Canon is actually vague on whether Anna's mom just had a heart attack or some kind of early manifestation of Anna's ghost caused said heart attack, and Anna wasn't sane at the time so she doesn't remember, so if we could avoid those questions IC?

"Um, it's kind of...gross. And hard to explain. I mean, I didn't usually have a mirror. But I get...a lot stronger, and a lot more violent, and I would like to avoid it as much as possible, and I'm so glad you don't feel any kind of...yes."