A woman has shown a hostile, suspicious, and socially withdrawn manner for as long as anyone who knows her can remember, tracing back to her teenage years, with no identifiable triggering event or illness at any point. Before revealing the answer: is this enduring personality change after a catastrophic experience?

No, this is more consistent with a personality disorder in the general sense than enduring personality change after a catastrophic experience. Enduring personality change requires a genuine change in character with an identifiable onset following a specific catastrophic event or severe illness episode, in someone without a premorbid personality disorder; here the pattern has instead been present as a lifelong trait since adolescence, with no identifiable triggering event, which is the defining feature of a personality disorder rather than an enduring personality change.