How do people with Alzheimer’s not forget everything? For example, I have seen people with Alzheimer’s who do not remember loved ones and other stuff, but they still remember how to speak and how to move etc. What stops them from forgetting every single tiny little thing they know?
In: Biology
People have already provided good explanations, but I just wanted to add: procedural memory (how to do things like tie your shoes), semantic memory (facts, like who was the president during 9/11) and episodic memory (your own life experiences, like what you ate for dinner last night) are all stored in completely different places in the brain and operate on different pathways.
Episodic memory and semantic memory together are called “explicit memories” which means you can say out loud exactly what the memory was. Procedural memory is also known as “implicit memory” which just means that you don’t have a memory of a specific event, you just generally know how to write your name for example, without remembering who taught you and where you were when you learned it.
Often times when people’s memories are affected in any way, whether by Alzheimer’s, amnesia, stroke, or something else, explicit memories are affected but not procedural memories. Especially at the beginning of Alzheimer’s, you might start forgetting who your grandchild is or where you put your keys, but you still remember how to knit or how to put on clothes because that’s a different kind of memory. Eventually, though, those other memories can also be affected, leaving people with Alzheimer’s unable to care for themselves. Memory is definitely a wacky thing and I highly recommend reading The Man Who Mistook His Wife for a Hat by Oliver Sacks, it has some good examples of some really fascinating memory conditions (like the man whose memory completely resets to 1966 every 30 seconds- every memory before that general year is perfectly intact, but he can’t make new memories at all so is always stuck thinking it’s still 1966 and is shocked to see how old his wife looks every time she comes into the room).
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