Article continues below advertisementMary Trump isn't holding back when it comes to her thoughts on Donald Trump's mental state.Article continues below advertisementIn a candid conversation on "The Daily Beast" podcast, the daughter of Donald's late older brother, Fred Trump Jr., broke down why she believes her uncle is showing the same troubling signs she once saw in her grandfather, Fred Trump Sr., who battled Alzheimer's "for a very, very long time."Article continues below advertisementSource: The Daily Beast/YouTubeMary Trump believes Donald Trump is showing signs of dementia.