My wife and I were just watching an episode of Columbo tonight.
Peter Falk--who, of course, played the part of the disheveled detective--was incredibly sharp, mentally (even though he did not appear that way, on the surface).
That is why it does seem ironic that Peter Falk spent his final years as a victim of Alzheimer's disease--in other words, without his right mind.
It is my understanding that his second (and final) wife would not allow the (adult) children from his first marriage to visit him at the end, as she simply did not want them to see him in that terrible state.
This, I think, is rather sad...