Looking for tips on getting my aunt, who has early dementia, to change her adult diaper when it has leaked.

You need to change her on a regular schedule. There is no convincing an elder with dementia of anything, unfortunately.

You can’t talk sense into someone whose brain is dying. take her hand and say, “come on, love. It’s time for a fresh pair of underwear” (don’t call it a diaper)

It sounds like it's well past time that someone else now step up to change your aunts diaper every few hours as with her broken brain she can no longer be responsible to do this herself.
And you don't ask, you just tell her that it's time to get cleaned up now, and take things from there.

She cannot perform this task anymore. It's beyond her. Someone else will have to change her, and on a regular basis.

If it is truly leaking, perhaps they are the wrong size? Sometimes one size smaller can make a huge difference with leaks.

If the leaks are because she is a heavy wetter, for example overnight, there are companies that sell “booster pads” that go inside the diaper.

finally, if the issue is truly cost, look into your local PCA for assistance getting low cost or free Incontinance supplies through state assistance programs.

if all else fails, definitely call them underwear and just tell her it’s time to change, even if you set an alarm for every 4-6 hours.

She is no longer in early dementia. If she lives alone, she is no longer safe. Who is her POA? If no one is, then contact APS to start a record that she lives in an unhygienic situation.

Tikiara: With that kind of mindset, she is no longer in early dementia.

There is little you can do about any of this in the case of advanced dementia. At some point it is well to have placement simply because one on one care 24/7 isn't sustainable. If Aunt isn't in a care facility I think it's time to consider that she may require now a few shifts with a few people each to provide her care. I wish you good luck.

This is no longer early dementia . We had the same problem with my mother and FIL . They resisted all attempts because they could not feel the wetness , until it leaked ( and later not even then ). I also think part of it was it became too difficult to do themselves and did not want help . Later , my FIL totally did not acknowledge he was incontinent at all . I found that moderate dementia with extreme stubbornness requires NON family caregivers in assisted living . My mother’s doctor said , “ Mom won’t listen to you because she sees you as a child . Often a time comes when homecare does not work any longer “.

Does she go to the bathroom at all on her own? You mention being wet but does she still go when she needs to poop? If so, I always left a change near the commode where it was accessible during this stage. Find a spot within her reach to tuck a clean pull-up. You’ll soon know if this will work at all. I did this for DH aunt and it worked for awhile. Try not asking her if she is wet, just make an excuse for her to get up and start to walk then you can more easily guide her to the bathroom. Sort of a “once begun, half done” idea. Come see this mom, you might say or I wish you could see this! Going to change is not fun, so don’t mention that. Sit her on the commode and if she can change her own, let her. While she is on the commode, give her water to drink. After she changes and washes her hands give her a little lotion or lipstick or brush her hair or a fresh spritz of lavender or favorite scent, perhaps another drink of water and then let’s go see what’s cooking or some little travel idea. I used to sing Chattanooga Choo Choo for DH aunt and she loved it.
I had a firm boundary but didn’t mind handing wipes and giving prompts and suggesting maybe another wipe or two is needed. So we did okay while she could handle those steps.

Many elders are used to needing a pad long before they start with pull ups for a leaky bladder. I know my mom would be dry while sitting but if she didn’t go on a regular basis, like every hour, she would stand and her bladder would empty. She knew if she went every hour or so, her pull-up would last until night time. But with dementia, so hard for them to remember. My mom would drink her water while going to the bathroom and coming back. She had numb finger tips so she had her glasses of water lined up on her kitchen counter with a straw and would stop on the way.

i mentioned the water because you said she didn’t notice the odor. The odor is much less when she is properly hydrated plus her skin will be beautiful.