If I had to try to sum up the central theme of the story, it might be this: discombobulation.
Of course, Anthony's discombobulation impacts other characters.
If I had to try to sum up the central theme of the story, it might be this: discombobulation. The entire narrative plays out as if on wobbly ground, we don't know from scene to scene if the events we see unfolding are "true" or some sort of "tainted" memory or experience of Anthony interfacing with reality.
Of course, Anthony's discombobulation impacts other characters.
-- Anne is increasingly crushed by her father's slip into dementia.
-- Paul becomes so frustrated, he eventually leaves his marriage with Anne.
-- Laura is at first charmed by Anthony, only to realize how messed up he is.
-- Bill and Catherine as caregivers have to respond to wherever Anthony is in his personal timeline.
Every scene has this kind of wobbly nature, the script reader unsure about the veracity or lies of what unfolds in the moment. This dynamic helps the script reader experience what Anthony's experience is.