Probably peri-menopausal it is harsh with the emotions and hormones.
HOWEVER Do not suggest this to her, because all she will hear is "I think you are getting old.."
Ask her if she has been to the doctor lately at an opportune time, like after watching a medical drama on TV. Because, one of my sis-in-law had a mentally ill father, she was perfectly sane and really smart productive person and then in her mid-forties....well she did end up with some serious issues.
She should see a doc get medicine for herself it's probably hormonal pre menapas..I don't think its genetic.