At first I thought dementia was just part of getting older. Now she can't remember that we live in the same town. I telephone her daily and visit. at least once per week. I am disabled or would visit more. Recently she asked me if it was dark yet where I live. She is never unpleasant, just horribly confused. She sits in her room, won't read and avoids phone calls from friends and family. Please advise.
I agree with Babalou - if you would call this a sudden or marked change in her, get her seen at once. If you're not sure, call your mother's GP and explain your worries, and don't be so polite that you don't spell out very clearly the changes you have noticed.
And if you are confident it can wait, still make sure that you or another advocate go with her to her next appointment. I have seen my mother lie through her teeth to her lovely long-time GP - you should have seen his face when I told him what was really going on.