The Word "Dotard" and Walter Scott's Ivanhoe

I recall years ago hearing how the use of the word "dotard" in an official statement of the North Korean government led to a certain amount of confusion and amusement in the American press on account of the word's obscurity to the folks in the news media.

Remembering it I found myself thinking some time ago "I guess they don't read Ivanhoe anymore"--in which classic novel that word appeared frequently. (The villainous Brian de Bois-Guilbert uses it in reference to the Grand Master of the Templars at least a half dozen times.)

Recently thinking of this I checked out the word on Ngram and was surprised to find that the last great spike in the word's popularity was at about the time of the novel's publication (1819). Granted, it had already been bouncing back from its drop from earlier heights (generally rising from 1815 on), but all the same dotard's post-mid-eighteenth century peak was in the years after the book's much-celebrated release, the word having a score of 0.000045% in 1823-1824.

Since then the decline has been pretty consistent, with the '90s seeing the word's usage drop to about 4 percent its 1823 level circa 1991 (with a score of 0.0000016%). It edged upward a little after that point, but in 2016, the year before the word made the headlines, its usage was still at a level scarcely a tenth of its Ivanhoe-period peak (with a 0.0000049% score).

Is it possible that one of Ivanhoe's unexpected consequences was to make the word a little more popular than it was before? And is it possible that the book's falling out of fashion as it has has made the word a little less familiar than it might otherwise have been? I can certainly imagine that being the case.