Clinical meaning
PTSD develops after exposure to a traumatic event involving actual or threatened death, serious injury, or sexual violence. The pathophysiology involves maladaptive fear conditioning: the amygdala (fear center) becomes hyperactivated and encodes the traumatic memory with intense emotional valence, while the medial prefrontal cortex (mPFC), which normally inhibits fear responses, shows decreased activity. The hippocampus, responsible for contextualizing memories (placing them in time and space), shows volume reduction and dysfunction, causing traumatic memories to be experienced as current rather than past events. Neurochemically, the HPA axis is paradoxically dysregulated: cortisol levels are often LOW (unlike depression where they are elevated), but the stress response system is hyper-reactive, producing exaggerated catecholamine (norepinephrine, epinephrine) responses to perceived threats. This creates a state of persistent hyperarousal. The noradrenergic system is overactive (explaining hypervigilance, exaggerated startle, insomnia), and the endogenous opioid system may be dysregulated (explaining emotional numbing). Traumatic memories are stored as sensory fragments rather than coherent narratives, causing intrusive re-experiencing through flashbacks, nightmares, and emotional/physiological reactions to trauma-related cues. The practical nurse provides trauma-informed care, monitors safety, administers medications, and supports the patient through recovery.