I'm 29. My dad is 65. He's not very old at all really, but I've noticed over the last few years his cognition has declined quite a bit, and he's always had problems doing things everyone else takes for granted (like turn on a computer or use a self check out). He's been VERY isolationist and antisocial his entire adult life, like to the point most people can't really conceive of people like him. He doesn't even know what Star Wars or Xmen is and was totally blown away by the fact my laptop came with speakers (as in the speakers that are built into the laptop). It's always been like dealing with a caveman.
Recently, however, he's become more agitated, confrontational, combative, and really just idiotic. He can't regulate his emotions and throws tantrums, can't really seem to understand reason or logic, does weird things that don't make sense, and really has no understanding of anything outside of his daily routine the way you would think of what would be the case for a 90 year old who has lived out in the country for the past 20 years. It's bizarre... I can't think of anyone else I've ever known like him.
I'm struggling with what to do. He's worked in construction his entire life (the kind where you operate dozers and loaders and motor graders, etc), and because of that, he can do it pretty much in his sleep because the pathways in his brain for that have been used so much it's pretty much automatic at this point. He can still do that kind of work but not much else beyond that. There have been times when he's been told to go to the store to buy X, Y, or Z, even had it written down on a piece of paper for him, and yet he's unable to complete the task about 60% of the time (he ends up buying other things that are only somewhat related for some reason, like kleenex instead of paper towels, etc). He cannot take a photo using a camera even when you show him how to aim the camera, then push the button down. He just can't do it. Combined with his hostile behavior, ranting, and anti-social behavior in general, it makes being around him pretty difficult.
What exactly am I supposed to do? I don't really feel any love for him because of how much he failed as a parent, but I also don't feel it's right to completely abandon him as if we're of no relation at all. He seems to be completely oblivious that there's anything wrong or off with him, so even talking to him about his issues would be a major ordeal. Any help?