“Adverse life experiences have been associated with an increase in risk for mental illness, putatively by inducing long-lasting changes to brain function. Of particular interest is stress-induced neuroplasticity within regions that appraise potential threats and initiate behavioral and physiologic coping responses such as the prefrontal cortex (PFC), amygdala, hippocampus, and parts of the salience network. Studies in laboratory animals support this hypothesis, but evidence in humans is mixed, with adversity being associated with increased, decreased, or no difference in brain activation responses to test stimuli.
The lack of consistency might be related to varying factors including the operationalization of adversity, which can include nutritional deprivation, sexual and physical abuse, war exposure, social isolation, and limited financial resources. Additionally, judgments about the amount of adversity vary, with some studies relying on frequency counts, some that separate levels of severity (eg, adversity vs trauma), and others that make qualitative distinctions about different dimensions of adversity (eg, threat vs deprivation).”