The brain is the key organ of the response to stress because it determines what 
is threatening and, therefore, potentially stressful, as well as the 
physiological and behavioral responses which can be either adaptive or damaging. 
Stress involves two-way communication between the brain and the cardiovascular, 
immune, and other systems via neural and endocrine mechanisms. Beyond the 
"flight-or-fight" response to acute stress, there are events in daily life that 
produce a type of chronic stress and lead over time to wear and tear on the body 
("allostatic load"). Yet, hormones associated with stress protect the body in 
the short-run and promote adaptation ("allostasis"). The brain is a target of 
stress, and the hippocampus was the first brain region, besides the 
hypothalamus, to be recognized as a target of glucocorticoids. Stress and stress 
hormones produce both adaptive and maladaptive effects on this brain region 
throughout the life course. Early life events influence life-long patterns of 
emotionality and stress responsiveness and alter the rate of brain and body 
aging. The hippocampus, amygdala, and prefrontal cortex undergo stress-induced 
structural remodeling, which alters behavioral and physiological responses. As 
an adjunct to pharmaceutical therapy, social and behavioral interventions such 
as regular physical activity and social support reduce the chronic stress burden 
and benefit brain and body health and resilience.