I think my Dad is mentally ill (and has been for years), but not sure exactly what the illness is IYSWIM......

[Hesbarking]

This will see so ludicrous, but I am not a troll - I just can't possibly post about this stuff under my usual name as it is hideously embarrassing.
My Dad has always been odd, and I struggle to understand what is wrong with him. He's always worked, still does in his late 60's, so his mental health has never prevented him from holding a job down. He's been a heavy drinker for years and I wonder if the booze has simply rotted his brain.
I could recount loads of strange things he has said, but here is the strangest.
About 4 years ago he told me that he was once abducted by aliens. They did experiments on him, and as a result he now has 2 anuses.
He will never recognise that he has problems and would never see a doctor about it.
I'm just perplexed by him. I don't see him much since my Mother died, but keep an eye on him.
I'm not sure what I'm expecting people to say, I just needed to let that out!

I'm so sorry, it sounds painful - even from a distance.
I wondered about 'wet brain' too, as I read your post...its basically a term used to describe what happens to minds that have been pickled in alcohol over a long period of time. At some point, the damage becomes (to some extent) irreversible - and people start to lose some of their faculties.
In my experience, chronic alcoholism alone can cause people to have delusions like this - though its also possible the drinking is masking another condition: it would be hard to tell without removing the booze.
Has your Dad ever had any help re the drink? AA, or counselling, or anything?

Oops - sorry, you already said he doesn't acknowledge a problem or want help. Teach me to post when over tired

He may have a personality disorder especially if he has behaving this way all his life.

if there are times when he seems well, and not relating crazy stories I would it be more likely to be something like schizophrenia.

I think there is little you can do to help. Unless he finds himself hospitalised, and visited by social workers etc. Does he tell these stories to anyone else or just family members.

Here is a link personalitydisorders

You could also try giving MIND a call for advice.