Alzheimer's

Feeling a bit helpless. My Dad has Alzheimer's. He's had it for a few years now, and is on Aricept. His behavior has been changing lately, he's become more aggravated, outspoken. I have not seen this firsthand, but what my Mom tells me. Living an hour away with 3 kids makes it difficult to just go and visit for a few hours. Plus, when we are there, the kids get rowdy and this unsettles him too. I really want to be there to help my Mom, as she has now been told that he should be with someone when he goes out on his own. He's fine going into town alone most days, but sometimes he says and does things that are inappropriate. My Mom has a very active life, she spends many hours volunteering throughout the week. To expect her to give everything up is unreasonable. I just wish I lived closer, or had an idea how to help them.