Biden's "dementia" isn't an "act", it's a Republican LIE. Biden has never claimed to have dementia. Only the Trump Cult, and right wing media say he has dementia, and RWM know it's a lie.
Biden's has been made laughable gaffes all of his political life. It's because of the brain processes he's always used to overcome his stutter lifelong stutter. These aren't "acts", nor are they a sign of a cognitive deficiency.
I've had 80 year old employers with the energy and intellectual capacity of a 50 year old. They never seem to slow down, physically or mentally. Joe Biden appears to be one of them. Slim, relatively fit, certainly mentally sharp.
Donald Trump does not. He can't put a sentence together and his speeches are rambling. Transcripts make little to no sense at all. Trump is famous for sleeping six hours or less a night, has a diet of unhealthy fast foods. Both raise the risk of Alzheimers. His skin, underneath the orange spray tan, is pasty and white. Trump's speech and vocabulary is at a Grade 5 level. He no longer speaks like a Wharton Graduate. Last but not least, his father died of Alzheimer's and it is hereditary.
The belief in conspiracy theories, the paranoia, the false accusations, rewriting the past, are all signs of Dementia, as are the rages, threats, and driving loved ones away. I watched it all happen with my MIL. She died miserable and alone lashing out at anyone who came near her. A doctor friend told me that dementia for people who are "difficult" to begin with, is a process where they become abusive to everyone around them.
Trump's wife and children have all abandoned him. The Republican Party is now suing to keep him off the ballot in the 2024 primaries. Trump and everyone around him are facing indictment for the crimes they committed trying to keep him in power.
And Trump's still lying about a "stolen election".