I know all about the frustration experienced by those suffering from dementia. I've seen so much of it.
My grandmother reached a point where she only spoke the Napolitano regional dialect. But once in a great while, the clouds in her eyes would momentarily part and she would say, in English, "Michael, what's wrong with me?" Then it would disappear as quickly as it appeared and English was forgotton. Along with everything else.
My father was a City of Stamford fire fighter who did electrical work on the side. In short, he was a working man, but still an old school gentleman. However he might have talked while working, at home or socially, he never used bad language in front of women, children, or in any place it might be deemed inappropriate. Man how that changed with dementia! He used words constantly I had never heard come out of his mouth.
Funny though, while he cursed out my younger brother who worked in Stamford and so was there every night on his way home from work, he only did it to me once. My brother had gone home and I said something that annoyed him. He said, "fuck you too Michael!" I replied, "hey! This isn't Robby. This is me! You talk to me like that again and that will be the last time I drive down here to see you."
He paused for what seemed like forever, but was probably only a few seconds, and said, "yeah you would do that. I'm sorry."
And he never did it again. He swore at my brother, swore something awful at George his caregiver, but never swore at me, no matter how far gone he got.
I understand your point about joy being possible. When I visit my wife's sister and I envelop her in a hug and she curls up against my chest and lets me hold her, sure I feel like I'm accomplishing something positive. As I did each night I kissed my dad and said, "goodby dad, I love you." Call me selfish but I have no wish to provide that same opportunity to my children and friends. I'd rather be dead.
Edit: Me thinking about this some more and it is really the double combination of my chronic pain condition which is relapsing and remitting thus it comes and goes, combine with my ADHD and how those two separate conditions impact the affective brain network, which is also the pain network, which is also the network that experiences joy (one of the attention networks but not all the attention networks, how our affective emotional state or sensory stimuli causes us to "gear shift" our attention.)
Yeah and what I am saying is my stubbornness is a type of cope. For I prefer to be joyous or empathetic or a dozen of other emotional states, but if that is hard to do due to my chronic pain, at least I can choose to be stubborn (agency), and thus the opposite is terrifying to me for the lack of control is scary.
But yeah that is the trick for stubbornness is the other side of mercy, or as the Buddhist call it (god I am searching my memory for I been a bad repeater and let myself lapse with "the practice" years ago) karuna. googles that word to remind myself looking up the many meanings for it even though I recall the word.
Oh god damn it when I see one of the meaning, I do not want to feel pathetic and thus not practicing that "self-compassion" with a "kind heart" to myself.
FUCK!
(and this was going to be an edit, but became a separate post for I see you have replied at the time I was typing this.)
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Enneagram 5 problems.