Antidepressants can be a BLESSING in the elderly with dementia.
We put my 92 year old father on a low dose of Zoloft (25 mg.) about a week ago, to see if it would help his incredibly mean verbal abuse that seemingly comes out the blue and is always directed at my husband. So far, it seems to be working! He has had anxiety issues for YEARS that never were addressed; OCD issues that were never addressed either so we also have to deal with that.
But I cannot recommend enough that you speak with your elder's internist and ask about prescribing a low dose of antidepressant. The elderly seem to tolerate and metabolize these well and if it makes them a bit more happy and less crabby, combative and verbally abusive....what could be wrong? DO IT!