Brewwwwwwdal, and all true. My uncles have lived this description.
Ime medication and clinical severe depression can also do this to your memory, though at least your body isn't (always) failing you too, and once you come off the pills or find a way back to a dopamine/serotonin baseline you can bounce back at least somewhat.
e.g. I've never been a drinker, but have been misprescribed very naughty powerful medication and had a dark night of the soul, and there are months & years in the 2010s I cannot recall much of. I know what job I had and where I lived, but that's it. There again, most of my dull miserable adolescence is all just a blur to me now, too, and I'm not even 40--that's half by design and more normal though, I'm guessing.
Now we're on the depressing subject: wonder whether this is one reason Opie has cut off Anthony so harshly. Besides the noncing and racial invective, I mean. It must be heartbreaking for Gregg to have to look at this decomposing shell of his former partner & friend, or talk to him and realise he remembers so little of a time that they shared. It's easier to grieve someone with time & space, even and especially if they aren't dead yet, so they perhaps Opie's gone early on the mourning?