My mother has been calling all her friends and our relatives telling them I stole from her. How do I react?

You can not argue with someone who has dementia. They absolutely believe what they are saying is true. You write that everyone she’s told knows it’s not true, so let it go. It’s easier said than done, I know. Everyone on this forum who has watched a loved one sink into the quicksand of this disease and slowly disappear knows exactly what you’re going through. Sending hugs.

Let it go. You’ll spend all your time chasing down her tall tales. Even IF someone remotely believed any of it, it won’t be long before her stories get obviously ridiculous

It's very normal for the person the closest to the patient to be blamed for the most. Does she know you are her daughter? I use to deliver medicine to Dementia wards and the patients would always tell me stories about how the nurses are stealing from them (the people they see the most). Honestly, the fact that she recognized you is great. I know its upsetting but you don't have to prove yourself to anyone. Alzheimer's/Dementia is something that's different for each patient and hard for most people to understand, regardless. Does she do it with anyone else? It's normal that when a patient loses/ misplaces something they blame it on others. She's not understanding that she was the one who did it. Most patients don't accept the fact that they even forget things. Anger is a normal stage. Stay strong.

The only thing I can tell you is that this stage will pass.
For whatever reason a person with dementia can become attached to only one person and they can single out one person to become very angry with.
Make sure brothers get her tested for a UTI. As strange as that sounds, a UTI can cause dementia like symptoms while it may not cause symptoms you would expect like frequency of urination or burning. The only way you would know is a simple pee test. An antibiotic would be needed. A UTI can be toxic.
I’m sorry you are having to deal with this. The spoken word, true or not, is powerful.
It’s good that your family knows she is ill.
edit: how do you react? With compassion if possible. Come here to vent. We understand.

I'm so sorry this has happened to you.

I'm sorry your mother is so frightened and angry, too; but at least that's not something you or anybody else did to her.

The pain and grief that you have because of losing your relationship with your mother is a big issue that will take time to address. Meanwhile, though: your mother is living in a mobile home close to your brothers? Hey, that doesn't sound any too safe. Hadn't the three of you, you and both brothers, better get together and work out a care plan for your mother?

I don't know if it's any consolation for you that at least one of your brothers now understands what you've been going through. It does, at the very least, make you safer from any potential misunderstanding of the accusations your mother has been making.

For the time being I think it would be the right choice not to go and see your mother if it leads only to confrontation and aggression on her part. I know you're the one who gets lashed out at, but she is the one feeling the fear and anger - all the more reason not to go, it doesn't do either of you any good. I hope this won't be forever or even for very long, necessarily, just until things are more under control.

Does your mother get any medical, psychiatric or other professional input? Have any recommendations been made about her care?

These seem to me to be a direct product of her dementia.
When my grandmother became ill, she turned on my dad, accusing him of throwing human waste on her property.
Previous to this, she had dearly loved him all the years head beenher son-in-law.
As her dementia increased, she forgot her accusations and became peaceful towards him.
Sometimes it’s hard to remain focused on the widespread damage that dementia does to even very close, very dear relationships.
Whether you attempt to “prove” that you didn't steal from her, or ignore what you are told she has said, it makes NO difference to her, and in the long run, no difference to the sadness you feel about it.
If you are able to forgive her and realize that it is her ILLNESS TALKING, NOT the loving soul you have begun to lose to her disease, I promise you that you will ultimately find yourself at Peace.

I, too, like many of the other caregivers, was in the same boat. My once stable, grounded, and intelligent mom became paranoid and distrustful once Alzheimer's was in full swing. In a book I wrote about it, "My Mother Has Alzheimer's and My Dog Has Tapeworms: A Caregiver's Tale," I have chapters entitled, "Steel Yourself for Stealing," and "Paranoia Can Annoy Ya." At first, I tried to reason wit my mom. When she accused "coffee thieves" of coming in a second story window to steal her coffee, I reminded her that she just drank a cup (of decaf), but since she didn't remember doing that, the only "logical" explanation was that someone came in and siphoned it out of her cup. When she accused someone of trying to put poison in her cup of coffee, I offered to drink it to prove otherwise, but it just escalated the situation, so I went in the kitchen, banged around some pots, poured her coffee into another cup, and she said it was delicious. I learned to think on my feet, and get rid of logical thought when necessary. It's so counter-intuitive, but it was our "new reality." At first, her insults really hurt my feelings. We had always gotten along so well. Sometimes my husband would mouth, "It's not really your mother," and he was so right. You just have to view your mom's insults as the disease talking, and not her. Best of luck.

My mom has done this for over ten years. No dementia. She has a hoarding problem. Very suspicious of my sister Ian's I once when we cleaned her home. (We did NOT grow up that way in filth). Now while in hospice for renal failure, and other issues that impact blood flow and clear thinking, I think, she blames everyone about the loss of even trash envelopes. All I can say is hang on. Best wishes.

Firstly - don't even try to justify yourself over anything she says, you know its not true, family and friends know it is not true, so you are putting more stress on yourself for no need.
Secondly - think seriously about whether you go and see her. If it disturbs her and makes her behaviour more difficult, and upsets her, then it may be time to stop. So many people go on visiting when they are unknown, or it distresses the patient, or worst makes them violent and impossible for carers to handle. I know it is hard when one has been especially close but you are not (from what you say) adding anything positive to her life. If you feel you need to go to convince yourself you have done everything, and ensure you do not feel guilty or uncaring, that is a different matter - but you go for you, you are not going for her at this time, give yourself permission to make whatever choice you feel best for YOU.

I can emphasize with you. My mom was just entering dementia when she started telling friends and family I was stealing her money. I lived 90 miles away but that didn't stop them from believing her. To this day I'm ignored by family. I even lost a great relationship I had with my favorite uncle who died believing the lie.
Its hard but you have to count on your integrity and reputation to stand tall. You can't convince your mom she's wrong.