Briefly describe the neurotrophic theory of mood disorders.

The general premise of this model is that exposure to chronic early life stress (e.g., abuse, neglect, parental loss) instigates a cascade of hormonal changes (e.g., release of glucocorticoids stress hormones) that then decrease the levels of chemicals (e.g., brain-derived neurotrophic factor BDNF) necessary for neurogenesis and neuronal growth and development. Eventually, this leads to the neuronal atrophy and cell loss in brain areas critical to mood (e.g., prefrontal cortex, hippocampus), which then result in the symptoms of depression.