Medicine Makes No Sense to Me

Why on earth would anyone prescribe a potentially addictive narcotic for a 93 year old woman? My grandmother, since being released from the hospital, has been on two medications: a blood pressure pill, which I get, and something called a duragesic patch which releases a painkilling narcotic into her bloodstream over the course of three day intervals. It also seems to have the side effect of making her rather out of it until around the end of a cycle, which makes sense since it is after all a narcotic. But I have no idea why it was prescribed... she has not, to the best of my knowledge, complained of pain. Let alone a level of pain where I would think something so extreme would be used to counter it. The nurse told us the other day that when it is discontinued it will need to be stepped down gradually since it's a narcotic. I don't know about anyone else here, but I would think that unless absolutely necessary no medicine should be given to a 93 year old Alzheimer's patient that has the potential to cause her to go into withdrawal when it is discontinued... isn't that just common sense?

Definitely asking this doctor some pointed questions about her condition and treatment when we see him tomorrow.