This whole thing is so dumb. Stimulants do not make you smart, and they certainly would not treat or reverse dementia. I mean this guy knows this I'm sure, he's just an asshole.
Sure I mean give a perfectly normal person a stimulant and they might feel like they have more energy for a bit (though to an observer they might just appear anxious, jittery and amped up even if the person themself feels great). Calling it performance enhancing for something like a debate is a huge stretch. Equally likely to hurt a speaking performance, unless someone maybe actually had true adhd or something.
What I mean is, the narrative being pushed here is Biden is this old man with dementia who can't string two words together, and then he takes adderral or modafinil and suddenly he's magically cognitively normal but just for a few hours. Dementia does not work this way, you would just get a very energetic and equally confused person. It's all a ridiculous fantasy, something for Trump supporters to hold in their heads to help with the cognitive dissonance as they watch the debate. Otherwise they'd be forced to reckon with the fact that Biden speaks like a normal human being with coherent thoughts while Trump sounds like a rambling lunatic on a barely traceable flight of ideas.
I also don't want this false narrative giving people ideas that force feeding their relatives with dementia stimulants would be a good idea that would improve their cognition for a while or something.