How long can you live with AD, vascular dementia and several mini strokes? Husband was just placed i

My husband recently had to be placed in an assisited locked AD unit & DR doesn't think he'll live long. He has calmed down quite well with anti psychotics and anti aniety meds which makes his walking look shuffled now. Whenever I go see him ( with a friend) it gets him stirred up and he got out 2 days later.It took 4 people to get him inside, as he wanted to come home. He is is physically fit, thin but has had a lot of mini strokes. he is currently not on aspirin or a prescription med that was tried before because of a bleeding problem. He has had the vascular dementia, AD and ocd for 12 years. he seems to be going downhill fast, can't rememeber his name or age sometimes, or dial the phone or use his Ipod aymore. DR said he would not last very long, said they lose weight, get pneumonia and they would do no heroic measures to save him. Just bring in hospice

I haven't even adjusted to being alone at home and him there and now he's talking death and hospice? How long do they typically have? ( I know everyone is different.)