p < .05). These results show that the changes in SFR, which represents changes in parasympathetic tone, could be employed in future studies as a noninvasive marker of working memory performance in child studies.

Acute psychosocial stress and working memory performance: the potential of physical activity to modulate cognitive functions in children

Background

Research suggests that physical activity (PA) enhances cognitive performance and prevents stress-related impairments of higher order cognitive functions like working memory (WM) performance. The aim of the current study was to investigate the effect of PA on WM performance after acute stress exposure in preadolescent children.

Methods

Regular PA was assessed for seven consecutive days during a typical school week using accelerometers in a sample of 44 preadolescent children (14 girls, M_age = 11.29 years, SD_age = 0.67). Following this period, participants performed an automated operational span (OSPAN) task immediately after being exposed to the Trier Social Stress Test for Children (TSST-C).

Results

Children exhibited prototypical response slopes in salivary cortisol and salivary α-amylase as markers of the endocrine and autonomic stress response immediately after psychosocial stress induction. A subsequent two-way ANOVA comparing high- and low-stress responders revealed a significant interaction between group affiliation and PA level on WM performance for both stress markers. Interestingly, best WM performance was demonstrated in children showing both high PA levels and high cortisol (or low α-amylase, respectively) stress responses.

Conclusions

Though patterns differed for salivary cortisol and salivary α-amylase, overall findings suggest that PA buffers the negative effects of stress on cognitive performance in children.

Cortisol Impacted on Explicit Learning Encoding, but Not on Storage and Retrieval, and Was Not Associated With Sleep Patterns-Results From the Trier Social Stress Test for Children (TSST-C) Among 9-Years Old Children

Background: Learning is the relatively permanent change of behavior as a result of experience and tightly related to memory and cognition. Learning is particularly important for children. Further, restoring sleep is associated both with improved learning performance and lower cortisol levels as a proxy of the so-called hypothalamus-pituitary-adrenocortical axis activity (HPA-AA). With the present study, we investigated, if and to what extent explicit learning performance was associated with cortisol levels at baseline and under challenge conditions and with objective sleep dimensions among 9-years old children.

Methods: A total of 39 children (mean age = 9.5 years; 39% females) took part in the study. Verbal and figural working and long-term memory were tested before and after the Trier Social Stress Test for Children (TSST-C). Further, children underwent sleep-EEG assessment, and cortisol awakening response (CAR) was assessed.

Results: Higher cortisol levels were associated with lower explicit learning encoding (verbal, but not figural learning). Higher verbal and figural working and long-term memory performance predicted lower cortisol secretion under the TSST-C, along with higher verbal and figural working and long-term memory performance after the TSST-C. Cognitive test performances were not mediated by cortisol secretion under the TSST-C. Cognitive performance, cortisol secretion under challenge (TSST-C) and basal conditions (morning) and sleep patterns were unrelated.

Conclusions: The pattern of results suggests that among a sample of 9-years old children cortisol secretion and stages of memory processes (encoding, storage, retrieval) are associated in a complex and bi-directional way. Further, it appears that cognitive-emotional processes underlying cognitive performance and its evaluation might impact on subsequent cortisol secretion as a proxy of neuroendocrinological response to cognitive-emotional processes. Last, cognitive performance and cortisol secretion under challenge conditions were not related to objective sleep patterns and baseline cortisol secretion.

Stress physiology and memory for emotional information: Moderation by individual differences in pubertal hormones

In contrast to a large body of work concerning the effects of physiological stress reactivity on children's socioemotional functioning, far less attention has been devoted to understanding the effects of such reactivity on cognitive, including mnemonic, functioning. How well children learn and remember information under stress has implications for a range of educational, clinical, and legal outcomes. We evaluated 8-14 year olds' (N = 94, 50 female) memory for negative, neutral, and positive images. Youth had seen the images a week previously as a part of a laboratory stress task. At encoding and retrieval, and in between, youth provided saliva samples that were later assayed for cortisol, salivary α amylase (sAA), testosterone, and dehydroepiandrosterone (DHEA). Overall, higher cortisol reactivity to the lab task predicted enhanced memory for emotional but not neutral images. However, cortisol further interacted with pubertal hormones (testosterone and DHEA) to predict memory. Among girls with lower pubertal hormone levels, greater cortisol reactivity was associated with enhanced memory for negative information, whereas among boys with higher pubertal hormone levels, cortisol reactivity was associated with enhanced memory for positive information. sAA, was unrelated to memory. Overall, our findings reveal that individual differences in hormone levels associated with pubertal development have implications for our understanding of how stress-responsive biological systems directly and interactively influence cognitive outcomes. (PsycINFO Database Record

True alignment of preclinical and clinical research to enhance success in CNS drug development: a review of the current evidence

Central nervous system pharmacological research and development has reached a critical turning point. Patients suffering from disorders afflicting the central nervous system are numerous and command significant attention from the pharmaceutical industry. However, given the numerous failures of promising drugs, many companies are no longer investing in or, indeed, are divesting from this therapeutic area. Central nervous system drug development must change in order to develop effective therapies to treat these patients. Preclinical research is a cornerstone of drug development; however, it is frequently criticised for its lack of predictive validity. Animal models and assays can be shown to be more predictive than reported and, on many occasions, the lack of thorough preclinical testing is potentially to blame for some of the clinical failures. Important factors such as translational aspects, nature of animal models, variances in acute versus chronic dosing, development of add-on therapies and understanding of the full dose-response relationship are too often neglected. Reducing the attrition rate in central nervous system drug development could be achieved by addressing these important questions before novel compounds enter the clinical phase. This review illustrates the relevance of employing these criteria to translational central nervous system research, better to ensure success in developing new drugs in this therapeutic area.

Acute stress and working memory in older people

Several studies have shown that acute stress affects working memory (WM) in young adults, but the effect in older people is understudied. As observed in other types of memory, older people may be less sensitive to acute effects of stress on WM. We performed two independent studies with healthy older men and women (from 55 to 77 years old) to investigate the effects of acute stress (Trier Social Stress Test; TSST) and cortisol on WM. In study 1 (n = 63), after the TSST women (but not men) improved their performance on Digit Span Forward (a measure of the memory span component of WM) but not on Digit Span Backward (a measure of both memory span and the executive component of WM). Furthermore, in women, cortisol levels at the moment of memory testing showed a positive association with the memory span component of WM before and after the TSST, and with the executive component of WM only before the stress task. In study 2 (n = 76), although participants showed a cortisol and salivary alpha-amylase (sAA) response to the TSST, stress did not affect performance on Letter-Number Sequencing (LNS; a task that places a high demand on the executive component of WM). Cortisol and sAA were not associated with WM. The results indicate that circulating cortisol levels at the moment of memory testing, and not the stress response, affect memory span in older women, and that stress and the increase in cortisol levels after stress do not affect the executive component of WM in older men and women. This study provides further evidence that older people may be less sensitive to stress and stress-induced cortisol response effects on memory processes.