My Dad's becoming more obnoxious and ungrateful. How do you attempt to carry on caring and not respond likewise?

I actually said this to my mother recently (she's not demented, so she could understand. She's just been mean and vindictive and accusing for a long time. She prefers complaining to having anything solved, she doesn't like to feel "beholden" (i.e. grateful), and she is paranoid.): "You don't have to thank me, and you don't have to like it -- you're impossible to please anyway, so I've given up on that long ago. I'm doing this because it's the right thing to do and someone has to do it." She had no way to respond to that, so it shut her up briefly. But that's not why I'm reporting it to you all on this site. I'm reporting it because that expresses a shift in ME, one that has taken many slow years. In other words, my satisfaction comes from doing the right thing -- it DOESN'T come from her gratitude, or from feeling loved or appreciated, so I'm no longer hooked in to longing for it. It took me a very long time to stop wanting my mother to be loving towards me -- who doesn't want that?! But that's the way it is, and really getting in line with reality is the path to freedom......

Ignore, ignore, ignore.. Change the subject.. Let his doctor know about this sudden change in his behavior..

My mother was mean, rude, combative and ungrateful. I had to keep telling myself "She really doesn't mean it!" I've found that our elders have a tendency to act out worse around those of us that are the closest and be an angel around everyone else. Meds have helped wonderfully. I now have a kinder, gentler mother.

My mother was like mgcarter's until I was able to get her on the Excelon patch. Mom was bipolar and refused medication for years. The Excelon patch gave us five wonderful months before she passed.
We were able to apply the patch on Mom's back after daily washing & while applying lotion to all but the current patch area. Distracting Mom this way allowed us to get the med into her without any objection. She didn't question her change in feeling, so there was no problem with her distrusting her food, for example.

I wish you success in finding a solution.

The more dependent an elder becomes, the more this may occur. Try not to take it personally. Caregivers bear the brunt of bad behavior. Be sure to have support outside of this relationship... it will keep you going. Illness really messes with the mind. In the end, you will not regret your decision to do the right thing (becoming a caregiver). You will regret responding in kind.

Welcome to the site. I have had this same problem with my Mother whose personality has gotten very self-centered and lets everything fly from her mouth because she has no more boundary filters. She has hurt all of her friends feelings and they now avoid her. You are going to have to change your attitude because his is not going to change. I do my best now, do not expect any type of gratitude from my Mother because she acts like a teen and teens are not very grateful and I demand my respite because that is what keeps my sanity at this point in my life. Come here and vent or get some solutions because there are many in the same boat and we do understand.

How? - do you carry on caring about the person? 1. By putting yourself in his shoes: how chirpy and grateful would you be feeling? 2. By not taking his lashing-out as a personal insult - easier said than done, and it doesn't make it any less tedious or discouraging, but it does help to remember that your father isn't setting out to hurt you. 3. Come back and vent! I've found this forum more help than just about everything else put together.

I completely understand your thinking on this. I have two guys and they both have behaved this way. I felt and sometimes still feel so hurt by the way I was invisible to them as to how much I did for them or how extremely exhausted I was. But then I realized Dad and Hubby are teenagers! Seriously! When my kids were teens they were ungrateful and even mean at times. Never did they give a thought to my wellbeing but only thought of themselves. So I treat them as such. When they are rude and noncompliant I stand up for myself as much as I think they will understand. I don't think "they don't mean it" because I think they do mean it. I think they have lost the ability to think of anyone else besides themselves much like a child, so like a child I train them (more for myself than for them). I don't allow them to bully me because trust me with two guys who "know it all" it can be a fierce struggle to not believe their rants. I think responding to them like I would my teenagers helps me still respect them and not begin to hate them or dive into depression. I think the mistake I make is thinking they are the same guys. But they have a disease that has changed them and they will never be the person they were again. My guys both know I love them and want the best for them.
I also agree with mgcarter sometimes it's just a tweak in their meds will help smooth things out.
Welcome to the group. I too am new to the site and am very glad for the support of those in the trenches with me :)

Many thanks for the help & advice will get on to it. Really appreciate your help only learnt about this site today good to share with people who have been or going through the same experiences

Don't respond to insults.
Ignore.
Act as he is always right.
Walk away when you begin to get upset.
Imagine what you would be going through if your mind & body does what his is doing.
Give yourself a pat on the back for not responding and getting him further upset.