December 31, 2021:
My only previous up close experience of neurological disease was of my great friend Keith.
In the dorm you'd find him asleep on the floor in public spaces, one or another lobby perhaps, back against a wall, with eyes open. Eerie, but, at the time, we all shrugged off this behavior as a quirk of character, in a context where quirky characters were pretty much the norm.
Later in San Francisco I'd discover him staring into the television. If the television were powered on he'd pull up a chair two or three feet from the screen, then sit staring, unable to break away. He'd watch CSPAN, of all things, potentially for hours, until I or a housemate found him there and switched it off. Eventually he learned not to have televisions in the house. This was a decade before Internet...
Some time later, perhaps ten years, he was diagnosed with dementia. Young. I think, early forties.
He was sent to live in a specialized care facility, where slowly his memory faded. Of school, CSPAN, me. Everyone. For his room there I sent him a colorful Peruvian tapestry, with a careful note explaining who I was and how I knew him. He didn't respond. Some years later I was told he'd died.
I don't think there's anyone who ever met him who didn't love him. There's never been anyone more well-meaning, or more generous.
Nowadays I think of him more often than usual.