Editors' ChoicePsychiatry

Early life stress: It’s all in the timing

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Science Translational Medicine  31 Jul 2019:
Vol. 11, Issue 503, eaay3581
DOI: 10.1126/scitranslmed.aay3581

Abstract

The effects of childhood maltreatment on adult amygdala function depend on when the maltreatment occurs.

Childhood maltreatment is a potent risk factor for psychopathology. Alterations in amygdala function are commonly observed following exposure to early adversity and are implicated across many psychiatric disorders. However, some studies have identified exaggerated amygdala reactivity following maltreatment, whereas others have observed blunted amygdala reactivity. Given the dynamic changes that occur during brain development, the developmental stage at which an individual is exposed to maltreatment may be an important factor in shaping neural and behavioral outcomes.

Using machine-learning techniques, Zhu and colleagues examined how age and type of maltreatment exposure were associated with subsequent amygdala function in adulthood. Participants viewed emotional faces during functional magnetic resonance imaging and retrospectively reported on their history of maltreatment. The authors found that physical abuse at ages 3 to 6 years old and peer emotional abuse at ages 13 and 15 were most strongly associated with adult amygdala function, but in different directions. Whereas maltreatment during childhood was associated with blunted amygdala reactivity later in life, maltreatment during adolescence was associated with heightened amygdala reactivity later in life.

These findings suggest that the effects of maltreatment on adult amygdala function vary depending on when the maltreatment occurred, and that timing might not only relate to the degree of susceptibility but also to the direction of neural effects. One potential interpretation is that blunted versus exaggerated amygdala reactivity is adaptive at different developmental stages. However, future research will be needed to inform how these neural effects might be adaptive for individuals contending with adversity. Because participants in the current study were only assessed as adults, it is unclear how the timing of maltreatment affects amygdala function during development and whether the effects are consistent across the intervening years between maltreatment exposure and adulthood.

Identifying sensitive periods of development, during which environmental exposures have particularly strong effects on the brain and behavior, has the potential to enhance understanding of risk for psychiatric disorders. Moreover, this research could inform efforts to tailor treatments based on specific factors such as developmental stage or type of trauma exposure or to target periods when the brain may be especially amenable to intervention.

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