system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What actually happens to our memories when we have Alzheimer's? Do they fully disappear, are they still there but we can't remember them? And how much does a person actually forget?
gpt
Memories are a little more complicated than what we imagine, they're not simply like a folder on a pc that can get corrupted, but rather a Mish mash of many different things. For instance, the sights of a certain memory might be "stored" in a different place to the sounds, to oversimplify it.

So for a person with Alzheimer's, the part of their memory that links a name to a person's face may die, so they forget their name, but a familiar smell like that person's perfume might allow them to access that lost memory of their name even if they no longer remember their face. Or any combination.

Sometimes a memory will be gone entirely. Other times, it might simply be one of the "pathways" to retrieving that memory, like a sight clue, a sound clue, a smell clue and such.