Couldn't handle the stress-I think it's rated the most stressful thing possible to lose a child. I've heard of married couples passing on the same day or next-also twins. First time I've head mother-daughter.
She had several strokes recently, I heard on the news that she was planning her duaghter's arrangements when she took ill, probably another stroke, or cardiac related. Losing a child at any age is overwhelming
Somebody told me somewhere in "Postcards From The Edge" there is a line or quote about how Carrie Fisher's biggest pet peeve/ fear is her mother upstaging her.