How do I help when someone has forgotten how to use the bathroom?

That’s amazing she can do those things with late stage. From my reading, consults and experience, it’s my understanding that learning new things is not likely with dementia. Most people become incontinent in the late stage.

@keithchappell, I completely understand your situation as my mother whom I care for has Alzheimer's. It sounds like your wife is still fairly high functioning so you might try typing out in a large font on the computer the "Steps" to using the bathroom and posting it on the side wall where she can see it when she sits down. If she can still read, this has proven enormously helpful for us. She will then have each step written out and can hopefully follow your directions. We also use this method for helping my mother remember to keep her disposable panties on at bedtime and not removing the disposable bed pad. I typed a humorous message from the "bed" and laminated the paper so we could place it on her pillow every night. It works great! Hope these ideas help.

sorry i meant late onset

Hi @keithchappel, My husband forgot how to shave and I did something similar to what @ladyaceintx1 posted. He's also benefitted from a whiteboard on the fridge with my mobile number and the names of people he tends to forget and instructions, like don't leave the house when Teri's out.
Would it be possible to post a sign or whiteboard across from the toilet with step by step instructions for your wife to follow? Pictures may also be helpful. I'll see if I can find anything online.
I've also read that putting a person with bathroom issues on a schedule is helpful, like take to the bathroom every two hours, etc.
I wish you the best.