Direct and moderating links of salivary alpha-amylase and cortisol stress-reactivity to youth behavioral and emotional adjustment.

Recent studies have revealed evidence for interactions between autonomic nervous system (ANS) activity, indexed by saliva alpha amylase (sAA), and hypothalamic-pituitary-adrenocortical activity, in predicting psychological functioning. The present study extends this work by examining individual differences in sAA and cortisol stress reactivity in relation to behavioral and emotional adjustment in youth. Participants were 56 healthy children (age 7-16). sAA, cortisol, and other physiological and affective responses were measured before, during, and after stressor tasks (either performance or peer rejection). Basal and stress responsive sAA and cortisol as well as their interactions were assessed in relation to externalizing and internalizing behaviors and trait anxiety. sAA was positively related to anxiety, while sAA reactivity moderated associations between cortisol reactivity and problem behavior. Results highlight the importance of measuring multiple physiological systems to elucidate mechanisms underlying behavioral and emotional dysregulation.

Neurobiological basis of failure to recall extinction memory in posttraumatic stress disorder.

BACKGROUND: A clinical characteristic of posttraumatic stress disorder (PTSD) is persistently elevated fear responses to stimuli associated with the traumatic event. The objective herein is to determine whether extinction of fear responses is impaired in PTSD and whether such impairment is related to dysfunctional activation of brain regions known to be involved in fear extinction, viz., amygdala, hippocampus, ventromedial prefrontal cortex (vmPFC), and dorsal anterior cingulate cortex (dACC). METHODS: Sixteen individuals diagnosed with PTSD and 15 trauma-exposed non-PTSD control subjects underwent a 2-day fear conditioning and extinction protocol in a 3-T functional magnetic resonance imaging scanner. Conditioning and extinction training were conducted on day 1. Extinction recall (or extinction memory) test was conducted on day 2 (extinguished conditioned stimuli presented in the absence of shock). Skin conductance response (SCR) was scored throughout the experiment as an index of the conditioned response. RESULTS: The SCR data revealed no significant differences between groups during acquisition and extinction of conditioned fear on day 1. On day 2, however, PTSD subjects showed impaired recall of extinction memory. Analysis of functional magnetic resonance imaging data showed greater amygdala activation in the PTSD group during day 1 extinction learning. During extinction recall, lesser activation in hippocampus and vmPFC and greater activation in dACC were observed in the PTSD group. The magnitude of extinction memory across all subjects was correlated with activation of hippocampus and vmPFC during extinction recall testing. CONCLUSIONS: These findings support the hypothesis that fear extinction is impaired in PTSD. They further suggest that dysfunctional activation in brain structures that mediate fear extinction learning, and especially its recall, underlie this impairment.

Is posttraumatic stress disorder a stress-induced fear circuitry disorder?

Neuroimaging studies of posttraumatic stress disorder (PTSD) have reported functional abnormalities in brain regions involved in fear conditioning, extinction, and emotion regulation. These findings have prompted researchers to consider whether PTSD can be characterized as a stress-induced fear circuitry disorder. In this review, the authors summarize the results of functional neuroimaging studies and conclude that there is a strong argument for characterizing PTSD as a stress-induced fear circuitry disorder. They also acknowledge that (a) fear is not the only emotion associated with PTSD, (b) a state of fear is not required to observe fear-circuitry abnormalities in this disorder, and (c) not all functional abnormalities in PTSD are related to fear circuitry. Implications for future diagnostic classifications are discussed.

Differential patterns of HPA activity and reactivity in adult posttraumatic stress disorder and major depressive disorder.

Despite a number of overlapping symptoms, individuals with posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) often display hypothalamic-pituitary-adrenal (HPA) profiles that appear quite different from one another. This review describes the patterns of HPA-axis activity and reactivity in healthy individuals compared to individuals with these two disorders. Measures of HPA-axis activity and reactivity include cortisol levels at rest, in response to the dexamethasone suppression test (DST), and in response to psychological stress. The research reviewed presents the possibility of diagnostic specificity with regard to HPA function. In particular, the differential response pattern to the DST suggests that, while it cannot be considered a pure diagnostic tool, it should be one measure taken into consideration during diagnosis.

Stress response and the adolescent transition: performance versus peer rejection stressors.

Little is known about normative variation in stress response over the adolescent transition. This study examined neuroendocrine and cardiovascular responses to performance and peer rejection stressors over the adolescent transition in a normative sample. Participants were 82 healthy children (ages 7-12 years, n = 39, 22 females) and adolescents (ages 13-17, n = 43, 20 females) recruited through community postings. Following a habituation session, participants completed a performance (public speaking, mental arithmetic, mirror tracing) or peer rejection (exclusion challenges) stress session. Salivary cortisol, salivary alpha amylase (sAA), systolic and diastolic blood pressure (SBP, DBP), and heart rate were measured throughout. Adolescents showed significantly greater cortisol, sAA, SBP, and DBP stress response relative to children. Developmental differences were most pronounced in the performance stress session for cortisol and DBP and in the peer rejection session for sAA and SBP. Heightened physiological stress responses in typical adolescents may facilitate adaptation to new challenges of adolescence and adulthood. In high-risk adolescents, this normative shift may tip the balance toward stress response dysregulation associated with depression and other psychopathology. Specificity of physiological response by stressor type highlights the importance of a multisystem approach to the psychobiology of stress and may also have implications for understanding trajectories to psychopathology.

Associations between sleep and cortisol responses to stress in children and adolescents: a pilot study.

A growing body of animal and human research suggests reciprocal associations between sleep and activity of the hypothalamic pituitary adrenocortical (HPA) axis. However, few studies have examined associations between sleep and stress-induced cortisol responses in children and adolescents. This pilot study examined associations among 3 sleep parameters (sleep-wake behavior problems, daytime sleepiness, sleep quantity) and cortisol responses to stress in 31 participants ages 10 to 17 (15 males, 16 females). During a "rest" session in which participants habituated to the laboratory, daytime sleepiness, sleep-wake behavior problems, and sleep quantity were assessed using a modified Sleep Habits Survey. On a separate day, participants completed a laboratory stress session involving 3 performance stressors. Salivary cortisol was collected during baseline, stress, and recovery periods. Significant associations between participant reported sleep-wake behavior problems and cortisol reactivity were found, with greater sleep-wake behavior problems associated with decreased cortisol responses. No associations emerged between sleep quantity and cortisol responses to stress; daytime sleepiness showed a trend toward an effect on cortisol reactivity. Although preliminary, results suggest there may be important influences of sleep quality but not quantity on HPA regulation and responses to daytime stressors in children and adolescents, and further study is warranted.