Statnews ran an article on it back in 2017^[1] highlighting his already then clear mental decline, noting as an example that in the 80s and 90s:

…Trump fluently peppered his answers with words and phrases such as “subsided,” “inclination,” “discredited,” “sparring session,” and “a certain innate intelligence.” He tossed off well-turned sentences such as, “It could have been a contentious route,” and, “These are the only casinos in the United States that are so rated.” He even offered thoughtful, articulate aphorisms: “If you get into what’s missing, you don’t appreciate what you have”