In this review, we report on studies that have assessed the effects of exogenous and endogenous increases in stress hormones on human cognitive performance. We first describe the history of the studies on the effects of using exogenous stress hormones such as glucocorticoids as anti-inflammatory medications on human cognition and mental health. Here, we summarize the cases that led to the diagnosis of glucocorticoid-induced 'steroid psychosis' in human populations and which demonstrated that these stress hormones could thus cross the blood-brain barrier and access the brain where they could influence cognition and mental health. We then summarize studies that assessed the effects of the exogenous administration of glucocorticoids on cognitive performance supported by the hippocampus, the frontal lobes and amygdala. In the second section of the paper, we summarize the effects of the endogenous release of glucocorticoids induced by exposure to a stressful situation on human cognition and we further dissociate the effects of emotion from those of stress on human learning and memory. Finally, in the last section of the paper, we discuss the potential impact that the environmental context to which we expose participants when assessing their memory could have on their reactivity to stress and subsequent cognitive performance. In order to make our point, we discuss the field of memory and aging and we suggest that some of the 'age-related memory impairments' observed in the literature could be partly due to increased stress reactivity in older adults to the environmental context of testing. We also discuss the inverse negative correlations reported between hippocampal volume and memory for young and older adults and suggest that these inverse correlations could be partly due to the effects of contextual stress in young and older adults, as a function of age-related differences in hippocampal volume.

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Early-life stress (ES) has been associated with diverse forms of psychopathology. Some investigators suggest that these associations reflect the effects of stress on the neural circuits that support cognitive control. However, very few prior studies have examined the associations between ES, cognitive control, and underlying neural architecture. The present study compares adolescents with a documented history of ES to typical adolescents on a cognitive control task using functional magnetic resonance imaging (fMRI). Twelve ES adolescents who were adopted because of early caregiver deprivation (9 females, age = 13 years ± 2.58) and 21 healthy control adolescents without a history of ES (10 females, age = 13 years ± 1.96) who resided with their biological parents performed the change task (Nelson et al., 2007) -a variant of the stop taskduring fMRI. Behaviourally, ES adolescents took longer to switch from a prepotent response ("go") to an alternative response ("change") than control adolescents. During correct "change" responses vs. correct "go" responses, this behavioural group difference was accompanied by higher activation in ES subjects than controls. These differences were noted in regions involved in primary sensorimotor processes (pre-and postcentral gyri), conflict monitoring (dorsal anterior cingulate gyrus), inhibitory and response control (inferior prefrontal cortex and striatum), and somatic representations (posterior insula). Furthermore, correct "change" responses vs. incorrect "change" responses recruited the inferior prefrontal cortex (BA 44/46) more strongly in ES subjects than controls. These data suggest impaired cognitive control in youth who experienced ES.

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BACKGROUND AND OBJECTIVES: Kangaroo mother care (KMC) is a multifaceted intervention for preterm and low birth weight infants and their parents. Short-and mid-term benefits of KMC on survival, neurodevelopment, breastfeeding, and the quality of mother-infant bonding were documented in a randomized controlled trial (RCT) conducted in Colombia from 1993 to 1996. The aim of the present study was to evaluate the persistence of these results in young adulthood.

SYNOPSISPerhaps the most prominent feature of human aging is the variability in decline of intellectual processes. Although many research avenues have been used to study the origin of such an increased variability with aging, new studies show that some biological factors may be associated with normal and pathological cognitive aging. One biological parameter that came under scrutiny in the past few years is the hypothalamic-pituitary-adrenal (ΗΡΑ) axis, an endocrine closed-loop system controlling the secretion of stress hormones (glucocorticoids). In this review, we summarize data obtained in both animals and humans suggesting that cumulative exposure to high levels of glucocorticoids can be particularly detrimental for the aged hippocampus, a brain structure involved in learning and memory in both animals and humans. We then analyze the implication of these data for the study of dementia and depression in later life, two disorders characterized by increased glucocorticoid secretion in a significant proportion of patients. Finally, we suggest various factors that could explain the development of glucocorticoid hypersecretion in later life.

The effects of adrenergic and corticosteroid hormonal systems on emotional memory were measured in 64 young men. Placebo, propranolol (40 or 80 mg; beta blocker), or metyiapone (corticosteroid synthesis inhibitor) was administered before the viewing of a story composed of emotional and neutral segments. Short- and long-term declarative memory for the story was assessed. Propranolol 40 mg had no effects on declarative memory. Propranolol 80 mg impaired short- and long-term declarative memory for emotionally arousing material. Metyrapone did not impair short-term declarative memory but impaired long-term declarative memory for emotionally arousing and neutral material. Results demonstrate that adrenergic and corticosteroid hormonal systems differentially affect declarative memory for emotionally arousing and neutral material, and suggest that interactions between adrenal hormonal systems modulate emotionally arousing declarative memory in humans.

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