Not a doctor. But based on what I've read and seen a diagnosis requires tissue samples of the brain and analysis through a microscope. So it might be possible w

Not a doctor. But based on what I've read and seen a diagnosis requires tissue samples of the brain and analysis through a microscope. So it might be possible with some kind of brain biopsy, given there is no treatment for it cutting open someone's head and cutting out some brain to diagnose it is pointless. Without taking tissue sample diagnosis could only be based on behavior.