Advice wanted. Why does my cat jump out of his skin?

My parents adopted a quirky cat that seems to have had some past trauma. She's finally getting more friendly and less skiddish - AFTER FOUR YEARS.

Sometimes it's just love and time that helps them get over past trauma.

My cat was not a trauma victim, we got her quite young, but she sometimes still jumped out of her skin while doing nothing - because she got an itch. You'd see her skin twitch in a spot, and then she'd jump out of her skin to dash off to somewhere else just to scratch it. It was just the sudden unexpected unpleasant physical sensation that triggered her, so it's not always a trauma thing. Admittedly she was a rather flighty cat, despite her leisurely safe flea-free existence.

However, for a new rescue, they're definitely going to be extra jumpy for a while. I hate his format, but Jackson Galaxy gives solid and practical cat behaviour info. He doesn't go into trauma and memory anywhere near enough but here's a perspective on cat memory you might find useful. Maybe your cat remembers a smell from a cleaning chemical at the rescue place?

I took in a cat that had been abused by his mentally ill owner who would take his psych meds, get drunk, then bully and harass his cat...it took 5 years before it really 'settled down' another 5 to subside its ticks and this most recent 5 years he seems to be comfortably aging into retirement. He was an outdoor cat that ate rabbits, rats, mice and birds. 20lbs at his peak. he's down to 14lbs now because he's not sleeping in the snow like a freak anymore. he still goes out into the garage and just vibes out on the dog bed like a husky in winter. Always have to buy dewormer because of the raw pest animals he devours. so with that all said. Cats Definitely can have PTSD. i'd argue Mammals in general are particularly susceptible to it because of our emotional links.

Give him nothing to be scared about and he will slowly forget.