As an aside, my nearly 71-year-old widowed sister-in-law is visiting right now. She has convinced herself that she's already in the early stages of dementia, apparently. She also has convinced herself that her late father had dementia or Alzheimers, but Mr. M and I saw him a lot more than she did - several times a week - and he had nothing of the sort. She's sure she's right.
Nevertheless, last night she discussed the book "Still Alice" and raised the subject of killing herself "when the time comes." She asked whether we'd try to interfere. She said she's already had this talk with her sons and close friends. As a big Obama supporter, perhaps she should just call Dr. Emanuel and have him take care of it for her.
Did your sister-in-law drive to visit you? Forgetting how to get to where you want to go is one of the first signs. It's like losing your keys, and not being able to find them. Most of us can retrace our steps and eventually find them. Those with dementia can't. Another sign is forgetting what we went to the grocery to get. I forgot a lot, but eventually remember. People with dementia don't remember. When we get older, it's not so much that we are forgetful, but it just takes longer to retrieve.
Simple questions can give you a hint if the person might have Alzheimer's. Ask them the day, month, and year. You can also ask them to spell the word, "world" backwards. Also, if they have ever played the card game, solitaire, have them play it, and see how they do.
Alzheimer's is a disease that affects each individual differently. Your sister-in-law should ask the pharmacy to check her meds, providing she is taking any. Many medicines cause memory loss. I suspected my husband had Alzheimer's, in part, because I worked with dementia patients all day. I took him to a neurologist to verify it.