LeeLee replied: "I don't believe Aricept is the culprit. My grandmother was diagnosed with dimentia/alzheimers. It's my understanding that sometimes dimentia can cause the individual to react in ways that are completely against thier nature. Ex: before the disease they are always calm and accomodating then become irritable and irrational.
This just could be the disease itself progressing.
Please get in touch with support groups, your doctor can give you advice on where to find them. They do help, quite a bit and get as much information as available to you.
Also, talk to your doctor about the differences you are seeing in your father. Talk openly with him, this will give him a better perspective on how the disease is progressing and how to treat it.
Good luck and God Bless."