It's pretty obvious he has mental health issues going on. Surely ADHD is one of them, alongside the Narcissism, compulsive lying and sociopathy (lack of compassion). This much was obvious during the campaign.
So I don't think it's getting worse. It's just folks like Scarborough are seeing it more clearly. It's more apparent when he is either cornered or starts talking about things about which he is ignorant.
He's obviously not fit to be president on grounds of his ignorance as well!!!!
But he's not going to get turfed out until the Republican party thinks they will lose their seats by supporting him.
So as a practical matter, the US (and everyone else) is stuck with him. If I was General Mattis, I would make sure there's a second red button so that an insane man isn't making the irreversible decisions alone.