Volatility, which refers to active defense to avoid or eliminate threats..
Withdrawal, which refers to passive avoidance: inhibition of goals, interpretations, and strategies, in response to uncertainty or error.
Because it is linked to many negative individual and social outcomes, Neuroticism has been studied more extensively than any other Big Five trait, and we have a decent grasp of the underlying causes...
The fight-flight-freeze system
Your Fight-flight-freeze System (FFFS) responds to threats with a decision to escape or eliminate the threat.
It's there to protect you (think about how it kicks in if you were to stumble upon a snake as you're hiking in the woods), but it can also respond to threats that are not necessarily dangerous.
The behavioral inhibition system
Your Behavioral Inhibition System (BIS) responds to threats of punishment, confusion, and uncertainty.
Recent studies have linked Neuroticism to high sensitivity of both of these important defensive systems, which can come as a result of low serotonin levels.
The HPA Axis
Your HPA (hypothalamic-pituitary-adrenal) axis regulates your body’s response to stress.