The experts noted clear changes from Trump's unscripted answers 30 years ago to those in 2017, in some cases stark enough to raise questions about his brain health. . . John Montgomery, a psychologist in New York City and adjunct professor at New York University, said ”it's hard to say definitively without rigorous testing" of Trump's speaking patterns, ”but I think it's pretty safe to say that Trump has had significant cognitive decline over the years."
No one observing Trump from afar, though, can tell whether that's ”an indication of dementia, of normal cognitive decline that many people experience as they age, or whether it's due to other factors" such as stress and emotional upheaval, said Montgomery.
. . . Linguistic decline is also obvious in two interviews with David Letterman, in 1988 and 2013, presumably with much the same kind of audience. In the first, Trump threw around words such as ”aesthetically" and ”precarious," and used long, complex sentences. In the second, he used simpler speech patterns, few polysyllabic words, and noticeably more fillers such as ”uh" and ”I mean."