Yes, I think it's about memory loss. Also, since rational thinking seems to disappear about this time, it's impossible to explain to the person that it's their memory loss which is causing the problems.. Since nothing is wrong with them (we throw denial into the mix), it must be that someone is stealing their money, and the most likely person is the one they see the most.
Harley, AD patients will also take other people's things or shoplift simply because they think they are theirs or they want that item & take it, much like a young child. Again, it comes down to impaired cognition and the loss of social inhibitions, which isn't only about taking clothes off. My mother used to make LOUD remarks about others' fatness, big noses, bad skin etc etc. Obesity was a favourite topic of hers, even when she was almost 4 stone overweight & looked like a little lumpa-lumpa. She told me once - staring me in the eyes & stark naked, with her stomach hanging out and down attractively - that she had never been fat. Sigh......
These days are now gone, of course.
Joanne