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REVIEWS
REVIEWS
Effects of stress throughout the lifespan on the brain, behaviour and cognition
Sonia J. Lupien*, Bruce S. McEwen, Megan R. Gunnar and Christine Heim||
Abstract | Chronic exposure to stress hormones, whether it occurs during the prenatal period, infancy, childhood, adolescence, adulthood or aging, has an impact on brain structures involved in cognition and mental health. However, the specific effects on the brain, behaviour and cognition emerge as a function of the timing and the duration of the exposure, and some also depend on the interaction between gene effects and previous exposure to environmental adversity. Advances in animal and human studies have made it possible to synthesize these findings, and in this Review a model is developed to explain why different disorders emerge in individuals exposed to stress at different times in their lives.
Every day, parents observe the growing behavioural repertoires of their infants and young children, and the corresponding changes in cognitive and emotional functions. These changes are thought to relate to normal brain development, particularly the development of the hippocampus, the amygdala and the frontal lobes, and the complex circuitry that connects these brain regions. At the other end of the age spectrum, we observe changes in cognition that accompany aging in our parents. These changes are related to both normal and pathological brain processes associated with aging.
Studies in animals and humans have shown that during both early childhood and old age the brain is particularly sensitive to stress, probably because it undergoes such important changes during these periods. Furthermore, research now relates exposure to early-life stress with increased reactivity to stress and cognitive deficits in adulthood, indicating that the effects of stress at different periods of life interact.
Stress triggers the activation of the hypothalamus-pituitary-adrenal (HPA) axis, culminating in the production of glucocorticoids by the adrenals (FIG. 1).
Receptors for these steroids are expressed throughout the brain; they can act as transcription factors and so regulate gene expression. Thus, glucocorticoids can have potentially long-lasting effects on the functioning of the brain regions that regulate their release.
This Review describes the effects of stress during prenatal life, infancy, adolescence, adulthood and old age on the brain, behaviour and cognition, using data from animal (BOX 1) and human studies. Here,...