The outer layers of the brain — the ones that evolved more recently — deal with complex, intellectual, and distinctly human forms of cognition. These outer layers also seems to be where most mental illnesses arise.
The prefrontal cortex is part of the outermost layer of the brain. It’s heavily involved in mental self-observation (thinking about thinking), selective attention, and the creation and manipulation of mental representations.
Put another way, how you see yourself and everything in your world — the mental models that form your unique version of consciousness — are generated in your prefrontal cortex. And this may make your PFC particularly vulnerable to the stresses of modern life.