This finding is another piece of the puzzle regarding how stress and prolonged distress may impair our ability to think in creative and flexible ways. Research in both mice and humans has demonstrated an association between stress exposure (footshock in mice, life events in humans) and shrinking of the hippocampus – the brain center responsible for forming new, time-sequenced memories. Studies in women with PTSD resulting from childhood sexual abuse and Vietnam veterans with PTSD have shown 12-26 percent decreases in hippocampal volume, relative to those without PTSD. In another study, patients recovered from long-term major depression showed a 15 percent decrease in volume of the hippocampus, compared to nondepressed patients.
Major Life Stress Damages the Prefrontal Cortex
In addition to hippocampal shrinkage, major life stress may shrink brain neurons in the Prefrontal Cortex (PFC), the brain area responsible for problem-solving, adaptation to challenge, emotional processing and regulation, impulse control, and regulation of glucose and insulin metabolism. In a studty of 100 healthy participants conducted by Dr Rajita Sinha and colleagues at Yale University, and published in the journal Biological Psychiatry, those with more adverse life events had greater shrinkage of grey matter in the PFC, compared to their less-stressed peers. Recent major life events, such as a job loss, make people less emotionally aware while life traumas, such as sexual abuse, seem to go further, in damaging mood centers that regulate pleasure and reward, increasing vulnerability to addiction and decreasing the brain’s ability to bounce back.