My mom: Shoplifting and suspected Alzheimer’s

I hope you are all doing fine and first and foremost, thanks for reading this. This is a very sensitive topic for me.
My mom is 75 years old and she was caught shoplifting at a supermarket yesterday. The supermarket manager decided not to press charges. My mom has done this in the past but when we where all at home (we were a family of 9) and during financial distress, when she was around 48 years old. She actually received therapy and improved and stopped shoplifting, as far as we know. Fast forward to yesterday, and this happened again. I believe this was triggered by stress since my oldest brother decided to move back to her house and she doesn't want him there. I feel that she has no need to to do this since we provide for her food and her fridge is full with groceries. We also suspect Alzheimer since she has been insulting her daughters (me included) for no apparent reason, plus forgetting little things here and there. My grandmother also had Alzheimer. We are worried and decided that she needs to see a neurologist (to assess if she has Alzheimer) plus a psychiatrist to start treatment. What else can we do for her? I'm so worried that this may happen again and she may end up arrested or in a very difficult situation. At least she is not living on her own which is a relief even though her current situation is very stressful for her. Thanks for reading and any advice is greatly appreciated!

Have you asked her why she is shoplifting? If she can answer you coherently, it may have to do with an issue that is stressing her out and not be Alzheimer's. The oldest brother may be that issue.

It good you're taking the pre-caution of having her see a neurologist, but your post indicates you're making assumptions about her behavior without having talked.to her directly. If you ask her and she can't give you a coherent answer, it's a good thing you have a neurologist also checking her out.