The Brain and Body on Stress
Neuroscientists have treated the brain in isolation from the rest of the body, while endocrinology and general medicine have viewed the body largely without regard to the influence of systemic physiology and pathophysiology on higher brain centers outside of the hypothalamus and pituitary gland. But now there is greater recognition of brain–body interactions affecting the limbic and cognitive systems of brain and altering systemic physiology; these are conceptualized as allostasis and allostatic load and overload. These concepts look at both the interactions of brain and body to stressors and health-promoting and health-damaging behaviors, and they help integrate behavior and mood with systemic functions. These interactions involve genetic predispositions and epigenetic alterations mediated by circulating steroid and metabolic hormones. Comorbidity and multi-morbidity of disorders will be illustrated by the relationship of systemic and brain insulin resistance to the psychopathology of depression and to the increased risk for dementia.