Insanity, Dementia or CDS

I always thought that insanity was a unique perversion of humans.
That dementia and alzheimers was particularly human.
Not to make fun of these horrible diseases, as we all have made reference to ourselves at one time or another when we forget something.
But I am beginning to see that animals can have something like which they call
CDS - Cognitive Dysfunction Syndrome.
This is a much nicer term and one that I think I personally often do suffer from. But I am getting off topic.
This is about our 12 year old cat!
Misha(named after Mikhial Baryshnikov)I think has begun to lose his mind.
He would go outside and turn back around right away and sit at the door to come back in. When back in, within minutes he would cry to go back out.
We've decided to keep him in now that he is getting old and it is so cold out.
He is not at all happy at that and he meows so loud they turn into howling sounds that pierce the ear drums.
He was always good about going in the litter box when in, but now prefers to dump in front of Peters workbench (You probably guessed that Peter stepped in it, and you would be correct).
He just doesn't always seem to know where he is. He often will settle just to get up and pace again as if he forgot where he was going.
I liken it to me, when I go into a room and forgot why I did and then have to walk back out thinking that way I will remember what I went in for. CDS for the moment.
So I am reading about Cognitive Dysfunction Syndrome.
Then of course I go through my usual guilt diatribe: "Why didn't we keep him in all along, why didn't I make my own organic pet food, maybe it is what we fed him, we are bad pet owners" and on and on until I am worn out of guilt and realize I need to take him to the vet.
So I am calling the vet in the morning to talk to him about CDS and how to give Misha the best last years of his life. Should I be grinding up that organic fresh raw chicken tomorrow for his meals...