I guess taken to the logical extreme, what does the brain of someone/thing that's good at playing this (or any game of N dimensions) look like?
While there is definitely something to the plasticity of young brains, for example in language acquisition, or the fact that the Fields Medal eligibility ages out at 40, I believe it's not a linear thing and not a one-way thing.
My curiosity is if this is like you suggest, ingrained patterns, or if there is actual slow down with age. I hear different opinions and am finding it difficult to navigate as I deal with my own, albeit mild, aging.
I actually noticed serious mental decline when I was burned out in my late 20s. There were real physical symptoms like not being able to look at a text editor for more than 2 minutes. Post recovery of that, I actually feel like my brain recovered a lot once I started learning languages very seriously (mandarin and japanese), starting a few years ago. Brain feels healthy now but I'm acutely aware of where it's not as sharp as before. Playing around with this felt a little like when my brain is trying to build a new grammar dictionary.