Another issue is that evaluating memory disorders like AD is really hard if your subjects don't have language and can't discuss their subjective experience. A mouse that can still find its way around a maze that it learned is hard to compare to a person that can still find their way to their office but can't remember colleagues' names or whether they are married. Apes wouldn't help with the problem that AD symptoms are tied up with relationships and experiences unique to the only species that has language. (Side note: as someone approaching retirement from a family with a strong history of AD, I'm not entirely sure that the unique faculty of language is worth its associated cost: that we're the only species whose members know they will senesce and die,) Edit: shit, that's maudlin. Need a drink. Ignore me.

Or how about people?

I have family suffering from the disease and if I develop it, I want to be experimented on. It's not like I'll have the mental capacity to comprehend or remember most of it.

Join a clinical trial here (organized by the Alzheimer's Association): https://www.alz.org/alzheimers-dementia/investigacion/ensayo...

Speaking as a researcher in this field, more people willing to volunteer for clinical trials is incredibly important.

We've got tons of clinical trials going on. None of them have worked so far, but nevertheless, we spend billions experimenting on humans, and trials are always looking for volunteers

Lifespan is a general problem with aging disorders. These studies take forever to run and cost so much, but we pour the money in anyway. Theres definitely some work with nonhuman primates - but with the brain no model is really that great. I mean, it's not surprising, our brain is kind of our defining characteristic as a species. Though with organoids made from our brain tissue, maybe we'll have better luck.