My mother began suffering from dementia a few months before she passed. The biggest clue to the similarities was one time when she was telling me that she was seeing demons in the corner of the room. About a month prior, I'd had a pretty potent DMT experience that seems to have innately "taught" me a few things. Based on that, I told her to think about Jesus Christ (she was quite religious), I gave her about 30 seconds (which, I was presuming, felt like much longer to her). When I then asked her what she was seeing, she said "bright colors and flowers". Emotion having that high of an effect on what she saw was very much like how psychedelics tend to amplify your emotions and bring them to the vision system.
She also would talk about how she just got back from writing a novel or a movie. Before my DMT experience, I didn't have the knowledge to be able to lean into it, so I'd challenge it. Afterwards, I knew enough to lean into it. I'd ask her about her latest "work". I believe that in her mind, she was actually traveling to write books and movies.
If you have a loved one suffering from dementia, I almost want to suggest that you should take some time (if possible) and have a small psychedelic experience (or, if you want, dive into DMT). It may help you greatly understand and support your loved one. If you don't want to have such an experience yourself, at least lean into what they say their experiences are, never fight against them.